The Risks of Flying Gyroplanes

[Udi]

Are gyros inherently safe or inherently dangerous?

The subject of gyroplane safety is important to all of us. We talk about safety all the time, which is a good thing. Lately, however, the subject of gyroplane safety is getting much attention as a result of two tragic fatal accidents. What makes these accidents special is that both of them occurred in gyroplane models that are considered very safe, and the pilots who flew these gyroplanes are considered responsible and capable.

Many people are wondering what the heck is going on. If it can happen to Terry in a Sparrow Hawk, it can also happen to me. If it happened to Alan in a 'Bee, it can also happen to me. Are gyroplanes really the safest aircraft out there, or is there some inherent flaw in the way these things operate that makes them all death traps?

The reason I am starting this thread is because I believe we should not brush this subject under the rug. Fixed wing pilots who come to our forum, interested in learning more about gyroplanes, will be put off really quick when they sense the level of confusion and uncertainty among us - gyroplane people.

The real problem at the bottom of this is that gyros are really not very well understood - not even by gyro pilots. I believe the number of people who can really gauge the true risks of flying a gyroplane is small - because gyroplanes are really hard to understand.

Fixed wing planes in comparison are very simple to understand - this guy stalled his plane on takeoff and crashed - case closed. That guy had an engine out over woods and crashed - case closed. People are not questioning the inherent safety of fixed wing planes, because the operation and aerodynamics of FW aircraft is very well understood and there is no black magic involved (ok. not including the dreaded downwind turn). People KNOW that IF they maintain their aircraft well and if they don’t make stupid mistakes while flying, they will be OK!

But when a good gyro pilot is crashing in a good gyro model, many people start wondering what the heck is going on and ask whether "gyroplanes", as a category of aircraft, are just unsafe.

My intention in starting this thread is to try and give this question an honest answer that will be easy for everyone to understand. I want us, as a group, to get a grip on this subject. I am not sure this is possible to do in an Internet forum, but we can give it a shot. The benefits of this discussion, if successful, are many. Mostly, I want people to understand the REAL risks that are involved in participating in this sport so, when there is an accident, they can better come to terms with the results.

I have a lot more to say in this subject but I will take a break and let others express their views. My only request is that we keep black magic and voodoo out of this discussion. We all know why gyros are supposed to be the safest powered aircraft in existence, but lets be honest and talk about the risks of flying home made gyroplanes and try to quantify the risks in a meaningful way. If we know what the risks are, we know where we should place out attention. This will lead to better safety and better confidence in our wings.

Udi

disclaimer - I do not allow any reporter to take my words and publish them in a newspaper or any other publication. Especially, out of context.

[rtfm]

Udi,
Thanks for initiating this thread. I think its timing is excellent, not only in light of recent tragedies, but because there are signs of a general resurgance of interest in gyros.

I'd like to draw attention to something which I have always found strangely at odds with what I was taught to be mandatory behaviour in the FW world - well, in GA anyway. I'm talking about adherence to basic safety issues like a detailed pre-flight EVERY time you fly; using standard radio calls especially in the circuit; and basically, conforming to best practice as has been established over hundreds of thousands of flying hours in the FW world.

And the reason I raise this as an issue here, is that in my short association with gyros at flyins and so on, I have been alarmed at the cursory glances at a few bits and pieces which so often passes for a pre-flight. I have been gob-smacked to see experienced pilots walk up to a gyro, give it a quick glance-over, hop in and start her up. This sort of behaviour is inexcusable.

I have also been alarmed at some gyro pilots refusal to carry (or use) radios. Why not? It is the single most obvious safety device in a flying aircraft.

I know neither of the recent tragedies had anything to do with being NORDO, but I mention this out of a growing concern for what I perceive as a "Gyros are simple, gyros are safe - we don't need all the FW crap" sort of idea which seems to me to be the attitude of an alarming proportion of gyro pilots.

The fact is we DO need the discipline and the best practice guidelines the FW guys have developed over the years if we wish to be taken seriously by the rest of the recreational flying world.

Regards,
Duncan

[Chuck_Ellsworth]

You have opened an interesting discussion here Udi.

There was a time when I was very keen on gyroplanes and put a lot of time and money into getting my commercial gyroplane pilot license as an add on to my advanced flight training business. I also bought and built a gyroplane kit to use for training.

However I seldom post here anymore as I do not wish to get back into the situaton in which I became stuck in where I could not comment on anything without being put down as a malcontent.

However I do read this forum and am interested in where this discussion will go.

I also am interested in why the gyroplane community has not expanded.

I do not think that there is an inherrent safety concern with a properly designed and flown gyroplane.

Chuck Ellsworth

[Udi]

I completely agree with your points, Duncan. I can add to the list of behaviors you mentioned the attitude of some pilots that gyros are "just toys". Anyone can hop on them and go fly. Minimal, if any, training required. This attitude is shared among novice pilots and, maybe surprisingly, very experience FW pilots who think a gyro is not a "real" plane - it's just a toy with a lawn mower engine on the back.

Udi

[Udi]

... I do not think that there is an inherrent safety concern with a properly designed and flown gyroplane.

Chuck Ellsworth
Thank you, Chuck. I am glad you have joined this discussion. Pilot/owner attitudes towards his gyro is a large part of this subject and I know you can contribute where it comes to being professional.

I have a question for you regarding the above quote. Do you think that gyroplanes might have regions in their flight envelope where they may be less forgiving to upsets or pilot errors than fixed wing planes?

Udi

[whbriley]

I get two responses from folks at Lumberton airport in NC when I fly.
1. That thing is cool.
2. Arent those things (gyros) dangerous?

I think General aviation does not understand gyros and the risks because of the lack of info in mainstream aviation magazines. I understand the risks involved with flying my high thrust line RAF but I try to minimize the risks and thats the best we can do as pilots--educate and be informed flyers.

[Chuck_Ellsworth]

"I have a question for you regarding the above quote. Do you think that gyroplanes might have regions in their flight envelope where they may be less forgiving to upsets or pilot errors than fixed wing planes? "

Yes, one of the more demanding regions of flight in most gyroplanes is their relatively narrow forgiveness limits with regard to directional control during landing and to some extent takeoff.

Due to their relatively high C of G and narrow and stiff suspension they are prone to tip over accidents when they have drift present during this phase of flight..

Unlike a fixed wing aircraft where a loss of directional control results in a wing drag that usually does not result in extensive damage a gyro will just eat its self up as the inertia in the rotor blades is dissipated through ground contact.

This of course is pilot error, not machine error.

More structured and in depth training will prevent these events from being so common.

Also it concerns me that so many gyro pilots seem to accept smashing up their gyros as part of the accepted risks that flying a gyro entails.

Strange that those of us who fly aircraft and helicopters will go our whole life time flying tens of thousands of hours with zero accidents or damage to aircraft. Quite frankly it is my beliefe that better training and a cultural change with regard to acceptance of smashing up your gyro being part of being a pilot will result in a better safety record in gyros than in fixed wing aircraft.

For the simple reason that gyros are inherentley easier to fly and safer than fixed wing aircraft.

Those are my thoughts udi.

Chuck Ellsworth

[dick]

Thank you, Chuck. I am glad you have joined this discussion. Pilot/owner attitudes towards his gyro is a large part of this subject and I know you can contribute where it comes to being professional.

I have a question for you regarding the above quote. Do you think that gyroplanes might have regions in their flight envelope where they may be less forgiving to upsets or pilot errors than fixed wing planes?

UdiHi neighbor, I think there just might be
with the wrong disk loading

[brett s]

I've never seen people in helicopters that only wanted minimal training & a solo signoff, with no intent to finish getting the rating. Yet it seems fairly common in the gyro world - there's a huge culture difference for sure. As Chuck pointed out, most other types of pilots also definitely don't consider periodic crashes in any way normal - I certainly don't!

There's no reason gyro flying shouldn't be the safest out there, other than the attitudes of pilots. There's no reason to not get proper training & fly a properly designed aircraft in this day & age.

[TomCarlisle]

The "camera" syndrome seems to be much stronger in the gyro world and some of the things I have seen would scare the most experienced pilot. I have seen people fly at fly-ins without a helmet and safety belt unfastened and flopping in the breeze. No one said anything to him and when I asked the "safety guy" he just said "Oh thats crazy Steve, he does that all the time"
Charley Presnell would never allow that to happen. A few years ago at El Mirage they had a "Preflight contest" where they intentionally made 10 things wrong with a Bensen style gyro and each person did a preflight and turned in their findings. I don't think anyone found all 10 items. They were all simple and very noticiable items, ie: empty gas tank, flat front tire, loose wires, etc. I have seen people drinking at fly-ins and then go fly with that "Lookie here" attitude. And then, once in a while, there is actually a mechanical default and that seems to get the good ones. I just don't think you can get enough training. I try to get one or two hours of instruction at every fly-in I go to where there is an instructor and I have a gyro rating on my PPL. I learn something every time I talk to Ernie Boyette or Steve McGowan and I learn a lot from many others. The last time I flew with Steve McGowan, I asked him to teach me several manuvers and he just told me "Your not ready to learn that yet." I respect his opinion and would not try those things until he tells me I'm ready. Some would just go try on their own and add to the statistics. I'm just rambling, but there are a lot of things people do with their gyros that scare me when I'm just sitting and watching.

[GyroRon]

I get two responses from folks at Lumberton airport in NC when I fly.
1. That thing is cool.
2. Arent those things (gyros) dangerous?

I think General aviation does not understand gyros and the risks because of the lack of info in mainstream aviation magazines. I understand the risks involved with flying my high thrust line RAF but I try to minimize the risks and thats the best we can do as pilots--educate and be informed flyers.

Bill if you crash your RAF, it would be very likely that the thrustline placement on your ship played a big part in the crash. So if you went down we here on the forum would know why and would just be upset that another needless accident happened due to a unstable configuration. But other people, such as those based at Lumberton would just know that A gyro went down.... and that is further proof that all gyros are dangerous.

Do you see my point?

And by the way, where were you during the fly in? We never saw you or your gyro

[automan1223]

Flying is a dangerous activity. Anyone who says it is not is selling you something or has not been around a while. Any motor vehicle is dangerous and can kill you. The week I was away at bensen days the local roads claimed 3 or 4 lives in a total of 7 separate accidents. In a rural country setting this is abominable.

There are times during the year when everything seems to go wrong and its best just to keep a low profile.

I feel that the main cause for most accidents is mechanical failures or issues. There are stats that say otherwise but after an accident investigation there is little to go on.

You can be the best pilot in the world but that will not help you if some nut or bolt comes out, or your engine goes away over hostile terrain.

I feel too many people have put blind faith in the slide rule engineers and do not know what it takes to keep an airframe and engine on a gyro.

Both accidents are horrible events but they should only serve as lessons for better preflight, upgrading percieved deficiences, and not waiting for a problem to arise etc.

Jonathan

[Udi]

Chuck E - I also feel that gyroplanes require tighter control than FW during T/O and landings and if the pilot is not 100% on top of it, the risk is high for a rollover. This part of the flight envelope is not only risky for the novice - some of the more experienced gyro pilots on this forum have rolled over at a moment of weakness. The risk of a roll over may be reduced with training, experience, and by not flying when the cross wind component is higher than your comfort level.

There are other parts of the flight envelope that gyros are especially sensitive to and Dick mentioned one of them - low or negative disk loading. In a fixed wing aircraft there is almost nothing a pilot can do, other than over-stressing the wings, to cause the plane to self destruct in the air. Some gyros (HTL) are more sensitive to low disc loading events than others, but NO gyro will survive a loss of disc loading for more than a few seconds.

What is the risk of having a fatal loss of disc loading? It depends on the type of gyro you are flying, the type of flying you are doing, and the weather conditions you are flying in. People who fly stable gyros, don't do any kind of aerobatics, and do not fly in extremely gusty weather conditions have, in my opinion, a very very low risk of ever encountering a sustainable low disk loading event.

People who fly unstable gyros, are doing any kind of aerobatics (i.e. maneuvers that can all by themselves cause an extended period of low G), or fly in very gusty conditions have a fairly high risk of encountering a sustainable low G event. A PPO is the classic self destruction of a HTL gyroplane due to unloading of the rotor, but even a stable gyro can be pushed by the pilot into a fatal low G event.

One more thing to remember – when the rotor is unloaded, even for a short period of time, it slows down. It takes time for the rotor to accelerate back to full speed once it had been re-loaded. This means a loss of altitude. Therefore, unloading of the rotor at low altitude could be unrecoverable, even if the rotor hasn’t slowed below the no-return point.

Udi

[Udi]

... I feel that the main cause for most accidents is mechanical failures or issues. There are stats that say otherwise but after an accident investigation there is little to go on....
I believe that home-built aircraft (not only gyroplanes) have a higher risk of having a mechanical failure than a certified aircraft. People don't like the FAA and all their rules for certified aircraft but the reality is that these rules are there to ensure that the aircraft meets a minimum level of airworthiness. I know -- some people will say certified aircraft can also be poorly maintained and fall apart in flight. But 99% of the time you fill be hard pressed to find any problem with a plane that is maintained by the rules.

I have seen some gyros in fly-ins that I wouldn't let my cat fly in. They were maintained so poorly that I thought the pilots really had a death wish. Ultrallight aircraft do not have to meet any standards of maintenance and experimental aircraft are signed by the builder for the annual inspection. Statistically speaking, we should expect to see more amateur built aircraft falling out of the sky than certified aircraft. No one is looking over your shoulder - you are on your own. It's your responsibility to make sure your aircraft is 100% air worthy on EVERY flight.

Another risk factor that is related to home-built aircraft is aircraft design. Who designed your aircraft? Who tested it? Is it a proven design and did you make any modifications to the original design. If you made any modifications - what is the risk that the change you have made will have consequences you havn't considered?

Udi

[birdy]

100% of the risk taken is the responsability of the nut on the stick.

[rtfm]

Hi,
I try to get one or two hours of instruction at every fly-in I go to where there is an instructor and I have a gyro rating on my PPL.
This is an enormously telling admission. Good on you for raising it. I'd like to expand on it, if I may, but by way of preamble, allow me to briefly relate an incident which happened about half way through my PPL training...

I'd been flying for about three months, and had accumulated about 40 hours of flight time. I was seriously looking at doing my first cross country flights pretty soon. And then my wife decided that the combination of Christmas, her annual vacation and the beckoning lights of Sydney took precedence over my flying, and so off we went across the Tasman for three weeks. When I returned, I rushed out to the airfield, booked a plane, and zoomed off down the runway.

I've told this story many times, but that was the most panic-sticken 8 or 9 minutes of my life. Everything happened too quickly. I just didn't have time to do the checks. When I did remember to do them, it took me too long to get through them. I was turning downwind without checking for other traffic. I'd forgotten to raise my flaps. I got the downwind radio call wrong. By then it was time for the BUMPFW checks. They took forever to do. Throttle back. Too late, I was having to turn and line up the runway. Too high. Bugger. Radio call. Bugger again. Position, altitude, intention. Get it right! Throttle control, monitor height, drop flaps, watch speed... It was the closest I've ever come to crashing on landing. Everything I did was too slow, too late. I was classically "behind" the plane. I did a go-round, but forgot to raise the flaps, and it took AGES to cotton on to why I wasn't climbing.

Once back on the ground, I was all shakes and nerves. What did I do? I went back to the club house, and immediately booked an instructor for a check ride.

I made it an obligatory part of my flight preparation from then on to do a few circuits with an instructor if I even suspected that I was even mildly off the boil. I've accumulated quite a few more hours now, of course, and have my PPL. But I still routinely book an instructor just to make sure I've not developed any bad habits or am taking short-cuts.

For me, flying is a dangerous activity. Tragedy is never far away while strapped into a vehicle hurtling through the air at 100kts. I'm no hero. I need all the help I can get. Personally, I think this is a prudent world-view for any pilot. And so I salute your habit of seeking out an instructor at fly-ins for check rides. Let's face it - it's just plain sensible.

And I hasten to add that it is something ALL gyro pilots (bar none...) need to consider doing on a regular basis. After all, even the professional instructors in the FW world take check rides with other instructors on a regular basis as a safety measure. If they think it necessary, what makes gyro pilots think it unnecessary? Pride, probably.

Regards,
Duncan

[Brian Jackson]

Udi,
Good discussion. I'm currently building and have only been airborne in gyros twice, so I'm no expert.

I have noticed a certain "economy" component to gyro flight, of which I am a proponent. One can build a gyro for a fraction of the cost of many fixed wings. That mentality initself seems to lend itself to shortcuts in training; a simpler aircraft requires less training. Nothing could be further from the truth however.

I believe, as part of society, we tend to equate dollars with value. Humanity has dreamt of flight since seeing birds. Igor Bensen introduced many of us to flight on a budget. The original ads in the back of Popular Mechanics fueled that passion and hence the '60s saw the growth. The "freedom of flight" is an alluring power that attracts many, especially when gyros can be built so inexpensively.

Part of the allure is its simplicity. That was certainly the case for myself. But I can see where this "budget-mindedness" can carry over into training. When you weigh the two, training is a significant cost when compared to building the gyro itself.

I can't comment on why some forego training other than this brief observation. Any flying craft should be treated and accepted as such. We have guys like "Bob" on this forum whom have decided to self-train. I wish them the best. But air and gravity aren't forgiving. There's no do-overs.

Respectfully,
Brian Jackson

[BoB T]

In my early B8M days my first mentor made me aware of a simple point of learning regards gyro and fixed wing flying. Safety in flying, FW or GYRO with nonstandard characteristics, resides in the partership of the vehicle and its PRACTICED Pilot . EX., You can safely walk on the top of a wall with proper width ,but a risk is always there of a fall. Walk on the ground and you eliminate or at least reduce that risk. Practice wall walking and you will get better, soon it becomes easy and with ease narrowness of safety margin fades.We forget despite taking millions of steps without mishap even an experienced walker may one day trip. UDI you started a great thread hope it catches . thanks

[Doug Riley]

Udi, your points are excellent. Homebuilt aircraft in general do have a much higher accident rate than certified craft, reflecting a cluster of issues: design quality, construction quality, maintenance quality, pilot proficiency in type. We have all those issues here in Gyroville.

Then, to top it off, we have an aircraft design whose development was abandoned by the professional aircraft industry in the 1940's. Several issues -- low G most especially -- simply were never systematically explored by people with the money, training and equipment to do it right.

As far as I know, the only people to use pure teetering rotors in gyroplanes are the homebuilders. These rotors are miracles of simplicity, but they are especially unforgiving of low G (never mind the vibration). They were first tried on gyros AFTER the era of professional gyroplane research was over.

OTOH, I don't know of a single gyroplane crash EVER that resulted from low RRPM or flap following low G, where airframe pitch instability wasn't the main problem. Perhaps there have been some, and the PPO (i.e. incompetent design) problem just overshadowed them. However, well-designed gyro systems on a stable frame appear to fight off low G to such an extent that it MAY not be that big a deal. But, without systematic research, that's little more than a hunch.

Pusher propulsion is another issue. Some FW designers (such as Ladislao Pazmany) are on record declaring that pusher aircraft should be banned. In a nose-down crash, the pilot ends up serving as an airbag for the engine. Put that engine mass up front and it gets to tangle directly with Mother Earth on its own, thank you.

IMHO, the absence of research money and knowhow is the most serious of this bunch of issues. Heck, you CAN get good training if you are persistent enough. You CAN build, maintain and fly your machine in a first-class manner. You CAN pick a design that at least can't PPO.

But there's nothing that an individual can do about the fact that we don't have the brilliant, well-equipped PhD's at NACA (now NASA) doing gyro research anymore. Damn.

That's my view of the dirty laundry.

[Brian Jackson]

I've seen this brought up twice now... Low G. I understand the scenario, but doesn't that further the cause for CLT arguement? If a gyro pilot is flying along and suddenly experiences a wind shear, couldn't that sudden and unexpected change put him in a low G situation? To compound the problem, if he's flying a HTL machine wouldn't that off-center thrust tend to roll his ship over when the drag of the rotors was removed?

[Bill Clem]

I was once accused of being a bit callous in criticizing the relatively frequent deaths that have occurred in the gyro community. After only 10 years and at least 6 deaths of friends and colleaques in the gyro community, it is quite clear that there are system problems. The following are some personal observations.

"It's just a toy." This was one of the first lines I heard when I was introduced to gyro's. It was used to justify using cheap parts from Radio Shack and the auto parts store. While those parts may not the direct cause of an accident, most accidents are the result of a chain of events, possibly starting with the failure of a cheap magneto grounding switch. Toys break.

Often construction techniques do not adhere to standards. The classic example of this would be the aluminum cyclic torch heated and bent into position which broke off causing the Parson's accident. And this occurred after it was pointed out that this was dangerous and a substitute steel cyclic was made.

Minimizing costs. All of us would like to minimize the costs that we put into our machines. But that is NOT a reason to start flying gyro's. If you cannot afford to buy aircraft quality materials and parts, then you can't afford to fly. One available option is to use the money that you save to buy more life and health insurance. It is likely that you will need it.

Gyro training is expensive and inconvenient. Often there is a push to get a solo signoff and go back home. How many pilots are even solo competent after 6 hours in a gyro? Compenent enough to forgo further training?

Changing Plans. Every gyro is a little different. The builder-owner wants to do this or that a bit different, without the knowledge needed to judge the effect. Even engineers can foul-up. My best friend, an experienced engineer who spent 2-3 years building a plans-built gyro, died when he changed the design to a low thrustline machine. He made the gyro safer for one part of the envelope, but ended up making it unsafe in a completely different part.

Every flight is a test flight. That word, "Experimental", that the FAA requires on the aircraft should not only be a warning to passengers but a warning to the pilot as well. Every aircraft needs to have its operating envelope carefully and slowly explored, pushing the limits in tiny increments. It is mandatory that each pilot know the limits of his machine. No surprises.

Expect failures. With so few machines flying, it is impossible to develop parts life expectancies and failure rates. Only religious preflight inspections according to a checklist, routine thorough annual inspections and the occasional look-over from another pilot will likely find failures before they occur.

Maintain currency. Many of us in the colder climes fly little in the Winter months. I am constantly amazed at how poorly I can fly after a few month hiatus. It is necessary to slowly regain competency and confidence.

All of the above are my opinions, but I noticed that they are echos of some of the other posts.

[Udi]

I've seen this brought up twice now... Low G. I understand the scenario, but doesn't that further the cause for CLT arguement? If a gyro pilot is flying along and suddenly experiences a wind shear, couldn't that sudden and unexpected change put him in a low G situation? To compound the problem, if he's flying a HTL machine wouldn't that off-center thrust tend to roll his ship over when the drag of the rotors was removed?
That is correct, Brian. Instead of using the term CLT, I like to say the gyro has to be pitch-stable. Gyros don't have to be CLT to be pitch stable. A gyro that is pitch stable will try to restore rotor loading all by itself when the rotor becomes unloaded due to gusts or unintentional actions by the pilot. In contrast, a gyro that is unstable in pitch will try to unload the rotor even more once it started unloading. As Doug pointed out, it is probably extremely unlikely for a stable gyroplane to self destruct due to rotor unloading. I believe the exception is intentional log-G maneuvers like loops rolls and even simpler maneuvers that involve extreme pitch attitudes (like a himmelman or pushing at the top of a zoom).

Udi

[Aussie_Paul]

A great post #21 by Bill Clem.

Udi, I like to use the words "stable gyro" rather CLT.

Thanks guys.

Aussie Paul.:)

[Rehan K.Janjua]

Hello Udi.
Excellant thread.
Thank you for the wonderful inputs by the wiser gyro pilots.
Definetly these are the finer points of life.

Best regards.
Rehan

[EI-GYRO]

The real point at issue hear is FATAL accidents.
Rollovers rarely result in serious injury or death.
Even injuries can be recovered from.

What is disturbing about the recent accidents is that they appear not
to be attributable to PIO/PPO, and occurred on what are regarded as
very safe machines.

Whether or not a student is looking towards a licence is not necessarily relevant.
The fact that I have no real interest in the certificate does not mean that
I'm not interested in learning to fly well.
I believe the fact that I'm not focussing on a licence, allows me
to have a more unhurried approach to it all, which should be good.

In fact, the pursuit of certificates sometimes masks a lack of in-depth interest in flight and flying, a serious issue in the fixed-wing area.
In Ireland, the average pilot only flies 40 hours or so after acquiring the licence. Tells you something.

At root, and in general terms, the machine is as safe as the pilot, with the caveat that sh1t happens.

However, a machine that can fly lower, slower and in more challenging
weather than most others, is likely to figure poorly in the stats.

Fully agree on the perfunctory pre-flights, by the way. Wish I wasnt guilty
of it too.

My own feeling on the difference between fixed-wing and rotary, is that
with fixed-wing, adherence to the trained routine, even without in-depth
knowledge, will usually keep you alive.
With rotary-wing, I feel you NEED to know WHY you are doing what you're doing. You need to know how it works, not just how to drive it.

My 2%.

[gyroplanes]

"It's just a toy." This was one of the first lines I heard when I was introduced to gyro's. It was used to justify using cheap parts from Radio Shack and the auto parts store. While those parts may not the direct cause of an accident, most accidents are the result of a chain of events, possibly starting with the failure of a cheap magneto grounding switch. Toys break.

Often construction techniques do not adhere to standards. The classic example of this would be the aluminum cyclic torch heated and bent into position which broke off causing the Parson's accident. And this occurred after it was pointed out that this was dangerous and a substitute steel cyclic was made.


Bill,
I appreciate your numerous accomplishments and the credibility you have given to our sport.

I disagree with you on the two items quoted.

First, by definition, most gyroplanes are "toys" and toys don't have to break. As the builder of an experimental amateur-built aircraft you are charged with the responsibility for determining the suitability of a chosen part, regardless of it's source.

Many "approved" parts used on Cessnas, Pipers, Lycomings, etc. are actually made for automobiles. Often the only difference is an inspection or safety wiring. Frequently there is no difference and it is allowable to use a part procured from an auto supply store on a certificated aircraft.

Second, there are several schools of thought on what caused the Parsons accident. I saw the joystick in question and do not believe it had anything to do with the accident.
Your comment "And this occurred after it was pointed out that this was dangerous and a substitute steel cyclic was made. " is used in error.

This quote was actually in reference to Bill's sprung "safety stick" and not his bent aluminum cyclic.

I think it is unfair to disparage Bills memory by not using a word like "probable" or "possible" when suggesting any cause for his accident.

I would like the same consideration if it were you or I.

[Udi]

So I just re-read all the opinions expressed in this thread and I think that the consensus is that a properly designed, built and maintained gyro, flown in the hands of a well trained and responsible pilot is a safe gyro - no less than a fixed wing plane.

There are some risks that are inherent to flying experimental home built aircraft, but these risks are not unique to gyroplanes. One may minimize these risks by building a "proven" design, using only high quality hardware, and not making changes that may affect the proven design.

The need for extra-careful pre-flight inspections was mentioned a few times and this requirement seems to be related to the experimental nature of the home-built gyroplane where, unlike certificated aircraft, the useful life of the different parts is unknown. Again - using a proven design alleviates some of this risk because, supposedly, many people have already tested the same hardware before you and so if there were any critical design issues they would have been discovered already.

Human factors came up a lot in the discussions. The bottom line with human factors is that many people don't give gyros the respect all aircraft should get. Whether it's the lack of sufficient training or currency, choosing a bad design to build, not building the gyro to acceptable quality standards, deviating from plans, not maintaining the gyro properly, skimping on the pre-flight inspections, or flying the gyro beyond your skill level. These are all consequences of poor decision making that significantly increase the risk level for these pilots.

To me, it is very comforting to know that there is nothing inherently unsafe about gyros. The risks involved in flying gyros (as any other aircraft) can be managed. I have the choice of make/model, I have complete control of the building process, and I am the one to decide whether I am qualified and ready to take it out for a flight or not.

The problem is that we are all humans and we don’t always make the right decisions. Therefore, unfortunately, the rate of accidents that we see is a reflection of how well or how poorly we manage the risks. This seems to be the reality in the un-regulated sport of experimental gyroplanes. There is nothing wrong with the gyros, it is us, humans, who are not perfect.:o

Udi

[Bill Clem]

Tom, I object to the use of the word "toy" because of the connotation. "You don't have to take it seriously because it is only a toy." Would you class a Pitts, or a Sukhoi as a toy? The aerobatic pilots that I know certainly wouldn't. It doesn't really matter how you use it, for fun, recreation or transport. The machine remains an aircraft and as such, demands respect and care.

Whether the cyclic was indeed the direct cause of the Parson crash remains uncertain. But I'm certain that you must have been there at Mentone when a few short weeks later we disassembled a Parsons bent aluminum cyclic only to find a crack that would have likely separated the tube from the horizontal push rods in the next flight or two. I still have pictures. Prior to the accident, Ernie Boyette had made a steel tube cyclic for Bill and installed it. For whatever reason the aluminum cyclic was on the machine the day of the crash. The quote was not about the rubber tube "student stick", it was about the aluminum cyclic.

[gyroplanes]

Yes, I would class a Pitts or Sukhoi as a toy, unless flying it earned you money and it was work. It's not about the price of the toy.

Wikipedia defines a toy as: A toy is something to play with, for children, adults or both, or pets. They may be either the sole device used in an enjoyable activity or one of many.

I stick with my assesment and take all of my toys seriously. Virtually any one of them could kill me if improperly maintained or abused.

I heard from both Ernie and Bill that Ernie's replacement stick was to be used in lieu of his sprung stick after a harrowing flight, solo, in which Bill's sprung stick was suddenly not rigid enough to control the rotor disc. That flight was at a grass strip in Lake Wales(?) and some time before the fatal flight.

An eyewitness told me how Bill bent aluminum tubing, it didn't involve a torch, but it did leave a series of nicks or creases on one side of the inside diameter of the tubing.

I do have a memory of another Parsons stick being examined at Mentone. I was not around at the time but do remember a scared looking guy walking around. Could you post those pictures for us.

[birdy]

Part of the allure is its simplicity.
And unfortunatly, looks are deceiving, coz theres nuthn symple bout autorotating blades.
And its not till you have a good understanding of it, and how you 'cyclicly' control it, that you'll know how to use it safely.

"It's just a toy."
And its a damn dangerous toy,................. in the hands of a 'child'.

[pbradley]

You are to be congratulated Udi for raising this important topic but I fear you have done a disservice to your own thread. I believe it is too early to have attempted to sum up the evidence by stating that the general belief by the informed that gyros are as safe as ultralights if one sticks to a proven type and maintains high standards of airmanship, workmanship and pre-flight checks. You raised this topic because of two recent fatals that had all the ingredients just mentioned. The pilots were very experienced well respected people, the machines were proven types, and the evidence is that maintenance on these machines were high.
I like most in my gyro community in Austalia will willingly advise anyone interested in this discipline that they are the safest aircraft in the sky in the hands of the capable but the most dangerous in anyone elses. I base this on my experience of several deaths involving gyros that I had the misfortune to have first-hand knowledge about. All these fatal events occured to very inexperienced or 'rusty' pilots who were not current. This thread however was meant to go in a different direction exploring the inherent safety of our flying machines, in the hands of the experienced, to explain why experienced people are dying in proven types of gyros. These crashes could be blamed away on unstable machines, ie high thrust lines, lack of HS or tail authority, but in reality it is very unlikely given circumstances and I don't buy it. Very easy to say stick with proven products for safety sake but they were proven products. I have owned quite a few machines and not one was a brand name product, and not one has ever lead me to believe it was unstable in my hands. I am sure they would all have needed continual pilot input to maintain flight and special attention in strong gusty winds, but that has never worried me unduly. At the moment in Australia it is difficult to find two gyros that look anything like each other, other than the RAFs. They come in all shapes and sizes and weights and mostly from the imagination of the builder, some of who are not well qualified to design gyros. But most fly well in the right hands and the design in itself is not the cause of most crashes. Pilot experience or bad decision making is the real culprit.
My point is that tragic accidents were in well respected designs that were piloted by experienced people. What are we missing here?

[Jens]

Sometimes I read something in the direction that others should design, build, approve, maintain and certify our gyros, and an instructor is almost as important as ourself.
I think - this attitude don't belong in EXPIMENTAL or ultralight aircrafts.
YOU should learn enough or all about it - if you can't or will not, go to another category of aircrafts or play golf or something.

The basic game in experimental and ultralight aircrafts is (mainly) YOU are responsible - not rules, papers or other people.

A litle harsh put - but only meant to get my point across.

Otherwise I appriciate very much all that help a higher safety, and this thread is very relevant.

[Doug Riley]

Pete: Terry Eiland, the pilot of the ill-fated Sparrowhawk that crashed at Bensen Days, was an experienced and well-respected CFI. Alan Coates, the victim in the Gyrobee crash, had a few dozen hours at most. It's not clear than Alan's relative inexperience had anything to do with his accident. We do need to keep apples and oranges apart, though.

Bill and Tom, you're using the word "toy" to mean two different things, and so talking past each other. Tom labels any pleasure craft a "toy," Bill labels something not taken seriously a "toy."

Bill's point is a valid one; failure to take gyros seriously not only leads to shoddy work, it also leads people to modify gyros casually, in the belief that there's nothing to 'em. Appearances are deceiving; many of the systems on gyros go seriously haywire if modified or even just scaled up. Tom's right that sensible people can and do take pleasure aircraft seriously, even if they are "toys" of a sort.

(The State of Vermont, in one of its quaint little anachronisms, labels all private automobiles "pleasure cars." That's what everybody's registration says. I don't have a sense of play when driving to my @*&$ job with the other drones on a Monday morning, though.)

[Udi]

My point is that tragic accidents were in well respected designs that were piloted by experienced people. What are we missing here?
I did not mean to put the lid over this discussion, Pete. If you disagree with any of my "conclusions" please go ahead and post your views.

We don't know the cause of the two recent accidents but I believe that if we did, there would be a link between these causes and the list of risk factors I have mentioned above. I don't want to turn this thread into a discussion of the causes of these accidents - there are already other threads just for that. But let me just mention some risk factors I know for a fact existed in these accidents.

The Sparrow Hawk is not yet a proven design. I have a lot of confidence in the engineering that went into this specific gyro but EVERY piece of engineering has to go thru a test period with the end users before all the bugs can be found. This is a risk factor. Further more, we know that Terry was making some modifications to the original design. That is also a risk factor. I am not trying to imply that I know what caused this accident – I don’t.

Alan was flying what I would consider a proven design. However, Alan was an inexperienced pilot. This is a BIG risk factor. In addition, we know that his bee was under-powered with a Rotax 447. Alan has just installed a new prop because his old prop was damaged during a bad landing. Can you see a few risk factors here?

I had no intention to rush into summarizing this thread pre-maturely - please keep this discussion alive and add anything you see fit to the list of risk factors that are unique, or not unique, to gyroplanes. Any additional information will only help everyone manage their exposure to risk.

Udi

[Hognose]

Udi's original post asked -- what about gyros, are they safe?

Very quickly people posted, less about intrinsic gyro safety than about risk management attitudes in the community. So we've gotten sidetracked a bit in comments about individual mishaps, etc.

But it's natural that that happened. The fact of the matter is that safety is a systems issue, and pilot and machine (and to a lesser degree, instructor, designer, builder and mechanic) are all factors in a highly variate safety equation.

Nobody sets out on a sunny day to commit suicide by gyroplane. We've all known people who loved life, and who were not ready to go, but went anyhow. The thing is, many of you are outside of the fixed wing community, and don't see how many of the same situations occur over here.

Somewhere in the USA, an experienced and generally safe pilot crashes a proven and generally safe fixed wing airplane several times a day. Every day of the year, somebody crashes. Tuesdays in February, with most of the US being temperate, not so many; holiday weekends in the summer, there are whole bunches of crashes. The whole sad business is in AOPA's Nall report (http://www.aopa.org/asf/publications/nall.html) which tell the tale of 500 crashes and 300 deaths, mas o menos, every year. The numbers might not be that high in other lands, but I'm sure our friends in Europe, Asia, Africa and the Pacific have similar things going on.

An old pilots' saying is, "there are no new accidents. Just new pilots having the same old accidents." Boy, is that ever true.

Even good pilots. Even crews of two 17,000 hour ATPs. The thing is, Death is waiting any time you are in anything that lifts you off the ground -- even a stepladder can kill people, and does. Death only has to win once, and we all have to win every time.

To accept risk knowingly, to actually manage risk, the first thing you have to do is come out of denial and admit that you have an opponent in this card game, his name is Death and he's seated at the table every day. He doesn't need to have a great hand, he just needs to beat one of the players, and he never gets up from the table.

So what you have to do is think at every point about what cards he needs in his hand to beat you, and make sure you don't set them down for him to pick up.

Unfortunately, many people do not understand what is a risk and what is not. Guys have pointed out many examples of risks in this thread: long lay-offs from flying; non-professional engineering and its unintended consequences (but as an aside, wasn't Bensen a pro when he adapted the teetering rotor to the wartime German glider/kite concept?); metal fatigue; inadequate training; weather conditions; sub-optimal design features; hazardous attitudes.

It looks to me like a lot of people who get hurt in gyros are being hurt not because they get caught by the risk percentages, on risks they knowingly took, but because they got surprized by unexpected risk factors, risks that they didn't realise they were taking.

The crux of the problem is the small denominator in the gyro risk fraction. Accidents loom large because the pool of participants is so small. Especially compared to half a million fixed-wing pilots. Several Van's RVs have suffered inflight breakups from doing aerobatics with loads beyond aerobatic weight, but no one says RVs are deadly. That's because everyone understands that thousands of RVs fly every month, hundreds every day.

But this also means that we are so few and far between that, unlike fixed-wing aviation where the military and commercial carriers develop best practices (aircraft certification, professionally calculated loads and weight limits, CRM and hazardous attitudes training, to name a few) and regulators impose them on GA over time, that we are left to our own devices as far as safety is concerned.

In the end, we have to pull our own heads out of our fourth point of contact with respect to safety. For years we have been saying that "gyros are safer because they can't stall and spin, unlike f/w, and you can't be too slow to enter autorotation, unlike helicopters." That's bullfeathers. What it really says is that "gyros do not have these particular failure modes that are killers in other aircraft." Whoop dee doo. There are ways to get killed in a gyro you just can't do in another aircraft. Flap the blades on takeoff. Unload the rotor. Exceed sensible yaw limits and cause mast bumping. Plus there are all the ways to get killed that are common to all aircraft. These are the cards in Death's hand.

My personal impression is that, equalized for hours flown, gyroplanes are less safe than fixed-wing experimentals, ultralights, LSAs, trikes, and PPCs. They need not be, but I believe that this is the result that the current systems equation of plane and pilot, etc., is producing. [EDITED TO ADD: I am not talking about potential safety. I believe that gyros are potentially safe. I am talking about actual, obtained safety. We need to get a handle on understanding what that is in order to close the gap between real and potential safety, I believe.]

How many gyroplanes active in the US, actively flying? 300? 500? And how many hours do they average in a year? 20/per? That's the risk statistic that would be useful if we could derive it -- accidents as a ratio of events to exposure.

Nobody's tried to do this, as far as I know, which is the first step in defining the problem -- we've had a number of attempts to address the problem including several pushes for formal instruction, and several attempts to address gyro design issues.

Let's go back to Udi's first question because it's the ur-question we need to answer first. Are gyros safe? How safe?

THEN we can address the next questions: WHY do we have this safety record, and HOW do we bring it into line with what we all believe to be the safety POTENTIAL of the experimental amateur-built gyroplane. But why not start by crunching the numbers?

Perceived risk and actual risk are different things. People think roller coasters are risky and roller coaster fatalities, which average two a year according to Wikipedia, are Page One news. Yet, about 300 miillion people visit theme parks featuring roller coasters a year, more than half of whom probably ride the coasters at least once. (Some parks have many coasters).

I suspect the perceived risk of flying gyros is higher than the actual risk, buit the actual risk is nonzero and higher than comparable recreational aviation activities. That is little more than casual, informed speculation until someone does the numbers.

Now, even if we can get our stuff together and make things safer, the perception will lag the reality -- just like roller coasters.

Anyway, until we have some kind of credible safety data which counts accidents (numerator) measured by exposure (denominator) then these discussions will all wind up like this one, as a somewhat circular conversation.

cheers

-=K=-

[Hognose]

To put a statistic before you, in a study of GA mishaps (a/c < 12,500 lb to exclude the big stuff) over 10 years, the AOPA Air Safety Foundation determined that the accident rate declined from 9.06 to 6.71 per 100,000 flight hours.

The fatal accident rate declined from 1.82 to 1.36 per 100,000 flight hours.

Personally, my opinion is that this statistic results from a higher percentage of the flight hours being flown by professional aircrews in highly proceduralized operations and a concomitant decline in recreational and personal flying as a component of the flight-hours denominator.

These statistics represent 1994-2003. Grab the .pdf your ownself: http://www.aopa.org/asf/publications/topics/gatrend.pdf

Anybody care to make an estimate on experimental and ultralight gyroplane fatalities per 100,000 flight hours? I have just done so in my head. Ouch. And in my mind I am working out methodology for a more scientific approach to determining this number.

Like Mr Gradgrind, we must begin with the facts.

cheers

-=K=-

[birdy]

Unfortunately, many people do not understand what is a risk and what is not
Spoton Kevin.
Ignorance plays a big part in most misshaps, wether ignorant of the machines abilities, the weather conditions or your own abilities.
Experiance plays little part in this respect, coz as one becomes less ignorant, he generaly gets more comlacent, which is just as bad.

As the thread asks, are gyros risky, answer, no.
Your gyro would happily spend the next 100 years sitn in y hanger and do nuthn, and hurt noone, but put a human brain in control and that can change pretty quick.
As far as i'm concerned, the gyro IS the safest craft to ever leave the ground to date. Why? Coz wot other craft has the enviable combination of such simplisity and excellent control characteristics? Absolutly none. So why do people get hurt in gyros? Coz they choose to take the risk, and thats their responsability.
As i said, a gyro will happily do nuthn for ever, but a human can make it a very dangerous machine.

[chuter]

Correction to info in Udi's post #34:

Alan was flying what I would consider a proven design. However, Alan was an inexperienced pilot. This is a BIG risk factor. In addition, we know that his bee was under-powered with a Rotax 447. Alan has just installed a new prop because his old prop was damaged during a bad landing.

Alan's Gyrobee had a single-carb 503.

He had put several hours on the Powerfin prop; not sure how many.

[Papa Smurf]

Here's a few numbers from the NSTB.

Fatal incidents from 1986 to 2006.

Helicopter: 802. 26 homebuilt.
Gyrocopter: 89.
U/L FW: 19.
GA FW: >5,000. 1024 homebuilt.

http://www.ntsb.gov/ntsb/query.asp

Sobering numbers. About 4 per year for the last 20 years.

Anyway I look at the numbers, flight time, number of machines, et. (all approximations), the number of fatal incidents for gryos are higher than the other classes of aircraft.

Why?

Even if you take out the ones with plausible explanations (IE: something broke, or weather related) there are too many uncontrolled decents into terrain...

[Doug Riley]

You don't need much precision to get the grim picture. Four fatalities per year sounds about right for the recent rate (it was more in the Bensen era). Five hundred active machines in the U.S. sounds about right, too.

Let's be generous and assume those 500 gyros are each flown 50 hours per year. That's 25,000 annual fleet flight hours. The death rate is then one per 6250 flight hours. Even if that's off by a power of ten, it's still appalling. Even if the estimate of active machines and hours is half the real number, it hardly matters.

Some similar statistics came out during the committee discussions around Sport Pilot. By memory, gyros were 20 times more dangerous than other forms of general aviation.

The type of risk that is the toughest to swallow (for me) is the type that CANNOT be reduced by any diligence on the part of the pilot-builder-mechanic. I don't know how much of that there really is, but I suspect some. This is the risk caused by inadequate engineering... the wind tunnel/computer model/fatigue tester/strain guage kind of engineering that none of us can afford.

Still, check EBay and you'll find any number of lowrider, PPO death traps still for sale. Review last year's crashes in the U.S. and Canada. Three-fourths of those I know about were PPO's, thanks to these defective designs still being traded as both new and used equipment. IOW, three quarters of the fatalities were due to a 100% preventable design flaw.

THAT we can do something about. (Hint: Simply being "nice" toward those who persist in selling and promoting fatally flawed rigs is NOT the way.)

[Udi]

...Sobering numbers. About 4 per year for the last 20 years.

Anyway I look at the numbers, flight time, number of machines, et. (all approximations), the number of fatal incidents for gryos are higher than the other classes of aircraft.

Why? ...
I have a little theory as to why the number of accidents per (estimated) hours flown is so high for gyroplanes. Like any other "statistical" analysis - one has to be mindful of what goes into the calculation.

The NTSB does not investigate or report ultralight accidents. I don't know how many three axis, two axis, trikes, PPGs and PPCs ultralight are flying but I would think there may be as many of these as there are "recreational" GA fixed wing planes and experimentals. All these aircraft are not registered with the FAA and many, if not most, of the pilots are not certificated.

When an ultralight crashes, this crash does not go into the NTSB statistics reported above. How many fatal accidents are there in the ultralight world? What is the ratio of accidents per hours flown? I don't know. But I know one thing for sure - ultralight pilots are generally not as well trained as certificated pilots and ultralight aircraft are generally not designed, built and maintained as well as registered aircraft. This means there should be more accidents per hours flown in the ultralight world than in the registered plane world.

Back to gyroplanes. If you just look at most gyroplanes you would say - these are ultralights (my old "FAA registered" 582 Air Command sure looked like an ultralight). In fact, in most of the world, gyroplanes are considered ultralights (in Europe they call them microlites). But - in the USA, due to the very low weight limit for Part 103 legal ultralights, most gyroplanes are registered with the FAA as experimentals.

So, here we have a whole class of ultralight-like aircraft that is registered with the FAA as experimentals. The fact that they are registered doesn't change the fact that these aircraft are designed, built, flown, and treated by their owners as ultralights. They are cheap, they are simple, and many people even fly them without the proper pilot certification.

Since gyros are registered as experimentals, when they have accidents they are entered into the NTSB database. So now we have this sort-of statistic for gyroplanes, but what are we supposed to compare it to? We can't compare the gyroplane statistics to the rest of the ultralight world - should we really compare it to other experimentals like home built RVs?

I believe that if we had the numbers for all the ultralight accidents, gyros would not look so bad.

I have another interesting thought regarding statistics. Look at the "statistics" of the gyro that is most popular in Europe – the Magni. I don't know how many Magnis are flying worldwide (maybe the Magni factory can supply these statistics), but based on pictures from European fly-ins I would estimate that there are a few hundred of them out there. Out of all these Magnis, I know of 2 fatal accidents - one in the hands of a 747 captain who was also a FW aerobatic pilot, and one recently with a flight instructor flying alone (I don't know the cause, but the description sounded a lot like what just happened to Alan). No fatal accidents I know of with your "regular" weekend pilot. What does that tell you about the inherent safety of the Magni gyroplane?

A few additional notes regarding Magnis. Magni sales are tightly controlled by the Magni factory. Most Magnis are not home-built – they are built by the factory in Italy. You cannot build a Magni from plans. People who buy Magnis are required to take flight training, in a Magni, with one of the Magni flight instructors. The Magnis are pretty expensive, which says something about who owns and flies a Magni. I believe only in the USA Magnis are home-built and even these gyros are built with the assistance of no other than Greg Gremminger. Does all this help explain the very low accident rate of Magnis? Sure it does.

It all comes back to design, construction, maintenance and pilot training.

Udi

[gyroplanes]

Doug, Bill,

I will take the blame for arguing past Bill Clem. I understood what Bill meant with his reference to the "toy" attitude and I couldn't agree more. We shouldn't think of our rotorcraft as anything less than what it is, a potentially deadly flying machine.

We also have to overcome the outlaw mentality that most gyroplane pilots have. Look around your club hangar or gyro flyin. How many legal aircraft do you see?
Typically, the answer is a very small percentage of the aircraft there.

FAA rules exist for a reason. I used to think of the feds as "the enemy". My line of thinking got turned around by Marion Springer. Marion was (is?) an FAA Aviation Safety Counselor (formerly Accident Safety Counselor) She showed by example, that we could work with the FAA and not have to run and hide from them. It's hard to move forward and up, when you are constantly looking over your shoulder.

SLSA (factory built aircraft meeting ASTM standards) and ELSA aircraft (kits meeting the ASTM standards(after 01/2008)) will contribute greatly toward improving the safety of Sport Aircraft. We need an organizational voice to be heard in Washington to allow gyroplanes to be included in SLSA & ELSA program (after 01/2008)

[scott heger]

Udi, your logic is somewhat flawed. First other gyro fatals occur that are not reported to the NTSB. These are "ultralight" gyros or unregistered(no N number)ones. Also many gyros get balled up, and don't get reported .The statistics that are gained are less than perfect. No matter how you cut it, the risk of gyro aviation is far greater than in almost any other type of flying by flight hour. Certain model gyros probably have much worse records than other models.

I believe Doug Riley has it right. Any gyro pilot that tells someone interested regarding getting the sport that gyros are safer than any other aircraft, is not being straightforward. Just face it, flying gyros will always be a fringe part of aviation.

Scott Heger,Laguna Niguel, Ca N86SH

[Udi]

...the risk of gyro aviation is far greater than in almost any other type of flying by flight hour...
How do you know that, Scott? What is the statistical risk of flying a trike or any other ultralite? Do you have the numbers to back the statement above or is it your gut feeling? I am curious - what is it about gyros, Scott, that makes them more dangerous than any other aircraft?

The purpose of this thread is exactly that. Separate facts from fiction. What you wrote in your last post is the reason I started this thread. People think gyros are dangerous. I believe that the terrible safety record of gyros is not the gyro's fault. I believe a person CAN build a gyro and operate this gyro safely as any other aircraft. No aircraft is completely safe, but there is no reason gyros should be more dangerous than any other home built aircraft.

Udi

[Aussie_Paul]

I just pulled up 20 gyro fatals in the data base. Geez, most were HTLM and/or untrained uncertificated pilots in unregistered gyroplanes!!!!:o

Do people get a fixed wing and decide to fly it next weekend without training??? I guess most fixed wings bought do not have an abnormal aft CofG. Gyroplane design still plays a major roll in gyro fatalities, :mad: followed by lack of or inadequate training!!!:mad:

I do not like getting lumped into the TA catagory. TA = Temporary Australian!!!:o

Aussie Paul.:)

[gyrofly]

One more thing to remember – when the rotor is unloaded, even for a short period of time, it slows down. It takes time for the rotor to accelerate back to full speed once it had been re-loaded.
I have a question with regard to the above.
Do the heavier rotorblades like McCutcheons hold their inertia and lift better than a light set like Dragonwings?
Thanks, Ron

[Udi]

Yes, Ron. High inertia rotors lose RPM slower than low inertia rotors when unloaded. The other side of this coin is that high inertia rotors will take more time to accelerate back to normal RPM once they slowed down.

Ernie is using weights at the tips of the Dragon Wings to achieve the desired inertia. I have asked Ernie how he decided what weight is best and he said that he found the optimum inertia with a lot of experimentation. Apparently more inertia is not necessarily better. There is an optimum.

Udi

[Hognose]

Udi, specifically --

I think you're whistling past the graveyard by trying to compare F/W and weight shift ultralights to gyros. Both of them have the same problem we have with training-averse "pilots" and yet both of them have many fewer fatal mishaps.

Trike mishaps are particularly rare.

Trike instructor/DE John Ballantyne and I once had a discussion about training. John's pet peeve will sound VERY familiar to gyro instructors: people who drop out of training when they in their vast experience think they now know enough, when the instructor knows damn well they don't. (I've heard the same bitch from many gyro instructors).

A guy like that is probably going to whack himself whether it's in a gyro or on a motorbike. You just have to hope he picks another sport for his terminal haphazard adventure. And if you're an instructor, you can be a dick about giving solo signoffs. A solo signoff is not so a guy can fly forever, it's so a guy can fly for ninety days to finish his ticket, period.

But returning to the theme, despite the fact that these antiauthority attitudes are at least as widespread in the three-axis and weight-shift communities (we'll skip PPCs cause you have to really apply yourself to commit suicide by PPC), despite the fact that many of their a/c are no more crashworthy than ours, they don't have anything like the fatal mishaps per hour we do.

How can I say that? Because, while an ultralight prang is seldom investigated by the Feds (they are getting more pro-active especially with "fat" ultralights, which are really "unregistered experimentals," but they do ignore most of these), while it may not make an entry in the database, it DOES make the news, at least locally. If it makes the news, even in Podunk, we probably hear about it at Aero-News, and may even write it up if it is a slow news day or has unusual circumstances.

FAA estimates there are 12,000 ultralights (I think their estimate is low). I estimate there are about ~10-12 ul fatals a year nationwide, the bulk of them in three-axis machines.

Canada, which does keep records, averages 5.4 ul fatals a year (see http://www.ionline.net/~elubitz/ulrisks.htm). The conclusion of that paper, which is that UL flying is safer than GA, is suspect; by using "aircraft registered" as their denominator they are biasing exposure. (Also note that Canadian and US ultralight definitions are not comparable). If we had figures, "per hour flown" figures would express the risk more accurately, and "per operatiion [landing/takeoff]" would probably express the risk more accurately still. Getting the denominator right is the hard part.

One thing I'm learning from this thread: there is probably a better hope of teasing out a valid statistic than I initially thought. Just based on Doug's and my back-of-the envelope numbers:

Risk of fatal mishap, GA:

1.6 per 100,000 flight hours. (Nall reports median, eyeball estimated)

Risk of fatal mishap, experimental/ul gyroplane:

16 per 100,000 flight hours. (Estimate from Doug's post: 500 gyros x 50 flight hours = 25k gross flight hours/year vs. 4 fatalities/year).

Now, "general aviation" covers everything from Part 135 ops (although the Nall report sticks to <12,500 lb a/c) many of which run with military or airline precision, to sport flying (which we all agree is not as safe, I hope), to helicopter medevac under NVGs (which is hairy).

Yet our community has a risk level that I believe to be higher than medical evacuation helicopters, a risk level that alarms the helicopter guys and that they're working to address.

Let's do a similar calculation. Here's a ten-year study of medical evacuation helicopter fatalities: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15211144&dopt=Abstract from which I derive that there are about 8 fatalities/year. (That's teh abstract. Full paper (requires login): http://www.jtrauma.com/pt/re/jtrauma/abstract.00005373-200406000-00025.htm;jsessionid=G7qN5l0141QB7BzhJLy15Pg8grls1 2QTQljHvZj27Qz13t0TTvnZ!-801141804!-949856145!8091!-1 Their conclusion, by the way, that accidents is increasing, is a "duh!" cause they don't calculate exposure... accidents were going up, but the sheer count of medevac copters was exploding...)

There are 650 such helicopters. http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=6763

I dunno what they fly for number of hours. My flight school planes flew 50 h./month to make money. Figure EMS could average half that, it's still 300 hours/year. The number would be four fatalities per hundred thousand hours. If the hours were double that, of course, you'd be at the two-fatality level, and only a noodge higher than the general GA accident rate.

Now if you were to ask what's more hazardous, flying a gyro for ten hours or riding along with Life Flight for ten, and you hadn't seen these numbers, what would you pick?

Now, this kind of meta-analysis, taking values from different studies of different phenomena, has no real scientific validity. For a meta-analysis to be valid we'd need much, much, much more data and we'd need to do the calculations with more rigour.

cheers

-=K=-

[scott heger]

Udi, I should have said worse than most++REGISTERED++ aircraft by flight hour. There is no way to know the true statistics of all gyros, because of such a large percentage are underground(unregistered or uncertificated) pilots from my observations of the gyro pilot population. These are not the ones that are going to report every year to the FAA the numbers of hours flown.
The only ones that may know are the insurance companies from past claims experience. You notice not many of those around wanting to insure gyros(like 2), and they are picky on the models and pilots that they do insure. That is probably a very good indicator of risk as compared to general aviation as a whole. We are very lucky to have Cody a member of this forum in that regard. If the risk of loss was low, all of the big aviation insurance companies would be involved. You tell your insurance agent you fly a gyro, and they run from you like you have the red plague.

Scott Heger,Laguna Niguel, Ca N86SH

[EI-GYRO]

Does anyone know what the safety situation is in France?.

The reason I ask is that, from what I hear, regulations are reasonably
relaxed over there, yet we dont hear a lot of bad stuff. Insurance doesnt
seem to be a problem.

The sub-plot here is the question ' is there a culture difference'?.

[NoWingsAttached]

Everyone is responding, but I have don't see what helps resolve the safety problem. You guys are arguing semantics and throwing out statistics. That is not going to get a safe gyro built. I am not critisizing, just observing. The general consensus is that Gyros are "unsafe at any speed". THe general consensus is right. No one has really done enough to advance the gyro design in a safer direction since Benson first put his plans out on Popular Mechanics. Innovations have been made, but safety is altogether at the forefront.

The following thoughts occur to me.

1. Hydraulic pump/motor pre-rotators, coupled to adequate HP.

2. Straight-blade rotor design, which freely spins up better than anything twisted.

3. The prop to be an enclosed fan design to improve control and thrust. The aft control surfaces to be equal in all four quadrants in the output wash. Horizontal stabilizer to be controllable as well as the verticle.

Gyros are at the mercy of the rotor. And the rotors on gyros are not equipped to restore rotation in the unloaded situation. Am I wrong to suggest that hydraulic pre-rotators would help here?

And when any amount of unloading of the rotor occurs, NONE of these aircraft have ANY horizontal pitch control. When everything is doing what it's supposed to, great. But when something goes badly wrong, why not have a horizontal surface that can be used to help control pitch?

4. Clean up the frame and landing gear drag. There is just no excuse for 2" square tubing to be facing windward, and following it with no airfoil. It all just wants to help flip you forward that much quicker when things are going badly.

[Hognose]

Everyone is responding, but I have don't see what helps resolve the safety problem. You guys are arguing semantics and throwing out statistics. That is not going to get a safe gyro built.

Well, the purpose of the thread was not to redesign the gyro. It was to determine how safe is gyro flying?

No one has really done enough to advance the gyro design in a safer direction since Benson first put his plans out on Popular Mechanics. Innovations have been made, but safety is altogether at the forefront.

But a technical solution can only address a technical problem. This is a systems problem which has several related underlying contributing factors, only one aspect of which is design. That said, let's look at your suggested solutions.



1. Hydraulic pump/motor pre-rotators, coupled to adequate HP.

Any hydraulic prerotator I've ever seen could not restore flight RPM if lost. Indeed, if flight RPM are lost problems get worse, for all practical purposes, instantaneously.


2. Straight-blade rotor design, which freely spins up better than anything twisted.

You're going after the same thing as above... look before your RPM get down to where a prerotator will do you any good, your rotor blades will lose rigidity and flap violently or even fold. Once you start losing RRPM the situation gets out of hand very quickly.


3. The prop to be an enclosed fan design to improve control and thrust. The aft control surfaces to be equal in all four quadrants in the output wash. Horizontal stabilizer to be controllable as well as the verticle.


Having an enclosed fan design will help one type of mishap only, ground prop strikes. Model plane guys love ducted fans because theory says they are superior, and they do seem to work at model Reynolds numbers. They've been tried on aircraft since 1911 at least, and almost 100 years of practice says they're not superior in any meaningful way. If they were, somebody credible would be using them. Instead, Paul Moller, the Joe Isuzu of VTOL flight, is.


Gyros are at the mercy of the rotor. And the rotors on gyros are not equipped to restore rotation in the unloaded situation. Am I wrong to suggest that hydraulic pre-rotators would help here?


I think you are. An unload goes from initiation to control loss extremely quickly. Eyewitnesses often say it was well under a second between the initiating event and the fatal tumble. Even if you had by some miracle a Newton-defying prerotator that could go instantly to flight RPM without having to accelerate the rotor mass, you have the problem that it takes ~ four seconds for the pilot to recognise the problem and take corrective action.


And when any amount of unloading of the rotor occurs, NONE of these aircraft have ANY horizontal pitch control.

The loss of lift and rotor rigidity will get you anyway.

When everything is doing what it's supposed to, great. But when something goes badly wrong, why not have a horizontal surface that can be used to help control pitch?

a. How does the control system know whether the pilot is trying to move the rotor head or movable tail? How do you do that w/o adding weight and complexity?

b. What you have assuming you clear that hurdle is a control surface that can take up different angles as you're falling like a rock.

4. Clean up the frame and landing gear drag. There is just no excuse for 2" square tubing to be facing windward, and following it with no airfoil. It all just wants to help flip you forward that much quicker when things are going badly.

This is a very good point. Round tubing is even worse than square, oddly enough. I noticed on Larry Neal's Super Sky Cycle that he has been replacing some of the tubing with airfoil shapes.

If you look at the radio antenna on your car, it has an airfoil cross section. Look at an older car and it is round. The old, round antenna was the cause of significant drag. Aircraft designers figured this out long before World War II and replaced round flying and landing wires (in old wire-braced aircraft) with streamlined wires, which significantly reduced drag.

cheers

-=K=-

[rtfm]

G'day,
Hi. Can't help but notice that you're new here. Now, before I give you the impression that I/we don't like newcomers wagging the finger and telling us off (got to admit, though, that there is a bit of that feeling in the back of my mind... :) ) I think this is an excellent post. Let me explain why I think so.
Gyros are at the mercy of the rotor. And the rotors on gyros are not equipped to restore rotation in the unloaded situation. Am I wrong to suggest that hydraulic pre-rotators would help here?
You've hit on something useful here. The ideal situation is (I think) is the one I've designed into the Razorback gyro currently under construction. It has what I call "RRP" or Residual Rotor Power. The engine drives a hydraulic pump, which feeds into a constant flow valve. This constant flow valve can be set, and the flow it produces is independent of how fast or slow the engine is turning. It in turn powers a hydraulic motor via a sprag clutch (ie freewheeling) attached to the rotor itself. What happens is that when engaged, the engine powers up the rotor for prerotation. This much is pretty mundane, and has been done a thousand times before. However, as the rotor continues to gather speed, it turns faster than the driving hydralic motor, and freewheels on the clutch. What we now have is a "normal" autorotating rotor, backed up by a residual drive which will not allow it to drop below a given RRPM. While the rotor is freewheeling, the hydraulic system encounters no resistance, and so power consumption is minimal. In this way, the rotor can never become unloaded. One of the major safety problems largely eliminated.

And when any amount of unloading of the rotor occurs, NONE of these aircraft have ANY horizontal pitch control. When everything is doing what it's supposed to, great. But when something goes badly wrong, why not have a horizontal surface that can be used to help control pitch? Again, the Razorback will have a full elevator system to manage all pitch control. I know that the LittleWing used this earlier on in its development cycle, and Ron Herron thought the handling of the gyro was excellent. He didn't like the ground handling, though. But so much of the design process is a matter of compromise. It's all swings and roundabouts. Since the Razorback will also be a SRC (Slowed Rotor Craft) with wings to fully unload the rotors at 80kts, horisontal elevators are mandatory, anyway.

4. Clean up the frame and landing gear drag. There is just no excuse for 2" square tubing to be facing windward, and following it with no airfoil. It all just wants to help flip you forward that much quicker when things are going badly. I couldn't agree with you more. Again, instead of placing the engine immediately behind the pilot, the Razorback has the engine nearly a meter (3 feet) behind the pilot. Why? Simply to ensure a long gradual tapering fuselage aft of the passenger pod. This now allows for over 120 litres of fuel and almost 60 litres of baggage space (not sure yet how I'll divide the area) between the cabin and the engine. Everything is designed with streamlining in mind, since the Razorback is going to fly considerably faster than most gyros.

Finally, while I can understand your frustration with this group - it is an excellent group, full of really good and knowlegeable people. I'd recommend (especially for a new member) a slightly less agressive style. You'll find folks a whole lot more inclined to help, if you do.

Kind regards,
Duncan

[birdy]

Hmmmm.................. Greg, ol mate, your profile speeks volumes when it comes to understanding you post. Flight time; nun. Aircraft; nun.
And after reading your post, i'll take a stab in the dark and say your understanding is the same.......... nun.

The general consensus is that Gyros are "unsafe at any speed".
Buggered if i can see how you come to that conclusion.

THe general consensus is right.
Blow it out your ear you w@&*$.
They are only as unsafe as the next 'human propeling machine', wether its on water, the ground or in the air. IOW, only as 'unsafe' as the opperater.

And sum people wunder why i have a dislike of keybord ledgends.

BTW, for your information, i wouldn't be useing one of these machines for a liveing if it was deadly, or do you think i'm as missinformed as you?

[rtfm]

Birdy,
Hi. Heh-heh-heh. Straight from the hip, as usual, Birdy. Good on ya. Inexperienced, yes, but you're being a bit harsh, don't you think?

Cheers, mate,
Duncan

[birdy]

Harsh? No. Probably too diplomatic actualy.:D
When sumone with no experiance, and seemingly no real understanding tells me i'm reckless,dangerous or, [if he's stupid enough,] an idiot, then i'll treat him with the same lack o respect.:mad:
And its not just me he's calling stupid,[ yes, stupid, coz he recons we're all flyn sumthn thats go'n t kill us, and that'd be stupid.] coz theres alota people with alot more brains than this SCG here, and he's put us all in the same basket.
I use gyros for my job not coz it's cheap, but coz it is the best available machine for the job. Be'n also the cheapest is a big bonus tho.:)

I'v said it before, i could afford to use sumthn more common, like an R22, but why would I? They cost 10 times as much to buy, 4x as much to opperate and you not alowed to even change the oil.[ sum lacky ina workshop dose that, and his ass int in the seat.:rolleyes: ] All that, just to do the same job as my trusty ferel, fat chance.;)
Like i said, i don't have much time for keybord legends.:mad:

[Butch S.]

This has been very interesting for me to read
I feel after 13 years of involvement with gyro pilots & in particular would be gyro pilots that gyros attract a large number of people who have there abilities & aspirations confused a lot of them want to redesign the gyro & haven’t even learnt to fly one yet, let alone understand the principals of flight of a gyro & some want to hover others want to break the sound barrier the fact is gyros attract F…. wits & some of them will end up dead this is sad but true
However it is not within the government’s power to legislate against stupid peoples rights to live however inconvenient it is to the rest of us
I haven’t answered any questions as to safety but hopefully shed some light on some gyro accidents involving unlicensed unregistered un inspected gyros of which we have had a few lately

To say that gyros are completely safe would be an overstatement any equipment that has 26 ft of blade spinning at 330rpm with an approximate tip speed of 325 mph followed by a propeller with possible tip speed of 520 mph cant be completely safe add to this poor ground handling and you’ve got your average gyro

Duncan
I have serious reservations about engaging a prerotator in flight as Newton’s law dictates the result will be a spinning gyro but I wish you all the best in your efforts to design out an easily avoidably problem
Butch S.

[Chopper Reid]

I'm right with you there Birdy, whats this bloke think we are ?? Like, I wouldnt even wheel the gyro out of the shed If I thought it was 'risky'.
Its pretty ordinary getting rocks chucked at us gyro flyers by people who havent got any idea of what they are saying !!!! Worse still is that someone might even think old mate here actually knows what he's talking about and that would be dangerous !!!

[Vance]

I believe that what we have here is a cultural divergence. Growing up in a bicultural home helps me to recognize the symptoms.

I don’t believe that Greg set out to insult anyone. His comments show that he has tried to understand the dynamics of an aircraft that continues to confuse me. Ignorance can be cured with information.

I believe that this thread is about the risks of flying a gyroplane. It is undeniable that there is a level of risk attached to flying gyroplanes. I believe that the source and level of that risk is what is up for discussion here. I believe that there is value in exploring ways to mitigate the risks. I believe that the dissemination of information is useful in reducing the risks to us all.

Greg has correctly identified the rotor as a critical system. I don’t believe I understand the reference to twisted rotor design and spin up.

I don’t share his enthusiasm for enclosed props and I don’t understand the reference to quadrants.

Greg is not the first to suggest an elevator controlled by the pilot. I believe that the horizontal stabilizer is meant to dampen pitch and it sort of takes care of itself, but I wouldn’t discount the value of a pilot controllable horizontal control surface.

High drag airframes would not seem to be best practice in fast forward flight and some improvement here might even help at the low speeds where a gyroplane generally operates. On the other hand, I can think of lots of excuses for high drag airframes.

I never intend to insult people with my questions. I apologize if I have.

Thank you, Vance

[Doug Riley]

Hoo boy.

Actually, one of the problems that gyros have is new guys who think the existing machines are crude/ridiculous. The new guys think they can improve on these bogus designs in ten minutes... with time left over for a quick beer. This leads to a lot of ill-advised mods made by brand-new pilots (yup, I did it myself way back).

Granted, ducted fans aren't necessarily foolish. "Jet" airliners haven't really been jet-propelled in decades. They're all turbofans, with a big ducted fan blowing plain cool air out the back of its ring duct, bypassing the turbine. Simple is cheaper and usually safer, however. It's hard to argue with a couple sticks of good hardwood or plastic as your propulsion device.

Bensen and others have experimented with partial rotor drives. Feeding somewhere in the neighborhood of 15% of engine power to the rotor improves efficiency while still not needing a tail rotor. That's not enough to re-establish RRPM "instantaneously," however. Assuming the blades hadn't already been ruined by the RRPM loss, the airframe spin with such a massive torque input would be uncontrollable.

One doesn't need a controllable HS to cope with a second or two of low G. All one needs is for the machine to track straight and level, perhaps with a mild nose-up bias. CLT gyros with adequate HS's already do that. These craft will fly though transient low G with no ill effects beyond the "floaty" feeling in your stomach. Problem already solved.

The gyros that do diverge viciously in low G have problems with thrustline placement, inadequate tail surfaces or both. They are simply defective designs. The problem with them, then, is not a design problem but a cultural/legal one -- how do we get defective designs fixed in an "experimental" environment in which few "designers" even understand high school physics?

Gyroplane RRPM is self-governing. Low RRPM won't progress to a dangerous extent if the self-governing mechanism is allowed to do its work. Pitch-unstable airframes screw up this mechanism to such an extent that crashes result. The Occam's-Razor (simplest is best) answer is not to add a second, complex RRPM restorer but to fix the damn airframe so it doesn't defeat the mechanism you already have.

That, and buy a Pitts if you want to fly inverted.

Twisted rotor blades are standard on virtually all rotorcraft. The purpose of twist is to assure something closer to a uniform angle of attack all along the blade's span, which keeps the inboard sections from stalling so readily. It's hard to see how that's a bad thing. The fact that it doesn't autorotate quite as readily below 100 RPM is irrelevant in flight. If you get THAT deeply into low RRPM you are long gone anyway. But there's no reason ever to do so.

[Aussie_Paul]

Great post #60 Doug.

Aussie Paul.:)

[Ralph]

I think it is worth looking at a reasonable analogy by asking "How safe are motorcycles?" Like the gyro question, the motorcycle question is meaningless without a frame of reference. If we add "compared to an automobile" we now have a frame of reference. While we could come out with lots of qualifications, most reasonable people would arrive at the conclusion that motorcycles operation is inherently more dangerous then driving a car. The primary reasons are:

(1) They are inherently unstable

(2) They are darn hard for people to see or, better yet, recognize

(3) They are maintenance-intensive and should be inspected carefully prior to each ride

(4) The vehicle itself provides little protection should an accident occur

(5) Their apparent simplicity is a recipe for abuse

If fact, were motorcycles invented today, I doubt that they would be permitted on the roads. They have a significantly higher accident rate than cars, but, like our gyros, most of those accidents occur with newer (not necessarily younger) riders. States have accommodated to this reality by requiring specific motorcycle endorsement for driver's licenses and mandating additional training to obtain such endorsements. Some very conservative individuals consider motorcycles to be suicidal and would never think of riding one. On the other hand, short of flying, it's hard to beat the sheer joy of a winding road on a beautiful day. Long-term riders manage the risk and enjoy their machines, knowing that absolute safety doesn't come with motorcycles, cars, bicycles, horses, or even walking!

Now back to gyros. Anyone who says that no progress has been made doesn't know anything about the subject. A decade ago the death rate was much higher then today. The first inroad into the carnage was the gradual adoption of dual flight training as the universal standard. That has happened, but, by the late 90's we were losing people (at a significantly lower rate) who were either well-trained or experienced pilots. That led to work on the question of gyroplane stability and the almost universal appreciation of the need to get a reasonable alignment between engine thrust-line and the vertical center of mass, along with the use of effective horizontal stabilizers. That work has significantly reduced the potential for fatalities but that potential will always be higher then in more conventional aircraft, if for no other reason than the gyro equivalent of #3 and #4 above.

The problem of unloading the rotor is remarkably similar to the problems inherent in stalling a fixed-wing. In both cases, control power is reduced or lost for the duration of the event. While some aircraft designers have produced stall-proof designs, the functional solution has been to teach stall avoidance and stall recovery. In gyros, keeping the rotor loaded is a no-brainer, but, in the event it happens, a horizontal stab and properly aligned thrust-line will assure that you get through it. If you have been properly trained, any unloading of the rotor will be a transient event that will produce no significant loss in rotor speed. By any measure, unloading the rotor should be far less traumatic than stalls in a fixed wing. Despite Alan's recent accident, engine-out landings should also be routine. Most experienced gyro pilots have done several. Most Cessna-drivers have not. Fatalities as a result of engine failures in gyros are rare, but they are common in fixed-wings.

In 1901, Wilbur Wright wrote, "If you seek perfect safety, you should sit on a fence and watch the birds…". The simplicity of our machines, like motorcycles, is one of the things that attracts us and one of the things that will always make us more vulnerable. You can re-engineer the motorcycle until it looks like a Volvo - a lot safer, but ???? People ride motorcycles, climb mountains, fly hang gliders, and yes, fly gyros. They accept risk to have the experience. If the risk is not acceptable, don't do it! On the other hand, each accident we do have, in addition to being very personal in our small community, provides the opportunity to see what we might have missed, be it in terms of training, engineering, or operations. We have a responsibility to manage risk to the best of our imperfect abilities. Fatalism has no place in the equation, but, despite our best effort, s--t will happen and it will have a name and it will be very personal.

Ralph

[gyroplanes]

Ralph & Doug. Posts # 60 & 62. WOW !

[Chuck Roberg]

Ralph and Doug, both GREAT posts. I saved them both.

[rtfm]

Duncan
I have serious reservations about engaging a prerotator in flight as Newton’s law dictates the result will be a spinning gyro but I wish you all the best in your efforts to design out an easily avoidably problem
Butch S.
Hi,
G'day, mate. There is a serious difference between a prerotator and Residual Rotor Power (or even partially powered rotors). A prerotator applies all the grunt it can get to the rotor. If this is more than about 12 - 15 HP, then yes, you're in trouble. You've got yourself a helio without a tail rotor. However, partially powered rotors do not try to twist the entire gyro round in the air. They don't provide enough power for that. Apparently, even in a hover, up to 12-15HP seems to be controllable simply by the pressure of the propwash over the tail feathers. Apparently.

But I'm not even considering a partially powered rotor system, with a fixed HP going into the rotor. Mine is a fixed RRPM solution of about 300 RRPM. When the rotor exceeds this speed in autorotation, the powertrain provides no actual force on the rotor at all, since the rotor spins freely on its overrun clutch. Dip slightly below the 300 RRPM limit, and the engine smoothly begins to add a little grunt to keep things nice and speeded up. At anything above a snail's pace, the airflow over the tail feathers will keep things pretty straight, anyway.

Regards,
Duncan

[Hognose]

Ralph and Doug, both GREAT posts. I saved them both.

Yeah, I concur with Chuck and Tom. Doug, your approach to the inflight prerotator guy was much better than mine. Thanks.

Ralph, you are right that things are safer now than in self-taught Bensen days or low-rider AC days. And your five points of motorcycle risk are an almost exact parallel.

There are two components to gyro risk -- the inherent part that can't reasonably be anticipated and eliminated, and an extrinsic part that comes from human error -- pilot error, design error, maintenance error. That part can be hunted down and reduced.

You mention stalls in fixed-wing a/c. A fundamental f/w text is Wolfgang Langeweische's Stick and Rudder. In it, he describes the typical stall-spin accident, and bleakly notes that it not only is a leading cause of death in light aircraft, it will likely continue to be. And over sixty years after that was published, it still is.

Nothing you can do can take the risk -- or the accident rate -- to zero. We can make things safer; our mishap rate is too high and it's higher than the inherent safety of the concept should permit. The positive way of looking at it, is to note that the right safety approach has the potential to yield very great benefits.

cheers

-=K=-

[NoWingsAttached]

1. My profile is a bit misleading, isn't it? I do fly gyros. I am taking lessons from a very good instructor who was also a Viet helo vet. I expect that in due time he will have me heading down a very sound path towards safe, enjoyable gyro flight. Yes, I am as green as the spring grass to gyros. That is why I am writing, asking questions, and trying to discern what is good and what is bad about design options. The only stupid question is the one not asked.

2. If you find your pleasure in public abuse, I can't help that or end it. However, as uninformed as I may seem, I am seeking knowledge in order to make good decisions about a Dominator I have just purchased from a fellow in my home state of Michigan. I thought this thread was about safety, not chest and browbeating.

3. The quote "Unsafe at any Speed" is not to be taken as my personal stab at this machine. It is the name of a book written by Ralph Nader in the 60's, when I was drooling over the new Mustangs, and it referred to Corvairs - the automobile equivalent of the gyro. (Rear-engine, unstable front-end in certain operating conditions, but what a blast to drive!) You should instantly recognize the analogy for what it is: The car was considered by the general public as dangerous. I too was referring to the general public opinion of this machine. Try as you might, that perception is not about to change anytime soon. I am not attacking. I said that in my post. I said I was observing, and from my observation I listed things I wanted to learn if there was room for improvement on. It is deeply telling, my Aussie "friend", that you were counseled by your peers that you were being rash and abusive, and yet your beligerent reply to even them was that you were not being rude enough. If in my post my obvious ignorance speaks volumns about me here, imagine what has been learned about your character.

4. I notice the rudest folks are the ones who have the least to offer in the way of helpful solutions to dangerous problems. The kindest folks here seem to be the most thoughtful, and the most helpful. Thank you for your consideration. I have years of hovercraft design and experiment experience, and found that not only did ducted fans offer greater ground safety, but when they are design properly they add a good amount of prop efficiency, due to the dynamics of washout at the prop tips. But it has to be done right. No big deal. What I meant by quadrants, were the four quarters of the prop wash in the fan duct.

5. As for the new guy having crazy ideas, you have no idea. Crazy like a fox. Allow me to introduce myself. This thread is, after all, my first - not my last - posting. In my first year racing GT1, I took my shade-tree 930 Porsche to the winners circle in just 3 races, and watched factory-built cars with Le Mans podium drivers spin off the track in my mirror trying to follow me through a turn. I also know what happens to time reference during driver crisis. It broadens, and slows down enough that it gives you plenty of time to react. How long will it take for a gyro falling from a vertical speed of zero to hit the gorund 2000 feet below? Or even 1000 feet? If the controls are available, perhaps you can get out of a bad situation and even correct a mistake. If the controls do not even exist, you gave up the fight for flight before you cranked the motor. I, for one, do not give up just because I've temporarily lost control of a machine. I would have been dead years ago if that was my attitude.

6. Twisted rotors are supposed to produce equal efficiency across the entire length of the blade. I have talked to pilots with gobs and gobs of air time under their belts who have flown negative twist blades (like a prop is built), positive twist blades (Dragon Wings), and the orginal Benson straight blades. It is their learned opinion that the only noticeable difference in performance is with spinning up prior to lift-off. And the Bensons do that better than either of the other two designs, apparently. If more twist at the tips is better, than why do we also have blades with more twist closer to the hubs?

7. My grandma always told me: If you don't have anything nice to say about somebody, don't say anything at all.

[NoWingsAttached]

Oh, and sorry - I grossly exaggerated about things not moving forward enough since Benson. It's great that there is a guy out there trying to work out the powered rotor thing. Am reading everyting here as fast as I can. I have a lot of catching up to do. This place is a wealth of info, and I am a REALLY glad I found it. Matter of fact, it is where I found my machine. I'll try to figure out the thing you said about the Pitt. Does that have a horizontal control?

[birdy]

Everyone is responding, but I have don't see what helps resolve the safety problem. You guys are arguing semantics and throwing out statistics. That is not going to get a safe gyro built. I am not critisizing, just observing. The general consensus is that Gyros are "unsafe at any speed". No one has really done enough to advance the gyro design in a safer direction since Benson first put his plans out on Popular Mechanics. Innovations have been made, but safety is altogether at the forefront.

For sumone who, I am not attacking. I said that in my post. I said I was observing, and from my observation I listed things I wanted to learn if there was room for improvement on., You got a funny way of maken your point.

THe general consensus is right.
The general consensus ISN'T right.
Just coz it IS the general consensus, don't make it right.

Your first post[ for sumone who wants to learn] showed little respect for all the inteligent people here. Just reread your own post from the point of veiw of these people who'v spent years on improving gyros, and tell me it wouldn't be insulting.

I'll give you the benifit of dout and not answer any of your posts [ coz i know nuthn], but for sumone who wants to learn, you started on the wrong foot.

[Udi]

...How long will it take for a gyro falling from a vertical speed of zero to hit the gorund 2000 feet below? Or even 1000 feet? If the controls are available, perhaps you can get out of a bad situation and even correct a mistake. If the controls do not even exist, you gave up the fight for flight before you cranked the motor...
Hi Greg - I don't know what scenario you had in mind when you wrote the above description of loss of control. What would make your gyro fall from 2000 feet out of control to the ground? You may have the wrong idea about gyroplanes. If you are thinking about unstable gyroplanes like the RAF 2000, who can tumble out of the sky out of control – well, that problem has been solved a long time ago (oh, about 73 years ago by a guy named Cierva) but some amateur gyro designers insist on keep making and selling these death traps.

There is no reason for a gyro to fall out of the sky. Like any other aircraft, gyros can crash due to mechanical failure or stupid actions by the pilot. But why would you want to design a gyro that is idiot proof? The Dominator that you just bought is a very safe gyro and if you get good training and keep your gyro in top shape there is no reason you will ever have to use race car driver instincts to save a tumbling gyro.

If your intentions are to fly aerobatics than you are in the wrong form of aviation. Gyros are not good aircraft for aerobatics. They don't like it when the rotor is unloaded and I really hope you are not trying to design THAT out of the gyro because you will no longer have a gyro - or at least not the light, simple, and fun to fly gyro we all love around here.

BTW - Pitts is a type of aerobatic fixed wing plane. A good choice if looping, rolling and flying at zero-G is your kind of flying.

Udi

[Butch S.]

6.rotors twisted with more pitch at the tip are done so because of what is refered to as the elastic section of the blade when in flight which with some blade designs alows the outer end to depitch.
& the extra twist inboard is to increase lift by the fact that the inner parts surface speed is less with more pitch/wider cord it should produce more lift
But I tend to agree with what the guys you spoke of said about spinning them up
also you get nothing 4 free its all a trade off
Butch S.

[Doug Riley]

I don't know anyone who does NOT recognize that Dragon Wings out-perform other brands in their size range. Chuck Beaty did some tests on them a few years ago and found that they flew at a shallower angle of attack on a given gyro than others, including pretty good ones with accurate 8H12 airfoils.

Bensens are among the worst-performing blades. They do have gentle startup qualities and a smooth light feel -- because they ARE light. They lose RPM rapidly when unloaded, however, which makes the responsive but somewhat less forgiving of a botched flare or unintentional low-G maneuver. I won't sell my old ones but I don't fly them anymore, either.

There are a few ol' -boy gyronauts who will not accept any innovation, from the (clearly improved) D-W blades to horizontal stabilizers to centerline thrust. The again, some are out to sell you the brand for which they are the dealer, regardless of its merits. Still others are fanatical anti-intellectuals and reject any advice that appears to proceed from any form of book-learnin'.

One of the essential tools in gyronauting, just as in voting in public elections, is a sensitive and well-tuned crap detector.

[greeny]

At the risk of being abused because not having sufficient gyro flying hours, I dare to hint at two points that have been mentioned as main sources of incidents/accidents: tip over and rotor unloading.

Tip over: Gyros have grown higher in recent times, with bigger propellers and higher COG. Yet, the average main gear has remained largely unchanged. Is there a sound reason why we do not make it wider, say 6 to 7 ft.?
One would think, the higher drag would easily be compensated by the improved safety margin it gives us on the ground.

Low-G-warning device: FWs have stall warning devices since times immemorial. It does not prevent you to stall the plane, but by the time, its signal will give you a feeling when a stall situation is about to occur.
I daresay a similar "Low-G-warning device" might be a useful gadget. With single chip dual axis accelerometers readily and cheaply aviable, it wouldn't be a great challenge to build a low-G-warner with a buzzer output for something like 20 dollars. I mean, even I could handle that.
Again: It does not prevent you to unload the rotor, but it might warn you in time.

Peter

[Gary_in_Orygun]

My stomach works perfectly as a low-G warning indicator.

[gyrogreg]

Anybody care to make an estimate on experimental and ultralight gyroplane fatalities per 100,000 flight hours? I have just done so in my head. Ouch. And in my mind I am working out methodology for a more scientific approach to determining this number.

I'm still working through this terrific thread. I congratulate Udi on this work!

There have been questions about gyroplane accident statistics. If anyone is interested, attached is an accidents per flight hours report we prepared for the FAA a few years ago. This report was developed using NTSB data and other data and estimates gleamed mostly through a special project on the old Rotorcraft Forum. As this report says, there are "Confidence Factors" involved in the statistics - because we really do not have good ways of collecting the data!

This report was requested by the FAA after we provided another report on gyroplane accidents causes requested by the FAA. That first report is essentially what is posted on the PRA website:
http://www.pra.org/index.php?module=article&view=23

These reports were an attempt to address the basic question on this thread - what are the causes of gyro accidents and fatalities, and how serious is it compared to other aviation types. The FAA's response to these reports was basically astonishment that the accident record is indeed much worse than other aircraft types - AND they said "Something has to be done about it!" That is why, with the encouragement of the FAA, we organized the ASTM Gyroplane Standards Committee to develop a standard for gyroplanes that addresses these causes. The FAA said to the PRA, you need to do this, becasue if you don't do it, we will do something, and we don't know how to do it and you won't like what we would do!" The FAA believed we could improve gyroplane accident statistics by influencing safer gyros and pilots through the acceptance and use of a credible standard.

FYI: That standard sets easy ways to determine what the flight staiblity characteristics of any gyro might be - assess the risks! I have been on a long campaign to get people to read, understand and use at least the Static Stability criteria in this standard! This has been a very frustrating experience for me because of the slow acceptance by many in these principles - capped off by the recent death of my frieind Bill Finnegan!

The FAA is still looking for an improvement in gyroplane fatal accidents!!!!!!!

[Vance]

Thank you Greg,

Why do you think that two place gyroplanes are almost three times as likely to crash as single seat gyroplanes?

Why do you think that two place gyroplanes are almost twice a likely to crash per hour flown?

Do you find your two place more difficult to fly than a single place?

Thank you, Vance

[gyrogreg]

Why do you think that two place gyroplanes are almost three times as likely to crash as single seat gyroplanes?

Vance, I think this may be because there may be a large proportion of unstable 2-place gyros flying - one in particular I can think of is very popular and shows up on the NTSB reports a lot!

Why do you think that two place gyroplanes are almost twice a likely to crash per hour flown?

This may be for the same reason as above. But, notice the Confidence Factors ("CF") on the stats in the report. Most 2-place gyros are registered and accidents are generally reported and investigated! The CF on single-place gyros is much worse - and perhaps this might be the source of some of the bias.


Do you find your two place more difficult to fly than a single place?

No, the 2-place I fly is much easier to fly than probably any single place gyros short of the LW. I attribute this to tandem design, large and effective and proper "balancing" HS, good drag aerodynamics, a moderate but properly balanced HTL, and a rotor response/inertia that is slower than the airframe pitch response/inertia to allow the airframe inherently to restore rotor loading before anything bad can happen. But, there are some 2-place gyro designs that are probably much less easy to fly than many single place machines.

I think the data reflects more the proper application of gyroplane stability than of single or 2-place configurations! Read the report (http://www.pra.org/index.php?module=article&view=23) to see the likely correlation between fatal accidents and the use of a HS.

(The ease of flying the trainer gyroplane I fly does present some training problems - it does not provide good training to fly many other types of gyros! That is a BIG issue with me when I get general requests to train people to fly "gyros" - I can't do that well in this machine, and I consider it likely that training solely in this trainer gyro would lead to a certain accident in many other gyro types because of the inability to experience proficiency requirements of many other gyro types.)

Thanks, Greg Gremminger

[Doug Riley]

At 0-6 accidents per year, the statistical sample is so small that the random "noise" is nearly as big as the valid information.

PPO in the older designs still out there on the market dominates other crash causes. PPO is 100% preventable with correct design.

Proficiency is relative. Often "inadequate proficiency" accidents obscure the fact that extreme proficiency wouldn't be needed if the craft's poor design didn't require the pilot to compensate continually for built-in instability.

I suppose all PPO accidents could be reclassified as inadequate proficiency (the manufacturers in fact do just this, sometimes with FAA/NTSB agreement). A really fine test pilot could fly quite an unstable machine for years without incident. Why fix the thing if, with enough training-training-training, you don't have to?

REAL men can smoke cigarettes without getting cancer, either, right?

This is one of those thorny legal/cultural issues that bedevil us in gyroland.

[Udi]

I have copied Raghu's post from the UK fatality thread because it really complements this thread and I want to comment on it in the context of this thread...
Following the thread by Udi on the safety and accident rates of gyros a week or so ago, I looked up numbers for UK gyros and microlights. I chose to compare gyros with microlights given that the engine used, type of construction and gross-weights are roughly similar.

UK microlights are limited to having a gross weight of under 300kg (660 lbs) single seat and under 450 kg (990 lbs) for a 2- seater. Microlights are typically either fixed wings or flex wings. Here is what I found:

1: The statistical validity is always questionable given the small number of gyros in the UK register( approx 250) and the limited hours flown, estimated for gyros by the CAA at around 20 - 25 hours per year. There are however over 10 times more microlights in the UK and they are estimated to fly more hours (approx 40 per year).

2: Based on data for the ten year period 1990-1999, the fatality rate for gyros is 119 per million hours flown, and for microlights the fatality rate is 20 per million hours flown- gyros have a 6 times higher fatality rate.

3: As for non fatal reported accidents during the same period, the numbers for gyros are 516 per million hours and for microlights 129 per million hours- gyros have 4 times higher non-fatal accident rate compared to microlights.

4: The fleet of the UK gyro register is dominated by Bensen type gyros and their variants Cricket, Everet etc. Most are without effective HS and predate CLT type modern gyros, though some of the Bensens clearly are near CLT.

Given the above data here are a few observations

1: Looking at the fatal accident causes ( see attachment) it is clear the big culprit is pitch instability related issues. At least 3 of the 5 fatalities appear to be PIO/ PPO related (though, I have not verified the actual detailed accident reports).

2: But the pitch instability is not quite the whole story. Given that pitch related accidents are almost always fatal, its worth looking at non fatal accident rates. This gives us a rough idea of non pitch related risk factors.

It turns out gyros had a 4 times higher non-fatal accident rate than microlights. Further, the serious accident rate per million hours was 1.5 times higher and minor injuries 2.2 times higher for the gyro. My suspicion is many of these where of the typical landing rollover or flapping during takeoffs types though I have not done a detailed study of individual accident reports.

3. What does all this mean in terms of the risk profile of a pusher type gyro?

Designing out the pitch related deficiencies in gyros will certainly greatly improve the safety of gyros but even then it appears pusher type gyros will still be less safe than a microlight. The serious and minor injuries rates attest to this.

Essentially in an accident a microlights typically will have more linear momentum and more potential energy from linear motion than a gyro. On the other hand the gyro will have more angular momentum (due to the rotor) and hence angular energy than a microlight.

The relative safety of a microlight and gyro in an accident will depend on which of these two energies dominate and how the structure is designed to dissipate the related energies. In the ten year period studied, in gyros, 11 percent of non-fatal accidents where serious but in a microlight 30 percent of accidents where serious.

So it does appear that a gyro fairs better than a microlight in an accident, but perhaps this is because a large number of accidents are rollovers and flapping accidents where the pilot walks away unharmed.

However gyros have a lot higher rate of non fatal accidents on a per hour basis and hence overall are less safe- recall gyros have a 1.5 times higher rate of serious accident and 2 times higher rate of minor accidents on a per hour basis. Essentially, the rollover rotor bust up accidents may not be that dangerous but they do happen a lot and hence the overall serious accident rate is high.

In summary, not withstanding the limitations of the data, microlights come out clearly more safer than gyros. While the pitch stability related issue dominate the fatality rate, the non fatality accident and serious accident rate on a hourly basis rate is higher for a gyro compared to a microlight. Assuming that most of the serious and minor accidents where non pitch stability related ( seems reasonable), designing out pitch instability in gyros will greatly improve safety but still pusher type gyros may be less safe than their fixed wing and flex wing counterparts.
attachment (http://www.rotaryforum.com/forum/attachment.php?attachmentid=21834&d=1149532429)

[Udi]

I have a few questions/observations with regard to Raghu's post:

1. Are gyroplanes considered microlights in the UK? If yes, are the fatality numbers in the microlight table including gyro fatals? If this is indeed the case, gyro fatals should be deducted from the total to get non-gyro microlight fatals.

2. What is the distribution of accidents among non-gyro microlights? Can we learn anything from the other categories of microlights?

3. If anyone has any information on microlight/gyroplane accidents in mainland Europe it would be interesting to know because, as far as I know, the Magni gyros dominate that market. It is my impression that the Magni gyros/pilots have a very low accident rate - and I understand they fly more than 20 hrs/yr.

If my suspicion is correct, we can use the “Magni model” to help us understand how to make our sport as a whole safer. I also suspect that we will never be able to duplicate the Magni model due to the cost of hardware and the associated pilot population, but at least we can say with better certainty that gyros are not inherently unsafe, as compared with other light aircraft.

Udi

[Chopper Reid]

At the risk of being abused because not having sufficient gyro flying hours, I dare to hint at two points that have been mentioned as main sources of incidents/accidents: tip over and rotor unloading.

Tip over: Gyros have grown higher in recent times, with bigger propellers and higher COG. Yet, the average main gear has remained largely unchanged. Is there a sound reason why we do not make it wider, say 6 to 7 ft.?
One would think, the higher drag would easily be compensated by the improved safety margin it gives us on the ground.

Low-G-warning device: FWs have stall warning devices since times immemorial. It does not prevent you to stall the plane, but by the time, its signal will give you a feeling when a stall situation is about to occur.
I daresay a similar "Low-G-warning device" might be a useful gadget. With single chip dual axis accelerometers readily and cheaply aviable, it wouldn't be a great challenge to build a low-G-warner with a buzzer output for something like 20 dollars. I mean, even I could handle that.
Again: It does not prevent you to unload the rotor, but it might warn you in time.

Peter


Peter, if you finish your training and your instructor hasnt taught you to recogonize low G or 'getting light in the seat' then he hasnt taught you to fly ! You can feel getting light in the seat way before the rotors start to slow and its so simple to avoid getting low g's and thats by keeping holding a little back stick. You dont need much but you should be able to 'feel' how much backstick in a very short time.
Most of us who have a few hours up, fly mainly by 'feel', the gyro is only too willing to tell you whats happening as long as you re prepared to feel whats coming back through the stick and whats happening through the seat of your pants and what you hear !!!

I have actually pushed the stick forward to get negative g's and the rotor doesnt stop, it does slow but you would have to hold the stick well forward and ignore the warnings coming from the stick and the seat of your pants to get into trouble though if you were flying some types of gyros, this manourver could well be your last. The bigger [27 ft plus rotors dont slow as quick as the 24 ft rotor's[

[gyrogreg]

If my suspicion is correct, we can use the “Magni model” to help us understand how to make our sport as a whole safer. I also suspect that we will never be able to duplicate the Magni model due to the cost of hardware and the associated pilot population, but at least we can say with better certainty that gyros are not inherently unsafe, as compared with other light aircraft.
Udi

Not withstanding that I am a representative of Magni, I do not believe a gyro needs to cost as much as a Magni to exhibit some of the safety advantages of flying a Magni. I'd like to mention some of the things we are trying do demonstrate to the gyro community - with the Magni as the example - not all of which are hardware based:

The Magni safety strategy is multi-legged - not all hardware based. If you are interested in the examples that Magni can contribute to gyroplane safety and minimizing risks, please see the attached. I am not trying to sell you a Magni, I realize an important attrraction of the sport is less-expensive flying. A lot of what a Magni and the Magni factory demonstrate are not necessarily expensive. But, safely flying any aircraft cannot be considered "cheap" - there are prices that need to be paid for safety. That price may be money, time, attention, research, training, informed modifications, etc. Safety is not different than a car, house or gyroplane in that "you get what you pay for". You need to be prepared to pay some price for safety and minimizing risks.

Thanks, Greg Gremminger

[raghu]

I have a few questions/observations with regard to Raghu's post:

1. Are gyroplanes considered microlights in the UK? If yes, are the fatality numbers in the microlight table including gyro fatals? If this is indeed the case, gyro fatals should be deducted from the total to get non-gyro microlight fatals.
Udi

No, the data I took from the CAA document separated microlights from gyros. Microlights are in the main a mix of FW and flex wing.

I think this goes back to the fact that microlights are managed by the BMA and the gyros fly under the CAA permit to fly scheme. I could be wrong though on this last bit.


2. What is the distribution of accidents among non-gyro microlights? Can we learn anything from the other categories of microlights?
Udi

Udi, if you mean list or types of accidents microlights where involved in, the CAA document has the details for the ten year period. It is available on the web if you search in the CAA website.Alternatively, I could email you the PDF if you like.

[rtfm]

Tip over: Gyros have grown higher in recent times, with bigger propellers and higher COG. Yet, the average main gear has remained largely unchanged. Is there a sound reason why we do not make it wider, say 6 to 7 ft.?
One would think, the higher drag would easily be compensated by the improved safety margin it gives us on the ground.
Hi,
Brian took you up on your second point, eschewing technology for seat-of-the-pants, but didn't mention the first. You have hit on something which to explain properly will open a can of worms. So allow me 2c worth of poking a bit of fun at the gyro community. I don't think the guys will mind too much.:D

There are a number of gyro 'design features' which over the years have become entrenched in the psyches of the gyro community, and are regarded as - if not essential, then certainly desirable. One of these is the maximum width of the main gear. This might at first seem an odd sticking point, but it has its roots deeply entwined in a far more fundamental premise: gyros don't fly cross country well; so if you want to attend a fly-in three or four hundred kilometers away, you strap the gyro onto a trailer, and road it there. And to do this, the wheels have to fit onto a trailer, which have maximum widths laid down by local laws. QED.

Of course wider main gear is a safety enhancement. But then you couldn't road your gyro all over the place. Well, why not widen the wheelbase, and fly to the destination like other aircraft do? After all, most FW microlites fly to whewre they want to go... Because gyros don't generally have good long distance capabilities. Why's that, you ask? Because they are aerodynamic disasters. So why not streamline them by adding a cabin and aft fuselage fairing? Complexity, dear boy. And weight. Not to mention adverse yaw in x-winds. OK, so why not compensate for this by adding a bigger vertical stab? Why not indeed? Or why not extend the tail boom a few feet to provide a greater moment arm for the tail feathers? Again, why not indeed? Then we'd have a faster, warmer, more comfortable gyro (and a safer one, to boot) far better able to propel its passenger(s) x-country rather than having to be tied onto a trailer and roaded there.:confused:

But we'd also basically need a new gyro. Too many changes. Far simpler to keep things as they are. Simple and cheap. And draggy and slow. Not to mention its tendency to roll over in x-wind landings. And brass monkeys for the pilot sitting out there in the icy wind perched on his 6061-T6 broomstick. But hey - at least we can tie them onto our trailer and road them to the fly-in. Right?:p

Regards,
Duncan

[Doug Riley]

Duncan, it's sometimes goofier than that. In the U.S., the standard sheet of plywood is four feet by eight feet. There are those among us who are too cheap to spring for more than one sheet to deck their trailers. Of course, the 8-foot axis goes fore-and-aft, leaving us four feet across, wheels and all.

Here in the States, even the usual five or six-foot-wide gyro axle is far narrower than the law allows for road vehicles. My present Gyrobee, and also my very first Bensen of 35 years ago, both have/had 7-foot axles. Both saved me from likely tipovers a time or two -- and both are road-legal.

Having recently returned from a delightful ramble around Ireland, I realize that in SOME places the main roads are the width of our sidewalks... but are 7-foot axles really too wide elsewhere?

[EI-GYRO]

Bleedin Yanks,,,,,,, comin over here and criticisin' our superhighways.

At least ya dont have to worry which side to drive on............right?...no .. left..
whatever------- :)

Went up in an Extra 200 today, still have my lunch.
My limit appears to be about 4Gs.

[Doug Riley]

The highways were super, Fergus, they just weren't superhighways... in the grand Los Angeles style, at least. God willing, it will never come to THAT in Eire.

Passing an "articulated" at a 130 mph closing rate with inches to spare, whilst driving with "sword hand to the centre of the road" was fun, in a kiss-the-ground-when-you-get-there sort of way.

What IS the maximum legal trailer width over there?

[EI-GYRO]

Legal?

Now if you start thinking like that, life gets complicated.

If you get there, and it's still attached, it wasnt too wide.

[dragonflyerthom]

Preflight, preflight, preflight. It is sooo important that we as pilots do a careful walk around before we take off. Another thing is when we fly a FW aircraft we fly the wing for attitude of the aircraft. Well Fly the rotor not the cabin and it will help eliminate problems. Then there is training. Everytime you fly your gyro it is training. Short, simple, sweet. Most accident happen on take off and landing when we should be most attentive. It is by looking at these events as training that we can avoid that lazydasical attitude to takeoff and landings. Some of us also try to squeeze the most speed out of our birds and approach the Vne too closely. Any wind gust can and will effect the rotor and could put us into a dangerous and dreaded -G situation.
Well that is my 2 cents worth.

[Aussie_Paul]

Preflight, preflight, preflight. It is sooo important that we as pilots do a careful walk around before we take off. Another thing is when we fly a FW aircraft we fly the wing for attitude of the aircraft. Well Fly the rotor not the cabin and it will help eliminate problems. Then there is training. Everytime you fly your gyro it is training. Short, simple, sweet. Most accident happen on take off and landing when we should be most attentive. It is by looking at these events as training that we can avoid that lazydasical attitude to takeoff and landings. Some of us also try to squeeze the most speed out of our birds and approach the Vne too closely. Any wind gust can and will effect the rotor and could put us into a dangerous and dreaded -G situation.
Well that is my 2 cents worth.

In a stable gyroplane the fuselage follows the rotor. Pitch is attained by reference to the horizon with the fuselage, no different to a fixed wing.

A correctly set up gyroplane is a 3 axis aircraft that operates with the sensitivity of a helicopter. There is of course the rotor management that is different on the ground and has to be taught to a fixed wing pilot.

I teach in my stable gyros exactly the way a fixed wing instructor teaches in say a C-152. The principles for normal operation of taking off, s/l, turns up to 45*bank angle, approach and landing are the same. I can talk a fixed wing pilot, after 1/2 air work for them to get the feel of the more sensitive aircraft, to take off, fly a circuit, approach and land using 30% power.

Ten years ago I did not believe that this would ever be possible, and of course a lot of gyro people still don't.

In a stock Raf, or an equivalent unstable gyro, it is impossible. A stab, depending on size, improves the situation greatly, BUT it is not until you operate a correctly set up stable gyroplane that the above is possible.

It ain't rocket science, to quote a few knowledgeable people over the years.

Aussie Paul. :)

[dragonflyerthom]

Well Guys

I have thought about this several times and days. I have read and re-read the NTSB reports.

One of the things they say up front is that it only includes N-numbered aircraft.

44 to be exact also stating that there were probably 3 times that number of unnumbered accidents.

The HS is the number one method to reduce the number of accidents that they recomend for the General Gyro population.

I have read Gregs reports on the Magni site. Good work. I have also read the individual NTSB reports.


When you have builders and pilots flying a gyro with 5 hours PIC or less (no experience) by them selves who is to blame...Laws aren't going to stop stupidity.Anyone who flys a Gyro and is not ready has a death wish. Take off and landings is what gets us into trouble. If you haven't flown for a while then you should stay in the pattern and do T/O and Landings. Most Gyros fly similar to other A/C when in the air.


We as a community have to see if we can influence the other pilots. If we don't do something then the FAA will.

Now you can shoot me down for being a low time Gyronaut, but I would never get into a gyro of any type without proper instruction. My life is worth more than that
http://www.pra.org/index.php?module=article&view=23

Live the DREAM

[NoWingsAttached]

In many dangerous situations if you have to think about it, it is probably already too late.

[Aussie_Paul]

Well Guys

Most Gyros fly similar to other A/C when in the air.

Live the DREAM

I respectfully disagree. unfortunately, there are still more unstable gyros out there that do not fly like other A/C. The good part is that the ratio of stable to unstable gyros is improving, thanks probably to the internet.

It was a good post though.

Aussie Paul.:)

[Vance]

Well Guys

I have read and re-read the NTSB reports.

The HS is the number one method to reduce the number of accidents that they recomend for the General Gyro population.

I have also read the individual NTSB reports.


When you have builders and pilots flying a gyro with 5 hours PIC or less (no experience) by them selves who is to blame...Laws aren't going to stop stupidity.Anyone who flys a Gyro and is not ready has a death wish. Take off and landings is what gets us into trouble. If you haven't flown for a while then you should stay in the pattern and do T/O and Landings. Most Gyros fly similar to other A/C when in the air.


We as a community have to see if we can influence the other pilots. If we don't do something then the FAA will.

Live the DREAM

Hello Thom,

I have not seen where it says what to do to prevent accidents in the NTSB reports. Where do I go to find this information about the NTSB recommending horizontal stabilizers?

I have flown several types of gyroplanes and several types of aircraft and it seems to me they are quite different in the way they fly. For instance, I have not flown a fixed wing that is so sensitive to low Gs as a gyroplane seems to be.

I feel confused; I would love to have more information.

Thank you, Vance

[dragonflyerthom]

Vance I added a link in the above post. I love the way you have tried to bait me...Ha

Thom

Live the DREAM

[Fl90]

And you bit. The link is a PRA report using NTSB data.

Phil.

[dragonflyerthom]

Well Phil

Someone has to compile the data. I feel that the PRA is a viable organization that is here for the benifit of all of us. Now, are you saying that the PRA is not????

[Fl90]

Just pointing out that the NTSB does not make the recomendation for a H.S.. I believe that's the point Vance was focusing on. However, I'm not Vance.
You can not say the NTSB is recomending a H.S. from the link supplied.

I'm not trying to anger you, but you need to be more specific.

Respectfully, Phil.

[dragonflyerthom]

You are right. The NTSB is nothing more than an accident reporting agency.

The PRA has assembled information on the the HS. The FAA has been trying to produce data that will standardize the Gyrocopter handling. If youvisit the magni web site you will find a lot of info from Greg Grimminger. I think he is on here as gyrogreg.
http://www.magnigyro.com/USA/usa.htm

Look Phil I am the type of person that does a lot of research in my business.
I would like a lot questions answered that I have. I would like to make my hobby safer for myself as well as others. If we don't take a proactive stance soon the Government will and I can see my hobby going down the tubes. You have not angered me in any way. Now are you part of the solution or part of the problem?

[Fl90]

Part of the solution, I agree with the use of a H.S.. However, when presenting a position it should be done correctly. If not presented correctly, the position can be attacked on incorrect statements, witout reguard to it's validity.

Phil.

[dragonflyerthom]

Phil you are starting to sound like my old Oral Com Teacher. Ha.

Thom

LiVe the DREAM

[Aussie_Paul]

This is worth reading from time to time. Written by a Frenchman who is not happy with the US and the Iraq situation so I have deleted his name.

Aussie Paul.:)

[dragonflyerthom]

Paul

That is a great article. You might want to look up Gregs articles. See above posts.

[Aussie_Paul]

Paul

That is a great article. You might want to look up Gregs articles. See above posts.

Thom, I have read everything from Greg and had some contact with Greg during the ATSM debate. I have flown a Magni, and that proved to me that I was sheer lucky that when I was trying make Hybrid CLT I only got to within zero to 2" and had an effective positivily loaded H/stab.

It turns out that this is the best method. After I had flown the Magni I realised that I had accidentaly got it right, even though I was trying to get closer to CLT. The Magni was only more stable than Hybrid over a larger speed envelope.

Aussie Paul.:)

[dragonflyerthom]

Aussie Paul

Once again Thanks for that article. I sure would like to pick your brain about the RAF type Gyros. You have apparently solved most of their problems. You are a regular one man band. Ha.

Seriously are you coming to the U.S. any time soon for a fly in or anything?

[Aussie_Paul]

Aussie Paul

Once again Thanks for that article. I sure would like to pick your brain about the RAF type Gyros. You have apparently solved most of their problems. You are a regular one man band. Ha.

Seriously are you coming to the U.S. any time soon for a fly in or anything?

Maybe bringing a Firebird to Mentone 2007, or Bensen Days 2008. (Sorry Ron, another Commercial):D

I will try and dig out the articles I have written as we developed each step with the Raf. At each step I thought it was great, BUT then I would improve it again!!!!

Drop me an email paulbruty@tpg.com.au

I will most likely be away for 3 weeks from this weekend and am not sure re i'net access.

Aussie Paul.:)

[Vance]

Hello Thom,

I am not sure what you meant by trying to bait you.

I wondered if you had found an additional source of information that I was not aware of.

I do not disagree with Greg Gremminger’s analysis of the NTSB statistics.

In that same series of articles by Greg Gremminger he also focuses on training and I concur with his conclusions there also.

There has been a good deal of research done and a lot of debate here on the forum related to thrust line offset. I believe that this is an important concept also, and one that is particularly applicable to your particular aircraft.

I make an effort to not engage in debate about rotary winged aircraft as my understanding of the dynamics is limited. I am always trying to learn more, but the more I learn the greater my understanding of my limitations.

I enjoy your intellectual curiosity and I would not want to do anything to discourage your posts.

Thank you, Vance

[Aussie_Paul]

...there is enough information backed up by aerodynamicists and physicists that the safest gyroplane is one that has CLT plus or minus a couple of inches and has an effective H/stab to adjust for the variations of fuel burn, pilot weight, and turbulence etc. In other words a stable gyroplane.

Having achieved that, you then get good and adequate dual training from an instructor that understands the above, and who will test fly your machine to set up the stick and rudder offsets etc, and be able to tell you at what speeds it does the required flight maneuvers, ie when the nose comes up, lift off, climb, cruise speed and engine rpm, approach speed etc.

Why do many try and make more complicated than that???:eek: Beats me.:mad:

Aussie Paul.:)

[dragonflyerthom]

Aussie Paul




Have you devoleped an adjustable H/S???????Do you have any thing on your website? What does it look like and do you have any pics'

Thom

Live the DREAM

[Aussie_Paul]

Aussie Paul




Have you developed an adjustable H/S???????Do you have any thing on your website? What does it look like and do you have any pics'

Thom

Live the DREAM

Thom, my website is a disaster at this point in time. I have a gyro kindred spirited friend in NZ who is going to update the Firebird web site soon. I will train him as compensation for the web sit work. A lovely contra deal. I would say that in 6 weeks we will have sufficient product to start the new Firebird Web site.

The h/stab is ground adjustable, and is the only way to go because peoples and empty weights of machines vary quite a lot.

The stabs we are producing for Firebird do not have the fins because we have a large enough fin and rudder. We can produce stabs with fins for the Raf people. These were made by my friend in NZ but now we produce our own due to having to supply products for this elusive Firebird!!!!!

Email me for details, paulbruty@tpg.com.au

I will be away for 3 weeks from Saturday and am not sure of i'net access during that time.

Aussie Paul.:)

[Cobra Doc]

I am always trying to learn more, but the more I learn the greater my understanding of my limitations.

Thank you, Vance

Vance, very well put. I think we all suffer the same affliction. I think it was a book by either Heinlen or Asimov where it was said "A generalist knows nothing about everything and a specialist knows everything about nothing."

[dragonflyerthom]

Cody
It is really strange how the autogiro has progressed since its inception in the 1930's.

An aircraft fuselage was initially used with the elevator and rudder with multi-wooden rotor mounted on top.
Then comes the benson models with their small rudders open framed fuses and motor raise up enough to clear the keel and the dream begins. All of us want to be gyro pilots sit or stand on the ground wishing we were up there. CFI's and instructiors of any type weren't available so most Gyropilot want to be's had to teach themselves. The would tow it, hop it, low fly it until they had enough experience to fly it. PIO and PPO's were terms that were not known but would come into the gyro terminology very quickly. Ken Brock, Air Command and Benson continued to improve on the Benson design every year.
Safety was paramont but pilots continued to push the envelope and some of them are no longer with us.
The changes in the last 15 years have been fast and furious. Center Line Thrust, High Thrust Lines, and Low Thrust Lines have been identified. Stabilizing the air frame has been identified. Fuselage drag and yaw has been identified.
All of these concepts have been explained on this forum with detailed scientific and mathmatical precision so I will not go into it.
With all of this knowledge we have designers such as the retro Little Wing, the sleek looking RAF not using the horizontal stab.
My point being, with all this knowledge why is it taking so long for our governmental agencies to mandate this so that the new young pilots can be safe in the learning curve. If all of this knowledge is designed into the gyro, then when the younger pilot get up there (and they will)hot dog, push the envelope,it will give them a chance to live and tell about it.


Just a few thoughts

Thom

[brett s]

That's what the Experimental category is all about - it's one of the great things about our system in the US. You as a builder have the freedom to decide...

You can't have it both ways, if the government starts mandating specific designs you lose that freedom to build whatever experimental aircraft you want. Now, for other certification categories it's a different issue...

I'd hope that market forces take care of companies that are selling flawed designs eventually, with all the information out there these days why do people insist on buying dangerous machines? Personally, I'd do a bunch of research on anything that's either expensive or potentially fatal before spending a dime - any aircraft fits that description!

[Vance]

The changes in the last 15 years have been fast and furious. Center Line Thrust, High Thrust Lines, and Low Thrust Lines have been identified. Stabilizing the air frame has been identified. Fuselage drag and yaw has been identified.
All of these concepts have been explained on this forum with detailed scientific and mathmatical precision so I will not go into it.
With all of this knowledge we have designers such as the retro Little Wing, the sleek looking RAF not using the horizontal stab.
My point being, with all this knowledge why is it taking so long for our governmental agencies to mandate this so that the new young pilots can be safe in the learning curve. If all of this knowledge is designed into the gyro, then when the younger pilot get up there (and they will)hot dog, push the envelope,it will give them a chance to live and tell about it.


Just a few thoughts

Thom

Hello Thom, I have a different view of what you describe. All of these concepts were developed in the thirties and not in the last 15 years.

The retro Little Wing embodies all of these advanced concepts and the designer used all the formulas from the thirties to design it.

I am grateful that our government hasn’t gotten more involved as they have in many other countries. I enjoy the freedom.

It would be nice if all gyroplane kit manufactures availed themselves of this readily available knowledge and incorporated it into their designs.

The reality is that the market is so small that most manufactures have a severely limited engineering budget. This requires that the consumer become more knowledgeable and puts the responsibility for surviving on the consumer.

Thank you, Vance

[PW_Plack]

Thom,

I'm grateful for one of the few things left that government doesn't take from me, in the name of protecting me from myself.

Market forces will eventually solve this problem, but right now, there are so many gyro accidents due to flawed construction, maintenance and piloting that the role of bad design is not yet evident to everyone.

The insurance companies are favorite targets of anger, but they are starting to serve a very useful role here as a market force. The requirement at many airports for liability insurance will make insureable gyros more popular. Underwriters have already figured out that if you weed out the pilots who are not rated for rotorcraft/gyroplane, and machines which flagrantly violate the laws of physics, risks go way down. This will eventually hurt sales of unsafe machines, and provide an economic incentive for pilots to train allthe way to a certificate.

And yet, if someone has a new idea and he really wants to build and try it, he'll have the freedom to do so. To let the government throw a blanket over all experimental aviation just to save a few stubborn gyro pilots would hurt the designers and engineers who are dilligently seeking product improvements.

[mikejh]

Hello All

In light of Udi's very sensible thread I though I would copy-in a set of links I put up on a UK forum after doing some research on these issues. These are below.

I see that Aussie Paul is here and the issue of the HStabs for RAFs have been discussed.

What I can't comprehend, as a potential buyer, is how RAF themselves can go on saying nothing about HStabs when American Autogyro, who make an essentually identical Gyro, not only have Hstabs but make KITS for FIXING your RAF !!! Hstabs for the RAF seem to be available from Australia and the US but - incredibly - not from RAF themselves.

Here in the UK, the RAF2000 is very widely known but almost no-one seems to be aware of the American AutoGyro unit.

I had been interested in the RAF and contemplated taking a course in one, but having read what I have about Horizontal stability, I now consider a RAF without an Hstab fitted as just needlessly unstable - so personally, I would not step into one now if you paid me.

I do wonder, sometimes, if anyone actually understands Gyros. Why, for example, does no one ever talk about why Teetering 2-balde rotors are used ? A few minutes commonsense analysis will tell you that a teetering rotor of 2 blades will always have an inherent vibration (at 2 x rotor speed) which would not be there, in a fully-flapping design. And would be much reduced in a 4-blade design... (but completely eliminated by a true cyclic) ?

Best reagrds all (see links below)

Mike H
London England



Re: Gyro Stability Links

I've been doing some research on Gyro stability, and feel I should share some links with anyone else interested in Gyros.

Mike H

Steve Kirkby's original page on pitch stablility concerns
http://www.gyroplanestability.com/index.html

American Autogyro's notes on stablility
http://www.americanautogyro.com/Centerline%20Thrust/Centerline%20Thrust%20P1.htm

Aircraft Designs page on stability and accidents
http://www.aircraftdesigns.com/gyro2.html

American AutoGyro - Sparowhawk
http://www.americanautogyro.com/index.html

Firebird Gyros Australia - Paul Bruty
http://www.firebirdgyros.com/

Paul Bruty's Horizontal Stabiliser add-on for RAF2000s
http://www.retro-composites.com/

American Autogyro's STABLITY FIX KIT for the RAF2000 (their competitor)
http://www.americanautogyro.com/Pricing/AAI%20Price%20List.htm

[Cobra Doc]

Thanks Paul W. I try. Some people are mad at me because of my decisions. I must have been an armadillo in another because it doesn't bother me. But, I am limited to "the lower 48". I wish I could help everybody, but I can't. Considering the number of one-off aircraft and the STC work I have underwritten, as long as I understand the concept I may be able to work with it.

[Doug Riley]

Thom:

Please allow me to add to your history just a bit. (Yes, I was a gyronut back in the late 60's, 70's and on down to the present and I memorized all the gyro literature I could get at the time.) Bensen, Brock and the ORIGINAL Air Command did little to address the pitch stability problem.

Bensen stonewalled the issue throughout his career.

Brock was an ace pilot who (I suspect) didn't care that much about design stability because eventually you reach a skill level where you can fly the box it came in. If you live that long.

The Fetters Air Command company initially had much the same attitude as the other two. They added a small HS eventually, but they did not know how to "do the math" nor really understand what caused PPO. Hence their fix was too timid to solve the problem. See attached photo of a PPOed Air Command that went down here last year; the factory HS is clearly visible; it wasn't enough to save this fellow's life.

The problem is not that the knowledge doesn't exist. The problem is that it got shunted off into dusty archives where it remained unseen for decades. Since the advent of the Internet, patent files can be called up from your living room. That's how we learned that Cierva had patented CLT in the late 20's in England and the early 30's here in the States. The knowledge was there all along!

At the same time, the 'Net has allowed today's thinkers to trade ideas cheaply and quickly. That's how a consensus has been reached among people with formal engineering/physics training throughout the world: people like Jukka Tervamaki of Finland, Jean Fourcade of France, Stewart Houston of Scotland and Beaty and others here in the U.S. Each of these individuals is or was in the aerospace or transportation technology business, and each has an advanced university degree in a relevant branch of science. (Sorry if I skipped one or more of you PhD's out there...).

The only people who don't "believe" in the basics of pitch stability are those who don't understand or don't want to understand. There's no controversy among serious people.

The teetering rotor is used because it isn't susceptible to ground resonance and it allows the use of a light, inexpensive hub. It does shut off all control forces at zero G, which is not that big a deal if the airframe tracks straight. Low G results in the same loss of RRPM, not matter what kind of hub you use.

[dragonflyerthom]

Doug

What amazes me is that, people are waiting for market demands to change the manufactures designs.

As long as the average consumers looks at a gyro it looks good and is tainted in its design rather than do the research then goes and buys it. The mfgs will not change. It doesn't matter how bad the design as long as it sells enough to stay in business.
You say you can fly a box if you can stay alive long enough. Look at the incident yesterday in PR. That was a very high time pilot and now he is dead.
How is a guy susposed to trust the different aftermarket equipment if the construction is faulty. Where is the QC on these Blades. There can be no type of QC on experimental because we build them ourselves. How would ap person know if the rotors weren't constructed correctly??
I personaly don't know enough to know what to check so I will have to rely on and put my life on the experience of my CFI. I guess I'm lucky that I have someone like that.. Ron Said that we would do small hops for about 10 hours before we will even go around the patch.
There has to be a way to straighten all of this mess out.

Thanks


Thom

[Doug Riley]

"There has to be a way to straighten all of this mess out."

Yes, you would think so.

You can dig into the general idea of "experimental" for the root of the problem.

For decades "Experimental" has been a legal cover for those who are marketing aircraft that are very pretty to look at and SEEM to be professionally designed -- but were really eyeballed by untrained shade-tree mechanics. It's perfectly legal to do that. The "Experimental" catgory is the ideal cover. It actually works fine for the seasoned builder-buyer, but it sure can be a trap for the newbie. The slick paint and fiberglass make people think they're buying a Honda Goldwing. All too often, the beauty is only skin deep.

It definitely is a Wild West world out there -- buyer beware!

[Ga6riel]

two rather nice posts from
Brett and Doug
and nice avatar Mike :)

[PW_Plack]

Thom,

What needs straightening out is the idea that consumers will make life-threatening purchase decisions without taking any responsibility for learning about the products first. That's fatal laziness.

Government regulation is a double-edged sword. Government approval can mean either the product was really proven safe, or that it was passed on for the political or economic benefit of the bureaucrats who approved it. The public interprets the approval as a government endorsement of product safety. The government often gets it wrong on the first try.

The US Food & Drug Administration has kept life-saving new drugs out of the hands of consumers for a decade or more in extreme cases, while drugs they approved have later turned out to have terrible side effects.

Give me open reporting and access to news archives, and resources like this forum, and I'll decide for myself.

[chuter]

Ditto what Paul W. said.

[Doug Riley]

Yes, Paul, but...

The "Experimental" category has been misused for decades. Newcomers are apt not to take it seriously. Manufacturers that make other products (say, motorcycles) look out for the safety of their products out of a sense of self-preservation, even if they are basically amoral. In contrast, mom-n-pop marketers of experimental aircraft "kits" have a complete liability shield that Honda, et al, can only dream of. The tiny size of the mom-n-pop kitmakers makes suing them not worthwhile anyway.

Still, some of those kits are (a) marketed using very strong promo language about "engineering" and "design teams" -- even though the machines were in fact eyeballed together by someone who can't even find the area of a rotor disk with a calculator* and (b) are actually complete aircraft knocked down for ease of shipment, requiring only the sort of final assembly that a consumer does with a Wal-Mart barbecue grill. These "kits" might as well be finished aircraft.

Both of these sales tactics, IMHO, throw buyers off their guard and amount to abuses of the spirit of the "Experimental" category. The buyer doesn't realize he's buying something that's amateurishly designed, because he's been led to believe otherwise. Moreover, the aircraft isn't really even "experimental" (small "e") because it doesn't test any new potential advance of the state of the art; it's in fact designed so poorly that it doesn't even meet the CURRENT state of the art.

Asking people who don't know this to see through the glossy advertising is asking a lot. We talk among ourselves, but most of those newbies don't get to listen in.
____________________________
* I'm not exaggerating; I've coached a few gyronauts on this very topic. None of them is designing anything, however, and they had the good sense to ask.

[mceagle]

See attached photo of a PPOed Air Command that went down here last year; the factory HS is clearly visible; it wasn't enough to save this fellow's life. Doug, some very good and informative posts.
The picture of the PPOed Air Command dosen't seem to fit the normal profile of a PPO or PIO accident. The complete tail is still intact and still attached to the tail boom. Very strange!

[dragonflyerthom]

Tim

I went back and looked again You are right. The Rudder is still attached. There is a mark on the rudder but I can only see the mark. I can't tell if it was struck and scrapped by the rotor or the paint is just missing.



Thom

[Timchick]

Doug,
Good posts.

[Doug Riley]

I didn't want to rehash Roger's accident in detail, just wanted to point out that simply slapping some kind of HS on isn't enough. The designer has to understand the principles and be able to do some arithemetic. Many don't, and can't.

(In this crash, the rotor hit the prop. I drew a white circle on the picture at the left to show the spot where the prop dug into one blade. Damage to the rotor head shows that the rotor went wild as a result of a stall on the left side of the craft: spindle bolt bent, contact and gouging of rotor head parts consistent with uncontrolled flapping, etc. The new owners of Air Command company fixed this problem years ago. Roger's aircraft was one of those Fetters-era antiques that still kill someone occasionally. Sadly, the manufacturers of other designs from that era refuse to do what the new Air Command did.)

[PW_Plack]

Doug, all valid points, well expressed.

Asking people who don't know this to see through the glossy advertising is asking a lot.

Perhaps there should be a mandatory test for anyone who'd fly a kit aircraft, making sure he's an informed shopper. I don't welcome more government intrusion than is in my life now, but this would be way better than a ban on anything without a stab, or without CLT. People who've been driving cars for years, and get into motorcycles, get an insurance discount for taking a motorcycle safety course administered by a private-sector organization. Maybe there's a parallel.

We talk among ourselves, but most of those newbies don't get to listen in.

Sure they do. They're reading this discussion right now. All they have to do is Google "gyroplane" and they'll find us. If they don't have at least that much concern for life-or-death decisions, then they're candidates for any number of decision-making failures in the air, too.

Edit: I just tried Googling "gyroplane", and the forum doesn't show up in at least the first four pages. However, if you enter the names of some of the scarier, unstable gyroplane kits, you will find accident discussions in the first few hits.

[Doug Riley]

Paul, a good approximation of the "informed shopper" qualification test would be CFI's who themselves really know and disclose the truth.

Many of them, while great guys and quite dedicated, generous and sincere, really don't know the tech stuff. They're "good sticks," which is admirable but not transferrable to their low-time students. You can't transfuse flight hours like you can Type O.

The concept of "experimentalness" isn't taught or tested in the CFI training regimen. That means it often doesn't trickle down to the students.

It would be great, IMHO, if CFI's were required to have a separate tech merit badge for the privilege of teaching in homebuilt aircraft -- or homebuilt gyros at any rate.

Needless to say, there should be severe sanctions for any CFI who deliberately taught false aerodynamics. Jail would not be too harsh for that, if it were intentional.

Perhaps some of this could be a quid pro quo for FAA's allowing factory-made Light Sport gyros.

Yes, people ought to have the sense to Google "gyroplane" before buying, but obviously many don't. As we know, they're lulled by slick promotion into thinking they are dealing with Honda. Some Honda buyers Google "Honda" before they buy, but how many?

[PW_Plack]

Doug, maybe it's just me, then. I read the web for weeks before I bought my Toyota Tundra in '03. I also researched the competitors in great detail. Perhaps I over-do it. I become very frustrated when I can't find a salesman who knows as much about his product as I do.

[dragonflyerthom]

There you go. Information overload. They get paid to sell not research.


Thom

[mceagle]

The unfortunate situation is that many purchasers of the hogs with lipstick have already made up their minds what they want, and all their subsequent inquiries or investigations are only used to back up their choice. They only hear what they want to hear, and much of what they want to hear comes from the factory.
The few exceptions are those that really want to find out the truth, and go the extra mile to do so, and these mostly go on to do the required modifications and enjoy many safe hours flying.

How to convince the former to do their homework, that is the question.

It should be easier in Australia because you can't get a gyroplane licence unless you are a member of the Australian Sport Rotorcraft Association. Strangely enough, RAF's in Aus haven't got the same bad safety record for some reason - might be simply a lack of numbers.

[dragonflyerthom]

Tim

How many hours are you required to have before you Solo, and then are let loose on a RAF??

Here you can solo and then need only 25 hours for a Sport Pilot License.


Thom

[Ga6riel]

is it too silly to suggest
that, seeing as how there are numerous pdf documents about, and Im thinking of those from asra and others, that are tracking the nature of safety issues with gyros. Could we not provide links too, or get permission from them and provide access too, some of this documentation.

Edit: to add, perhaps there is also some technicly relevent material that widens understanding, such as the documentation from NACA. Mostly stuff that doesnt herald a particular manufacturer

[NewsFlash]

Doug,
Yes, newbies are listening in to what you all are saying. I have been lurking here on this forum almost a month and am trying to stay pretty high on the "learning curve". This forum and NTSB articles about gyro crashes have gotten my attention about how serious the subject of stability is, not to mention you can't learn all about gyros in just a month.

I found Jean Fourcade's article on the internet about stability, coupled with what I am reading on this forum and other websites I have no interest in gyros that are not called "high profile" or "stable" in reference to thrust line and that do not have true horizontal stabilizers. I want to know the "how" and "why" of why gyros are the way they are and if they are unsafe.

I do understand the point of "running what you've got" if somebody has in their possession an unstable gyro that they've learned to fly, either on their own or they received flight instruction. As you say, if they live long enough they should be getting better and better at flying their machine.

Frankly, my interest in them is very slow going. I've never seen one in person or met anybody that had one/flew one. I'm too heavy to ride in a tandem as of right now. I'd be surprised if I even had my own machine 5 years from now, I'll have to wait and see how it goes. But I am enjoying learning all I can about them when I can. I plan to go to one day of SERFI 2006 in a couple of months. Look forward to meeting the people of the gyro community and their amazing machines.

Regards.

[Aussie_Paul]

It should be easier in Australia because you can't get a gyroplane licence unless you are a member of the Australian Sport Rotorcraft Association. Strangely enough, RAF's in Aus haven't got the same bad safety record for some reason - might be simply a lack of numbers.

Tim, it could be because I sold most of the Rafs in Oz, and required them to be fitted with an effective H/Stab. Even though this was a bandaid, it served the purpose by slowing the pitching enough that people could stay in front of the attitude changes.
I only only soloed two people in Rafs without a stab, my brother and a guy in Alice Springs, who had flown aircraft most of his life and who was very mechanical and had the "feel" that is required to fly an unstable machine.

When I was selling Rafs, the company would tell the purchasers that they did not require a stab:eek: . I just took them flying with the stab fitted and then removed the stab and took them flying again. They all fitted stabs. No salesmenship needed.:cool:

Aussie Paul. :)

[Doug Riley]

Newsflash: Good for you. If every gyro wannbe did his homework, especially the Fourcade article, we'd have a better safety record.

Don't be afraid to post questions here, too.

[NewsFlash]

Doug,
Thanks. I have a question already. Is there a list somewhere on this forum that categorizes the different brand gyros by "stable" or "unstable"? As of right now the only pusher gyros I know for sure are stable are the Rotor Flight Dynamics' Ultrawhite and single or tandem Dominator. I also know the Little Wing tractor gyros are stable, but I think they're out of my ability range as far as construction goes, plus I think they're more complicated at least so far as I can tell.

Can you recommend any particular makes or models? I believe your avatar shows you in a tandem Dominator.

Thanks in advance.

[Doug Riley]

Flash: Of course, no manufacturer will admit that its aircraft is unstable.

Even gyros widely recognized to lack objectively demonstrable pitch stability will exhibit some limited stability in a narrow range of circumstances. Those who sell these gyros are adept at showing you this limited stability and blaming all accidents on the "stupid pilot." In many cases, accidents in these craft are actually caused by the pilot straying outside the very narrow stability range of the aircraft.

The flight tests contained within the Light Sport Aircraft gyro certification standards are a rigorous, objective method of investigating stability. I've never run a formal set of these tests on any gyro. I doubt that even a Dominator would pass, as Doms pick up quite a bit of airspeed when the throttle is cut (the standards allow only a 10% increase, if memory serves). This type of non-compliance, however, does not represent a risk of PPO, the most common and vicious form of pitch instability.

There's no list of gyros that DO comply with the LSA standards, because the FAA has not yet authorized LSA gyros. Some manufacturers may have run all the tests privately. You can ask them and hope they tell the truth. The past record of some of them is not encouraging in this regard, though.

Based on thrustline location and the locations and dimensions of their horizontal stabilizers, I BELIEVE that the Air Command CLT models, the Dominators, Sparrowhawk, Gyrobee with Watson tail, Magni and Little Wing are PPO-proof. To my knowledge, there has never been a PPO in any of these models.

I have flown each of these craft except the LW. Again, I've not run the formal LSA stability tests. This opinion is based on numbers and the absence of any indication in flight that the numbers are wrong. My list is incomplete, since I haven't flown everything out there.

[gyroplanes]

There's no list of gyros that DO comply with the LSA standards, because the FAA has not yet authorized LSA gyros.

I have flown each of these craft except the LW. Again, I've not run the formal LSA stability tests.

Doug, I think you are muddying the waters a bit
.
There are ASTM standards that apply only to SLSA aircraft, and gyros are not allowed in SLSA at this time.

The only LSA requirement some gyros have difficulty with is the 1320 lb gross weight limit.

The FAA allows (for the next 17 months) LSA gyros and many have been certified already.

The FAA even allows factory built LSA gyros (for the next 17 months)

The ASTM standards do not become mandatory until the FAA allows SLSA gyroplanes.

Having said that, I would like to emphasize that I think all gyroplanes, from now on, should be built to meet or exceed the ASTM standards.

[Doug Riley]

Tom, I probably am.

I plead total ignorance as to the current Sport Pilot transition "process." I don't plan to participate in Sport Pilot in any way, so I haven't kept up with the regulatory alphabet soup.

The stability tests I referred to are those contained within technical standards published by ASTM. Greg Gremminger has summarized and explained them several times in the PRA magazine over the last few years. If, how, and to what extent the FAA applies them to existing "fat ultralights" or present or future Experimental-Light-Sport gyros, and how (or if) you must document compliance with them for these craft, I have no idea.

Is there in fact a list of those designs that comply?

[gyrofly]

In 1901, Wilbur Wright wrote, "If you seek perfect safety, you should sit on a fence and watch the birds…". The simplicity of our machines, like motorcycles, is one of the things that attracts us and one of the things that will always make us more vulnerable. You can re-engineer the motorcycle until it looks like a Volvo - a lot safer, but ???? People ride motorcycles, climb mountains, fly hang gliders, and yes, fly gyros. They accept risk to have the experience. If the risk is not acceptable, don't do it!
Ralph

Here, Here Ralph...Well said...

[mceagle]

Gidday Tom, a couple of questions
The only LSA requirement some gyros have difficulty with is the 1320 lb gross weight limit.Is it considered that this limit is too low? - 1320 lb would appear to be a fairly heavy Gyro to me.
The FAA allows (for the next 17 months) LSA gyros and many have been certified already.Who "certifies" these Gyros?, i.e. who signs all the paperwork that says that they comply with the LSA standards?

[PW_Plack]

Tim, those standards have nothing to do with stability, or even or airworthiness. They're black-and-white check-boxes such as all-up weight under 1320 lb, no collective pitch control, etc.

[Dean_Dolph]

Unless Tom comes back and says different, Paul is right. The LSA standards apply to all LSA aircraft categories; fixed wing, trikes, powered parachutes and etc.

It is the SLSA aircraft that have to be ceritifed by the factories that they meet the ASTM standards. And those standards do deal with stability and etc.

[gyrogreg]

Seems to be some confusion between "LSA", "ELSA", "SLSA", and ASTM standards.

"LSA" is a definition by the USFAA - not even a certification, and certainly does not require meeting any standard. Just means it meets max weight, 2 seat max, and some other basic criteria that qualifies a "Sport Pilot" to fly it. the definition of LSA does not require that it meet any standard.

A Sport Pilot can fly any aircraft that meets the definition of LSA. That can be an ELSA, and SLSA, or any Experimental or standard certification aircraft that meets the definition of LSA.

There are two types of ELSA:
- "Converted" until Jan '08 from "illegal" uncertified aircraft
- Mostly factory built - factory builds 50% - 99% of the kit.

"ELSA" is an Experimental aircraft that meets the LSA requirements. Currently, and for the next 18 months or so, the USFAA is allowing that unregistered aircraft that meet the definition of LSA can be certified as "Experimental"- ELSA. This includes already existing "illegal ultralights" or unregistered aircraft; and it includes any new gyro built and sold by a manufacturer that is subsequently "converted" to an ELSA within the next 18 months or so. To become an ELSA from an "illegal" aircraft, for the next 18 months or so, requires a (FAA) Designated Airworthiness Representative (like Tommy) to certify it as an ELSA. An ELSA has an "N" number.

After the next 18 months or so, the only ELSA aircraft allowed will then be those that do meet the ASTM standard. These would be 50% - 99% factory built. Gyroplanes will not be allowed to participate in this kind of ELSA - 50% to 99% factory built - because the rules will also not allow SLSA gyroplanes. But, you could still build a 51%, Amateur Built Experimental aircraft- including gyros. Amateur Built Experimental aircraft do not need to meet the ASTM standards. If an Amateur Built (51% builder built) Experimental gyroplane meets the definition of LSA, it can still be flown by a Sport Pilot - it is an LSA. Amateur Built (51%) Experimental aircraft of any type do not need to meet any standard in the U.S. - but they can still meet the "definition" of LSA to be flown by Sport Pilots.

"SLSA" (Special Light Sport Aircraft) are fully factory built that meet the LSA definition. SLSA will be required to meet the ASTM standard. But, gyroplane manufacturers are not currently allowed to build SLSA gyros - excluded from the SLSA rules. This means the LSA market for new gyroplanes, after about 18 months or so, will be limited mostly to the 51% Amateur Built Experimental category.

All aircraft certified as ELSA now and for the next 18 months or so will retain their ELSA certification forever and can be flown by Sport Pilots, and other rated pilots, forever.

In the U.S., any pilot rated in gyroplanes (Recreational or higher rating) or with Sport Pilot gyroplane privileges can fly LSA aircraft - meets the definition of LSA, but does not necessarily meet the ASTM standard. But, Sport Pilot rated gyroplane pilots are limited to flying only gyros that meet the LSA definition - not necessarily meeting any standard!

The ASTM gyroplane standard applies legally in the U.S. only to SLSA and the 50%-99% ELSA gyroplanes. Since neither SLSA or the 50%-99% ELSA gyros are allowed under current U.S. LSA rules, the ASTM gyroplane standard is not currently required at all in the U.S. If, at some time the LSA rules change and SLSA gyroplanes are allowed, all SLSA and 50%-99% ELSA gyros will be required to meet the ASTM gyroplane standards.

The tough thing for some gyro manufacturers to meet is the LSA definition - mostly the weight limit of 1320 Lbs. So, a Sport Pilot cannot fly a gyroplane that has a declared full up gross weight more than 1320 Lbs. Since the gross weight of most experimental aircraft is not required to be declared anywhere, if that gyroplane does not have an established max gross weight (flight manual, nameplate, etc.) it can probably be declared to be no more than 1320 Lbs. But, the FAA would not allow aircraft that had been previously certified or flown at more than 1320 Lbs, to be suddently declared to be 1320 Lbs! Nor would the FAA allow a specific aircraft to be LSA at times it is necessary for a Sport Pilot to fly, but flown at more than 1320 Lbs at other times - can't "flip flop"!

A pilot with a gyroplane rating of Recreational or higher (Sport Pilot is lower) can fly any legal gyroplane - no matter what the weight, top speed, etc.. But a Sport Pilot with gyroplane privileges can only fly a gyro that meets the definition of LSA!

The ASTM gyroplane Design and Performance standard does include stability criteria. It includes other structural, design and performance criteria as well. The ASTM gyroplane standard applies to gyroplanes up to 1600 Lbs max gross wt. - higher than teh definition of LSA! So even heavy gyros can be built in compliance with the whole ASTM gyroplane standard! But, meeting the ASTM standard dows not automatically make it meet the definition of LSA, which sayxs it can weiigh no more than 1320 Lbs!

The U.S. definition of LSA does not require any standard! Only SLSA and the 50-99% ELSA certification require meeting the ASTM standard! (The "converted" ELSA gyros for the next 18 months or so are not rquired to meet any standard either!)

Without any real legal requirement for any gyroplane to meet the ASTM standard in the U.S. at this time, the main purpose of the standard is educational and safety promotion. We are using the standard, especially the stability aspects of the standard, to promote and influence more stable and safe gyroplanes. Armed with knowledge and information about stability that the standard provides and legitimizes, we hope gyro pilots, builders and prospective buyers will ask the pertinment questions to assure they are flying a safe gyroplane - or at least know the flight envelope in which their gyro will be safe and strongly resistant if not totally immune from such traditional gyro demons as PIO, PPO and buntovers. Inherently safer gyroplanes do not necessarily have to meet the full ASTM standards - but I feel the stability criteria in the gyroplane D&P standard is critical if we are ever going to overcome the dilema of continuing pitch stability accidents in gyros!

We encourage all gyro pilots to accomplish the simple static stability flight testing to identify the corners of the flight envelope that present instabilities and risks of PIO, PPO and buntovers - then set those limits (Vne, etc.) and avoid flying within those risky corners of the envelope. The ASTM standard sets the static stability crieria, and the flight testing identifies under what flight conditions (speed, power and loading) PPO and buntovers are prevented. But also, once some unsafe corner of the flight envelope is identified by flight testing, with this information, and the aerodynamic principles we are trying to educate people to understand, often easy and simple modifications can be applied to expand the safe operating envelope - verified again by flight testing!

- Greg Gremminger

[PW_Plack]

Greg says,

...the FAA would not allow aircraft that had been previously certified or flown at more than 1320 Lbs, to be suddently declared to be 1320 Lbs!

An FAA insider who shall remain nameless told me he believes there's a loophole here. If you put a dataplate on an experimental category aircraft and list 1320 max gross weight, then fly it at 1500, there's no violation. The max gross is where the performance charts in the POH (if you have one) stop counting, but there's nothing that says you can't fly above max gross.

And even if you did, are you going to make an "overweight" entry in your log? How would FAA know if you'd previously flown heavy?

[dragonflyerthom]

This is very interesting . Are you saying that if you under weigh your gyro you can make the weight in the certification process.


Thom

[gyroplanes]

Don't confuse issues here. "certified gross weight" applies to standard category certified aircraft only such as the McCulloch J-2 and the Air & Space 18. If either aircraft design were FAA certificated and under 1320 lbs gross weight, they would qualify as meeting the LSA requirements (except for the articulated, 3 bladed rotors).

Experimental Amateur-Built aircraft do not have a certified gross weight. If you bought one of those pre-fab data plates that has a spot for the gross weight, you need not fill it in. The only data plate information requirement is Make, Model and Serial number.

The only place the gross weight of your EA-B (and ELSA for the next 17 months) aircraft is found is in your weight and balance. Any kit manufacturer's estimated gross weight and payload is just that, estimated. You as the aircraft manufacturer, determine the gross weight and payload of your aircraft.

[Chuck Roberg]

Oop's Tom beat me to the post.....

An FAA insider who shall remain nameless told me he believes there's a loophole here. If you put on a dataplate on an experimental category aircraft and list 1320 max gross weight, then fly it at 1500, there's no violation. The max gross is where the performance charts in the POH (if you have one) stop counting, but there's nothing that says you can't fly above max gross.

To add to what Paul said. The only items required to be on the data plate are listed below. Note! it does not require any weights to be listed.

The only weights listed would be in the weight and balance. With any experimental you the builder determine the weight and balance. As such any changes you make to the aircraft would affect the W/B. So the W/B is not etched in stone.

If you change to smaller diameter rotor your W/B weight might go down. Of course this would be after you fly off the required 5 hrs test flight time and make the necessary entry in the aircraft log.

If after additional time you deem it necessary to lower the gross weight for "safety" reasons. Say you do not like the flight characteristics with a heavier passenger or fuel. Then you can change the W/B.

When you change the older W/B sheet(s) with the updated one(s) you are the only person to see them.

Now this might be a "sticky" loophole. I do not know how long before the gov. figures this out?

Data Plate
(a) The identification required by Sec. 45.11 (a) and (b) shall include the following information:
(1) Builder's name.
(2) Model designation.
(3) Builder's serial number.

[KenSandyEggo]

"I do not know how long before the gov. figures this out?"

Probably not long, seeing as we post everything here for everyone to see. But, maybe they're all on vacation this week.

[Chuck Roberg]

Ken, your right. Certain infomation should probably be kept to private emails. :)

[Jazzenjohn]

If someone was the builder of an experimental aircraft and they changed the rotorblades, or the prop, or carbs, or exhaust etc., wouldn't that change other weight, balance, and flight parameters? Would they be allowed to make those types of changes and how difficult would that be?

[gyrogreg]

If someone was the builder of an experimental aircraft and they changed the rotorblades, or the prop, or carbs, or exhaust etc., wouldn't that change other weight, balance, and flight parameters? Would they be allowed to make those types of changes and how difficult would that be?

Not difficult if you are talking Experimental other than 50-90% ELSA! For a 51% Experimental aircraft, you would need to change your Wt & Balance kept in the aircraft. And, if a major change such as these suggestions, you are required to declare another 5 hour Phase I flight test period - then sign it off at the end of 5 hours.

ELSA (50-90% type, after Jan, '08) will require more paperwork - those ELSA are supposed to conform to the ASTM Standard, and changes would need approval of the factory. Don't worry about that for gyros right now though - gyros are not allowed for SLSA or (50-90%) ELSA. After Jan '08, most gyros will be 51% Experimental - you can do almost anything you want to those!

Tom, please correct me if I am wrong. We are talking strictly USA rules here!

Greg Gremminger

PS: I believe that changing rotor blades between heavy and light or different efficiencies can affect stability and controllability. I suggest that rotor blades are not always interchangeable without impacts! The rate of response of one rotor might agravate or dampen natural airframe oscillation rates - change PIO or buntover potential of some gyros. To identify any buntover potentials, do the static flight tests! To avoid in-flight PIO in almost any aircraft, use a large HS mounted far aft of the CG. But, I suggest you don't ignorantly go switching rotor blades without some testing and understanding that things might be different! - that's what the additional Phase I test period is for!

[gyroplanes]

Spot on Greg!

[dragonflyerthom]

Greg I understand that the HS dampens the oscillation of the aircraft but what do you mean natural oscillation rate.?????


Thom

[gyrogreg]

I understand that the HS dampens the oscillation of the aircraft but what do you mean natural oscillation rate.????? Thom

Thom,

A statically stable gyro (also rotor, airplane, car, boat, etc.) will tend to oscillate around rotational axis if disturbed from its static steady state. Talking gyro pitch, it means that it can oscillate nose-high, nose-low, nose-high, etc. in pitch. How fast it does this is the natural oscillation rate. A faster natural oscillation rate is more difficult for a pilot to stop or “dampen”. If the natural oscillation rate is too fast or too strong, it may be difficult for the pilot to avoid PIO!

continued below:

[gyrogreg]

Continued from above:

An aircraft (also rotor, car, boat, etc.) that has positive stability in rotation about any axis - desirable in all vehicles - will tend to return to its "steady state" orientation. For an aircraft, talking pitch, this means that if disturbed from either airspeed, G-Load, or pitch attitude, it will inherently tend to return to straight and level, 1-G, trimmed airspeed. This is STATIC stability.

An aircraft that does not have positive static pitch stability will tend to further divert from trimmed, level, 1-G condition if disturbed. This requires the pilot to be constantly "balancing" airspeed, G-Load and pitch attitude on the "sweet spot". Any small deviation from the "sweet spot” trimmed pitch condition will require the pilot to make constant corrections - jabs and counter jabs - similar to trying to balance a yard stick vertically in the palm of your hand. This is a statically unstable condition - negative static stability. If an aircraft is statically unstable in pitch, especially in G-Load, it is very capable of a buntover! If an aircraft is statically unstable, there is no reason to talk about natural oscillation rate, it just diverts in pitch.
However, the rotational inertia of an aircraft will affect the rate of deviation as pitch diverts from trimmed condition - in other words it would be similar to trying to balance a 3 yard pole vertically in the palm of your hand, vs., a 12 inch stick. Try this, you will see that it might be easier for the pilot to balance a higher rotational inertia gyro, but it can still buntover if the pole gets too tilted in the palm of your hand. So, rotational inertia, mass and length of the gyro, can still can affect PIO or buntover potential. If the gyro itself is not inherently stable, the pilot must be the "stabilizer", balancing pitch at the sweet spot and not letting it divert beyond the pilot's ability to "save" it! A lot of constant work for the pilot!

Now an aircraft that has positive static stability - talking pitch for instance - will inherently try to return to the "sweet spot" of 1-G, level attitude and trimmed airspeed. An aircraft that has positive static stability does not require the pilot to constantly "balance" on the sweet spot, or return the pitch to trimmed condition. In fact, that aircraft will show a degree of resistance to being diverted from the "sweet spot" when the pilot intentionally does so with the stick! This shows up as resistance, or some feedback force in the stick. The pilot tries to divert the aircraft from steady state, and the aircraft inherently says “no you don't, you'll have to force me” - a bit at least! But, in rotorcraft, with the strong cyclic control of the rotor disk, it is still very easy to force the rotor disk to a different attitude and therefore maneuver the gyro - but a statically stable aircraft will resist this at least a bit, and if left to it's own after a diversion from trim, will tend to return to the trimmed condition without pilot help! But, the pilot can always help it too!

Now the gist of your question: The way that a STATICALLY stable aircraft returns to the trimmed condition is its DYNAMIC response. It can tend to return to the static trimmed condition quickly or slowly. It can tend to return by overshooting and oscillating around the "sweet trimmed spot" - oscillating nose high, nose low, nose high, etc. Even if it oscillates around the sweet spot, if it eventually stops oscillating and settles back to level attitude, 1-G and trimmed airspeed, it is said to be POSITIVELY DYNAMICALLY stable! You can see if it never even tries to return to the static "sweet spot", there is no DYNAMIC stability to talk about.

If the oscillations around the pitch "sweet spot" tend to get worse or larger oscillations, nose up, nose down, nose higher up, nose lower down, etc., the aircraft is DYNAMICALLY unstable - negative DYNAMIC stability. If the aircraft does this inherently, it is PIO even without the pilot - just PIOs itself!

If the pilot is the "static stabilizer" - no inherent tendency for the gyro to inherently return to level attitude without pilot help - the pilot's over-control and poorly timed reactions can cause "divergent" oscillations - this is true PIO. If the pilot has help, such as a good DYNAMIC stabilizer (large HS far aft of the CG), the pilot does not have to be so good to avoid PIO. If the natural oscillations of the gyro in pitch are too quick, the pilot will more likely cause that gyro to PIO! If the gyro is strongly inherently DYNAMICALLY stable, it will dampen the pitch oscillations on its own very quickly. Ideally, the pitch dampening is so strong, that even very quick pitch oscillations are stopped without even much "overshoot" on the first oscillation – does not require or even excite the pilot to do anything!

Even if an aircraft is weakly DYNAMICALLY stable or neutrally DYNAMICALLY stable - its natural oscillations just keep oscillating, not getting larger and not getting smaller, if those oscillations are very quick, the pilot’s wrong reactions may induce real, divergent PIO oscillations if he/she improperly tries to stop or "dampen" them. In all cases, and in this case, the natural oscillation rate of the aircraft, is a major factor in whether the pilot has the adequate skills to stop such natural oscillations, or makes them worse - PIO! Even if the airframe might eventually settle down in pitch, wrong pilot control inputs could make the whole system – pilot and aircraft – dynamically unstable – PIO!

The natural oscillation rate – quickness - of the airframe to rotate in pitch, is essentially determined by its rotational moment of inertia. Longer gyros, with the weight spread out along its length more, have higher rotational inertia and will have slower natural oscillations - easier for a pilot to properly correct if needed. (The pilot won’t be needed if the gyro is strongly inherently DYNAMICALLY “damped” though!) Strong inherent DYNAMIC "dampening" is most commonly achieved with a large HS placed far aft from the CG. For such gyros, the pilot does not have to act as the DYNAMIC "dampener" or stabilizer, and chances of PIO - pilot over control making natural oscillations worse - are reduced!

Even a STATICALLY stable gyro can PIO - if its natural oscillation rates are high and the pilot's poorly timed or incorrect corrective inputs just make it worse. (That PIO, however, may not actually end in a buntover, if the gyro is statically not capable of a buntover – so do the static flight testing to see if it is!)

Continued below:

[gyrogreg]

Continued from above:

An easy way to picture dynamic and natural oscillation rate is the analogy of a child on a swing: If the child is on a very tall swing - long ropes - the natural rate of oscillation of the child is very slow. If the swing is short - short ropes, the child will swing quickly back and forth.

Now, if the child pumps their legs at the right timing, "in phase" with the swinging oscillations, they can make it go higher - oscillations get larger or worse (PIO in gyro talk!). But if the child pumps their legs at a different "phase" or timing to the natural oscillations, they can reduce the height of their oscillations and bring the swing to a stop - "dampen" the oscillations!

Now, put a large weight on the swing seat, much heavier than the child. This increases the rotational inertia of the swing. The child will still be able to "pump" the swing to higher oscillations, and they will still be able to "dampen" the oscillations with their leg "pumps", but it will be a lot more work and take longer. Note, with light weight on the swing, or with heavy weight on the swing, the natural oscillation rate of the swing is still the same. But with a shorter swing, the natural oscillation rate of the swing is quicker. This would be analogous to a long, heavy gyro, as compared to a shorter version of the same weight gyro.

Now, on a very short child’s swing, it may oscillate so quickly that the child will find it very difficult to "dampen" the swinging oscillations with their legs, because it is difficult to "pump" their legs that fast, and/or it is difficult to do so with the right timing. This would be analogous to a quick natural oscillating gyro, that is very difficult for the pilot to be the DYNAMIC stabilizer - for this aircraft, it is essential that the gyro itself be strongly dynamically stable to stop the fast pitch oscillations on its own, and not present the opportunity for the pilot to make it worse - PIO!

One more child's swing analogy: Mount a very large flat "wing" on the swing behind the child - flat against the movement of the swing. The air forces on that "dampening" wing as it swings back and forth will make it very hard for the child to make the swing keep swinging. The air against the "wing" fights against the movement of the swing! This is exactly how a HS, mounted far aft from the CG, "dampens" pitch oscillations of the aircraft. As the tail moves upward faster, the downward lift of the HS "wing" increase – inherently dampening the oscillation, eventually stopping the oscillations.

Now on the child's swing, mount the "wing" rigidly much lower below the child. Now that same size "wing" has even more dampening effect, because it is moving faster against the "wind" even when the child swings at the same height. This is analogous to moving the HS further aft from the aircraft's CG! – works better!

Sorry for this length, but I’m on a roll - can't stop now!

So far I have talked only about the natural pitch oscillations of the AIRFRAME as it moves through the air - perhaps with fast natural pitch oscillations, perhaps with slow natural pitch oscillations, and perhaps strongly DYNAMICALLY "damped" or not! But, the ROTOR DISK, separately from what the airframe is doing, also has similar natural reaction rates. Different rotor (disks) will react at different rates when they get cyclic inputs. (It can get cyclic inputs from the pilot moving the stick, or the airframe moving the spindle itself!). If the response of the rotor to airframe cyclic inputs is at a bad rate, it can actually excite a worse or divergent oscillation in the airframe! And vice versa - the airframe can excite a worsening dynamic response in the rotor! Or, the natural oscillation or dynamic rates of the rotor and of the airframe might actually be a dampening effect on the whole system. This might be analogous to the child that just pumps their legs at a fixed rate - not concerned with what it actually takes to swing or dampen the swing. In the child's case, the swing will go through periods of swinging higher, and other periods of swinging lower! Change the rate at which the child pumps their legs, and the whole swing behaves more or less erratically! This is a bit analogous to putting different rotors on a gyro - the combined natural dynamic rates of the rotor and airframe might make things better or might make them worse and more erratic!

Now you say “HUHHHH”! Probably more than you needed to know? I think improved knowledge and understanding improves safety!

- Greg Gremminger

[dragonflyerthom]

O>K> Greg

The way I understand it is similar to shocks on a car. Good shocks bounce once or twice then travel in a smooth straight line. Right. While a car with bad shocks will bounce (like forever) when it hits a bump in the road. Now am I understanding this oscillation thing???


Thom

P>S> I have read your papers on your site.

[gyrogreg]

O>K> The way I understand it is similar to shocks on a car. Good shocks bounce once or twice then travel in a smooth straight line. Right. While a car with bad shocks will bounce (like forever) when it hits a bump in the road. Now am I understanding this oscillation thing??? Thom

Good analogy too! The car's springs and weight would determine its "bounce" Natural Oscillation Rate. But that rate is no different with or without shocks, just damped and not damped! A lot fewer words too!

[dragonflyerthom]

Thanks Greg

Sounds like I finally understand something.



Thom

[Udi]

At first I only saw Greg's post number 158 above and I thought, my gosh - Greg just gave a short and concise answer! Then I saw the rest... oh well.

Just kidding :) Very good posts, Greg. I am glad you are including the rotor in your stability analysis now - this is something I have missed in some of your previous publications. I have been interested in rotor-airframe interactions, with regard to gyro stability, for a long time. This is a subject we don't talk about enough around here.

Udi

[raghu]

But that rate is no different with or without shocks, just damped and not damped! A lot fewer words too!

Just to point out, in fact adding damping to a system does change the frequency. The undamped natural frequency is different from the damped frequency.

[C. Beaty]

But only a little, Raghu.

Reading off the chart, the critically damped frequency is ~80% of the undamped frequency.

[NewsFlash]

Flash: Of course, no manufacturer will admit that its aircraft is unstable.

Yes, I can see that would be the case.

Even gyros widely recognized to lack objectively demonstrable pitch stability will exhibit some limited stability in a narrow range of circumstances. Those who sell these gyros are adept at showing you this limited stability and blaming all accidents on the "stupid pilot." In many cases, accidents in these craft are actually caused by the pilot straying outside the very narrow stability range of the aircraft.

The flight tests contained within the Light Sport Aircraft gyro certification standards are a rigorous, objective method of investigating stability. I've never run a formal set of these tests on any gyro. I doubt that even a Dominator would pass, as Doms pick up quite a bit of airspeed when the throttle is cut (the standards allow only a 10% increase, if memory serves). This type of non-compliance, however, does not represent a risk of PPO, the most common and vicious form of pitch instability.

What is the mechanism behind this increase in airpseed when the throttle is cut? I take it you are meaning horizontal airspeed, not vertical (descending) airspeed. I am studying the FAA Rotorcraft Flying Handbook.

There's no list of gyros that DO comply with the LSA standards, because the FAA has not yet authorized LSA gyros. Some manufacturers may have run all the tests privately. You can ask them and hope they tell the truth. The past record of some of them is not encouraging in this regard, though.

Based on thrustline location and the locations and dimensions of their horizontal stabilizers, I BELIEVE that the Air Command CLT models, the Dominators, Sparrowhawk, Gyrobee with Watson tail, Magni and Little Wing are PPO-proof. To my knowledge, there has never been a PPO in any of these models.

I have flown each of these craft except the LW. Again, I've not run the formal LSA stability tests. This opinion is based on numbers and the absence of any indication in flight that the numbers are wrong. My list is incomplete, since I haven't flown everything out there.

Thanks for sharing this information. Since posting my question I have read your experience with the Gyrobee with Watson tail.

[gyrogreg]

What is the mechanism behind this increase in airpseed when the throttle is cut? I take it you are meaning horizontal airspeed, not vertical (descending) airspeed. I am studying the FAA Rotorcraft Flying Handbook.

I hope Doug or someone will spend more time on this answer. But briefly, any propeller thrustline offset from the CG is a pitch moment applied that is either trying to pitch the nose up or pitch it down. There are other pitching moments on the airframe at the same time - drag line, windscreen nose-down moments, Horizontal Stab up or down moment, and the lift of the rotor if it is not perfectly aligned with the longitudinal CG.

All of these moments change at different airspeeds, airframe pitch angles, propeller thrust, etc. all of these moments balance out to ZERO at some condition of airframe flight pitch angle. If you change or remove any of these, such as propeller thrust, if it is not otherwise compensated (by HS lift reacting directly to propwash for instance), the flight attitude of the airframe must change until all the remaining moments balance again.

In the case of a low prop thrustline (below the aircraft CG), application of thrust is a nose-up moment. Removal of this thrust, removes this nose-up moment and the nose must fly lower to find its new balance. The opposite happens with a prop thrustline that is high, above the aircraft CG.

This change in propeller thrust can be compensated, most easily by causing the HS moment, as a result of the change in propwash at the same time prop thrust changes - thereby reducing the airframe pitch effect of just loss of prop thrust. If done exactly, a change in power (thrust and propwash together), the two moments can exactly compensate each other and provide that the trimmed airspeed, or flight attitude does not change when power is changed. A little change is OK, but too much can be difficult for an inexperienced pilot to learn and can actually cause the gyro to be less statically stable in some flight conditions!

Why does a change in the flight attitude affect the trimmed airspeed?: Because the spindle is connected to the airframe, when the airframe pitch attitude changes, the rotor disk Angle of Attack (AOA) changes. If the nose of the gyro flies a bit nose-lower, the rotor disk will have a lower AOA also, and the trimmed (hands off) airspeed will increase. In order for the pilot to maintain the original trimmed airspeed after a change in power (for these un-balanced type gyros), the pilot must either pull or push on the stick to restore the original rotor disk AOA. But the "trimmed" airspeed, the airspeed the gyro wants to fly without pilot input, will vary directly with the flight attitude of the airframe. If the flight attitude of the gyro changes because of an un-balanced change in propeller thrustline moment, the trimmed airspeed changes as well - and the pilot must apply force on the stick to make it fly different from the "trimmed" airspeed it wants to fly.

Sorry, couldn't do this brief! - Greg

[Doug Riley]

Flash:

A gyro in steady flight will necessarily have all the forces and moments (or torques) on the airframe in balance. Lift equals weight, thrust equal drag and so on.

A high thrustline produces a nose-down moment, or torque. For balanced flight to occur, SOMETHING must be opposing and cancelling that nose-down moment. (Otherwise, the gyro WOULD nose down.)

A properly designed and loaded horizontal stab can do this for modest HTL situations, as in the Gyrobee. The stab pushes down on the tail, holding the nose up.

If there is no HS, or one that's inadequate for the amount of HTL present, then the rotor itself does the job of countering the nose-down moment. This, in turn, requires the aircraft to assume a stance in flight in which the thrustline of the rotor (which is very roughly parallel to the mast in a Bensen-type gyro with "leaned-back" mast) passes in FRONT of the CG. IOW, the rotor thrust pulls UP on the nose, keeping it from dropping.

When the throttle is cut, the rotor thrust pulling up on the nose causes the nose to rise, producing a mini-flare and loss of airspeed.

In a Dominator, the setup is just the opposite. It has a low thrustline (LTL). Engine thrust is well below the CG. Engine thrust tends to rotate the nose UP. To compensate, the rotor thrustline comes down BEHIND the CG. IOW, the rotor is pulling up on the tail. When power is cut, this up-pull by the rotor raises the tail and lowers the nose. This results in an increase in airspeed.

"Airspeed" is normally specified as speed thorugh the air parallel to the aircraft's own horizontal datum line (approximatley the keel's long axis in most gyros). This speed can be somewhat upward, downward, or parallel relative to the horizon. The key point is that this airspeed is what the lifting surface experiences. That's what we care about in managing an aircraft.

I see Greg posted essentially the same info. Read either one, or both.

[mrford61]

Given the above, could a basic test for PPO likelihood be chopping power from full gas and see what the nose does? ie. nose up you need to make changes.

I had one gyro that reared up quite severe years ago. I thought it was a good thing so if the motor stopped suddenly I wouldnt go negative!!:o :o


Mark Clifford - Aus.

[Doug Riley]

Yes. That's one of the tests of static stability contained in the ASTM standards that almost became law in the U.S. for factory-built Light Sport Aircraft.

The nose should neither "rear up" nor drop so much that airspeed increases greatly. The gyro should hold its airspeed within a narrow range as power is cut. That will require a gentle nose drop.

[gyrogreg]

Given the above, could a basic test for PPO likelihood be chopping power from full gas and see what the nose does? ie. nose up you need to make changes. I had one gyro that reared up quite severe years ago. I thought it was a good thing so if the motor stopped suddenly I wouldnt go negative!!:o :o Mark Clifford - Aus.

Don't chop power! I did this (before I knew better) on a LOW prop thrustline at 70 mph - to see what happens! - I was suddenly looking at the runway. My natural reaction was immediate aft stick - but an inexperienced pilot might initiate an over-reaction or not properly apply aft stick, or have enough aft stick, to avoid a precession stall of the rotor blades!.

What you described as "reared up" is the response of an unbalanced HIGH prop thrustline. These are the type that had been traditionally associated with PPO - most older design gyros of the past. In fact these are part of the reason for the old instructions to reduce power if you start getting uncomfortable at higher speeds. On a HIGH prop thrustline gyro, a reduction in power will raise the nose to a more G-Load stable flight condition. The opposite can happen if a low prop thrustline is unbalanced - resulting in a less G-Load stable flight condition with reduced power.

In any case, don't "chop" power. If your prop thrustline offset is significant, and if the HS is not appropriately balancing the offset prop thrustline by its reaction to propwash, a "chop" in power can severely pitch the nose up or down. This is the main reason the FAA strongly advises a good degree of "Power Static Stability" - the nose should not respond radically upon sudden changes in power - such as when a student might "chop" or pulse the power upon a botched landing - the nose might suddenly be eating the runway, or you might balloon up suddenly to find yourself ten feet off the runway at very low airspeed in a nose-up attitude.

But, the more important reason in a gyro that you want a degree of "Power Static Stability" is that upon changes in power setting, the gyro static G-Load stability is affected - maybe for the better, maybe for the worse. In the case of a significant unbalanced prop thrustline offset, a radical quick change in power could actually start the nose-dropping so fast toward an unstable condition that a buntover is possible! If the nose pitch attitude changes rapidly radically at all, it is possible to excite the pilot into over-reaction and possible PIO - if that gyro is also capable of PIO. If a gyro has poor Static Power Stability - pitch reacts badly to power change - it also probably has no significant horizontal stabilizer and is likely very capable of PIO!

Also, for a rotorcraft of any type, a sudden radical change in the cyclic input to the rotor - from the pilot or from a pitching airframe - is too severe, the rotor is capable of a precession stall. That means it "flaps" extremely and the rotor starts hitting things. This is often also refered to as a buntover, and the causes - G-Load unstable gyro - are the same, but it is not exactly the same progressive positive G-Load divergence of a true buntover. But, the results are still the same - parts hitting and separating from the gyro, and a grieving family!

The better and proper way to test for "Static Power Stability" is to slowly adjust power and see how much the trimmed airspeed changes from the original trimmed airspeed. You are invited to read my article on how to test this in the August 2005 issue of PRA Rotorcraft.

In fact, I recommend you read all that series of articles on static testing - your perception of what causes buntovers (or a PPO) may be a bit weak - knowledge is safety and none of us can have too much knowledge! G-Load static stability is a measaure of whether a particular gyro, at a particular combination of power, airspeed and loading, is possible to buntover!

Don't "chop" power, especially until you have actually performed the Power Static Stability test to see how bad it might be.

Please don't take this message of doom and gloom as meaning gyros are inherently unsafe for these reasons. A gyro can be easily designed or modified to be PIO, and buntover (including PPO) immune - with the proper balance of the Horzontal Stab to the propeller thrustline offset and the airframe drag characteristics. In fact, it is my belief, such a properly arranged gyroplane is much safer than any other type of aircraft - especially at higher airspeeds and in turbulent air! If you do a gyroplane right, it is the safest and easiest to fly and most forgiving and most wind insensitive secret in sport aviation! Do it wrong and - well that is the reason many people consider gyros to be unsafe!

Thanks, Greg Gremminger

[mrford61]

Appreciate what you are saying re chopping power Greg. In an unknown machine it could bring you unstuck.

The way I have set my current machine up you could work the throttle like a dirt bike without a significant reaction in pitch. It does however nose slowly over when I close the throttle but still requires some forward stick to maintain a reasonable glide speed.
In reverse, if I gas it she just climbs. If I want to climb fast it needs a little back stick.

Does Static Power Stability improve your "behind the power curve" recovery.?

Thanks

Mark.C.

[mrford61]

Appreciate what you are saying re chopping power Greg. In an unknown machine it could bring you unstuck.

The way I have set my current machine up you could work the throttle like a dirt bike without a significant reaction in pitch. It does however nose slowly over when I close the throttle but still requires some forward stick to maintain a reasonable glide speed.
In reverse, if I gas it she just climbs. If I want to climb fast it needs a little back stick.

Does Static Power Stability improve your "behind the power curve" recovery.?

Thanks

Mark.C.

[gyrogreg]

Does Static Power Stability improve your "behind the power curve" recovery.? Thanks Mark.C.

I can't think of how Static Power Stability has anything to do with behind the power curve recovery - except that a bad pitch response with power changes could put you behind the power curve real bad if the nose jumps up and you are suddenly nose-high and slow.

Static Power Stability comes in a number of flavors - Power, Airspeed, G-Load (Maneuvering), attitude, AOA. The first three are criteria identified in the ASTM LSA gyroplane standard - they basically cover the critical static stabilities - attitude and AOA being more a result of these three:

Static Power Stability: Airspeed and airframe flight attitude do not change radically with power changes

Static Airspeed Stability: Airspeed is inherently maintained at trimmed airspeed and always tends to return to trimmed airspeed upon a disturbance. This basically means to go faster you must push on the cyclic stick, and to go slower, you must pull on the cyclic stick.

Static G-Load (or Maneuvering) Stability: G-load is inherently maintained at 1 G and tends to return to 1 G if distrubed. (If G-Load always tries to return to 1 G if disturbed, the aircraft will be inherently resistant to or immune from a buntover. A buntover is a divergent G-Load. If G-Load always tries to get worse - diverge - when disturbed, it is G-Load unstable. If the G-Load disturbance is in the direction of less G-Load, and the gyro inherently tends to make it wors to even less G-Load, that is a buntover in the making!)

Knowledge is safety. You can't have too much knowledge. Power Curve is a different animal than stability - but also important to fully understand and appreciate. I recommend you read and review any stability articles you can find - old issues of Rotorcraft, my Magni USA FEATURES (http://www.magnigyro.com/USA/features.htm) page of articles, etc. I also recommend you purchase and read the FAA Rotorcraft Flying Handbook to learn about some basic gyroplane principles.

Thanks, Greg

[dragonflyerthom]

Greg

Please digress a little on the Static Airspeed Stability of a Gyro. My Question is If you are pushing on the cyclic in order to go faster and there is a disturbance, Why would the aircraft go back to trimmed airspeed????

Thom

[gyrogreg]

Greg

Please digress a little on the Static Airspeed Stability of a Gyro. My Question is If you are pushing on the cyclic in order to go faster and there is a disturbance, Why would the aircraft go back to trimmed airspeed????

Thom

Hi Thom,

If you are pushing or pulling on the stick, you are disturbing it from its trimmed condition and it IS trying to return to its trimmed airspeed - which is why you have to be pushing or pulling on it in the first place - to not let it return to its "trimmed" airspeed! Of course, if you are continuing to push or pull on the stick, it would not return to its trimmed airspeed until you stop pushing or pulling.

Essentially, when the pilot is "commanding" a distrubance from "trimmed" condition - you want to fly faster or slower - the pilot's arm pressure is actually an additional trim spring pressure establishing a new "trimmed" airspeed condition.

This new trim spring, or any trim spring, essentially sets the "trimmed" POSITION of the cyclic stick - a balance of the trim spring balancing the rotor load with the offset gimble lever, and any additional trim force provided by the pilot's arm (spring). So, Airspeed Static Stability actually says that the stick position, whether held there by the trim spring alone, or the trim spring and the pilot's arm, sets the airspeed (at that gross weight).

So, for Static Airspeed Stability, it should require both a push on the stick, and an actual movement of the stick to a new forward position in order to go faster. At this faster airspeed, the pilot can either maintain that airspeed by continuing to push on the stick - subtract some tension from the trim spring tension - or actually loosen up the trim spring to maintain that new "trimmed" airspeed. When the new "Trimmed" airspeed is established, the airspeed static stability of the gyro will inherently cause the aircraft to return to that "trimmed" airspeed if an outside disturbance occurs - such as wind gust. Hopefully, a power change doesn't change the airspeed that much, but that would be a measure of POWER stability, not airspeed stability. If the gyro is not perfectly Power stable, a change in power will actually change the gyros "trimmed" airspeed" - also requiring the pilot to push or pull on the stick to re-establish the original airspeed before power was changed. Hopefully, this isn't a lot of push or pull, or moving the stick a lot forward or aft when power changes. (I can't really think of any other real disturbance an aircraft might encounter - just pilot commanded input and/or wind disturbance!)


Whether the aircraft is flying at its own "trimmed" airspeed" or at a new one when you add your arm "trim spring", with a wind disturbance from that airspeed, the stable gyro will tend to inherently return to that "trimmed" airspeed condition - whether it is just the trim spring, or it is your arm adding to the trim spring.

Digressed enough? - Greg

[dragonflyerthom]

I have what you are saying now. Lets say you are on the lake. You are trimmed straight and going 40 mph. You hit a wake and it propells you into the air and you are now going 42 mph because you now nave less drag. When you hit the water again you will slowdown at first because of the drag on the water and the prop hasn't slowed yet and then go back to 40 mph. Is that about it? Now why is it important to go back to the Static Air Speed after the disturbance?? Wouldn't that be called Cruising??? Like a bump in the road. Why would a gyro not be able to achieve this all of the time??? Especially when you have the lock on.

Thom

Yes very nicely

Thom

[dragonflyerthom]

cruise control.

That I understand.

Thom

[gyrogreg]

Lets say you are on the lake. You are trimmed straight and going 40 mph. You hit a wake and it propells you into the air and you are now going 42 mph because you now nave less drag. When you hit the water again you will slowdown at first because of the drag on the water and the prop hasn't slowed yet and then go back to 40 mph. Is that about it? Now why is it important to go back to the Static Air Speed after the disturbance?? Wouldn't that be called Cruising??? Like a bump in the road. Why would a gyro not be able to achieve this all of the time??? Especially when you have the lock on.

I'm not sure I see the analogy of an aircraft's static airspeed stability and a skier on a lake!? A better analogy might be the cruise control in your car. You set the speed, and, regardless of any external disturbance - such as a hill or a lot of wind, the car always tries to return back to the cruise speed setting. The difference with the cruise control analogy is that if the car driver presses on the accelerator, the cruise control normally kicks our. But, if you imagined that the cruise control did not kick out, you would feel that the accelerator pedal resists your trying to go faster - doesn't prevent it, but resists your efforts. When you then remove your foot from the accelerator, the accelerator goes back to its "trimmed" condition and the car returns to the "trimmed" cruise speed setting speed.

Why do we want an aircraft to always be trying to return back to the "trimmed" airspeed? There are numbers of reasons, and I don't have time to detail all of them:

It is inherently more natural for a human being to make adjustments around a static condition in the direction of the change desired. In an airspeed unstable condition, when the airspeed would be above the "trimmed" airspeed, for instance, the pilot would be required to be pulling aft on the stick while maintaining the stick at the faster more forward stick position!!? This is certainly a confusing situation - especially for a low time pilot! Stick forces and stick displacement should always be in the direction of the desired speed change. This natural human response is more easily mastered by a student.

It is desirable that the pilot need not apply constant pressure to the stick to just cruise. It is not desirable for the pilot to have to hold constant pressure, or be balancing the airspeed on a critical point all the time. It is natural that the pilot apply stick pressures and movements in order to maneuver or change airspeed, but not to just maintain a steady state condition.

If airspeed is actually statically unstable, that would require constant pilot attention to keep airspeed on the "sweet spot" or maintain the "trimmed" condition. This is similar to the workload and skill required to balance a yardstick vertically in the palm of your hand. If the airspeed is disturbed from the "trimmed sweet spot" where pilot required pressures are minimal, it requires more pilot stick pressure the further the divergence is - and the airspeed unstable aircraft tries harder to further diverge from the "trimmed" condition.

Pilot workload: In an airspeed unstable aircraft, the pilot is constantly having to make adjustments to "balance" the airspeed at the "trimmed" condition - such as constantly working to balance the yard stick vertically in the palm of your hand. In a traditionally (old style) unstable gyro, this is why it was described that you fly a gyro "with jabs and counter jabs". That's what you have to do to balance a yardstick in the palm of your hand too! In an airspeed stable aircraft, the pilot has little or no workload. The only workload required is when the pilot wants to vary from the "trimmed condition - similar to hanging a yardstick vertically down from your fingers. In this condition, the pilot has to do something to move the yardstick to a new position over the floor, but, the pilot does not have to do anything to just remain stationary or static at a certain point over the floor!


For instance, if the aircraft is trimmed to fly hands off at 50 mph, the stick pressures at 51 mph are minimal, but the aircraft is inherently trying to go faster - 52 mph. If the pilot allows or does not correct this small divergence, the aircraft naturally tries to go faster - 55 mph! Now, as the divergence from "trimmed" airspeed is allowed to get worse, the stick pressures required from the pilot are heavier. At some point of higher diversion from "trimmed" airspeed the pilot may not actually be able to properly restore the "trimmed" condition properly - maybe the forces are too strong and discourage the pilot from applying the strong stick forces required, or maybe the heavy increasing forces initiate over-control from the pilot - possible PIO.

How could a gyro be statically airspeed unstable? One way I experienced is if the rotor blade has insufficient reflex on its trailing edge, when airspeed increases above the "trimmed" sweet spot, the stick starts pulling stronger and stronger forward, increasing speed and causing more forward stick pressures. This is certainly not a safe condition for any pilot, but it is certainly very dangerous for a low skilled pilot!

Another way that a gyro could be statically airspeed unstable is for the HS to have an up-lift on it in flight. Just as in AIRPLANE stability 101, a down-loaded HS balances the forward CG and adjusts its down-load in the airspeed restorative direction as a function of airspeed - so it regulates airspeed to the "trimmed" condition. But, if a HS has an in-flight up-load on it, if airspeed increases, the HS provides more tail-up, nose-down moment - speed increases or runs asway to higher and higher airspeeds. This works exactly the same in a gyro - if the tail is normally pushing up, it pushes up harder at higehr airspeeds and airspeed therfeore becomes higher. This is a divergent airspeed condition where higher airspeed feeds on higher airspeed and the aircraft just simply tries to go faster and faster. The same thing can happen in the slower direction below the "trimmed" airspeed point.

Thanks, Greg

[dragonflyerthom]

Now Greg everything you have just written is based on having the throttle set. Right? So with everything being equal Lift weight and thrust drag and the throttle set there should be no airspeed increase if the trim is in place. Only if there is a divergence from the "sweet spot" would instability have set in or divergence from the trimmed condition has initiated instability in the static airspeed. both are the same right

Thom

[gyrogreg]

Now Greg everything you have just written is based on having the throttle set. Right? So with everything being equal Lift weight and thrust drag and the throttle set there should be no airspeed increase if the trim is in place. Only if there is a divergence from the "sweet spot" would instability have set in or divergence from the trimmed condition has initiated instability in the static airspeed. both are the same right? Thom

Thom,

I am very glad you are asking such questions - knowledge is safety. But, I'd recommend you read some of the articles I have referenced to get a better understanding of the whole subject of stability.

I am happy to help educate, but I may not have time for a lot more here. I'll try to clear up your confusion here - but, without getting into the full subject of stability, I may just provoke more questions:

What I have described about static airspeed stability here does not have much to do with the power setting. If the gyro is not perfectly POWER stable, when power is changed, the "trimmed" airspeed will change. Hopefully not too much so as to complicate and confuse control of the aircraft when power is changed. Probably no aircraft are perfect in this, but, ideally, power could be changed and the aircraft would automatically return to its original "trimmed" airspeed. But, even if POWER stability is not perfect, and a change in power causes a change in the "trimmed" airspeed, static airspeed stability would now try to maintain the (new) trimmed airspeed.

Airspeed stability is always in play, no matter what the "trimmed" airspeed is – no matter whether the airspeed is at the trimmed airspeed or not! If you change the tension on the trim spring, or you adjust power, or even if you hold the stick in a new airspeed position, Airspeed Static Stability always would tend to maintain that (new) "trimmed" airspeed! Stability does not just kick in just when there is a divergence. Stability is always in play – OR NOT if the aircraft is unstable!

The trim spring working with the offset gimbal leverage will "trim" the gyro to a speed set point - the "Sweet Spot" - whether the gyro is airspeed stable or not!. But, if the gyro is airspeed stable, the gyro will always stay at that airspeed and return to that airspeed if disturbed or temporarily "commanded" by the pilot. An Airspeed unstable gyro, still has a "trimmed" sweet spot - where stick forces to change airspeed are minimal, BUT, if the airspeed changes from that "trimmed" airspeed, it will try to get worse - diverge - from that "trimmed" airspeed. This results in continued divergence from that airspeed requiring more and more force from the pilot to get back to that "trimmed" sweet spot again. AND, if the pilot did nothing, the gyro would just continue to get worse and worse in speed - faster and faster, or slower and slower - if the pilot does nothing when the airspeed is disturbed to above or below the "trimmed" airspeed.

One more comment: An aircraft may be stable at one flight condition (power, airspeed and loading), and unstable in another “corner” of its operating envelope! That means a gyro might be perfectly stable – in all regards (Airspeed and G-Load included) at a certain speed and power. But, it may be unstable at another combination of airspeed and power – such as at high airspeed and low or high power. This is why static stability should be confirmed to be positive over the whole range of operating conditions. A particular gyro might be perfectly stable and even buntover immune at a lower airspeed, but that same gyro might be unsafely unstable at a higher airspeed.

So, I guess you could say, for such gyros, an increase in power could lead to an unstable condition, but his does not have to be the case in all gyro designs. It is actually very easy to design a gyro to maintain good stability throughout the full operating range – but some things have to be done right and the gyro must be tested to verify stability over the whole operating range – read about Static Stability testing in recent past issues of rotorcraft magazine!


Thanks, Greg

PS: If you post any more questions on this forum thread, I am hoping Doug or someone will step in and answer for you – I’m not going to have much time for a while now! But, please don’t let that discourage you from investigating, reading or asking questions, there are lots of people that can help you too! Too many people don’t ask enough questions! - Greg

[dragonflyerthom]

Greg

Thank you for your time.

Thom

PS I have now read all of your articles twice. Can't say I really understand them better but. I will be working on my RAF after it is airworthy and I can begin to fly off my hours. This really gives me something to do while flying.

[Dean_Dolph]

........
IMHO, the absence of research money and knowhow is the most serious of this bunch of issues. Heck, you CAN get good training if you are persistent enough. You CAN build, maintain and fly your machine in a first-class manner. You CAN pick a design that at least can't PPO.

But there's nothing that an individual can do about the fact that we don't have the brilliant, well-equipped PhD's at NACA (now NASA) doing gyro research anymore. Damn.
.......Doug, you have mentioned several times that what is needed is a research effort(s) and Chuck B. has seconded that in a way.

But, the fact is that it is unlikely that this research will take place until someone, or a bunch of someones, that has considerable knowledge, takes on the task of approaching a university or organization and raises this issue. I'm not sure what credentials would be needed to get people to listen to a proposal but we have a few here that should warrant listening to. The following post by Paul Plack that was in a 'Grants' thread is a long this vein. http://www.rotaryforum.com/forum/showthread.php?p=125341#poststop

So, when do you, Chuck, Raghu, and others want to start?!

[PW_Plack]

Doug, the ZCAV prop guys (http://www.zcav.com) are 90% there on the test rig you imagined. Just need to increase AoA about 97 degrees!

[Doug Riley]

Paul, Jim McCutchen and Jay Carter (of Cartercopter) both did auto-mounted rotor test rigs, too. It's an old idea.

The new info I'd like to gather has to do with RRPM decay rates in low G and the behavior of the rotor when cyclic pitch is applied at quantified rates. I don't know of anyone who's done this with gyro rotors.

NACA modelled gyro rotors as the rough equivalent of fixed wings. That's nice but sheds no light into the dark corners that we've sometimes found ourselves in with Bensen-style gyros. The question boils down to the behavior of gyro rotors during and right after precessions of the disk. It would be helpful to quantify this transitional behavior so we know better where our limits are.

We already know that gyro rotors are inefficient (but amazingly docile) in steady-state flight.

[JPHarrison]

A gyroplane is an aircraft like any other and must be designed and operated to the various standards developed over the past 100 years. Why did the Autogiros developed by Cierva and his licensees establish the best safety records of any type of aircraft, even though each successive model incorporated technological and operational advances? The reason is the Autogiros were designed and operated by professionals who observed the prevailing aviation standards of the day. Compare this with the Bensen aircraft (and its derivatives): build it yourself from available materials and teach yourself to fly it. Bensen and his followers must have made an exhaustive study of preceding Autogiro technology and design standards (all which is readily available with a little effort) - because very little of it was employed in the various gyrocopters. Coupled with the use of a teetering rotor, the outcome of such activity is very predictable. Consider for a moment why the Cierva Autogiros did not use teetering rotors?

I own and operate two Air & Space 18As, and a Piper Twin Comanche - all maintained as specified by the FAA approved maintenance manuals by FAA licensed mechanics. Guess what? I don't have any maintenance problems. I also hold CPL/CFI certificates in gyroplanes, in addition to ATP multi-engine airplane, CPL single-engine airplane, PPL singe-engine seaplane, and CFI-ASE, CFI-AI and CFI-AME, and take very seriously the pilot training and currency requirements in each of these aircraft. Guess what? I don't have any problems in operating these aircraft either.

Attempting to engage in aviation activities on the cheap, with little or no training, in poorly designed "aircraft", while taking seriously an organization like PRA that is assumed to incorporate much more expertise than it has ever earned, is a recipe for disaster. Review of NTSB accident reports indicate that over 99% of gyroplane accidents are in experimental gyroplanes. Those very few accidents that do occur in certificated gyroplanes are due overwhelmingly to pilot error.

I display my 18As at aviation events but purposely avoid association with experimental gyroplanes due to the appropriately earned negative reputation established by the latter.

[Doug Riley]

JP -- That's a little harsh.

Cierva didn't use teetering rotors because they hadn't been invented yet. They were developed in the late WWII period, by Arthur Young, a mathematician, first working on his own and later as an arm of Bell Aircraft. The teetering rotor reduces weight, complexity, cost and number of failure modes. It also is immune from ground resonance. It's featured on many, many certified rotorcraft.

Ray Umbaugh of Air and Space fame began with Bensen-style gyros.

The 18A is a magnificent machine, but even it has a black hole in its performance envelope thanks to divergent slip-roll coupling. This nearly cost the design its type certificate. Most other gyros can be slipped as radically as you like with no ill effect.

The experimental gyro world certainly contains its share of nutballs and ignoramuses (as does the world of experimental fixed-wing aircraft). The lion's share of the experimental gyro crashes, however, are attributable to two or three manufacturers, past and present, who have refused to fix obvious defects in their designs.

We also have our share of professional engineers and PhD's who have found gyroplanes an intriguing and rewarding challenge, often for decades.

It's not fair to paint everyone with the same dirty brush. Save that for the jerks who really deserve it.

EDIT: Igor Bensen was many things, not all of them good. He was a professional engineer and a stickler about materials specs, however. Far from advocating construction with whatever is available, he included a multi-page materials spec sheet with his plans. The one that came with mine in 1969 listed four different aluminum alloys, at least that many steels, various kinds of wood and even a specific type of phenolic tube for the wheel spacers. The AN hardware list was longer still. The casual appearance of a Bensen gyro is deceptive in that regard.

[C. Beaty]

Coupled with the use of a teetering rotor, the outcome of such activity is very predictable.

Review of NTSB accident reports indicate that over 99% of gyroplane accidents are in experimental gyroplanes. Those very few accidents that do occur in certificated gyroplanes are due overwhelmingly to pilot error.
There is no difference in terms of control power between teetering rotors and multiblade rotors with central flap hinges. The minimal flap hinge offset of an A&S-18 makes it very nearly central.

That 99% of all gyroplane accidents occur with experimentals isn’t surprising since they comprise 99% of the fleet.

The A&S-18 isn’t without its warts. The built in yaw/roll coupling resulted in a number of fatal accidents when it first arrived in the hands of the public. And apparently one just a few years at Lakeland where Don Farrington lost his life.

The large amount of delta-3 coupling employed by the A&S-18 as part of the jump takeoff scheme also results in excessive roll/pitch coupling.

[Udi]

...Review of NTSB accident reports indicate that over 99% of gyroplane accidents are in experimental gyroplanes. Those very few accidents that do occur in certificated gyroplanes are due overwhelmingly to pilot error...
I found this claim interesting, so I went to the NTSB web site to review the numbers. The data is very interesting. Here are some actual facts from the NTSB database:

Between the years 1966-2004, 7% of all non-fatal gyroplane accidents (355) were A&S 18A and 7.9% were J-2 (a total of 14.9% for certificated gyros). During the same period of time 2.5% of all fatal gyroplane accidents were in A&S 18A and 1% J-2 (a total of 3.5% for certificated gyros).

Other than the latest accident, which involved a student pilot on a night cross country flight, 9 our of the last 10 accidents involving A&S 18A were piloted by either an ATP and/or a CFI - all with many thousands of hours of air time. Here is one example: http://www.ntsb.gov/ntsb/GenPDF.asp?id=MIA00LA133&rpt=fa

The FAA aircraft registration database shows 44 registered A&S 18A, 45 J-2s, 760 Bensens, 169 Air Commands, 245 RAF 2000s, 1334 Bensen B-8M, etc.

If anything, these statistics tell me the low-time amateur Bensen pilots have a MUCH better safety record than the highly trained A&S 18A gyro pilot.

Udi

[Udi]

p.s. another interesting way to look at this data:

Out of about 50 registered A&S 18A 30 had accidents, 5 of them fatal, between 1966 to 2004. One in every ten is dead. Most are seem to have been flown by professional pilots.

Udi

[dragonflyerthom]

Udi

I think we need you to review the stats from the war in Iraq. ha ha
According to your numbers then almost half of the A&S 18As and J-2s have been crashed or killed someone. It includes about 12% of the registered fleet and 14.5% of the total accidents? I wonder what the percent other than this is?? Looking at these stats makes me wonder if the Cabin drag has something to do with this.

Thanks Udi

Thom

[Udi]

These are not "my" numbers, Thom. Anyone can go into the NTSB database (http://www.ntsb.gov/ntsb/query.asp) and search under category "gyroplanes", and place 18A or any model you are interested in in the "make/model" box. Without hard data this discussion would have no basis.

Remember that not all the accidents reported are serious, but the A&S 18A seem to have a fair number of accidents for the fleet size.

Udi

[automan1223]

Doctors can kill a man by disabling less than 1% of his body.

I think the same can be said for all aircraft.

Good response doug, and chuck !

Jonathan

[dragonflyerthom]

Hey Udi

Did JP read the same report you did?????Figures never lie but liars can figure.


Thom