View Full Version : RAF 2000 H/stab
12-06-2003, 04:35 PM
I'm planning on building a RAF 2000 and I would like to hear about peoples H/stab opinions and experiances on the RAF or other machines. I know RAF still feels their rubber cushed mast is a stabilizer, and it is somewhat.
12-06-2003, 11:56 PM
I would like to suggest you explore the possibility of adding the AAI CLT Mod Kit. It costs a few more bucks but your finished aircraft will fly like a SparrowHawk. You are not all that far away from Buckeye Az. and if you want I will set up a demo flight in either an AAI modified RAF or a SparrowHawk. You will spend 300 to 500 hours making you aircraft. If you add the AAI Mod Kit you will have the state of the art in safe, stable gyroplanes and I believe your higher resale value would more than cover your additional investment. You will have center line thrust, tough forgiving landing gear and many more new features. Check out the info on the Mod Kit at americanautogyro.com
12-07-2003, 06:36 AM
Who told you that the RAF mast is a stabalizer?
12-07-2003, 12:57 PM
::) awwwwww geeeesh ...........
:o here we go AGAIN!! :'(
12-07-2003, 04:01 PM
Do you think it is?
If you do how about explaining it to me.
12-07-2003, 04:56 PM
RAF told me it was. Do I think it is, I don't know. That's why I asked.
12-08-2003, 05:38 AM
Gaylon, There is Absolutley no doubt the RAF can and will easily PIO and PPO with no stab. With out the Magic mast it would happen even easier.
the best thing the Magic mast does is help take out rotor shake.
A stab on a RAF makes it reasonably safe. It dampens the machine in turbulence and allows the pilot a chance to stay on top of the pilotage to keep the spinning side up where it belongs.
With all the evidence and proof on the rotorcraft fourms, Anyone that still did fly a RAF with no stab, is a - and sorry to sound like Craig Wall here - but that person is a Freaking MORON. It is rolling the dice with your life and your odds are low.
If you had a RAF it is best to do the CLT route, like the Sparrowhawk kit. this gives you a quite safe and user friendly machine. It takes away several factors that can become deadly in a standard RAF and leaves you with a stable flying machine that you can fly relaxed.
But you don't have to go CLT, Proper training and careful flying with a standard RAF with stab is reasonably safe. Without the stab there is only luck keeping you from Bunting over to your death. This is all fact not just my two cents.
12-08-2003, 06:04 PM
Thank you for your honesty. Sometimes that is a rare commodity. I believe a h/stab is necessary to safe flight.
12-08-2003, 11:07 PM
Ron, the "magic" mast actually makes the pitch instability worse, but it does absorb and dampen rotor shake.
12-09-2003, 08:58 PM
;D And another consideration.
12-09-2003, 09:04 PM
;D Here's a link to a nice home made stab.
12-10-2003, 12:46 AM
I added a stab from Don Parham, it's light and effective.
Where did you find that picture of the "stablator"?
Is RAF starting to market them?
12-10-2003, 04:46 AM
I called and talked with Duane yesterday and he explained his consept and design. It sounds very interesting. Duane is now in Seminole Oklahoma. Thanks for posting the pic. I had not seen the stablator.
12-10-2003, 06:58 AM
Duannes Stab does NOT NOT NOT NOT NOT stablize the airframe. Only the rotorblades.
The Airframe is the part with the extremely high thrustline with the 130 plus horsepower engine.
Without either CLT or a properly set up stab on the AIRFRAME, the gyro is still begging to do a buntover.
There is NO stablization to the airframe by Duannes Stab. Just look at it and picture the forces it produces and how they would stop or counter the high thrustlines desire to flip the gyro over.
It is my honest opinion that the only reason this RAF stab is even here is to tell folks like you Gaylon - folks that have learned enough about RAF and gyros to know you want a stab on your machine - that there is a stab for RAF's approved by the factory. It is just so they can say they offer a stab. But for some reason they refuse to put a proper stab in the proper place - on the airframe not the rotor.
Gaylon just order a Sparrowhawk upgrade kit, or order a Stab for Don Parham or Larry Martin. Don't be fooled into thinking the RAF is safe without one of these three aftermarket additions. RAF has a history of leading people to think their gyros were safe and stable, yet they in truth they weren't and the pilot ended up dead.
12-10-2003, 10:21 AM
I can retire now.... ;D ;D
I wrote a long reply re-RAF stability on another thread. You can see it here:
Although stability is not a matter of opinion, I would like to give you my opinion regarding your options:
1. Stock RAF. Very high thrust line without any airframe stabilator. The high thrust line is trying to bunt the aircraft forward all the time. The only canceling force is the rotor thrust vector (RTV). The RTV is dependent on positive G and may go away as a result of (1) aggressive maneuvering, (2) PIO, or (3) a strong down draft. This aircraft is dangerous to fly, especially in unstable weather.
2. Stock RAF with a stab. Still very high thrust line, but the airframe is stabilized. None of the keel-mounted stabs are canceling the high thrust moment. They are going a long way in preventing PIOs (for several reasons), but they do not make the aircraft statically stable. The aircraft will still bunt over in an event of rotor unloading. The likelihood of this occurrence is lower than with a stock RAF, but higher than a CLT machine. You still have a gun pointed at your head, but the trigger is less sensitive.
3. Stock RAF with the Duane stabilizer. This stabilizer may be a good addition to the normal offset gimbal rotor head. It stabilizes only the rotor. The airframe is not pitch stable and there is no pitch dampening. I would say that this gyro is better than a stock RAF and not as good as a stabbed RAF.
4. AAI modified RAF. This kit takes care of the root cause. It aligns the engine thrust line with the gyro CG, so the RTV does not have to compensate for inadequate moments about the CG. This gyro does not have a tendency to bunt under ANY circumstances. In addition, the AAI kit includes properly sized horizontal and vertical stabilizers, making the aircraft very stable both in the pitch and yaw axes. Another bonus is the tall tail, which acts to cancel some of the engine torque, making the machine easier to fly and safer in case of rotor unloading. Another bonus is improved landing gear and rotor head (optional). PIO and PPO risks with this gyro are close to nil, and your workload is much lower due to the improved stability (which means more fun to fly).
The only thing I can't understand is how come there is even a question. If there was one valuable lesson I learned in the air force, it was "when in doubt, there's no doubt".
12-10-2003, 03:37 PM
Chuck E....... I don't know what got a hold of me, It just happened ;D
12-10-2003, 05:35 PM
The arugument that I have heard is the the induced drag of a H/stab at high angle attack is just as dangerus as a PIO. Now I would like to see how the stabilator works and fly in a sparrow hawk. I think the truth would be in the "pudding" ;D
12-10-2003, 06:21 PM
I have to ask, if you haven't already purchased a RAF2000 why would you buy one? Why not buy a Sparrowhawk? If they're not shipping kits already, they will be very soon. Why not buy a machine thats properly designed in the first place?
12-10-2003, 06:50 PM
None of the keel-mounted stabs are canceling the high thrust moment.
12-10-2003, 07:08 PM
the first 10 SparrowHawk kits are supposed to be shipped out this month.
I think they are all spoken for.
12-10-2003, 07:21 PM
I noticed the introductory price of $24K for the SparrowHawk appears to have ended, replaced with something in the $27K range. At first look, that appears to be more than an RAF, but everybody seems to end up over $30K with an RAF anyway. The SparrowHawk looks to be a more complete kit, and way safer, so the choice seems like a no-brainer.
12-11-2003, 03:20 AM
Sorry Larry, but it is true!!!!! regardles of what you think. The aerodynamicists can and do prove it, as well as people like myself who are performing a lot more credible tests than "it feels better". I used to be in that catagory before I started on the Firebird project.
I have to do it right as I am putting my whole future, and my families futures on the line.
I am afraid the I have to insist that you learn to fly gyros so that you can perform the tests required. Then you will understand. I am afraid that at the moment you do not.
This is fact, I am not trying to start a flame war.
12-11-2003, 03:23 AM
I'll try to get some pictures out in the next couple of days. Although the holiday season is not the best time to try to get a lot of overtime out of the great guys and gals that work with me, we are trying to ship at least the first 10 or 12 by the end of the month. We have over 30 orders that I want to deliver by the middle of February.
The current delivery time is 91 days from order to shipment. I will try to shorten that time, but it is driven by vendor delivery lead times for the most part.
I'll be announcing a couple more CFIs and a few more dealers shortly.
12-11-2003, 06:59 AM
I'll be waiting to hear from you.
12-11-2003, 07:24 AM
Terry Brandt has your most recent e-mail. He and Devon Hansen (out of my dealer support office) will be contacting you shortly. I do not anticipate any problem with answering any of your questions, but if we drop you through the cracks, please stay on us.
12-11-2003, 09:38 AM
The question came up, why would anyone buy an RAF now that the SparrowHawk is coming.
It is called tradeoffs. As long as you know what you are getting into with an RAF and what you need to do to improve it, there are some features that make it more desireable (so far).
After AAI gets some kits out, hopefully any kinks will get ironed out. They already have improved the nose gear strut (on the RAF conversion). There might be a little more of that to go.
RAF is strong in kit availability, folding mast, good manual and video, good builder support (IMHO-I always was able to get help the few times I called in).
RAF is weak in the quality of key parts (rod ends in control system), lack of horizontal stab... There have been other problems that occur over time, like stress cracks in a number of areas. But RAFs have been around for years and flown like crazy to have exposed those weak areas. AAI has yet to get some time on a large number of machines to see what may crop up. But they have the advantage of learning from RAFs weaknesses, and so far the company is strong and committed to their customers.
Flight handling and safety are definitely key factors in a machine purchase, and AAI has gambled that those factors outweigh some possible features lost. If I didn't have a folding mast, my machine would not have gone to the Arlington fly-in the last two years. Those were the most fun times I had with my machine.
So yes, the RAF is not a stable machine compared to the RAF with conversion. But if a person knows the tradeoffs, it can be an ok machine to have.
AAI has the potential to win in every aspect with the SparrowHawk in a feature-to-feature comparison against the RAF 2000. But they are not there yet. And they need those 30 kits to get out the door, built, and flown like crazy to get any remaining kinks out of the design. I will be very interested to see the builder support that they have, or will come up with too.
So, in a couple years I may be sending in my money for a SparrowHawk that has been upgraded to fit in an enclosed trailer with a 7.5' ceiling and around a 6 foot wheel base.
I still don't like the machine-on-stilts look and feel. But maybe with time I could overlook that aspect.
I also continue to hope that maybe Paul's Firebird might be a good comprimise between a total CLT machine and one that is close. But Paul, I'm not sure how a one-man operation can develop the manuals, video, and crank out kits like an AAI or RAF.
And for those looking just at the bottom line, you need to compare the feature list of each machine. With the RAF you need to know what components you want to swap out and upgrade. (Like spending $100 for aircraft-quality rod ends, maybe some more to get aircraft-quality tires, and other stuff like that. It would pay to talk with an existing RAF driver on the extras needed to make it a decent machine.)
With the SparrowHawk you may need to pay extra for features that are standard on the RAF. Do I recall that doors are extra on the SparrowHawk?
So, to some of us the CLT issue is not all there is. Yes, it is a big part. But 30K+ is a lot of money to spend. You need to look at the whole picture and how you plan to use the machine.
12-11-2003, 11:43 AM
I appreciate the thoughts you expressed in the comparrisons between the RAF and the SparrowHawk. I can't give you a hands on comparison between the two as it is still seversl weeks before I receive my first SparrowHawk. I can compare the AAI modified RAF which is similar in hight and weight.
As you know I have trailered "Ruby" all over the country. About 13,000 miles this year. No folding mast. I know it won't fit into your trailer but my trailer only cost $1,300 new. I see the value of an enclosed trailer if that is the only place you have to store your gyro. I fly out of a hanger so a flatbed works just great and is much much cheaper.
As for the SparrowHawk costing more than the RAF, it should because it is such a different machine and you get so much more for the money spent. At the base price you get a much bigger cabin, you get a very modern insturment package for engine performance and engine condition along with the operational insturments. You get the stability kit as part of the aircraft. If you buy doors which are an option, as I think they are with other gyro kits, (because some people don't want them) you will get doors you can open from both the inside and outside. This is another big safety issue. The base price also includes a 148 hp fuel injected engine, shock absorbers, good seating so you can do some cross country in comfort.
I could go on and on about what I see as the value but I am starting sound like a salesman even to myself. Gary, you have said it to me that only time will tell about the SparrowHawk proving itself. I do agree with you but I think it will take very little time after Jim ships the first units before it is proven. I am training two CFI's right now so they can fly as many instructional demos and training flights as is possible. The build center at Boeing Field should have my SparrowHawk kit completed by the end of February or early March. We will need to do the 40 hour fly off and than I will get you into it so you can fly it and than you can write about the difference. That should be the middle or end of March.
12-11-2003, 12:06 PM
Hey Randy, Now how did I guess you might appear here? :)
Your comment about trailering your gyro across country on an open trailer would not be my first choice. I get enough bugs splattered on the windows and dust in all the nicks and crannys without putting road miles on there too. And if it rains or hails while trailering... Personal choice, as always.
My investment is well protected when I make the 4 hour commute to Arlington. I also trailered it down to Gary Brewer in Vacaville when I first got it, which was 12 hours each way on the road.
So, my choice is to trailer a machine in an enclosed trailer, and I hope AAI works on that.
I don't remember paying extra for my doors on the RAF. People can visit http://www.raf2000.com/images/Rotarybroch.pdf to see a rough list of what you get with them.
I personally would not question the SparrowHawk bottom line if it comes out more than RAFs, because like you said, you are probably getting better quality for the money with AAI. A side-by-side comparison of features lists would give a better idea. I'm sure Jim and "his people" have done a good job doing this kind of comparison to make things as reasonable and fair as possible.
I have nothing but good things to say about AAI and the way they (you) are presenting yourselves.
From a consumer perspective it is good to have more than one choice of product out there. And it is good that there is some competition in the marketplace. Although, it won't be hard to out-compete RAF in quality unless they get some qualified people in there to shake things up. But for now, they will probably remain as the VW bug in the market, while AAI starts to provide the higher end machines.
One of these days we may actually see something (2 place, enclosed) from Sport Copter too. But my hunch is there won't be too many people able to afford his 2 place machines.
12-11-2003, 03:33 PM
The influence of price on sales volume might turn out to be a surprise. Robinson has sold way more R-22s than RAF has sold 2000s. (I only make the comparison because RAF does.) If a really advanced, enclosed, safe two-place becomes available, it will draw some well-heeled people into the sport who have actually been scared away by the cheap stuff.
12-11-2003, 03:41 PM
Gary, Why trailer the machine when you are so close - 4 hour drive? - I thought those machines were cross country gyros? ;)
Seriously, You can still use a enclosed trailer with a Sparrowhawk. One option is to go order a new trailer with a ceiling as tall as you need to clear the mast. I personally don't like this idea because the trailer would be so tall it would take a Big diesel Truck to pull it down the highway. Option number two is to modify your trailer you already have. Maxie Wildes just did this to a trailer he bought to haul is equally tall Aircommand Elite trainer in. Basically you have to cut out a hole in the roof from the rear of the trailer up to where the gyro will be sitting for the mast, then have a frame welded up to box in the hole and then cover it with aluminum of stainless steel sheeting. You will also probably have to relocate the spring assembly that helps to lift the tailgate, but this could be mounted under the trailer and use pulleys to transfer the load.
anyway it can be done. I have seen several others besides Maxie using a trailer set up like this and it didn't look hard to do this conversion.
12-11-2003, 05:41 PM
I haven't flown in the Sparrowhawk (who has?) but I have flown in both the unmodified RAF (with Dofin Fritts) and the AAI conversion (with Terry Brandt). You probably couldn't find two guys who had more different instructional and piloting styles than those two: Dofin's a barnstormer type and Terry the quiet professional. I felt safe with both, FWIW. Terry gave me a more opportunity to put hands on the machine.
I thought from looking at the conversion (which I keep wanting to call the Sparrowhawk) that the height of the cabin would be a negative, but it wasn't really. Once it's off the ground, gear height doesn't matter.
Both machines are definite eyes-off-the-gages, VFR fun flying machines. The RAF did have a little oscillation in pitch, very slow and gentle. The AAI didn't. The RAF needed more rudder -- not much, but more than the AAI. The AAI rudder is so powerful you really don't use it except on takeoff and landing, for runway alignment - it isn't necessary to make coordinated turns.
The price on the AAI Sparrowhawk was announced from the beginning as an introductory show price that had a finite finis point -- which I think was 1st November? At any rate, it's behind us now, and if you read what they were putting out this past summer, everything with a price had that expiration date in there.
Barnett also makes a side-by-side enclosed 2-seater, the BRC 540, about which I know next to nothing. Magni and SportCopter are working on enclosed tandem 2-seaters, but nobody in this business is overcapitalized, so it may take a while.
Competition is good, I agree. I am a little concerned that RAF has a design that evolved (orginally, from a Bensen, if you've ever seen an RAF1000 you know what I mean) and they haven't always understood the consequences of the changes they make. Duane's "rotor stabilator" is an interesting mechanism but it doesn't alter the fundamentals of the system's stability much. It might turn out to be effective against PIO but with no one publishing the data, who will know?
12-12-2003, 06:56 AM
Paul, since you have NOT flown with my new stab, and I HAVE flown with it then you statement is just your opinion which I respect. But all the same it's just your opinion, based on theory and your experiences with OTHER stabs. I have flown in RAFs with "no stab", "Bad Stab" and the "Ultimate Stab". My obversations are not opinion. I have not flown in a CLT retrofitted RAF, but I have no doubt it flys great, I total agree with it as the best new building option but there is another option for a retrofit that flys just as great with safety. I read one of the post about flying in a Sparrowhawk and how it handled yaw, pitch, all with no rudder petals, it was a perfect description of a RAF with an Ultimate Stab. I don't remember if he said it was all stick hands off or not, but mine is without stick in very windy weather.
And, I like you do not want to start a flaming war. I accept your opinion, I just don't agree with it, so we leave it there.
12-12-2003, 12:00 PM
Don't get offended, but what are your qualifications as a pilot to conduct a test flight regarding stability and give your findings?
I respect your contribution to RAF safety, and I think your stab may very well be the best of it's kind. BUT, you can't make unfounded claims. Not when people's lives are on the line. It's one thing to say your stab is making the RAF safer to fly, but this is not good enough for you. You are saying that your stab is completely canceling the high thrust moment, making the RAF stable.
Please download** the attached Word document by Greg Gremminger. This is a step-by-step procedure for testing a gyroplane for static stability. I believe a similar testing procedure will go into the new Sport Pilot ruling.
Test your stab by following this procedure to the letter, and report your findings. This is one way to make your stab reports more credible. The other way is much more costly; you can take your RAF to Jim Mayfield and ask to use AAI's high-tech testing device (can’t remembers what it’s called). Jim made this offer a few months ago, and I believe the cost was around $4K. Jim, please correct me if this offer is no longer valid.
Do one of these tests, and your stab's credibility will go through the roof. I am challenging you to prove us all wrong.
12-12-2003, 06:11 PM
Nicely said Udi, thanks. Aussie Paul.
12-12-2003, 07:24 PM
I never knew I would get this kind of response I thank you all for your input. It is obvious that there is several options I could follow. Much more reasearch is required. Man its tough when you want to get the most value for your dollar, not to metion that safety is a must. However, I do know this. I LOVE GYROS, and I love to FLY!!!!! :)
12-13-2003, 03:39 AM
Hope to see you again soon. Our data collection equipment is probably not high tech compared to the devices available to Bell or another one of the bigs.
We use an air data probe that can very accurately measure airspeed, angle of attack, side slip, etc. This information, along with data acquired by several accelerometers mounted to the airframe is fed to an elecctronic data acquisition device and stored.
Depending on what we are measuring, we can collect data from about 100 sensors. The sampling rate, as you know better than me, is dependent on what we are looking at. The EDAC is capable of sampling from a few times per second to a few thousand times per second.
The offer is of course open. We will contract with any manufacturer to do a structural analysis or a stability analysis. Right now they would have to wait until after January as we are just a tad busy getting this first batch of kits out.
As the flight test protocols that I shared with Greg indicate, any of the manufacturers can conduct static stability testing for static longitudinal stability (airspeed) or manuever stability (AOA) uninstrumented and know within a few hours of testing whether the machine is at least statically stable or not.
By the way, I think your input, and the input of all the guys is very valuable to our community.
12-13-2003, 06:10 AM
Gaylon, What you have to consider is this, speaking mainly for myself - but feel most of the others feel the same way - I am not giving you any advise to take away a sale from RAF and give it to AAI. I personally don't care who get's your business. The reason several of us here are offering our two cents is to help you make the SAFEST choice possible.
There has been a lot of deaths in the RAF and it is apparent as to the level of dangar that is associated with flying one, Even with a stab.
The Sparrowhawk on the other hand is designed from the beginning to be stable and highly PPO resistant. You would have to TRY to screw up in a Sparrowhawk to have trouble in one.
It is like this, It is snowing and Sleeting outside. you have two cars to choose from to ride across town with your children in the back seat. One is a brand new Mercedes with New snow tires, anti lock brakes, traction control, dual stage airbags, side impact curtains, etc... The other car, a 1978 Chevy Malibu has balding tires, no airbags, no traction control, no ABS, it is just a old car. ---- Either car will do the job and either car could make the trip. But I think you would agree the first car would be the hands down choice with you and Your familys safety in mind.
The Sparrowhawk is like the firt car. Everything is built in to keep you on your way safely. The RAF is the old car with the bald tires. A stab addition on the RAF is like replacing those bald tires with a new set. But it still doesn't have traction control or anti lock brakes, so if you give it too much gas or two much brakes It will slide off the road into a ditch, tree or another car in a heartbeat. This is the RAF, what car do you want to drive?
12-16-2003, 02:34 PM
I loved your analogy of which car to drive. Not talking gyros but talking cars, I would choose the Malibu, with new snow tires wouldn't want to ding up the New Mercedes. ;D ;D ;D
Just having a little fun.
12-16-2003, 02:55 PM
I was going to use a Volvo in place of the Benz, but who wants to drive a Volvo!!! :P
01-03-2004, 11:00 PM
Even though I am a relatively low time gyro pilot(hundreds of hours in hanggliders,ultralights, single and twin engine land) I am experienced enough to offer a good experienced opinion because I have flown many type gyros.To lend credibility to this statement:parsons trainer , Air command elete CLT. Raf -no stab and Raf with a stab. I am truely amazed at the various opinions of some of the posters when it comes to the RAF. Every time someone dies is a RAF , it seems without question you blame the Machine. Using the car analagy,Volvo is supposed to be a very safe car.Yet People die in them.Was it the car? or the driver. Probably the driver.How bout the SUV issue several years ago. The manufacturers said it was the tires. Well was it the tires or the SUV or the driver?In all the gyros I have piloted, all seemed stable.My definition of stable is controllable.My Cherokee was stable. Pilots still died in them. And it was controlable.Down in Texas 2 years ago it was very windy. All aircraft were grounded by pilot choice. Not RAF.I flew with Duane Hunn. I was amazed at how stable the RAF was without the stab. At the time I had a Air Command Elete CLT. I thought highly of both.I flew with Ron Menzie in windy gusty hot thermal conditions. He had a Larry Martin stab. I thought it was astable, controlabe machine.Your sliderule may say different, but my experience says something else. You pick on Larry Martin because he says he has a new stab that really does the job. You want him to go spend thousands of dollars to get the tech data.That tech data don't mean a hill of beans to me and probably nothing to most of the gyroheads out there. I want stability. I fly my RAF with a Larry Martin stab in mild to moderate conditions. As my experience increases, I will upgrade the wind conditions I will fly in . It flies stable!!!YOu see, Its up to me and my skills. Duane Hunn and Jim Logan have thousands of hours in there unstabed machines. They survived. Must be their skills, not the RAF. Maybe it is both!!!If Larry Martin says that the people that fly with it are satisfied, then so be it. It sure would peave some of you RAF bashers if Larry's stab did get the tech test and proved what he said.You bashers would still not be satisfied. And you would find something else to rave about or pick apart. Don't forget, AAI used the RAF as the building block for their machine.
I would bet that the flight hours in the RAF machines over the years adds up to thousands of hours and there have been a few deaths.. It will be a while before Groen Brothers AAI catches up. When they have their first fatality, then what and whom will you blame? Answer! Had to be the pilot. Gee, we will be back to square one.
01-04-2004, 12:31 AM
Geez Larry, you said, " Not RAF. I flew with Duane Hunn. I was amazed at how stable the RAF was without the stab."
Unfortunately your definition of stability is way off the mark. There is more than enough info to be had about this subject if you use the search funtions of the forums.
I thought that we were making progress and then you put forward a post like that!!!!!! Is your motto like so many others "don't confuse me with the truth, I have already made up my mind"?
If your Cherokee was unstable how many more people would be dead?
I give up. It seems that the horse will not drink. Bloody hell!!!! All that leading to the well was supposed to bear fruit!!!!
Larry, you said "It flies stable!!!". Please produce the documented test procedures that were carried out to come to that decision, and by whom the testing was carried out.
Sorry to be so blunt, BUT your post is blunt about your incorrect opinions.
All Larry Martin has to do is have Ron Menzies run the stick fixed pitch stability test procedures. That won't cost much!!!!
Cheers for now, Aussie Paul.
01-04-2004, 06:57 AM
We all have the right to our own opinions.
However when anyone posts false statements on a public forum they could be partly responsible for someone taking this false statement as truth, buy an RAF and kill themselves.
There have been several very high time pilots die in the unstable RAF 2000 one of which was a military helicopter pilot with many hours on helicopters....
Your using Duane Hunn and Jim Logan as evidence that the RAF is stable is probably the most disturbing part of your post.
Of all the flight instructors on planet earth it seems that these two are the only ones that continue to deny physics and obviously have no idea of the term stability.
It is wionderful that you can blindly spout such incorrect information here on the internet, however people get killed beleiving such incorrect information.
To sum up:
(1) The RAF 2000 is unstable and a potential killer...just look at the record.
(2) Duane Hunn and Jim Logan either do not understand the very subject they teach or the rest of the aviation industry and the science of aerodynamics and physics are and have been wrong all these years.
(3) Lets assume that these two so called CFI's are right and the rest of aviation is wrong about the stability issue, then why do so many RAF 2000 pilots die when their RAF 's tumble out of the sky all torn to hell by the rotor?
Is because of poor instruction?
But hey Larry we are all entitled to our own opinion, my opinion is you are ignorant of the subject that you are trying to defend.
By the way Larry any idea who trained the last pilot to die in an RAF in Va?
01-04-2004, 12:31 PM
Your expierience is only based on feel. You do not address the two main points ( not even including the bad parts problem/deception) about the RAF problem which include non centerline thrust and horizontal stab.
You can feel everything is ok until it isn't and what will that prove? You mention that when someone finally dies in a redesigned RAF where will all the bashers be? I feel you are one that would be using it to somehow make a point that these two important design changes were uneeded somehow.
Implying that being scientific through calculations before just going out and trying to fly is too restrictive or uneccesary is foolish. Why don't we just forgo all the engineers on the space shuttle - say it works fine as proven by many sucsessful flights and just a few bad ones that it works just fine? Forget that there have been serious flaws discovered, lets just ignore them and act like we have learned nothing. There will always be room for improvement on any design. There is always high risk involving flying machines. I just can't imagine the kind of reasoning that you use to protect yourself or to shield yourself from something you refuse to see. Excuse me if I can't get excited about changes that should have been done along time ago by a company that still hasn't even seen the significance of current design considerations.
We have had 3 Raf's down in the last 2 years. I only knew of 4 machines in the area. One of those has not flown due to medical reasons. I believe it is why he is still alive today because he doesn't believe the stab or offset thrust is an issue as he points to others who to date have been lucky. Those lucky people have impressed some people enough to get them to listen to them for advice. I pipe in here in case there are other newbies in here that may be confused with the way you reduce the significance of these two areas. Feeling a certain way is your choice.
Ignoring facts or any other technical information that indicates a difference in your opinion is worth looking at. Leading others to think there is just bashers is just plain wrong. I too thought that finally people understood what is really going on from a technical standpoint. BTW Wright brothers spent more time testing than they did flying and through that testing swung from one side to the other until the data ended up in the center in every aspect of design. Looking at their props they were only 2% less efficient than the prop on your cherokee. Did they do that on how it felt or whether or not something fell off or was catastrophic? They did the numbers and boring or not to you it is the basis and the result of the first aircraft that flew. Do whatever you want to feel that you did all you could to protect yourself. I would rather tell you that you are wrong now than to see your name added to the LONG list of RAF'ers that also talked themselves in general feeling circles that are not here to tell you that they were once like you.
Those two principles ARE sound and when ignored are handicaps that are built into the machine. Almost like sleeper cells, when the conditions are right can surprise you as they add into the string of unfortunate circumstances that cannot be stopped once they are in motion. Since you referred to slide rule people - in a bad way - I am pretty sure that you had no equipment to document how close to the edge you may have actually been. So basically you just know that you made it without incident. In fact even the other people who have the hours just know that they made it. With them having a lot of hours it is easier for them to try to avoid the situations that start the string of events. Not so easy for a low timer, and just add in some unpredictable weather and it all starts lining up..... Almost like unlocking a box with a surprise you don't want. The tumblers are starting to get lined up...... Get them all lined up and the box opens..... and then you will know what many that have gone before you know but can't use.
Ask your wife or your family what they think about you ignoring this information. Ask them how it is that so many people who have nothing to gain from what you do - or how easy it is for us to not share our time to tell you - you choose to act like you know better.
Maybe you are a crocodile trainer and you think you are fast enough hand feed them when you could have just thrown it to them. Then put your own kid in your arms doing such an activity and make yourself feel that it is ok because you are fast. It still is stupid and looks stupid as you don't even realize that you never needed to risk all that you are if you just thought about it. Then spend all your time defending your weak position instead of learning or listening why you aren't getting support for your position. Step back and see what leads you to your decision and see if the path really leads you where you ended up. I don't think your family would appreciate it even from a novice standpoint.
Take the time to rethink things a little. I don't think they are bashers, just telling you what you don't want to hear. We just don't like hearing about the accidents and why they are still occuring. We should be done with these type of accidents and ignoring the reasons for them. It doesn't help anyone to keep ignoring the points so you can still maintain your preset impression. Go back to basics and get that worked out from a groundschool point of school and you will not so easily be able to ignore these things anymore. It is for your own good, not just because we want some kind of an argument. We care about you and your sucsess.
It is through learning that we can avoid further accidents that have really hurt the gyro community. We have seen to many problems in my little circle in Michigan. How many do you think worldwide? We can never know everything. When a person thinks this I think they become somewhat dangerous by letting their gaurd down. You have climbed a few hills to get where you are at now but you can still roll down them. jtm
01-04-2004, 12:49 PM
My 2 cents worth:
I'm a fixed wing pilot and about 8 years ago I demoed RAF's with Duanne and Dofin. I loved them but did not pursue gyro flying then as I was just starting an around the world sailing voyage. On a visit to the US in 2000 I again flew with the RAF crowd at Oshkosh fueling my dream to own one.
For 8 years I have carried an image of myself buying and flying a RAF- none of the other machines I saw even interested me. Recently in preperation for actually getting a machine I began more research. I did my research from internet cafes at isolated Pacific islands. I had not found any of the web forums and did not speak with any gyro pilots who could sway my opinion. I also did not have a clue about gyro physics or CLT issues.
Early research included the NTSB site. It took me about half an hour after reading the NTSB accident reports to come to the conclusion that RAF's had a SERIOUS problem. The numbers simply do not lie. You cannot attribute all those accidents to pilot error.
The dream I had carried for 8 years evaporated with the short reading of the facts from NTSB reports and without talking to a single gyro expert.
I also think it is pretty unlikely that nearly EVERYONE except RAF owners and the RAF principals have reached the conclusion that RAF's are dangerous.
Now after learning more thru communications with Greg Gremminger and reding these forums it boggles my mind that any company or people could be so greedy and irresponsible as to NOT pull their product from the market until they can make it safe.
01-04-2004, 12:57 PM
The group that fly gyros seem to have more than their share of people that ignore all the laws and rules of aviation.
That I can forgive.
What I can't forgive is any individual or company that insists in continuing to produce and defend a machine that is so clearly unstable and so easily fixed as the RAF 2000.
Even more puzzeling to me is the fact that some people can actually hold a CFI and teach that instability as exibited by the RAF 2000 is controllable with proper training.
This Larry person is just another example of how such inaccurate information can be sold and accepted by a few in the market place, in spite of all the facts that show RAF and their very few defenders and marketing people to be defending the indefensible.
Reading this site has a certain facination for me, I just have to look again, something like rubber necking a wreck on the interstate.......
01-04-2004, 01:41 PM
My experiance was some what like Rob's. 8 years ago, I fell in love with the RAF. I toured the factory, I took a demo ride. I would lay in bed at night and think about building a flying one. But life had many voyages for me too. I only went half way around the world by land :) Alaska to New Mexico 4279 miles to be exact. I reached apoint were I just thought it would never happen, so I diverted my engery (money) to fixed wing. God knows CFI's are alot easier to find. This was just about the time the H/stab issue on the RAF started to come out of the closet. I saw right away that an H/stab was not only a real good idea, but that not having one was like riding a motorcyle with out a helmet. I had not even heard about a sparrow hawk until I posted on this forum. I had been on Norms forum for years, but quit when I redirected my interest. I had heard about RAF's falling out of the sky back then. Now looking back. I'm glad I didn't get one back then. Now with what I have learned, I think it comes down to this. Can an RAF be improved? YES. How much do you want to improve it? That depends on what you want, and the price your willing to pay and the risk you are willing to assume. Is the sparrow hawk the perfect gryo? I don't know, but I intend to find out.
01-04-2004, 03:03 PM
My post was meant to do two things. First to express unhappyness at some people that blast inovators. Larry Martin is one.Don Parham and Aussie Paul are others. Paul liked the stab he produced a few years ago , even remarking that he looked for turbulence near a mountain to see what would happen. He was with some one and He thought they had the stick. He said he climbed with no input from either pilot. The tech people say it can't be. Paul said the stab worked. Who is right?Now Paul is trying more inovation with his firebird. I have never met Paul but I appreciate him for his courage to try new ideas. Larry Martin says his stab works. I have one and I say it does also. I don't want people flying without stabs, but I think they shoud get as many good opinions, then proceed with their decision on what to fly and who to train them.
Secondly, I like to get people to think.I am a proponent of stability. I like inovation!But one make of Gyro is not the only answer. If a stab is what one owner is willing to do, then it's a plus. If AAI is a direction someone wants to take.Great! Another plus. I bought a AIRCOmmand HTL in 1996. I never flew it till I put the CLT kit on it. I did that because that is what some people in the know said. Many people flew the AC without CLT but a stab. It was a matter of choice.Also the price was right. My friend Chris still flys his in the old configuration.(with a stab but HTL) The people that never made the clt change will argue that it doesn't need done. They think it flys fine. since I first soloed in the clt aircommand, I flew in other unstable machines. Its just that I thought they flew fine. Now I am told that was not the case.
Many of you don't realize I am working on a new keel change for my new RAF kit. It should bring me within 3-4 inches of clt on the RAF.If I didnt believe in CLT< why would I put time and effort into this inovation? I'll answer that now. I am not looking for profit in this weekend conversion. ( I am a financial advisor for 31 years)and I ain't changing my carreer. I hope that when what I believe will be a great improvement in stability by the sliderule, and my test of controllability, that a person who has been on the fence because of the time it takes to do a Groen Bros. conversion and the cost, that they just might buy 100 steel rivets and a few feet of 1/8 inch aluminum plate, and 33 inches of keel material 16 new an bolts and of course a stab if they don't have one and make the simple change. I hope and pray it will save some lives. But until I have this flying, I will still fly my stabed RAF.
An as for you Aussie Paul, you did lead me to water and I didn't stray. But you stood up a couple years ago and proclaimed to the world that you had achieved a much safer RAF. I think you did!!! Now you say you have an even better idea. I believe you do!!! If you flew the RAF in high wind and turbulence and you didn't even have the stick with just your inovative new stab, I am wondering what you are striving for with yourFirebird orRAF look alike.Will it fly in hurricane force winds without pilot input? Again the point is this. Inovation brought us from wright brothers designs to jets in 35 years. We are just beginning to understand the gyro. Inovation will take place. It will be a person like Aussie Paul who is never satisfied with what he had before and will continue to improve on his designs. He'll take some flack along the way, but it won't stop him. Others will try new inovation. Some of you will applaud, others will look for the flaws.
One other comment form one of you. I would never glory in a death of a fellow pilot. I would drink to his courage to fly.I also would not point a finger at the company and say they are to blame with out positive proof.
01-04-2004, 05:56 PM
Well Larry maybe you wouldnt point a finger at the company and say they are to blame without positive proof...
You have already very clearly stated that you were amazed at how stable the RAF was without a stab. and then stated your occupation is a financial advisor.
I found the RAF to be unacceptably unstable. My occupation is a professional pilot and advanced flight instructor, I also have flown for and learned about flight testing with Airbus Industries at their factory in France. It is beyond doubt that I can back up my findings regarding the instability of the RAF 2000 with many decades of experience in the profession of Aviation.
As well I lived with Don and Linda and was involved with RAF at their factory eleven years ago. The managers / owners of RAF had no idea of aerodynamics or the subject of stability and it was impossible to convince them that their machine needed serious redesigning.
Furthermore their methods of doing business was such that I had no choice but to severe relations with their company.
So as the years go by and more and more people die flying thier machine that clearly is unstable, and they refuse to change the design who else would you blame Larry?
And what in your mind defines a basher?
01-05-2004, 02:28 AM
Just for the record, I recommend everyone convert their Air Commands with their elite upgrade kit (clt) before flying it.
My newest machine,that I just built, is a clt AC. My next machine will be a Sparrowhawk or an Raf with the GB stability augmentation upgrade.
The difference between my 2 machines in flight is incredible. I will never defend HTL machines.
I am very anxious for Larry and myself to get a test flight in a Groen Brothers machine. I think they will then get an order for 1 stability augmentation kit.
01-05-2004, 04:28 AM
Larry you said "If you flew the RAF in high wind and turbulence and you didn't even have the stick with just your innovative new stab, I am wondering what you are striving for with your Firebird or RAF look alike. Will it fly in hurricane force winds without pilot input?"
I am trying to achieve gyroplane pitch stability that will pass the LSA standards when they are finalised.
By having an industry standard and being able to produce the figures as Jim Mayfield has, will be the only way a company will be able to penetrate some market share.
Larry, yes the Raf with the stab climbed hands off in the smooth air. When I flew it through the minor turbulence it was fine. It was the best that I had felt in a Raf at that time.
In rough air even with the stab there is no way it will fly for 5 seconds stick fixed. Today I flew around at an average of 60 mph with the stick locked. I say at an average because the day was rough and thermally. I had the video set up BUT I must not have pushed the start button hard enough and it did not record!!!!!!! Bummer!! I was so proud to.
At the moment I am not flying the most pitch stable blades, I am flying with the tapered blades with the changing airfoil from root to tip. We are slowly improving them in pitch stability. Tomorrow I am adding some 10" long trim tabs with some reflex to see if that will improve the pitch stability without losing the gains that we have made in the reduction of engine rpm required to fly the same weigh at the same speed.
So wish me luck. Aussie Paul.
01-05-2004, 07:08 AM
"All Larry Martin has to do is have Ron Menzies run the stick fixed pitch stability test procedures. That won't cost much!!!!"
Paul, you know very well that Static and Dynamic stick tests in accordance to the then proposed standards, have ben run my Ron Menzie on both of my stabs and they both passed with flying colors. The results are posted on my site.
As of this posting I have sold a combination of over 50 sets with zero complaints about flight characterics. Actually with the two orders I got last week, I think it is 54. That pretty much tells the story.
I am trying my best not to use this forum to push my stabs, but if you and some others don't want to accept the fact that they work, then don't. Unlike some others, I have no hidden agenda, they either sell or they don't. The tests have been done. The sales are there. I will not do any more testing, it would just be throwing money away to no reasonalbe end, the results would not change.
I too think CLT is the untimate solution, even if it is, in my opinion, very ugly. But, it is not the only option for a safer flying machine and still maintain the natural looks of the machine which is why most people bought the RAF in the first place. Plus it's a lot less expensive.
If any RAF owner wants to modify their stock RAF to it's safest possible configuration without spending an additonal 5 to 7k, then I suggest Don Parham's suspension and the Ultimate Stab. And that's the best it can get without going CLT.
As far as RAF's Stabalator is concerned, that dog won't hunt. It might help with pitch trim.
One of the main problems with building and flying experimental aircraft is that ignorant/gullible customers believe what ignorant/sleazy kit manufacturers and after market part suppliers are telling them. When you fly certificated aircraft you may be confident that your aircraft meets some minimum flight standards. You don't have that comfort with experimental gyros.
This is the beautiful RAF of an Airline Transport Pilot with over 14,500 hrs of air time:
Note the keel mounted stab. This looks to me like a Larry Martin "Bad Stab", with a rear wheel pant, but I can't tell for sure.
This is what the pilot wrote after flying this RAF for the first few times:
I have flown it for about 6 hours to date and it has operated flawlessly. This aircraft is one of the most enjoyable "toys" that I have owned to date.
And this is where this 14,500 hr. airline pilot found himself shortly thereafter:
Witness accounts point to a typical PIO/PPO progression. Now, don't tell me witnesses are not reliable; these witnesses didn't give some funky descriptions. Here is what they said:
One witness stated, "...witnessed helicopter heading southeast, flip upside down, and nose dive straight into ground. Copter immediately burst into flames...."
A second witness stated, "...I noticed a small helicopter heading southeast with helicopter going straight up and down and inverted flip, and doing a nose dive straight into the ground. There was something that flew off the aircraft just before it crashed...."
This is a clear description of PIO/PPO accident.
Back to where I started. Anyone who thinks they can prevent a PPO with a keel-mounted stab on a stock RAF is kidding himself. This physics don’t work this way. A 9” thrust offset multiplied by ~450 lbs of thrust is a PPO waiting to happen.
Some people say that ignorance is bliss, but you don't want to be an ignorant RAF pilot, or you may find yourself in a smoking hole in the ground. All the people who claim that an RAF with a keel mounted stab are PPO proof are plain ignorant. But this is experimental aircraft flying and you are entitled to kill yourself if so you choose.
01-05-2004, 08:48 AM
8) In responce to Chuck: My definition of what is a basher might be like Jeff Foxworthy's idea of what is a redneck? You might be a redneck if .......
You might be a basher if:
1. you don't like your potatoes whole.
2. your wife has bruises she doesn't want to talk bout.
3. you work for a company a long time and become gisgrunted and might say anything to hurt them.
4.your car has dents on the side because it left you sit.
Also, I have flown hang gliders to twins. I am not a pro, but I fly like one.
Aussie Paul: I hope your quest for the perfect gyro works. We will all benefit. Thanks for your contributions to Aviation and good sparkling clean well water.Hope all is well.
Larry Martin: I have to call you to order a new stab for my new RAF kit.I love my other one!!!! I like how stable it makes me think my RAF is.
The cause of Northam's accident will never be known because there isn't enough left of the ship to figure out what happened. I would assume that the body was so badly burned that an autopsy could not be performed either.
In my opinion it is very possible that either a mechanical problem with the ship or a medical problem by the pilot could have caused the accident. Surely the pilot had sufficient training to know to reduce power when the PIO started (if that is what it was).
If the pilot became incapacitated the ship would behave just as the witnesses observed, oscillations would become more and more divergent until the blades unloaded and the ship bunted over.
A failure of the control system could cause the same sympthoms. Ask Jim Logan who had a control system failure and lived to tell about it.
Another possibility is fixed wing reaction which I suspect has caused a number of bunt-overs. I experienced one on my solo flight and lived to tell about it.
Bill Parsons "twisted my arm" and convinced me to solo when I was so ill from a bad sinus headache that I could hardly focus my eyes. I encountered a strong updraft shortly after beginning my solo flight and pushed the joystick to the front stop before I realized what I had done. It was pure fixed wing reflex from thirty years of fixed wing flying.
If I had lost my "cool" I would have been another statistic, but I recovered at about 50 or 60 feet above the runway on the first oscillation. Had I over-controlled and started a full PIO I probably would have died. I don't think the incident would have happened if I had been feeling good and was more mentally alert. I will never fly again when I am not feeling "up to snuff."
I am convinced that scenario has happened many times in the past with high time fixed wing pilots who were low time gyro pilots. Fortunately I owned and flew a Cessna Cardinal (C-177) that was prone to PIO if over-controlled and I think the C-177 flying experience is what saved my life. I porpoised the Cessna on my check ride and never did it again.
Any aircraft or rotorcraft can get into a PIO if an inexperienced pilot over-controls excessively. I once watched a C-182 porpoise several oscillations during the landing approach and the nose wheel hit so hard that the tire blew. Fortunately, the aircraft was not damaged. The low time pilot simply over-controlled after ballooning in the landing flare.
This accident, like many others, will remain a mystery because "dead men tell no tales."
01-05-2004, 09:43 AM
Udi, what type gyro do you have. Do you fly it regularly?
When i flew my aircommand CLT, I encountered up drafts over hot fields, also gusty winds aloft. The nose would come up and I would decrease throttle and add back pressure on the stick. Just like I was taught by Ron Menzi and Bill Ortmyer. Because I fly on a regular basis, I encounter the same climatic issues in the RAF. I have had it pitch up hard, and without a second thought of what to do, I made the corection.The airline pilot could have died in any gyro under the wrong climatic conditions if he gave the stick the wrong input.
most civilian fixed wing aircraft are stable. get in the wrong climatic conditions and push the yoke or stick the wrong way and you are in for trouble. I had it happen in my 140 cherokee where I got hit with a microburst. I was every way but upside down. I had fortuneately a few months prior to the incident taken a aerobatics course in NY. The training I got was a life saver. The airline pilot (if PPO) made a fatal error in the right response for control. I don't know who his instructor was or how many hours he had, it doesn'y matter now. It's to late.He should have known better. I
will admit that I don't believe the RAF is for a first timer. But in the right hands with the proper experience, with a stab, it is a good flying machine. And it looks good doing it. Your posts about the importance of stability are right on. No newcomer or someone without duel instruction in type should ever concider flying a high performance anything. Training and experience is most important in my mind. Stability #2.
01-05-2004, 09:45 AM
" I have flown hang gliders to twins. I am not a pro, but I fly like one. "
I would assume that you are making that statement tounge in cheek?
However I do not think that allowing ignorance to to go unchallenged and kill people should be condoned by any group including the gyro pilot group.
And allowing ignorant posts to go unchallenged should not be condoned.
For years Larry there has been a steady flow of defenders of these purveyors of death posting on the internet......in all cases they are newbies that have been seduced by the hype and B.S. that is part of the marketing ploy by the manufacturer of the kit. However not many are ignorant enough to hold to their false beliefe for long, may I suggest that you eventually will become educated to the reality of the danger in believing such B.S. as you appear to believe in now.
Have another look at the pictures posted above of that red RAF......... why didn't the stab prevent it from bunting?
It does not matter what started the chain of events in the Virginia crash. The fact is that the gyroplane has suffered a PPO. Medical condition is highly unlikely, as airline pilots pass thorough medicals every 6 months to maintain their Class A medical certificate.
The point I was trying to make is that a stock RAF with a keel stab is an unforgiving machine, prone to PPO. For those of you, who haven't had the chance to get yourselves up to speed on gyroplane aerodynamics, let me remind you some of the basics:
1. A CLT gyroplane OR a gyroplane in which the sum of all moments about the CG is zero will not, and cannot, PPO. EVER. Even if you tried to (PPO=Power Push Over). A keel-mounted stab in an RAF doesn’t even get close to canceling out the engine push over moment.
2. A well-designed gyroplane is just as statically and dynamically stable as a fixed wing airplane. Yes, there are a few fixed wing planes that are not completely stable, but they are the exception. This means that PIO is highly unlikely, even in the hands of a fixed wing driver.
I have no problem with people taking risks, as long as they are aware of the risks. I do have a problem with the RAF Company, advertising their aircraft as safe, and with stab manufacturers who claim that their stab makes the RAF PPO proof. Both claims are outright lies and are giving people a false sense of security.
01-05-2004, 02:33 PM
Even more serious is the fact that there are people that are licensed as CFI's by the regulator ( in the case of the USA the FAA ) and these people are allowed to teach that this kind of instability ( PPO ) can be overcome by you having them train you to fly this aerodynamic abortion.
I guess it is impossible for me to understand this.
If I were to issue type ratings with the notation that there is no need to worry about PIO'ing a large flying boat on the water because I gave them special training that over rides the physics involved in porposing I would have my license cancelled.
Something is seriously wrong when any licensed CFI can get away with teaching such patently false theroies as training will overcome physics.... I don't accept the excuse that this is experimental aircraft...teaching the physics and laws of flight is not an experiment.
I wonder if they also believe that on a properly balanced teeter totter you can lift someone twice your weight through special training?
Yeh, visiting these discussions is just like rubber necking a car wreck on the interstate, reading some of the sad, sad missinformed people who post here denying reality...
Chuck - I have a magic stab that you can install on your flying boat, GUARANTEED to prevent any future PIOs. It's on sale right now for only $1000. What a deal! Just remember that any future PIOs will be blamed on the pilots because there is NO WAY you can PIO your flying boat with MY magic stab! And you can blame your students if they PIO when you weren't looking.
You want one?
01-05-2004, 03:40 PM
You obviously do not have the expertise to produce such a valuable item, the proof is in the pricing.
If you had any credibility you would charge far more for your invention.
Get ahold of Don at RAF and get some training in marketing, then get back to me and try again. ;D
01-05-2004, 05:22 PM
Thanks for your intelligent and insightful post with the two pictures. Scrolling down the screen and seeing only the top one first and then scrolling further and seeing the other one was a sobering experience.
01-05-2004, 05:27 PM
Looks like another believer in experience and training will fix everything.
Instead of experience and training being priority I would submit that your Self preservation should make Safety number one and with that in mind it would affect your action and direction you take in regard to what you will fly and how stable it must be.
Using Experience and Training as # 1 means learning as you go and does nothing to move your safety to the priority I would have expected.
One point that is being missed is that somehow you can stop this happening with training. The thing that can be said with this kind of reasoning is that it is somehow the pilots fault. This is exactly what we have been hearing time and time again from people that either own such a vehicle or from the factory. This is a real problem and with reprioritizing your standards you will see that you have been sold down a long line of deception that allows you to still get in and think that everything is just fine. Everything isn't fine and that is what is so frustrating. It is unacceptable to fly passengers in a vehicle that needs to be physically corrected under penalty of death with the reasoning that you were trained to avoid something you can't stop.
Now I will try to distract and avoid all the attention by asking Udi - how is your gyro coming? Hey I hear that Steve so and so is coming over friday to ............ No - Back to the subject. Go back and read and look. Even if something costs 5 -7K. Your life is worth much more than that. And for the most part if something does happen to you in this machine - odds are higher - your wife won't even get the life insurence you have been paying on. Everyone will be at a loss. I see you believe in putting them on your machine but can't see the good in trying to post such in the first place. It has been a long road trying to get people to think about some basic things and the hardest thing has been getting people to take these changes due to 3 things. (maybe more) 1) people looking up to a manufacture and believing their ideas 2) many people have been flying without tails or CLT so it is more a matter of taste or preferences. 3) Accidents are usually blamed on pilot error and there isn't much left aftterwords to indicate what happened or the string of events is not apparent. 4) $ if there is a fourth big reason. People say it costs too much but if Safety steered them as the priority 1 it wouldn't enter into the consideration. It does though obviously.
In my pursuit of a dream I will save and budget so that when I go active in my sport I will have done everything I need to - so that I can minimize my exposure to risks. If I have to wait to be safe fine. If I have the money to do it now fine. Whatever it takes for my family and friends.
I won't however, ignore family and friends when they try to tell me something. I will not try to look the other way and hope for the best just because I don't want to be grounded any longer. Nothing is worth the penalty for failure in this sport. If you already spent xxx in the sport what is a little xx to keep current and keep flying. When you start talking about machines that carry passengers I think you take on a lot more responsibility. These people are looking straight at you and trusting your decisions. How much would they like the situation if they knew that the pilot was going against laws of physics because a company told them or because they knew a few pilots that were flying without the fixes? How will they feel if they find out that there are quite a few people that felt the same way are no longer here to tell you how important it is? I hope things change and that we don't have to keep defending the position about Stabs and CLT by people who don't know that minimizing it's importance it actually harming other people. Time for change, take the time to let people know. The company won't. jtm
01-05-2004, 05:55 PM
Boy, I didn't know the can of worms I was opening when I started this thread :) But I'm very glad I did. One reason I was really looking at the RAF was there subkit shipment plan. That is something that AAI does not offer yet. So I am considering getting a single place machine, until 1) I build hours 2) Can afford to buy a whole kit. I have posted once on the single place thread, and got 1 reply. I would like a full enclosure, and the only single place machine that I can find that had one is the Roto Hawk Falcon. Does any one know anything about them????
01-05-2004, 07:40 PM
Full enclosure = boring A pod on a gyro with a tall windshield and a good snowmobile suit will work fine.
Rob, I apologize for the graphic post, but I want to drive home the message that it's people’s lives that we are dealing with. We can't let manufacturers make irresponsible claims without a proper response.
James, my gyroplane is coming along fine. It's pretty much complete, now it's painting and re-assembly. The only problem is that my garage is frozen now that the temps outside are negative. Hope to fly it by spring. Steve who???
01-06-2004, 02:36 AM
Today I flew with a Raf pilot, Nael, who has an "effective" stab. He was a student of mine and he had the doors fitted. He gained his gyro certificate 8 months ago and has accumulated approx 100 hours.
Nael asked me to go for a ride with him to see how he was going. For the first 10 mins I felt quite uncomfortable with the feel of the aircraft even though Nael was flying quite ok. It is so long since I was in a Raf with a stab the doors on and a reasonable inexperienced pilot, that I had forgotten what a sh*t heap a Raf is.
I had just finished flying Hybrid conduction some stick fixed testing of some rotor blades. During the flight before I went with Nael I had flown for 13 minutes with the stick locked against the dash. The only reason I took the lock out was that I had to land because I had finished the tests. I could have flown all day with the stick locked against the dash. I was operating at 60 to 65 mph.
I was able to fly Naels Raf for about 3 mins hands free, but the oscillations had Nael grabbing for the stick at times, there was enough turbulence to upset the equilibrium, and the stab had to really do its job. I told Nael that those couple of times he grabbed for the stick, if we had not had the stab we would have done a PPO if we let the stick stay free. I felt much better when I had control. Naels is the nicest built Raf that I sold and Larry M you would be proud of his workmanship.
I am getting Nael to build my personal Firebird for my promoting exhibiting, and air show routine machine.
I then got back into hybrid, took off and climbed to 30', engaged the stick lock and flew around for 15 mins conducting turns climbs and descents. The I removed the stick lock and flew hands free for almost another 15 mins. I prefer to fly stick locked rather than stick free with these Oz blades that I am testing. The reason being is that they slowly vary airspeed approx 10 mph either side of the trimmed air speed and this causes considerable roll changes, so I have to use some rudder and leaning in the cabin to fly where I want to go.
I added some 10" long by 1 1/4" deep trim tabs, with 5 degrees tail up to give some reflex qualities, 31" from the blade tip. This improved the pitch stability of these new generation blades. The stick was 1/2" further forward and the rrpm was approx 10 more for the same testing speed of 60 mph.
I probably spent an hour actually in the air during the day and 3/4 of that was operating stick fixed.
Don't anybody tell me that anything less than as close to CLT as various fuel and passenger/pilot loadings will allow, PLUS an effective stab, plus the most stable rotor that can be purchased is worth flying. The trouble is that the people who will try (and they will) and tell me I am going overboard with this stability thing DO NOT KNOW !!!!!
These people have never flown a truly pitch stable gyroplane, and have not spent the day flying around in gentle turbulence with the stick locked against the dash for extended periods of time, as I have done today, conducting tests to obtain as much data as I can to improve the lot of the gyroplane pilot. Talk is cheap people.
There is only one way to have a gyro and that is as close to CLT as various fuel and passenger/pilot loadings will allow, PLUS an effective stab, plus the most stable rotor that can be purchased.
To think that I was happy when I put the first stab on my Raf. I could have just accepted that it was good enough, but Chuck B and others made me consider that what I had was good, BUT was it as good as I could do.
Ah! It has been a great learning day, and when son Matt shrinks the 10 Mb video file that I took whist flying stick fixed, I will post it.
Sorry for the epistle, but I am sure some people will enjoy it and some others will now be thinking of ways to argue against my pursuits.
01-06-2004, 06:06 AM
You have come a long way Paul. ;D
Remember telling me I was nuts about eight years ago when I was telling everyone on Norms confrence that the RAF was unstable?
I still hope to get down your way some day and get some upgrading training from you.
Any good looking sheep in your area?
01-06-2004, 07:05 AM
Those of us who have built RAFs seem to fail to remember some of the poor design features of it. For example, the control system uses eight ¼" rod ends. There is no redundancy of any kind. Some say they are of poor quality. I have two stock RAF rod ends in my junk pile off a turned over RAF that are bent, but not broken, I also have one broken. I've seen some of them adjusted out where there were only a few threads holding them. If any one of them comes out or breaks, it's all over. If I were to build another RAF, I would try and use a system of dual push pull cables like Ron Herron's Little Wing.
Then there's the trim system. RAF uses a standard 1" fender washer with a 1/8" hole drilled in it to hold the trim springs. It's not even a hardened washer. Ron Menzie had a trim spring break or come loose on him in a customer's machine. Those of you, who know Ron, know he is a very healthy and strong person. He lifts weights and does all the gym stuff almost every day. He told me that it was all he could do with both hands to keep the machine from nosing over. He also said if it were anyone with less experience and/or strength, it would have been over.
Their trim system definitely needs help, maybe that Stabalator thing will help, or dual springs.
There are just too many things that can happen to always pin it on one cause. It either case above, I doubt a stab or CLT would have prevented a major problem. A stab will not cause a problem; it will lessen the effects of a problem. I think we all have to agree that it is better to have a stab than not and the best is to go CLT. Even if I think it is ugly.
01-06-2004, 09:42 AM
Just to add some balance to this thread, I think the low rider RAFs are ugly. To me, beauty follows function. Once I gained knowledge of what CLT was all about, the low riders lost their appeal and suddenly the Dominators and other long legged machines started looking really cool. The SparrowHawk may not be beautiful, but it looks the way it does for a very good reason, and to me, that makes it an attractive machine.
01-06-2004, 10:33 AM
Then there is the Little wing with the Radial Engine.....
To some of us not only is it stable and functional but it is also very attractive.
That is why I am going to build and use one as a training machine. ;D ;D
Some day I plan on rebuilding the RAF 2000 that has been sitting in my hangar for about eleven years, but it sure will not be an RAF when I finish it.
01-06-2004, 11:08 AM
On my short list of persnal machines when I make the enevitable fortune (tongue in cheek) in the gyroplane business are;
1. Two seat Dominator
2. Two seat Little Wing
3. Two seat SparrowHawk TD with Lycoming 0320.
01-06-2004, 02:24 PM
Chuck E you said "You have come a long way Paul.
Remember telling me I was nuts about eight years ago when I was telling everyone on Norms confrence that the RAF was unstable?
I still hope to get down your way some day and get some upgrading training from you."
It is a bit embarresing for me Chuck, BUT on the other hand I guess that I must have been "convertable material" because you all succeeded in getting me to today. Tnx.
01-06-2004, 04:31 PM
Just a question.... I know we ASSUME a gyro with Clt and a good set of tail feathers is Stable but has anyone ran these tests on a Dominator or a Little wing???
01-06-2004, 07:09 PM
Ron, I don't have the plans in front of me here today but you can bet having the tail feathers at the end of an 18' overall length machine will make a huge difference over a 12' RAF that blocks airflow with engine out and far less arm for engine on. Remembering your weight and balance calculations you know that there is one heck of an arm moment available and calculated with the large tail with winglets. Even more effective by using an airfoil shape. I bet your tripacer has a similiar sized tail that works just as well - engine on or off due to size and arm.
Hmmm I wonder if those wings could come off there..... Imagine how much hanger room you would have and you could fly your gyro in the winter time... maybe that is boring but actually you would gain a better view and with the big grin wouldn't have to scrape the bugs off your teeth in the summer either...... lol could be a real timesaver. Saw please!
UDI - I am sorry, I think you took it seriously about me asking about your project. (Not that I don't care) I was just making note of the way that someone tried smoothly to change the subject from something very important to something less serious such as so, about the weather..... or about that Udi project.... You know, while you were busy trying to sell Chuck a stab for his PBY.......
I have to tell you that when I read your posts I now think back to the time that you mentioned that english wasn't your main language. I was impressed back then and every time I see your posts now. I saw your intelligence and attention to detail but never even knew you were crossing a language barrier. Very impressive.
01-07-2004, 11:41 AM
Udi, the picture of the crashed RAF is sobering. Could you post the picture of the New clt Dominator that bunted over last year? It is also sobering!that pilot died too.You and Chuck seem to think CLT is everthing. Well the Dominator accident is proof of that. Looks like when we survey the whole field, maybe training in type and experience may just be the ultimate solution. I guess I say that tonge in cheek also.
Also a fixed wing pilots experience regardless of hours, doesn't gaurantee success in any type machine.
udi, do you have a gyro flying? Do you have any gyro flight experience?
01-07-2004, 12:47 PM
You are free to have any personal opinions that you desire.
My only reason for continuning to post is so others who have little or no experience or exposure to gyroplanes can read all our posts and decide who has the most accurate and factual knowledge of the subject.
You have made a fair comment on the fact that a CLT machine crashed and there was a loss of life. However there is a great difference in using one instance of a fatality in a CLT machine in comparison to the high number of fatalities in the RAF 2000. There must be around twenty fatalaties in the RAF by now. all with the same root cause, loss of control in flight.
However as I previously stated you are entitled to your own opinion.
I am not stating an opinion, I am stating a fact, the RAF 2000 is unstable and a potential killer.
To claim that training is the answer to ensure safety in such an unstable machine as the RAF 2000 is wrong period and I make that statement based on being qualified to make it.
That is a fact not an opinion.
Larry, I think you misunderstood me. If you read all my posts in this thread, you will see that my message is consistent. I was responding to statements that a keel mounted stab may cancel-out the PPO moment of the RAF engine. This statement is absolutely not true and can be misleading to people who don’t know any better. The purpose of my post with the pictures was to demonstrate that even a stabbed RAF could PPO. I appologize for the graphics.
You know this very well, Larry, and that is why you are modifying your new RAF. Your new RAF, with only 3" high thrust line and a good stab immersed in the prop wash will be a very stable machine, and almost completely PPO proof. Your current stabbed RAF is much more stable than a stock RAF, and nobody is disputing this fact.
I guess you were referring to the Adler accident. Steve Adler's gyro was a highly modified dominator, not your typical Dominator. In essence, Steve's gyro was configured with a very low engine thrust line - the opposite of an RAF. Before Steve's accident, some people believed that a too-low engine thrust line cannot hurt, but I think that Steve's accident made people realize that any large thrust line offset, high or low, is bad.
I don't know what my own flying experience has to do with this discussion. I have flown a few AAI modified RAFs, a Magni M16, and a Dominator. I am currently rebuilding a CLT Air Command. I have hundreds of hours in various aircraft. But all this is irrelevant to our discussion; The Boeing Company is not requiring their engineers to hold a pilot's license. My theoretical understanding of gyroplane aerodynamics has nothing to do with my practical experience, and obviously the same is true for people who’ve got thousands of flight hours and next to zero understanding of aerodynamics.
01-07-2004, 02:02 PM
Udi, you said, "I guess you were referring to the Adler accident. Steve Adler's gyro was a highly modified dominator, not your typical Dominator. In essence, Steve's gyro was configured with a very low engine thrust line - the opposite of an RAF. Before Steve's accident, some people believed that a too-low engine thrust line cannot hurt, but I think that Steve's accident made people realize that any large thrust line offset, high or low, is bad.
That is why people should pay more attention to Dr. Stewart Houston at the Glasgow University, who conducted tests for the UK CAA.
With out confirming, I am sure he said "the thrust line should be within 2" of the VCoG."
Of course drag does play a part, but nowhere near as big a part as the VCoG.
In the speed range up to say 70 mph I believe that the drag component is probably in the 20% range. Of course this depends on fairings, extra large wheels way down low etc.
The experts might need to correct my 20%. Of course the higher the speed the bigger % the drag component.
01-07-2004, 02:04 PM
Larry, that was not a CLT gyro!!!
01-07-2004, 04:02 PM
I've kept quiet so far on this topic, which was probably wise, but I just can't hold back any longer. It simply doesn't make sense to me why anyone, no matter how experienced or talented, would knowingly build, buy or fly an unstable gyro. Flying is dangerous enough as it is without adding unneccessary risks. For student pilots, low time pilots and occaisional pilots, it is even more important to fly a stable machine.
However, in this country you are free to fly whatever you want to. As long as it is only the pilot's life and his/her passenger's lives at stake, I don't feel it's any of my business. BUT, don't lets any of us pretend flying an unmodified RAF, or and RAF with only a stab, is as safe as flying a Dominator or an AAI modified RAF. It's not.
It's like motorcycle helmets. I personally think riding without a helmet is absolutely stupid. If an adult wants to assume the added risk and ride without one, however, it's their business and none of mine. If, however, they start spouting nonsense about how it is safer, or just as safe, to ride without a helmet as it is to ride with one, it becomes my business, and my responsibility, to challenge such unfounded and unsuportable opinions that can get other people killed through ignorance.
I'm done now.
01-07-2004, 04:20 PM
You did well. ;D ;D ;D
01-07-2004, 06:59 PM
Larry M. brought up a good point about trim systems. I spent 4hrs. with Ron Menzie in his Raf. I asked him where his trim wheels were. He did not have them. He changed the offset in his gimble head. The machine flew great.
The chains and cables of an Raf trim system trouble me. If what Larry M. said about Ron is true, that means if the trim spring fails we crash and die.
I think that I could fly both of my AC gyros without trim springs relatively easy. Can anybody tell me what it is like to fly an Raf with a broken trim spring?
Inquiring minds what to know.
01-08-2004, 11:39 AM
The most discouraging part of this argument to me is the way the NTSB reports these crashes. If a veteran airline pilot, with years of experience in stable, well-maintained aircraft, does his homework and checks the NTSB database, he'll read nothing to suggest the kit's design is contributing to all these fatalities.
"Buyer beware" only works for buyers dilligent or lucky enough to find all needed information, including the internet forums.
01-08-2004, 12:17 PM
Chris, I have done quite a number of experiments with the Raf torque tube offsets. There is not one dimension that will allow you to trim Raf blades for all airspeeds and/or weights.
It would be quite demanding for a student to have to learn with Raf blades and no adjustable trim. The rotor would be hands free at particular speeds and gross weights. If the next student was much heavier or lighter then they would have unnecessary stick pressure to fight against.
The standard Raf offset is 3/4".
At the moment I am running some Raf blades with a 5/8" offset and some lighter trim springs. This works very nicely, BUT you run out of forward trim much earlier when wanting to go faster. Not a problem for training, and the stick is so much lighter to push forward when on the ground.
I have great respect for Ron Menzies, BUT there are a number of quotes on the forums re what Ron has or has not done etc that I find quite difficult to believe after my testing.
I think that I will email Ron privately and get some answers right from the horse’s mouth as it were. It is amazing how accuracy can change when info goes from one person to another.
Cheers for now. Aussie Paul.
01-08-2004, 12:31 PM
Chuck,Peter! WELL SAID!!!
I sure love a good argument. It was good to discuss the stability issue. I have always wanted a safe gyro. That is why I am working on converting both my new and present flying gyro to the keel and engine modification to achieve a better CLT configuration. I just ordered more keel material from Aircomm. Your passion for the issue really came through.I never flew the Aircommand till I made the CLT change. I really hope the modifications do improve the stability of my RAF to where I do very little stick input to fly level in higher winds. I hope my mods save lives. I hope you keep the word flying. Fly stable machines. I will keep saying train well in type.
01-08-2004, 01:00 PM
I am an experienced fixed wing pilot and when I read the NTSB reports I DID come to the conclusion that RAF's were deadly. Especially without HS.
RAF's reply to me was that there were more RAF's so of course more RAF accidents. There may be more RAF's flying but they still represent a porportionally higher accident rate. And in raw numbers the rate of fataliteis are simply unacceptable.
I do agree the NTSB could be doing much more. If they were certificated aircaft they would have been grounded a long time ago.
What really amazes me is that RAF should be leading the bandwagon to make their machines safe and instead they keep denying it. I find it morally unconsionable and bordering on criminal behaviour.
What is ironic is that RAF is pursuing its current course for econimic reasons. Yet if RAF admitted the problem and began taking action to correct it they could save their company. As it is they will keep it healthy longer but virtually guarantee its eventual demise at a later date.
01-08-2004, 01:15 PM
I will relate one of my experiences but first I'll say that trim controls are used to relieve control pressures applied by the pilot. If a trim control breaks or stops functioning, you're not going into an uncontrolled crash---unless you're asleep or unconcious. Just fly the aircraft.
Now-- my experience. I was on a cross- country to a small sod strip. On my takeoff departure roll I found the strip to be rather bumpy. On climbing out, my ship had a tendency to dip to the left. After leveling off, I released pressure on the cyclic and she dropped down and to the left. I had to keep aft and right pressure on the cyclic to maintain straight and level. Landing at home base was routine.
After shutdown Insp. I found the L/H trim spring had come out of the chain link; so I had no trim control on the L/H side. My fix was to use a Ty Wrap thru the chain loop and around the hook of the spring. I recommend everyone do the same with a Ty Wrap after you have your trim cable length set.
Anyway, never fly your gyro without your hand relaxed around the cylic.
01-08-2004, 04:08 PM
Just a question.... I know we ASSUME a gyro with Clt and a good set of tail feathers is Stable but has anyone ran these tests on a Dominator or a Little wing???
Hey Ron A, Ron H. here.
Yes, I have about 80 hours in the Little Wing LW-2. It's rotor head is BOLTED solid in the pitch axis. Anytime you are flying, the stick is fixed as far as control inputs to the head are concerned. It is like riding on rails.
The machines with tilting heads act the same way but you have to physically (like Paul has been doing) lock the stick against a block or something. There are no pitch excursions.
01-08-2004, 04:15 PM
I never thought of that.
01-08-2004, 06:56 PM
... the New clt Dominator that bunted over last year...
Larry, where was this accident to which you're referring? Do you mean this Dominator on 8th September, 2002? http://www.ntsb.gov/ntsb/brief.asp?ev_id=20020920X05186&key=1.
CLT does not provide immunity from unloading the rotor and losing RPM! There are still ways to unload -- as simply as pushing the stick forward. It does protect you from PPO as a mechanism for unloading the rotor. A stable gyro can protect you from PIO as well.
But the machine that can protect you from everything, including your own human error, doesn't exist. Anything that takes you up in the air can kill you.
01-09-2004, 02:22 PM
My concern with the NTSB stats is that they never mention instability as a contributing factor, but often blame "causes" such as adding a horizontal stab or inadequate training. It reinforces the company line.
Part of me is glad the government stays out of the business of grounding particular designs, but people need to do their homework. I'm not sure it even occurs to a guy who's flown Boeing products for 20 years that a design so openly for sale might be unsafe, or that he might have to look past the government or kitmaker's official line to find out.
01-09-2004, 04:40 PM
I agree completly with your point about pro pilots used to FAA oversight on every area of thier flying lives "assuming" that since RAF's are sold openly they must be safe.
I am not a heavy iron driver- just a single engine pilot -but I too find it amazing that gyro pilots spend so much time arguing on basic areas of physics and aerodynamics.
Pilots who have gone thru a formal FAA based ground school learn certaiin facts of aerodynamics and they then become gospel. Everyone learns them, knows them and there is rarely any debate about them. And if there is debate tons of data is available to settle the issue quickly.
01-10-2004, 05:51 AM
I went through an FAA Part 141 ground school for the Private certificate, (Airplane, Single-Engine Land,) and have the certificate, with about 160 total flight hours. The FAA says I'm legal to fly any small experimental, including gyroplanes, and carry passengers if I wish. Nothing in my training addressed vertical CG, let alone thrust alignment in gyroplanes. I would imagine this gap persists all the way up to ATP if you stay in the fixed-wing world, probably covering only the horizontal thrust alignment issues related to multi-engine flight.
Maybe what we need is an FAA certified Part 141 curriculum for Rotorcraft / Gyroplane. It really would not be hard to develop, using existing approved fixed-wing course materials as a base for weather, airport operations, powerplants, etc.
01-10-2004, 01:55 PM
I agree there was no gyro or thrustline aerodynamics taught to you and I as we were getting our PPL for airplanes.
I think your license only allows you to fly Catagory Airplane and Classification Single Engine Land, not rotorcraft unless you have a rotorcraft add on rating.
Maybe one of the CFI's will jump in here and clarify for us.
I am generally in favor of less government intervention in our lives but I agree with you that gyro pilots should have a ground school requirement. The gyro world would be better for it.
So far I have met two basic types of gyro pilots - gyro guys who have been doing it a long, long time and are often self taught or airplane guys who have gotten into gyros more recently. IMHO the airplane guys are much better aviators and bring a structured scientific perspective to the whole thing.
You have to admire the sprit of someone who knows little about areodynamics but is willing to make a major mod to his gyro then go out and be the test pilot. I do not know many Cessna or Piper or Boeing drivers who would do that which is partly why the accident statistics compare as they do.
01-12-2004, 08:59 AM
Your ASEL Private allows you to fly any small (under 12,500 lb., non-turbine-engine) experimental. Your homebuilt gyroplane is not considered to be in the Rotorcraft category, but in Experimental. Some people describe it as a loophole, but there are valid reasons for it to be so. Recent comments from FAA insiders suggest the policy is being revisited, but for now, any Private certificate holder can fly an N-numbered experimental gyro legally.
For the record, I'm not suggesting that gyro pilots be required to attend a ground school, any more than fixed-wing pilots, but it would sure be nice to have a part-141 course available. My fixed-wing ground school was the best $350 I ever spent.
01-12-2004, 11:46 AM
Thanks for the education on the gyro loophole.
Now that brings up other questions. Why is there a seperate gyro rating under rotorcraft. Would that only apply to gyros that were certificated? How can you build hours for a gyro rating if what you are building your hours in is classified as an experimental "airplane"?
Gyroplanes are a class in the Rotorcraft category. People can get flight training and be certificated in gyroplanes (many are). Your flight time in gyroplanes does count for your certification in type. Dual time only counts if your instructor is a gyroplane rated CFI operating under the PRA experimental exemption.
Let me explain the experimental "loophole". It all starts with the definition experimental. What is an experimental aircraft? Lets say I am building an aircraft that has wings and a tiny little rotor on top. Is it a rotorcraft or a fixed wing airplane? Until I go through the process of FAA certification, I might as well call it a space shuttle. The fact that the FAA has registered an aircraft as experimental means they have not yet defined a category and class for that aircraft (check out the FAA aircraft registry – some gyroplanes are registered as fixed wing). So they don't require you to have an appropriate pilot rating because it hasn't been decided yet what is the rating that you need. They only require that you hold "a pilot rating".
When flying experimental aircraft, there is an inherent risk that is not part of flying certified aircraft. You are the test pilot and the FAA assumes you don't want to kill yourself so they give you more leverage.
Bottom line – you don’t have to have a rotorcraft rating to fly an experimental gyroplane in the US. You will, however, if and when you want to fly a gyroplane that was certified under the LSA ruling. I am getting my gyroplane ticket anyway, simply because I do want to get thorough instruction in type, and I might as well go through certification.
01-12-2004, 05:28 PM
That was my question, too, but after picking brains much fuller than my own, I've been persuaded that the hours you log in an experimental gyro can be applied toward a gyro certificate. In fact, unless I've missed something, cross-country and/or night flights which are long enough to qualify can be counted as hours toward a commercial certificate, including fixed-wing.
01-12-2004, 09:49 PM
Paul and Udi,
Good explanation about the loophole but unfortunte that it exists. In my opinion the gyro will be better off when their is more not less structured instruction.
I am approaching getting my gyro commercial as no different than any fixed wing rating.
During my instrument training when I would ask some strange question or miss something in flight my instructor kept saying "don't worry it's not on the test" or "he won't make you do that in the checkride."
I told him if I did not know how to safely fly on instruments I did not want the rating. For me the point is being the safest and best pilot I can be -- the piece of paper is almost incidental.
01-13-2004, 08:54 AM
Will the gyro be better off if the government clamps down on experimentation which doesn't meet with the approval of the most conservative among us? I don't think so. Consider the situation in the UK, where the bureaucrats won't let RAF owners fly with horizontal stabilizers, because they're not "approved." I like our system better. As long as risk-takers don't involve the rest of us in their risks, I say, let them experiment.
If it bothers someone that insurance is expensive or not available because of the gyro's track record, the answer is to gather good enough data to demonstrate to the insurance underwriters what the real risk factors are, and let the more conservative among us qualify for better rates. (Like we do driving cars.)
Another point is that, unfortunately, only ultralight and experimental aircraft are affordable for most people. Sure, I would like to own a certified gyroplane, but right now the cost is prohibitive (and the selection is limited). The LSA ruling may provide a middle ground where people can fly affordable aircraft while having the comfort of knowing this aircraft design was tested to some minimum standards. I am looking forward for the first LSA gyroplanes to hit the market. The availability of LSA gyroplanes would hopefully lower the high death toll and help gyroplanes enter mainstream aviation. I know most general aviation pilots would much rather rent or buy an LSA gyroplane than an experimental kit. Insurance rates would become lower too for LSA pilots.
01-13-2004, 11:34 AM
I only said the gyro world would be better off with a more structured learning situation.
If all the facts and data were published and if a ground school and flying currriculum like fixed wings were in existence, and if good text books existed and there were plenty of instructors readily available, etc. Accidents would go down, insurance would be available, gyros would enter mainstream aviation and tons of fixed wing pilots frustrated with the high cost of aviation would get into gyros.
With more people in the sport more companies would crop up, they would produce better gyros, have funds for R&D, reduce production costs thru volume, increase our selection of available machines, etc. etc.
I agree LSA is the most likely vehicle to make that happen. There are lots and lots of pilots out there who have neither the skills nor inclination to become aircarft designers, builders or mechanics.
01-13-2004, 04:03 PM
Udi I think we will all be in a state of " Sticker Shock " when we see how much a LSA Gyro costs to buy and operate. Just price the Magni which will likely be one of the first - and maybe only LSA gyro. Once it is Approved as a LSA gyro I bet the price will go much higher than it is now.
As for me.... I am sorry, But for 40-60 grand I will buy a nice Dominator or Aircommand and forgo the Insurance and take the change and buy a nice RV-4 or RV-6 or a Thorp etc.... etc..... Or heck if I got 40-60 grand burning a hole in my pocket and I gotta have spinning wings over my head I would just buy a Exec 162 and take some helicopter training.
01-13-2004, 04:16 PM
If all the facts and data were published
Lots of people in the gyro world are working on this, Rob.
...and if a ground school and flying currriculum like fixed wings were in existence...
Jim Mayfield is trying to do something similar with a dealer/instructor network for his machine. It's been tried before (most recently by RAF). It's not quite a "curriculum" which runs into the problem I describe below...
... and if good text books existed and there were plenty of instructors readily available, etc.
The instructors will come with dealer networks. As you point out, Rob, Sport Pilot/Light Sport Aircraft has potential in this area. The textbooks and curriculum are another issue. Right now there isn't one textbook for private pilot -- gyroplane or any other rotorcraft-gyroplane rating.
Why not, when there are beautifully printed, crystal clear, lavishly illustrated, deep and accurate textbooks available for airplane and helicopter students? It's because the number of gyro students is very small. We've all seen instructors fold their tents because they were having a hard time. Jim is doing something no one has done in years and years, actually employing professional gyro instructors.
But right now, there are not enough students for anyone to make money on an instructional book -- and "no man but a fool ever wrote, but for money."
Think about it -- if Jim succeeds beyond many people's expectations, and he has 15 dealer/instructors nationwide who licence ten gyro pilots annually each, and say they also graduate five a month at AAI -- that's a market of 210 pilots a year. Say other instructors (RAF's people like Jim Logan, Duane and Dofin; independents) teach a wildly optimistic 100 others. That's 310 pilots. If they ALL were willing to pay $40 for a book, your publisher grosses $12,400 at point of sale. It probably costs half that to retail the books (seriously). $6,200 is left for the cost of printing & shipping, plus editorial expenses. Not a lot of money left for the fella that wrote and illustrated the book.
2003 was an atypically crappy year, but a lot of kit manufacturers only sold single digits of gyros. There were probably under 50 new gyro pilots training in the USA. If they all bought this mythical gyro textbook, your publisher grosses $2,000 at point of sale and nets $1k. After the printing is paid for the publisher is thousands in the hole and the author gets a "zero amount due" royalty check!
At some point, there are enough pilots training, enough instructors and examiners and legal instructional airframes, and enough interest that some kind of tipping point or critical mass is reached... then it makes economic sense, albeit as a risk or speculation, to launch such a book.
One answer might be to develop the gyro flight manual on a voluntary open-source basis, perhaps as a wiki. The intellectual property could perhaps be deeded to an organisation or organisations, such as PRA and EAA. Then they could assign the rights to a publisher to make a tree-bark version....
01-13-2004, 04:30 PM
Just price the Magni which will likely be one of the first - and maybe only LSA gyro.
AAI offers an assembled & tested Sparrowhawk for public use (i.e. governmental) aviation in the USA. RAF also offers assembled gyros to overseas customers, or they used to, anyway. There is some question as to whether their "rotor stabilator" will get approved or whether they will have to meet the stab standard.
I guarantee that, if there is any significant market for assembled Light-Sport-Aircraft gyroplanes, Air Command, RFD, Barnett and others will follow suit. All of these guys have lost sales
Look at how Ron Herron is doing with the Little Wing. People love his gyro but they are intimidated building from plans. Some of them are intimidated building from kits, too. If Ron could kit the plane he could sell more (I think the startup hassles & costs of a kit business hold him back, but that's really his to say, not mine). If he could have ready-to-fly Little Wings people whose dream is flying would buy them.
If I were a genius at rotorcraft design like Ernie or Ron I would probably be looking at having my gyros built overseas. I would probably look at India where costs are low, an educated population speaks English, and the rule of law exists (which is why I wouldn't look at other Asian countries, Russia, or Brazil right now). The reason that the Magni is so expensive, apart from the quality which is a factor, is that it is made in high-cost, low-productivity Italy. I know that Ernie got hosed at a previous attempt at dealing with a foreign outfit, so he probably won't reconsider it. But... my guess is that if you moved production of gyro resembling the RAF or AAI to India, you could have assembled and test-flown machines coming off a ship in American seaports for around half of what your costs are now.
01-13-2004, 04:38 PM
All of these guys have lost sales
I hate it when I forget to finish a sentence.
All of these guys have lost sales... because some customers want to fly and do not want to build, and under the current regs there are problems with building a non-FAR-23 machine for business reasons.
01-13-2004, 05:09 PM
I am not sure building it overseas would make it cheaper. In the airplane - light stuff mind you - side of it the only thing I see imported that is cheap for what you get is the X-Air Ultralight, but now that it is gaining a reputation here the price is going steadily up.
When the X -air first came out you could buy a complete Airframe kit with everything minus engine, prop and instruments RETAIL for under 6 grand. This was a Smoking Hot deal as the next closest plane equal to the X- air is a Flightstar SLll. the Flightstar handles a little lighter and will do okay with slightly less power but doesn't have the fit and finish or as much standard equipment as the X-air, And it costed more than twice the price of the X-air. Fast forward to today and the X-air is not but just slightly less money to buy than the Flightstar, and due to the low prices they used to sell for, the Re sale value is poor because people still think they can buy them new for 6 grand.
01-13-2004, 05:43 PM
What is that game? Hot & Cold?
You guys are getting warm . . . ;D
English has never been a barrier, laws can be broken, the collor of the game is green . . .
I did the first time I saw one flying, I did here on the forum and I do it again "there are commercial uses for gyros" and "do not keep the general public ignorant anymore"
Check the route the airplanes took when they had to go to Europe on WWII . . .
I am checking out now!
01-13-2004, 07:34 PM
When you order a Van's kitplane with the fast-build option, the frame parts are sent to the Phillipines, are welded there, then shipped back. It's crazy to think that transportation has become so cheap, or US labor so much more expensive than the rest of the world, that something as bulky as an airframe can be cheaper that way, but evidentally it is.
If you check the AAI website for the price of an assembled SparrowHawk, it's $37K for the kit plus the factory assistance plan, or $62K factory-built in law enforcement trim. That's probably a fair idea of the price range LSA gyros will occupy. If quality and safety are on a par with certificated airplanes of today, there will be people who will buy them because they're more expensive. Not everyone considers "cheap" and "primitive" desireable.
It would be relatively simple to put together a polished syllabus for the Rotorcraft / Gyroplane PPL. Start with the Jeppeson fixed-wing course for everything not specific to gyros, and augment with the FAA's Rotorcraft Handbook, available for free download, and a little additional detail on gyroplane systems, and you'd have it. I suspect this would have to be published on the web, given the obvious challenges of low-volume printing described above.
01-13-2004, 09:06 PM
Steve go do some homework. you can find Execs either nearly complete - if you must have brand new - or low time for under 50 grand. Also why would it take 10 grand to learn to fly in one? ----- Btw, add up the cost of 40 hours of gyro training at the current rates.... it ain't cheap either! -------
My secret is www.barnstormers.com ;)
Rv with a Subaru for 65 grand??????? Again do some more homework. If you like to build, you can put together a real nice RV-6 with a BRAND NEW Certified Lycoming 320 or even a 360 for under 50 grand. Used low time pristine examples are abundant on the aviation classifieds with many under 50 grand ready to go anywhere.
Can you buy a Rv-6 or a Rotorway Exec for 45 grand factory built to a " certified " level of standards? Nope. So if this is a big factor to someone then that may help with others decision making process.
But it is just my opinion that - I - would have a hard time forking out anywhere near that kind of dough for a gyroplane. A four place jump takeoff turbine gyro like the Hawk 4 is another story but for a Magni or a Sparrowhwk etc...? Not me bro! you see the way I look at it is a 45 thousand dollar Magni can't do anything a gyro costing half or even a quarter of it's price can do. Why spend 45 grand on a Magni when 20 grand could buy you gyro that could do every single thing the magni could do?
I know there will always be the few people out there that want the " best " and money is no object. If it was offered there would be someone willing to buy a 65 grand powered parachute. But I am the type of guy who wouldn't spend 100 grand on a particular car when I know a 50 grand Corvette Z06 can do all the same stuff for half as much money.
I also tend to think of gyroplanes - or compare and lump them into the same group - as ultralight airplanes. And if you had much experience with Ultralights you might see what I mean. They both fly in the same speed envelope, and they both use in some cases the same engines, etc... You can buy a whole lot of ultralight for a fraction of the cost of a 45 grand Magni.
But look my only point of all this is it will be great to see some positive changes in the gyro world when sport pilot comes out and we get some LSA gyroplanes. But I fear the price of these LSA gyros will be extremely high and too high IMHO to jumpstart a new surge in rotorcraft.
just for the record I am sure LSA ultralights will be priced through the roof too. Look at the prices of modern certified aircraft, it is crazy! But for a fraction of the price of that certified plane you can pay someone to build you a experimental that is more substantial, out performs, and in every respect is a far better aircraft. I believe LSA will follow this same path.
01-14-2004, 05:26 AM
Steve found this As soon as I logged on, Didn't go to see how many more were there...
1998 ROTORWAY • FOR SALE • 1998 Exec 162F kit, 35hrs. TT, 30mm & 35mm belt drive secondary, upgraded tail assembly, thermostat diverter, digital engine gauges, vox intercom, dark blue metallic paint, $42,000 • Contact Dan Verbonitz - located Freeland, PA USA • Telephone: 570-636-1207 • Posted January 13, 2004 • Show all Ads posted by this Advertiser • Recommend This Ad to a Friend
01-14-2004, 12:28 PM
Hi all, It has been my experance that becoming focused on the price of a toy can take a lot of the joy out of the experance. I have seen sports develop a focus on price that drives all of the true enthusists out of the industry. This also stops growth and inovation.
I haven't met anyone who is getting rich from this sport. I beleive that the focus on price has kept this sport from growing. I beleive that my gyro instructer canot make a reasonable living for what he charges.
I beleive that the price increases that have been described are because people discover that to make a living you have to charge a fair price.
A well run business might net the owner wages plus 10% of the gross income. If it gets higher than that competition comes in and levels things out. That is what makes this country great. Being focused on price and personal gain is, in my opinion, what is eroding this countrys future.
When a large box store comes to town many of the small retailers with their personal service and careful buying vanish. I enjoy the retail experance less and I am unhappy about suporting cultures that are at odds with the things that I hold dear.
I am grateful that there are people willing to put their heart and soul into helping me have fun. I think that they should charge enough to make a living and I will be happy to pay for my fun and their success.
We are all in this world together and denying someone a return on their investment and craftmenship diminishes us all.
I like to get a good value in my purchase, but I don't want to limit my choices because I haven't made enough money to suport the people that have the passion and the vision to help me realize my dreams.
This is not a condemnation of anyones style, only food for thought.
Thank You, Vance
01-14-2004, 04:27 PM
Getting a heli ticket costs $10K around here if you don't have a PPL first. That's fact. It's not getting cheaper.
And if you have your Gyro certificate, you can get your helicopter ticket without having to meet any specific hour requirements. You still have to pass the practical test, of course, but, if you are a good student, you may be able to do it in less than 40 hours.
At current rates a gyro ticket for a new pilot, like myself, should cost between 5 and 6 thousand dollars, (I'll let you know how much it has cost me when I finish). If you already have a PPL, you should be able to do this in 40 hours, which are required, as much as 20 hours of which may be solo time, which is cheaper. Given the price of helicopter rental, it may actually be cheaper to get a gyro rating first and then go for the helicopter add on, rather than going straight for the helicopter rating without a PPL or with a PPL, Airplane category rating.
01-14-2004, 05:23 PM
It is a experimental - the Exec - and therefore ANY rating is enough to be legal. You will still need lessons to learn to fly a helicopter but not a set number of hours. You might even find someone to train you in your own machine for a fraction of the "Normal" price of heli instruction. I am doing just this with my training to get my PPL. It costs me 20 bucks a hour for the instructor and 7 gallons of 87 octane auto fuel per hour and that is it cause I own the airplane.
Steve...... What is so real about a rotax 912 or 914? Fit and finsih as well???? Steve have you personally seen a Magni? Yes they are clean machines but not that much cleaner than most other brand gyros built with attention to detail by the builder. It certainly isn't fair to say it is like a Ferrari and Vw between a Magni and anything else!
Steve Ultralights are Flimsy????? Come on guy you know better than that! I am not talking about 20 year old Quicksilver Clones. I am talking about planes such as the Challenger, Any thing by Rans, Kit Fox, Avid, Aventura, Flightstar, Titan, Etc.... Several of these planes are stressed for aerobatics and none of them are anything near what I would call Flimsy.
Look guys, go spend your 40 or 60 or 100 grand on your new fancy gyro. If you all feel like you got your moneys worth and are happy then great. Justify your purcahse anyway you see fit, I just personally think your nutz ;)
01-14-2004, 09:33 PM
Ron said - "Steve Ultralights are Flimsy????? Come on guy you know better than that! I am not talking about 20 year old Quicksilver Clones. I am talking about planes such as the Challenger, Any thing by Rans, Kit Fox, Avid, Aventura, Flightstar, Titan, Etc.... "
Ron, you need to find other examples, if there are any, because none of the aircraft you have mentioned are true Part 103 ultralights! They either have too many seats, are too heavy, too fast or carry too much fuel.
I have a hunch that when LSA becomes fact that the FAA will come down hard on the 'Fat' ultralights.
01-15-2004, 06:33 AM
Dean I understand that most - if not all - of those aren't legal part 103 ultralights. That wasn't my point. I refered to them as ultralights because for the most part that is what most people including many in the Faa, refers to them as. Of course to be legal in a Rans S-6, or a Titan Tornado, Or a Clipped Wing Challenger II, Etc... You have to do either two things..... Either register it as a experimental and fly it with a PPL, or register it as a ultralight trainer and get your BFI rating through EAA, Or Aerosports, Or USUA.
I agree with you that once Sport Pilot comes out the Faa will not continue to turn their backs on the Fat ultralights. I don't think it will be a witchhunt either though. There is only so many Faa inspectors and so many places for them to go to find these illegal machines, and or operators.
01-24-2004, 07:40 PM
I have a hunch that when LSA becomes fact that the FAA will come down hard on the 'Fat' ultralights.
At Oshkosh last year I said something about 'Illegal ultralights' and it really set John Ballantyne (ex-USUA, now with the CommOne people) off. John made a good point that I always try to remember: when someone builds a plane that does not meet part 103 standards and tries to operate in under 103, it is not an 'illegal' or 'fat' ultralight. It's an unlicensed aeroplane -- best case, an 'illegal' experimental.
Dean, I'm not teeing off on you, please understand, I'm just riffing off the comment you made, because it's exactly what we all say, but as John pointed out, it's not quite that.
01-25-2004, 07:49 AM
If it walks like a duck, talks like a duck, then it probably is a duck or A rose by any other name..... Whatever!
It seems Mr. Ballantyne is a bit touchy about the Semantics. ;D
01-27-2004, 01:30 PM
Hello to all. My name is Bob McGuire and I'm currently in the process of building one of the dreaded RAF2000s. I've just read this thread from beginning to end and I must say that I'm greatly disturbed. To be honest, if I had read this prior to my purchase I would have certainly reconsidered. This being said, I have quite a bit of time and money invested in this aircraft. I have about two months of weekends left before it is finished. At that point I plan to pursue flight instruction in the gyro. I currently am a licensed fixed wing pilot with about 220 hours under my belt.
As I have built the kit I have incorporated several modifications. I have installed Don Parham's landing gear mod. I have purchased Larry Martin's "Ultimate Stab" and will be installing that. I have also purchased RAF's stabilator unit. The latest version of this unit incorporates two linear actuators. One is connected to the stabilator and provides the pitch trim and the other is used to provide roll trim. Together these replace the chain, spring and cable trim units.
My question to all of you is this, how do I make this aircraft as safe as possible to fly without scrapping the entire project? My background is electrical engineering, I'm not an aeronautical engineer and I have no pilot time in gryos. I have only ridden in a gyro one time and that was at Oskosh last year. The gyro was piloted by Jim Logan. My father had a ride with Duayne Hunn.
It is obvious from reading the various posts that there a wealth of experience here and I'd like to take advantage of it. Any suggestions you have will be appreciated and welcomed. My goal is to have a safe aircraft without having to start all over.
Thanks in advance,
01-27-2004, 06:12 PM
My question to all of you is this, how do I make this aircraft as safe as possible to fly without scrapping the entire project?
1. Get the best flight instruction you can. Jim Logan, whom you mentioned, is a very, very good pilot and a good instructor.
2. Fly within the machine's envelope. Indeed, construct a set of personal minimums for yourself. Gusts are your enemy with a gyro that has limited natural stability.
3. Learn all you can about Gyro Aerodynamics. Many good links in this forum. The initial report that started the whole stability fur-ball is here, as are links to good stuff on the PRA site and the Magni site.
4. Consider the AAI stability and control conversion for the RAF (yeah. Expensive). Talk to people who have had it done.
01-27-2004, 06:31 PM
My question to all of you is this, how do I make this aircraft as safe as possible to fly without scrapping the entire project?
Sell it and buy a fixed wing with a parachute. Gyros are safe if flown within the envelope. Flown out of it and there is no recovery in most circumstances.
Want to keep the gyro and make it as safe as possible? Get the AAI kit installed.
Don't want to do that either? then follow Hognoses reply especially #2. And if you do #1 with a RAF instructor, don't let them fool you into thinking your better off without the keel mounted stab.
01-27-2004, 08:03 PM
You can't go wrong with the AAI stability augmentation kit. You will end up with a truly stable gyroplane that will be both safe to learn in, and fun to fly when you get more experienced. You may have to get rid of the 'stabilator', however, which does nothing to eliminate pitch instability anyway. Give Jim Mayfield a call. He will give you straight answers to your concerns.
01-28-2004, 03:55 AM
You are correct that you, and all of us, can learn a lot by perusing this forum as well as Norm's forum.
As an engineer, you are trained in critical thinking. That is a tremendous advantage.
If you get a chance, I recommend that you take a look at the stability section of the American Autogyro web page.
I greatly admire your "search" for the truth.
I would like to offer some observations:
1. We, at AAI, do not understand how the RAF device can do anything other then provide trim force to the rotor system. We believe it is incapable of providing airframe stability. We do not say that the device is dangerous in any way unless a person thinks it is an airframe stabilizing device. The device appears to us to be a rather heavy and complex rotor trim system.
2. We believe that the Don Parham/Larry Martin horizontal stabilizer is a "decent" horizontal stabilizer and that it provides a degree of stability much greater than a gyroplane without a stab.
3. We believe that any gyroplane with a large engine thrust line offset requires a stabilizer larger than can be practically constructed to achieve deadbeat dynamic stability.
4. We believe that a gyroplane without a thrust line offset is physically incapable of suffering a power pushover. Further, we believe that the greatest number of fatal accidents in tgyroplanes result from power pushover.
The following can be articulated much better by Chuck Beaty or Doug Riley; and is offered simply as a thinking tool.
1. Force X Arm = Moment
2. If number one is true then the statement "there can be no moment about a hinge (CG) without an arm" must also be true.
3. Rotor thrust, in autorotation, is dependent on G loading.
4. If the preceeding statements are true, what happens to a gyroplane when it has a force (engine thrust) and an arm (thrustline offset) and rotor thrust decreases through misapplication of the controls or through gust effects?
There are several extremely knowledgeable folks that post on the forums. Almost all of them will be happy to correspond with you on the forums or by e-mail.
If it is convenient, we would be very happy to schedule a flight lesson at our Arizona facility or at Terry Eiland's facility in Florida.
Whatever path you choose, we wish you the best.
01-28-2004, 05:59 AM
Bob, there are a couple of key concepts to keep in mind when trying to "tame" a gyro with a high thrustline.
First, if the gyro has an ineffective horizontal stab (or none), the force that keeps the gyro from pitching over in response to prop thrust is the thrust of the rotor. The rotor's thrust line in such cases pulls up on the nose of the craft, countering the nose-down torque created by the prop. This is fine until rotor thrust is reduced -- say, in a downdraft. Then, with the suddenly insufficient rotor thrust to counter it, the prop's thrust is free to push the nose down until a PPO occurs.
This much is fairly well known. It follows, however, that no device that attempts to manipulate the rotor so as to prevent PPO can succeed. The rotor is simply out of the equation in a low-G (diminished rotor thrust) event. Devices that "manipulate rotor thrust" include the offset gimbal head, the RAF pivoting mast, Duane Hunn's vane gadget and ... yes.. a skilled pilot working the stick.
Again, the critical point is that no manipulation of the rotor can prevent PPO in a low-G event. PPO instability arises in the airframe, and the solution must be applied to airframe. This solution must do one of two things:either (a) supply a reliable force OTHER than the rotor thrust that continually supplies the right amount of countering torque to oppose the nose-down torque caused by the prop or (b) move the propeller or the various masses that make up the gyro so that the prop no longer produces a nose-down torque.
Second, bolt-on horizontal stabs alone (an attempt at the first type of fix) are not a complete fix unless they meet some pretty stringent criteria. The H-stab must generate a nose-up force that's proportional to the throttle setting (not proportional to the airspeed). It also must generate sufficent force at essentially zero aircraft airspeed to counter the nose-dowm torque of the engine at wide-open throttle. Finally, it must operate at sufficent negative angle of attack so that it is applying its nose-up force during routine cruising, as well as climbs and other power-on maneuvers. For a gyro with a nose-down torque of 500 ft.-lb. at wide-open throttle and a tail moment arm of 5 feet, the HS will have to load the gyro with 100 lb.of aerodynamic down-load just to balance the PPO tendency.
It is very difficult and inefficient to make a H-stab that meets all of these criteria for an otherwise stock RAF. The thrustline offset is just too large. A recent fatal crash of a H-stab equipped RAF in Virginia brings this truth into painfully sharp focus.
"As safe as possible" unfortunately probably means altering the engine and airframe configuration to improve the thrustline alignment... as well as adding a H-stab.
01-28-2004, 06:25 AM
In the last issue of Rotorcraft, Greg Gremminger wrote an article titled "Why are the Magni Gyros so stable?".
I suggest some of you who have a total mind set of CLT as being the only option to stability, read his article with an open mind.
The Magni is not CLT, has a keel mounted stab and is reported to be one of the most stable machines on the market. Greg outlines the reasons in a very logical and factual manner.
01-28-2004, 11:10 AM
Greg Gremminger constantly emphasizes the key point: the HS MUST continually and under all conditions balance any pushover moment created by the prop. As long as it does, there is no problem with a thrustline that is slightly above the CG.
In the case of the RAF, however, to achieve the result that Greg describes requires a down-load on the HS at wide-open throttle of roughly 100 lb. Since the down-load must be available at essentially zero airspeed (such as a full-throttle recovery from a vertical descent), the HS must be well-immersed in the propwash. A keel-mounted HS should be tested to verify that it actually "sees" accelerated air from the prop -- for example, by placing airspeed-indicator pitot tube ports at various spots along both surfaces of the HS and running the engine statically.
The HS also must have an appreciable negative angle of attack and/or negative camber. How much can be approximated from the lift curve of the HS, but this initial setting should be verified by formal flight testing of static pitch stability, using the tests Greg has published. Some adjustment will probably be necessary.
Despite all that, I just wouldn't want to add 100 lb. of down-load to my gyro. It loads the rotor just like 100 lb. of lead. The small HS down-load needed in cases where there's a smaller thrustline offset is tolerable.
Placing a HS with unknown aerodynamic qualities down on the keel and goin' flyin' is a "by-guess-n-by-gosh" process. It trusts simply to luck. It almost certainly will not make the craft fully pitch-stable.
That's right, Larry. The Magni gyro has a high thrust line offset of about 3". The Magni huge horizontal stab has a long moment arm and is partially immersed in the prop wash. This stab can easily counter the ~120 ft-lb nose down engine moment (which requires only about 20 lbs of down force at full throttle).
If Bob could lower his RAF engine thrust line offset from 12" to 3", and raise the stab into the prop wash, then I would say his RAF may become stable and PPO proof. The AAI kit is the only tested and proven fix I know of for the RAF problem. Ausie Paul has modified his RAF by raising the engine and turning the gearbox upside down. He claims good pitch stability. Larry Boyer is now attempting to do the same. Personally, I would go for a proven solution, which was designed and tested by a real aerospace company. $5K for the AAI kit is small change in the grand scheme of things.
p.s. the truth will become clearer than ever as soon as the LSA standards become law. Some kits will pass and some will not. I bet the Sparrow Hawk and the Magni will be the first ones to become LSA gyroplanes. RAF has no chance in the world.
01-28-2004, 02:26 PM
A customer who bought the last Raf that I sold, has ordered the Raf stabiliator.
He runs our stab.
It could arrive here late Feb or early March.
I am looking forward to testing this device.
This customer was told that the latest stabilator has 2 linear actuators and the trim springs and cables are removed as they are not required.
I have had to remove my customers name as Raf were giving him a hard time.
01-28-2004, 03:56 PM
What a great discussion. I don't find much time to explore these forums fully, but a little bird suggested I take a look at this one. I am tempted to jump in with both feet, but my efforts at developing the LSA gyroplane standards begs I be careful with objectivity and impartiality. Several of the guys in this discussion (Doug, Udi, Jim M, and others) are doing a great job of spreading the gospel of gyroplane aerodynamics. If gyroplanes are ever going to be accepted in the mainstream of aviation, we must adhere to good engineering and aerodynamics in order that gyroplanes might someday live up to their potential to be the safest aircraft type in the air! It is so very important that we educate the gyro community on the technical safety issues of stability so that the market will force safer designs.
But since my name was mentioned several times, I would like to comment on a couple of points:
1) I commend people like Larry Martin (and the Groen people, and Ernie, and Ron Herron) for making the effort to provide hardware for people that will make them safer.
2) While I do not feel a HS on a very high prop thrustline offset is the way to go or even as effective as needed. the DYNAMIC stability that an effective HS provides is a BIG improvement over no HS. Just a guess, but even if the HS does not provide full STATIC stability, the addition of a HS the size of Larry's product probably improves the safety by at least 80%. Just a guess! - testing tells the whole story!
3) You cannot determine the true stability of any aircraft by just looking. Some good technical people might be able to come close on paper, but the proof is in the testing - real, objective, pilot-isolated testing.
4) You cannot determine true stability of any aircraft by how it "feels". This is why professional Test Pilots use specific methods to determine the stability of an aircraft - to specific criteria.
5) Stability comes in several flavors. Many people base their conclusions about "stability" on mixed-up "flavors" of stability. There are three important STATIC stability issues, and then there is the DYNAMIC stability issue:
Static Airspeed Stability - stick forces in the proper direction to correlate with airspeed. This provides that the aircraft, in response to a wind disturbance, will pitch in the proper direction to return airspeed to it's "trimmed" airspeed.
Static Maneuvering Stability ("G-Load static stability") - the CG in flight is forward of the RTV. This is as it should be in any stable aircraft. This provides that the aircraft, in response to a G-load disturbance (from wind or pilot input), will pitch in the direction to return the rotor g-load back to 1 g!
Static Power Stability - this is the one it seems everyone is hovering around when you are talking about High or Low Prop thrustlines - but seldom hit the real bull’s-eye! This static stability means that the prop thrustline offset is "balanced" by other aerodynamic moments that neutralize the pitching moment of the offset prop thrustline - at all power settings. This is why you may need some immersion of the HS in the propwash - the HS must react in a countering pitch moment as a result of, and in proportion to, engine power (propwash). This should be at least a reasonable "balance" so that sudden changes in power (or sudden loss of power), or sudden loss of rotor drag, do not radically start the nose to pitch. A rapid down-pitching moment from either a loss of power or increase of power can initiate a bunt-over! Just the movement in this nose-down direction starts the CG moving further aft or possibly even aft of the RTV. For one thing, the sudden pitch reaction can initiate pilot over-control in a less stable gyro. For a second thing, the nose-down reaction changes the CG/RTV moment and changes the degree of G-load stability instantly - to a degree of stability the novice pilot might not be proficient to recover from a perturbation. Thirdly, if the nose-down reaction is so extreme that the CG repositions aft of the RTV, the G-load stability becomes negative and the reducing g-load on the rotor is self-propagating more nose-down pitch reaction - a true "buntover" propagation!
01-28-2004, 03:58 PM
When you are debating whether any HS is adequate to counter a prop offset, it is a VERY simple matter to test. I outlined this in one of my latest articles in Rotorcraft on Stability testing. But, all you have to do is trim the gyro to a steady airspeed - hands off or fixed-stick - and add power to see if the nose raises just the right amount to maintain the original "trimmed" airspeed. Do the same with less power - nose should lower and eventually resume nearly the same original trimmed airspeed. (This should be close, and our LSA standard says within 10% airspeed. This is considered close enough to avoid adverse pilot reaction to pitch/power reaction). This test takes less than 30 seconds to do at one airspeed. Repeat it for a number of airspeeds throughout the speed range of the gyro. There is no reason to debate whether the Prop Thrustline is properly "balanced" - just test it!
BTW, the first two STATIC stability tests are very easy to do, and very safe to do too! See the article. It may not be necessary to achieve all of these static stability issues, but, I'd say you certainly want static G-load stability to be positive throughout the full flight regime (power and airspeed conditions), and you want a reasonable Power Stability.
One more point on Static Power Stability. Everyone is agreeing that the HS must have some in-flight download on it in order to achieve STATIC Airspeed Stability. The down-load on the HS should be present in all flight conditions. In my opinion, this REQUIRES a slightly high prop thrustline - this means the HS must have some negative effective incidence relative to the resultant airflow on it (result of free air and propwash). A true CLT does not require any negative effective incidence with respect to the propwash. A low prop thrustline will actually result in a positive lift of the HS, to balance the nose-up tendency (moment0 of the low prop thrustline. So, IMHO, to achieve all three static stabilities to some degree, the prop thrustline must be slightly high so as to assure a negative lift of the HS.
What does it mean if you don't achieve Static Airspeed Stability? If you have the other two stabilities reasonable, it may not mean much to the experienced pilot. The stick will still trim to a neutral "feel" at the "trimmed" airspeed. But, any deviation from trimmed airspeed will produce higher and higher stick forces the pilot will have to confront. This is akin to balancing a yardstick vertically up from your finger - when it is "trimmed in the unstble neutral vertical position, it is not hard to balance. But, when it gets very far off the neutral position, the pilot has to actively re-balance the stick to the "neutral" condition. If there is a strong G-load static stability condition - which there usually is when power is applied to a low prop thrustline - this G-load stability probably helps a lot to avoid buntovers!
One more comment about Ron Menzie's testing. I highly respect Ron and he is a very good friend of mine. Ron has the safety of all gyro people in all his efforts. I think I am right on this: The testing Ron did on his modified RAF was to some earlier criteria we were developing for the LSA. Specifically, I don't believe Ron tested POWER static Stability - this should end all debate! Specifically also, he tested DYNAMIC stability in the free-stick condition. The free-stick condition is the best condition for an unstable gyro - it does not allow much of the errant pitch reactions of the airframe to couple into the rotor. The true test of DYNAMIC stability is with a fixed-stick. This is a much telling test - but one that we do not encourage people to do. If the standard DYNAMIC pitch stability tests were conducted on a gyro that was not very stable dynamically, it could be a real handful to recover - even for an experienced pilot! That is one reason they pay professional test pilots so much - they know how to test the DYNAMIC stability without getting into trouble - they carefully flirt around the edges with "frequency sweeps" that look for a tendency to resonate with the pilot's input - looking for a short-period natural frequency response of the aircraft - one that is too quick for the pilot to properly react to! For the LSA standard, we a re proposing that now natural oscillations should be present below 5 second periods! This takes a professional to discover! The LSA standard also requires that ANY natural pitch oscillations be "damped" - this just simply takes an effective HS!
But, since much of the solution to good DYNAMIC stability is simply an abundantly powerful HS, IMHO, a gyro may likely have adequate DYNAMIC stability if it has adequate and proper HS to meet the STATIC stability requirements! Except for manufacturers meeting the LSA criteria, we don't propose that the regular gyro guy try to meet this - just try to meet the STATIC criteria and fly with good respect for your limits.
I hope this helps - Greg Gremminger
PS: I am truly embarrassed by the price we must ask for the Magni gyros in the U.S. It is not even in the $40K range right now! The main reason for this price is the poor strength of the U.S. Dollar in comparison to the EURO Dollar, and the high shipping costs. Try to buy anything form Europe these days! I am not "pushing" the Magni gyro for financial reasons! I am demonstrating the Magni gyro because I think it is an outstanding example of the value of the right combination of "balance" and "harmony". It has taught me a lot! I don't propose that everyone must fly a Magni to fly a safe and stable gyro. I don't propose that it takes that kind of money to make a stable gyro! I do propose that we can learn from the Magni to verify good gyroplane aerodynamic design - and to use it as a demonstrator of these principles. It doesn't require expensive Rotax engines or steel frames or sexy lines to make it stable. Now, reliability, rotor smoothness, ruggedness, performance (80-100 mph cruise on 100 HP!) and sexy looks are other issues and a reason some people have actually paid the price! But, right now, if you have to ask the price, you can't afford one!
01-28-2004, 04:30 PM
I am by no means an expert at all on Gyro aerodynamics. I do think it is important to remember, however, that the vertical COG will change depending on load in any Gyro, and may change quite a bit in side-by-side lead-sleds. A Gyro that is CLT with two passengers and a full-load of fuel may very well be 2" BELOW CLT flown solo with 10 gallons. A CLT Gyro can be CLT only with a specific load. However, a shift of an inch or two, or maybe three is not really significant in the real world as long as one has a properly sized, shaped, and placed, e.g. 'effective', horizontal stabilizer.
A horizontal stabilizer, although theoretically unneccessary for STATIC stability in a true CLT Gyro is essential for DYNAMIC stability, in any case. And, since even a CLT Gyro can only be exactly CLT under specific conditions, a horizontal stabilizer in always neccessary even to ensure STATIC stability under all permisible loads.
Practically, I think when we describe a Gyro as being CLT, what really mean is that it is with 2" or maybe 3" of CLT under all loads and flight regimes. My understanding is that the Magni Gyros would be CLT under this definition, or very close to it. An RAF would not even be close.
01-28-2004, 05:13 PM
Greg, I liked your ending about the Magni and the high prices. I can't afford it so I won't ask! but I am curious if you would be willing to give us a break down on the current kits or designs out on the market that you believe will pass the LSA standards you are working on.
I would assume the Magni is going to pass. I would also bet the Sparrowhawk will be there as well. But is there any others?
01-28-2004, 08:38 PM
I've always maintained you can't pass an accurate judgement on any gyro from just looking at it or even by flying it. You can't rely on judgment of experienced pilots who are probably the "stabilizers" themselves! It must be specifically tested to objective, pilot-isolated criteria to know. Only two gyros that I know have recieved the full schedule to tests - Sparrow Hawk and Magni M-16.
I have run the Magni (M-16 only) through all of the static and dynamic tests - many times. I have even done fixed-stick dynamic tests by stepping the stick forward by 3" (severe nose-down input) at starting speeds as high as 90 mph - Wow, quite a ride, including some pretty serious reduced gs - but it did not bunt - obviously. An interesting piece of data is that the natural frequency of oscillation I found on the M-16 matches Dr. Houston's flight testing almost exactly at 14-15 second period. I conducted these tests in order to help understand and define the LSA stability requirements - to develop some testing methods and to see if the Magni lives up to theory. The damping rate seems to be 1-1/2 to 2 cycles at worst case - for very large fixed-stick excitation inputs. For small inputs, it would be hard to say it was not critically damped - returns immediately to steady trimmed state without pitch overshoot. I also conducted extensive "sweep frequency" excitation testing to try to find any faster natural oscillation tendencies (It is my belief that when there are very fast natural oscillations, that gyro is prone to PIO if the pilot happens to excite that natural frequency with matched rate or frequency stick inputs - the root of PIO) In these tests I also developed a neat and simple and cheap way to monitor the dynamic response - recorded the ring gear rotor tach pulses on audio tape - can record voice to set up the test then record the rotor RPM changes which follows the g-load almost exactly. My testing was done at high and mid loading conditions - I have not tested it at the lowest permissible loading - I have not had the chance to ask a light weight person to do the tests yet.
Jim Mayfield has also tested the Sparrow Hawk for all static and dynamic tests. Jim reports it passes all tests and that the natural oscillation is about 20 seconds ( better let Jim confirm these numbers before you go repeating them!) That would be even better than the Magni, but I'm not sure if that is at all speeds and power and loading combinations. Jim probably has used much more instrumentation than my simple recorder - looking at more dynamic parameters for his testing.
We have been trying to encourage many others to actually perform and report their tests - for two reasons:
1) It would be nice to have more data points from some other "stable" gyros to have more data to set the standards with. There are still a lot of people who seem to be relying on just their perception or "feel" as to declare the gyro "stable". - not seen many test reports
2) So that manufacturers may find whether their "stable" gyros truly meet the full stability criteria. We have been afraid that some of them, who assume they meet all the crioteria but have not really tested them, might not have the chance to either make changes or argue for different criteria. But, we think we have cut the stability criteria to just what is needed for safety. Note, this is a considerably laxer criteria than what the Sparrow Hawk or M-16 have tested to.
I expect that the issue that most gyros will have trouble with is Static Power Stability. This is the issue that so many discussions argue about. But, this is the simplest and easiest test to perform!! But, I expect that many gyros do not have adequately sized or tuned or positioned HSs to properly "balance" the prop thrustline offset. Note, this is not so much a high thrustline issue as it is an issue with a properly balancing HS. But, on paper, I don't see many ways to "balance" very low prop thrustlines for Power Stability and still end up with a down-loaded HS for Airspeed stability. Typically, for low prop thurstlines, you can't (on paper) have both Power Stability and Airspeed Stability at the same time - but we need more testing on this becasue this is all a very complex fucntion of other aerodynamic moments acting on a gyro's airframe. Testing is the only way to know for sure! Note, it is even possible (on paper) for a very large HS, acting in a lot of propwash, to "balance" a very high offset prop thrustline. But, as Doug points out, this results in a LOT of download on the HS and just that much more load the rotor and engine have to carry. Note also, that a very large sloping windscreen can present a need for even more HS download at higher speeds - also not very efficient. But some designers may elect to make the efficiency compromise in trade-off for some other desired quality such as looks or enclosure or sbs seating.
I would reserve comments on any other gyro models. I have tested a couple of others, and a few people have tested their one-of-a-kind models (including a drop keel Parsons trainer with a HS.) and found them to meet the some or all static criteria. But, some highly offset prop thrust machines do not meet the Power Stability criteria well!
We should let the individual proponents of each machine do their own testing and report the results for now. But after the Gyroplane LSA standard is approved, I will be encouraging everyone to perform and report on the simple static tests! This should get the manufacturers off their duffs and perform and report some real testing too!
We have not made a decision on whether the Magni will be offered under the new LSA rules - no one will likely be making that decision until the FAA releases the LSA rules and allows SLSA for gyros. And, we need to get the LSA gyroplane Design and Performance standard completed and approved before we can make a final decision. I expect the D&P standard will be approved by late Spring - I HOPE!
I hope Jim Mayfield will respond as to whether they expect to be selling under LSA - I know what Jim has told me, but that is for Jim and AAI to say.
Jim Vanek has also said he will be designing his new 2-seater to the LSA standards and will make any mods necessary for his other models to meet the standard. LSA interest has been also expressed by Air Command, and I would not expect their new models to be far from the mark - but I have not seen any test reports (my old "High Command" modification had good airspeed and g-load stbility, but Power Stability was not the best!)
Once we have the D&P standard approved, and if the FAA allows SLSA and ELSA (Experimenatal LSA), our ASTM subcommittee will also have to develop and approve several other gyroplane standards documents - QA, Acceptance testing, Continued Airworthiness monitoring, etc.) Actually, designing to meet the D&P standard may be the easy part. The QA and documentation requirements might be tougher. But professional companies like AAI, Sport Copter and Magni already have good tracking, QA and documentation procedures in place.
- Greg Gremminger
WOW - Greg! You can write faster than I can read :o
Thanks of these (as usual) great posts! I am afraid I have to disagree with one thing you've said:
One more point on Static Power Stability. Everyone is agreeing that the HS must have some in-flight download on it in order to achieve STATIC Airspeed Stability. The down-load on the HS should be present in all flight conditions. In my opinion, this REQUIRES a slightly high prop thrustline - this means the HS must have some negative effective incidence relative to the resultant airflow on it (result of free air and propwash). A true CLT does not require any negative effective incidence with respect to the propwash. A low prop thrustline will actually result in a positive lift of the HS, to balance the nose-up tendency (moment0 of the low prop thrustline. So, IMHO, to achieve all three static stabilities to some degree, the prop thrustline must be slightly high so as to assure a negative lift of the HS.
I cannot express myself as well as you, Doug, or some of our other contributors can (and I blame it conveniently on my foreign nationality), but let me try and explain why I disagree with the above sentence. Your argument assumes that, in order for the gyro to be airspeed stable, the gyro airframe must be airspeed stable. This assumption is wrong because the gyroplane teetering rotor, all by itself, is very speed stable, and it takes care of the gyroplane as a whole. Replace the airframe with a cannon ball and let the rotor glide back to earth. The rotor will maintain a constant airspeed.
The rotor airspeed stability is achieved by its natural "flapping" reaction to airspeed. When the airspeed increases, the advancing blade angle of attack increases, and the retreating blade angle of attack decreases. As a result, the rotor disc "flaps" back, which means the angle of attack of the whole disc, as a wing, increases. The gyroplane will start climbing, and the airspeed will bleed off.
Another result of the rotor flapping back as a result of higher airspeed is that the RTV moves forward, pitching the nose of the gyro up and, again, initiating a climb through trim spring response. Needless to say that the rotor flapping angle is independent of cyclic position so this automatic response mechanism will work also in a fixed stick situation.
This is the reason any Bensen-type gyro without a horizontal stabilizer, is airspeed stable (although it may be G-load, power, and dynamically unstable) if the CG is not too far behind the RTV. You don't really need the HS to take care of airspeed stability; the rotor is doing it just fine. Just an anecdote - I believe the Sparrow Hawk HS is level with the prop wash and the free air stream in level flight. If my memory serves me right, there is no negative angle of incidence built into the SH stabilizer.
Second point I would like to make is that there is no need for a nose down moment (such as a high thrust line), in order to justify a negative angled HS. You may have a true CLT machine and still have a negative angled HS if you so choose. As long as the HS is mostly outside the prop wash, a negative stab will move the CG forward of the RTV as a function of airspeed. The maximal angle that the CG can move ahead of the RTV is the angle in which you set the HS at (assuming the HS is not affected by prop wash).
For example. If we assume a true CLT gyro, in which the center of drag is in line with the CG, and no other aerodynamic forces are acting about the CG (in other words, a cannon ball), than the angle between the CG and the RTV (measured at the center of the rotor), will be determined by the airspeed and the angle of the HS. In a gyro with no HS, the RTV will pass right through the CG. If the HS has a symmetrical profile, than the angle between the RTV and the CG will asymptote the angle of the HS at high airspeeds, but will never meet it.
For these two reasons I have to respectfully disagree with your rational that a high thrust line is desirable in order to have a negative angled HS, in order to achieve positive airspeed stability.
01-29-2004, 03:17 AM
Hi Guys, we are certainly designing Firebird to meet the LSA standards. It is not that difficult when you are aware from the beginning of the standard to be met.
Udi, you mentioned "the gyroplane teetering rotor, all by itself, is very speed stable,
It is only now that I am finding that there are stable rotors and there are not so stable rotors. Hybrid is almost CLT, thrust line may be 1" to 2" above the VCoG depending on load, and an effective h/stab.
With rotors that are a 8H12 airfoil and balanced at the 25% point, Hybrid would meet the LSA pitch stability standards up to approx 65 mph. The unstable Raf cabin starts to take some control above that speed.
I have tried 3 other brands of rotors and have been very dissapointed in the reduction of stability.
I will be much happier when I have a true Firebird prototype to play with and test.
I am hoping that this will occur around April to May.
01-29-2004, 05:19 AM
I would love to see the " tests" performed on a new Aircommand Elite and especially the Dominators. I just hope Ernie will take the time out to have his machines tested.
I also don't totally agree that a gyro needs a slight thrust offset to be stable. That just doesn't add up to me. In the Dominator which is center line thrust, not below center line thrust as some say, when you pull the power back suddenly the airframe will keep going straight at the same airspeed and start desending. It does not nose up or down when power is pulled. Same thing when power is suddenly added the gyro stays level the airspeed stays the same and it climbs.
I also wonder if Ron Herron will be having the little wing tested. It has no thrust offset.
We first have to agree on the principles, Paul, before we can delve on the finer details of this brand of rotors or that. If a teetering rotor does not flap back with airspeed, than you have problems more serious than airframe stability to deal with. You cannot (or should not) expect the airframe to correct rotor-induced instability.
By the way – one of the static stability tests published by Greg (or Jim?) checks that the rotor actually flaps back with airspeed. This is the stick location vs. airspeed test. The location of the stick will move forward with airspeed to keep the RTV from moving forward as the rotor disc flaps back (in other words, stick forward for airspeed, throttle for climb). This test verifies that the rotor is responding to airspeed properly. If the stick stays centered or moves back with airspeed than the rotor itself is airspeed neutral or airspeed unstable, respectively.
01-29-2004, 06:51 AM
I can’t call what I do “typing” - I “peck” furiously though!
I’m reluctant to engage in such detailed technical paper analysis. As we discussed before, there are a lot of complicating things going on in a gyro. The rotor does things, the airframe does things, and the two influence each other. To analyze this without test data is pretty frustrating, and is one of the culprits, I think, that has led to some mis-leading theories and “cookbook” solutions! The real arbiter of any of these debates is to test it! Since the Sparrow Hawk has tested to be airspeed stable, and if it is truly CLT, perhaps the reasons for the stability include your theory.
But, I have a hard time resisting the fray – I get started and don’t want to throw away my thoughts. But, sometimes, as in the last several posts, I considered that I should not really start that level of engagement – but just can’t help myself sometimes! Here are some comments – not as well thought through as I’d like, but here goes:
1) First, there doesn’t have to be any visible angle of incidence built into the mounting of the HS on the airframe. The SH and the Magni appear to be neutral mounting incidence. But, if there is any offset of the prop thrust, the in-flight pitching tendency of that moment causes a nose-up or nose-down slight attitude that establishes an effective AOA of the HS. That AOA is exactly what is required to balance the prop thrust offset – resulting in a slight attitude in flight. Some designs might take this into account and actually angle the airframe (keel) so that it appears to be level, even though it may be slightly nose-down or nose-up. Also, the effective AOA of the HS is dependent on it’s placement in the propwash – or out of it - and other factors such as the inflow disturbed airflow into the prop. In some cases, especially for just minor prop offsets, there may not be a lot of HS AOA required to “balance” the prop moment. The point is simply, you can’t judge the HS in-flight AOA by how it looks on the ground!
2) Second, I don’t think we can say that the rotor, or the airframe, alone can determine the “stability” of a gyro. The rotor affects the airframe through g-loading at a minimum, and the airframe affects the rotor through cyclic action. So, your hypothesis may be correct as one of the mechanisms that happen, but the combination of mechanisms is very confusing. The point here is that I don’t think the rotor can do the Airspeed stability, or any of the stability issues by itself. The other effects need to be considered too – including the effect of the airframe!
For the fun of it, for your perfect CLT gyro with the RTV initially exactly on the CG, let me take your example of the rotor flapping back as a result of increased forward airspeed – forward wind gust. As you describe, the rotor disk will try to flap back or up, presenting some increased lift and drag and initiating a climb – all in the direction to restore the airspeed. This would be the correct initial response. Notice also that a downloaded HS would also pitch the airframe, and through cyclic action, the rotor in the same direction as well. All of this is a bit complicated if the trim/offset teeter is allowed to work, but fixed-stick, this is all the case.
As you present, at the same time the rotor is flapping “back”, it is also moving the RTV forward of the CG and presenting a g-load nose-up moment as well. This is in the correcting direction also, but we don’t know if the delay factor or timing is right – this depends on a lot of dynamic factors, not the least being the response rates of the rotor and of the airframe! With the wrong dynamic combinations, the whole system may over-compensate and then respond in the opposite direction. But, at least statically, this looks like the correct initial pitching direction to correct for the sudden increase in airspeed of a forward gust. But, if the g-load reaction of the airframe from the nose-up RTV moment is too strong, the unstable g-load reaction may take over and continue the nosing-up reaction and slower and slower airspeeds – definitely not static airspeed stability. At the same time the g-load RTV moment is pulling the nose higher, the HS is probably establishing an up-load condition – in the right corrective direction – but complicating the whole paper analysis further!
Now, what’s also confusing here, is that the offset gimbal/trim spring is intended to react in the opposite direction – when the increased G-load from the forward gust is trying to further move the nose up, the trim spring is attempting to temper this and prevent the rotor from tilting “back”. The intention of the offset gimbal is to improve the “stability” of the gyro by moving the RTV aft – this is a dynamic effect, so for the actual static airspeed stability result, it may be serving only to temper the dynamic overshoot of the pure rotor/airframe reaction. This is only true if the stick is allowed to float, so again we have another complication in our paper analysis. Not saying it all does not result in Airspeed Static stability, but it is complicated more than just considering the rotor reaction to the increased forward airspeed. The airspeed change causes a g-load change and the resulting pitching either tempers or aggravates the whole thing. Depending on the dynamic response, and the interactions of all these changing moments, I’d guess this aircraft might exhibit static airspeed stability, and it might not!
You may be perfectly correct in your hypothesis of the rotor mechanism providing airspeed stability without the need for a down-loaded HS. My guess is that this is pretty dependent on a lot of other issues, reaction rates, offset gimbal power, etc. My argument is simply to establish airspeed stability, we may be right or we may be wrong in such paper analysis. These are fun, but the answers are in the testing.
My previous post may not have made this clear, but when I suggest the down-loaded HS is probably required for Airspeed static stability, I really mean – and still be compatible with the other stability criteria. This may be possible with a neutral or slightly up-lifting HS, but it is beyond me to figure that out. If the SH is such a case, then perhaps your point, or some combination of all these points are correct. I believe the SH exhibits all of these stability “flavors”, but, I’m not sure what all the mechanisms might be. The designer might find a lot of satisfaction in achieving full stability with a purely “paper” design, but if it achieves all of these stabilities at all combinations of power, airspeed and loading, that is all the user really needs to be assured of. Point is if it tests OK, it is OK!
01-29-2004, 06:56 AM
I am sure you are correct in your hypothesis that the rotor affects the stability. I feel this is a highly overlooked issue. It worries me when a gyro designer recommends the use of a number of widely different rotors on their gyro. This suggests to me they do not appreciate your point – unless they have tested their gyro with all of those rotors – as you are doing. This is probably pioneering work you are doing, and will hopefully raise awareness of this issue among gyro designers. We are hoping that the LSA requirement for dynamic stability, at least for LSA gyros, will influence the testing that will make these determinations.
When you refer to better or worse stability, and from your many posts about the fixed stick stability testing, I suspect your judgment of “stability” is based more on the DYNAMIC results than on the static results. Perhaps the airfoil efficiencies and resulting disk angles and other factors do truly affect the static stabilities. But, I suspect a big issue also is the dynamic reaction rates of the rotor when combined with the dynamic reaction rate of the airframe, etc. I have always maintained that the rotor and airframe can be “tuned” to present a dynamically damping situation, rather than a dynamically resonating system. I believe this is a big issue with susceptibility of the design to PIO – DYNAMIC instability.
Again, this would be nearly impossible to determine on “paper”. Flight testing as you are doing is the only way this issue can be assure as a non-factor in PIO. If the rotor/airframe reactions are resonant at a fast enough frequency (less than 5 second period?), this might be a very PIO prone gyro! If the natural oscillations of the rotor/airframe combination are slow or interactively self-dampening, this may not be such a problem, but the damping rate may be weak and the pilot would be required to do more of the Dynamic stabilization him/herself – and in the right timing too!
Dynamic flight testing may be the only way to determine this! But, dynamic flight testing is not for everyone. Determining damping rate and slow rate natural oscillations is not so dangerous. But, “sweeping the frequency” at the higher oscillation rates – trying to excite oscillation rates the pilot might not be able to “dampen” if started – can be dangerous and require a lot of careful approach. I would suggest that even the most skilled professional test pilot should not try to “sweep” rapid oscillation tendencies unless the machine has at least passed all of the static and slow rate dynamic criteria. But, a good size HS, is probably a good thing in any case, because a large HS WILL tend to “dampen” ALL natural oscillations without pilot intervention.
One dynamic issue here is that a HS’s dynamic damping ability is a function of it’s “power” The power of a fully immersed HS is a strong function of power applied – propwash. Does this suggest that the damping affect of a HS, and therefore the dynamic stability factors of that gyro, are a function of the power? Or, did I just open my mouth and a new “can of worms” too much again?
I noticed this affect in my “High Command” – although I did not do the rigid dynamic flight tests to determine if my subjective assessment bears out! The High Command was a lower offset prop thrustline with a “T” tail – centered HS. At higher airspeeds (normal or high cruise power) it was very comfortable to fly in even the roughest winds (notice I did not say it was “stable”, but I would subjectively argue it was!). But, when arriving in my destination area at a fast cruise, I would reduce power and maintain airspeed to start a descent. In rougher air this lower power configuration did not “feel” good. I was uncomfortable. This was before I understood much about these “stability” things! But, I often found I would prefer to continue to directly over my destination at cruise power and then reduce power to idle and descend at a lower airspeed into the destination. This felt more comfortable than a low power descent at the higher airspeeds. Years later, I attribute this to a change in the dynamic stability with different power levels - different airflows on the HS. Not saying this is not OK, just suggesting that different power levels might present different stability characteristics – even dynamic characteristics. That is why the LSA standard will specify the stability criteria at all combinations of power and airspeed.
Did I just open my mouth a bit too much again? Or is this any food for thought?
- Greg Gremminger
01-29-2004, 11:36 AM
"In the Dominator which is center line thrust, not below center line thrust as some say..."
Now Ron, don't be offended because I just happen to be the one who's speaking up and asking you these questions (I know you hate it tremendously when I question you), but surely I can't be the only one reading your post who's curious how you know (with such apparent authority) where the CG is in relation to the thrustline on a Dominator? Have you done a double hang-test or a double weight-test on a Dominator, and do you have any documentation (photographs) to share with the rest of us? Also, which Dominator are you talking about and what's the configuration? Two-place or single-place? What engine size? What fuel load? What accessories?
"...when you pull the power back suddenly the airframe will keep going straight at the same airspeed and start descending. It does not nose up or down when power is pulled. Same thing when power is suddenly added the gyro stays level the airspeed stays the same and it climbs."
My experience in a two-place Dominator with Rusty Nance was quit different that what you describe. When we pulled the power back to idle from a cruise setting, the airframe immediately nosed sharply down and maintained airspeed (without moving the cyclic stick). Reapplication of power to a climb setting caused the airframe to nose up sharply while airspeed stayed the same, etc.
01-29-2004, 11:53 AM
Ron, it's Greg again! Responding to your last post about the thrust offset to be stable. You are probably correct - gyros with true CLT or even some low prop thrustline may be able to be configured - HS arranged - to provide either Power stability or airspeed stability. I had to make a bit of this compromise on the High Command by adjusting the “T” tail inclination! The point I am making is, that for low prop thrustlines, and maybe even true CLT gyros, it is difficult to achieve both at the same time. This is so, because if it takes an up-lifting HS to counteract any prop thrustline nose-up moment - that up-lifting HS may not be compatible with Static airspeed stability - Udi's arguments for rotor stabilization noted!.
Your Dominator may, or may not be true CLT. A lot of people say it is, and I don't disagree if they do the testing - Static Power Stability. And this will only verify that, if there is any prop offset, it is "balanced" by the HS. But, the vertical CG location is highly dependent on the loading - weight of pilot, fuel, etc. Many lighter people have reported to me the same results you are seeing - that is good, for that loading. But, for other loadings, for instance for me on a stock 618 Dom, the Power Stability was definitely a bit off. Others have also reported that too. So, it is probably loading dependant. I think one other Dom report similar to yours was on a 914 powered machine with a 68" prop - can't say for sure, but that larger prop probably has about a 4 inch higher thrustline!
The true Power Stability test is not as you have described. I used to say do it this "power chop" way and see if the nose over-responds - or pitches enough to resume the trimmed airspeed. But, this is a bit of a dangerous test if there would be a lot of unbalanced prop thrustline - as I discovered first time I chopped power in the 618 Dom (with my weight loading!). The nose dropped dramatically over 15 degrees!!! Other, more prop low configurations report similar dramatic nose drops. This is one indication of un-balanced prop thrust offset and Power static instability. But, it really needs to be quantified, there will probably always be some “unbalance”, but how much is too much?
A better way to run the test is to simply trim it for a cruise airspeed and then slowly apply full power without changing the stick position (either free-stick or fixed-stick should do the same thing!) With the stick in the same position, after the airspeed settles out, see how much the airspeed differs from the original trimmed cruise number. The LSA standard suggests within 10% would be OK. If the trimmed airspeed changes much, this would mean that you would have to apply either forward or aft stick pressure to maintain the original cruise airspeed when in a higher power climb or a lower power descent. This is the telling test. The "power chop" test could be a bit dangerous, and you cannot really quantify the results unless you measure before and after "trimmed" airspeeds. You don't need to "chop" the power to do this.
But, the rest of the story is whether, with this "power stable HS balanced” configuration, will it also be Airspeed stable. That test is very easy to do also. I suggest that on true CLT gyros, and on low prop thrust gyros, on paper at least, it looks difficult to achieve strong positive stability in both airspeed and power at the same time - because one or the other requires a different lift direction on the HS.
You say your Dom is CLT. That is hard to verify except by test. But, the Dominator is famous for its great stability. That is mostly g-load stability, which is the most important static stability issue. Airspeed and/or Power instability are readily compensated by an experienced pilot - G-load is what is most important and can cause the most problems in turbulence. The Dom has great g-load stability – in large part because the LOW prop thrustline is forcing the nose up and the CG forward - a result of the power instability! The Dom I flew had great g-load stability - but it also had a lot of unbalanced nose-up prop thrust. This made it super stable - the reputation of the Dom. I would suggest that if your gyro does not have this nose-up Power instability, it might not be taking advantage of one of the best features of the Dominator style gyro - it's tremendous G-load stability, and it's resulting great turbulence penetration!
Now I'm not suggesting any of this style is bad! Ernie is a pioneer in gyro stability and deserves our thanks and gratitude for focusing the gyro world on the stability issue. And, the Dom has demonstrated what really can be done in the area of gyro stability. When I suggest that there may be any flaw in the configuration, I may be more on the perfectionist side. Surely the stability performance of this style over the old Rotax Bensen derivatives has removed 90% plus of the pitch safety issues! When we talk about making gyros stable and safer, going 90% of the way to the best is pretty darn good! To get the rest of the way would probably mean making no compromises in the other "flavors" of stability - meeting all the static and dynamic criteria at the same time and over the range of power, airspeed and loading. This is the criteria in the LSA standard, this may not need to be fully met to have a very safe gyro!
You said you would like to see Ernie test the Dom. No need to wait for Ernie to do it - you can do it, at least for the loadings you can provide. The static tests are straight forward, are easy and take very little time to do. They are also fun to do! You also do not need any equipment more complicated than your airspeed indicator and perhaps a tape measure and a "jam stick" to put between the stick and the instrument panel to hold the stick fixed. I made an adjustable tube to fix the stick in a number of ½” positions to do the Power stability tests at several airspeeds. The details of the test proceedures are found in one of my latest Rotorcraft articles, or write me and I will send you a copy.
For the stick position measurements of the Airspeed and g-load tests, I simply secured a retractable tape measure on the center of the dash and held the end of the tape against the stick. The relative position of the stick can be related to the tape measure extended length - for the airspeed and g-load tests that require the stick position be either fore or aft of the original position.
You can do most of this testing in much less than an hour - different airspeeds, and power settings, etc. To document the testing, I plugged my headset microphone into a tape recorder - this makes it easy to record the parameters and results of each test. To feel like a real test pilot, tape a written test plan to your leg to follow when you get in the air, to make sure you covered the full range of airspeed and power. Generally just trying the combinations of idle, mid and high power with slow mid and high airspeeds will make a total of 9 test runs in each of the three Static tests. This will give you a very good idea of just what corners of the envelope are super stable and which corners of the envelope you might need to be a bit more cautious in.
Do not attempt to do the Dynamic testing. For the average gyro, I think meeting the three static criteria probably means there is plenty of HS to keep you out of PIO and dynamic problems. The dynamic criteria is for professionals and LSA manufactures and is just more assurance of a safe stable design. We'll learn a lot more about this when more gyros are truly tested, and we might then adjust our standard if data shows the need. For the regular gyro pilot, I think Static stability will tell you as much as will keep you safe. And, no matter what the results or what someone or a manufacturer says about the stability of a design, still respect the untested corners of the flight envelope and your own untested proficiency limits. As you gain experience in your gyro, you will have a better "feel" for when things are not right, and you can slowly expand your proficiency limits with lots of practice - and re-test the gyro static stability at those expanded corners of the envelope.
Thanks, Greg Gremminger
01-29-2004, 01:22 PM
Hi Greg, it will take a while to comprehend all of the info of the last day or so.
My blade designer/manufacyurer guy, Rob, mentioned to me the other day that Magni do not supply rotors for gyroplanes other than Magnis. I don't know if this is true or not, but does make sense.
With what Rob and I are learning is that to achieve the best all round stabilty for a particular gyro, "Firebird" for us, every aspect has to compliment each other.
01-29-2004, 01:28 PM
These are some CLT offset figures. I hope that they come through OK.
I can now see your strategy. It takes me so much time to read your posts that I have no time left to respond! This is one (good) way to detract challenges!
To make it short, I just want to say that I think you make the gyroplane stability issues sound more complicated than they really are. Take a look at simple and successful designs like the Sparrow Hawk and the Little Wing. Both designs are true CLT with no HS angle of incidence. You don't need a high/low thrust line or an angled stabilizer to achieve all four criteria of stability. I agree that the airframe must work in harmony with the rotor, but that can be done within these simple design traits.
Make a true CLT gyro. Design it with minimal drag/aerodynamic moments about the CG. Install a very large and effective horizontal stabilizer on it. Make the stabilizer parallel to the prop wash AND the flight path. Install good quality and stable rotor blades. That's it! That's all you need for a G-load/Airspeed/Power/Dynamic stable gyroplane. The proof is in the pudding!!!
I can get into complicated explanations why this simple combination works, but there is no need to - this simple design existed since the beginning of the 20th century with the Cierva machines and it still exists with new designs. And it works!
p.s. I am flying to Italy tomorrow. Wish I could visit the Magni factory, but no time this trip.
01-29-2004, 04:08 PM
John L. - I have no problem at all with you questioning me. Please do so anytime you feel the need to. Sometimes I need to be checked! I only got upset when you " attacked " me over my Lack of a full fledged rating, and now thinking back I am glad you did. Your comments along with some other factors finally got me off my lazy butt to go ahead and earn my rating. You will be pleased to know that I have a appointment at 9am tomorrow for my final checkride. Hopefully I will be a full fledged - Legal! - pilot by lunch time!!! :)
Also per my comments on Dominators. First I can't do any tests in one for now - might be able to see if Ernie will let me experiment with oe of his machines at Bensen Days though.... - Because I no longer have a Dominator and have no immediate access to one.
I probably should have taken more time with my earlier post about Dominators before posting. I don't personally know if one or all Dominators are true Center line thrust. I am only repeating what I have either heard or been told from talks with Ernie himself, or from reading posts on Norms forum. I do not believe it is a below center line thrust machine as some say, but this is only my best guess not fact.
when I talk about the way a Dominator handles when power is either chopped or suddenly applied, I meant to say the airspeed stays about constant and the airframe will slightly pitch up with power and more than slightly nose down with out power. But it doesn't drastically do anything except keep flying. I have one been for one ride in a two place Dominator and I was riding Bitch in the back! So It was hard to tell just what was going on. I have flown 4 single place dominators and all four flew slightly different. But for the most part they all flew the same.
I will leave the Is a Dominator stable and the Is a dominator CLT type questions to folks like Doug R and The Boyettes who do watch this forum and might jump in.
Greg, thanks for the posts. I wish they weren't so long!!! It takes me a hour to read them and then another hour to absorb them ;D
01-29-2004, 04:48 PM
Ron, you can do that in 2 hours!!!! I knews yous was smart ;)
Try doing on your head upside down. It takes me double that!!!! LOL
01-29-2004, 06:18 PM
Sorry for the long posts - I'll try to keep thjis short:
Paul, True, Magni will not sell rotors or any other major Magni component. All parts must act in "harmony" and "balance" and Magni would have no control over the rest of the configuration and would not want to risk being associated with gyro accidents in possibly less safe and stable gyros. The Magni rotor head and hub is also very unique and not readily compatible with other rotor heads. This design is part of what achieves the low rotor vibration and shake!
You said: "every aspect has to compliment each other." This is exactly the point Vittorio Magni has made to me many times - he calls it a "harmony". It has taken me several years of flying and analyzing the Magni and other gyros to start to comprehend what he means by this. And, I suspect there are still aspects that I don't comprehend yet!
Udi, You are exactly right - not so much about my post strategy, but about how to design a truly stable and safe and docile gyro - exactly the things you say. The issues I am presenting are a bit of "icing on the cake" for those pusher-type gyros that can't readily assure CLT and provide such high volume HS as some tractor configs - such as the Little Wing. When the configuration of the gyro allows such extreme HS power and assured CG, all stability issues converge toward perfection. I have always maintained that the LW and the old autogyro configuration is probably the gold standard in groplane configurations. But, the popular pusher configurations, if you are striving for the best you can do for stability, requires some attention to the details and "balances" and "harmonies". And, since I am heavily invested in the gyroplane LSA standard, my perspective is to tie down the issues that can be readily overlooked if attention to detail is not so good. I think I should stop talking design issues and keep to the test results criteria that we hope the LSA standard will make standard. I just get into trouble when I try to describe how to design to the test criteria - there are just too many combinations of things that must be considered and probably a whole lot of ways to "skin the cat"! But, the LW way is the very straight forward and effective approach.
One more point, and you can ask Ron Herron about this. Ron mentioned to me that one of his gyro configurations - I think it is the new Rotec radial engine gyro - does not have the best prop thrustline. I don't remember how he described this, but I think it was a bit of less than perfect Power Stability. Ron, if you are listening, could you please enlighten us! My point is, even Ron has to pay some attention to some of the details for perfection - but his job is much simpler because of the very large tail volume and easier positioning of the prop thrustline!
- Greg Gremminger
01-30-2004, 05:33 AM
The Euro two years ago was about $1.15 per Euro
Today it is $0.80 per Euro
- That's a 35% change in two years, not 10%.
Also, Since the price is already so high, I've included the shipping costs from Italy in the price - about $5500 if shipped alone - higher since 9/11 also! Also, Rotax prices have gone up significantly over that period. And, even aircraft parts that I purchase in the U.S. - qulaity rod-ends, instruments, etc., have all gone up appreciably. If you have to ask the price or worry about shipping charges, you won't be buying one. If you have to worry about price and you have to have a Magni, write your congressman or wait for the dollar to improve. Otherwise,examine the trade-offs and find a cheaper gyro.
My highest priority is improved gyro safety - I don't have any real hopes for selling a lot of Magnis. Since not many gyro people will be flying Magnis, that's why I'm working so hard on promoting the things we can learn from Magni!
We hope someday the U.S. Dollar will regain its former strength, until then, I don't expect to sell any Magnis to the average gyro guy!
Have you checked the prices on any sport aircraft from Europe these days? They all have similar problems!
01-30-2004, 10:28 AM
I'd expect the Magni Tandem to be pretty sluggish with only a 912S (the $14,000 one). My Dominator U.L trainer weighs about 485 empty and it's adequate, but no rocket, with the 912S. I think you'd have to spring for a 914 turbo for the heavier Magni. That engine costs around $20K.
As for the Greg-and-Udi discussion about down-loaded HS or not: First, you certainly can have HS down-load even with centerline, or below centerline, thrust. It will simply move the CG further and further ahead of the rotor thrust line as the HS power is cranked up. Some hang-test adjustment may be necessary to keep the frame flying level.
Second, it follows that, for most gyro designs, there's probably a range of HS loadings that will produce stability as defined in the tests. The difference among them seems to me to be the size of the restoring moment... which gets played off against the resistance of the airframe and rotor to being moved about. Airframe moment of inertia, rotor inertia and blade lift curve all could be relevant.
I'd guess that a craft with a low moment of inertia and a high HS load would have perhaps an uncomfortably fast, "snappy" response to a disturbance. Pilots might find it unnerving, even though the response is stable. The same tail on a long tandem (with higher MOI) might produce a response rate that's just right. A completely non-loaded HS on the long tandem might result in a leisurely response that tempts pilots to "help" the process. That's not what we want.
The situation is a bit like two playground seesaws: both balanced to sit level, but one by a big kid sitting on each end, and the other by a little kid sitting on each side near the center. If one of the big kids jumps off, the upset is going to be faster than if one of the little kids does.
This looks like a minor point of design. Once we fix all the grossly unbalanced craft with the 500 foot-pound PPO torques, maybe then we can focus on fine tuning.
01-30-2004, 01:20 PM
Well said Doug. Great post. That is what I have been on about. Let's get the CLT offset down to below 3" and then fine tune from there.
My beef is not with the machines that have the T/Line 3" above the VCoG and a sizeable h/stab.
It is with, as you said " all the grossly unbalanced craft with the 500 foot-pound PPO torques, maybe then we can focus on fine tuning."
01-30-2004, 06:55 PM
Doug and Steven,
The 912S, 100 HP is very appropriate for the Magni M-16. We only recommend the 914 if you might be operating at higher elevations where you could use the turbo 914 DA compensation. On the Magni, the 914 is set up on a detent for takeoff - only use the boost if desired for another 15 HP for takeoff - can be used for only 2-3 minutes at a time. Normal TO is at the 100 HP setting. The boost is not really needed except at higher DAs, and you can't use it continuously anyway. The 912 does lose a little HP on warmer days, but that barely affects climb rate - can't notice much difference in takeoff run or cruise speed. The 912 does not cruise any slower either - essentially the same output as the 914 for all throttle settings under 100 HP. No need to spend the extra money for the 914. I'm not saying either engine is a rocket at full load, but both provide a real single-seat thrill!
I have a 914 on my M-16, but that is only for demo purposes, and I very seldom the boost - and I quite often reach the 600 Lb useful load - I weigh 270 and everyone sends the heavy guys to me - and I have rarely used the boost for takeoff! Rick Marshall instructs in his 912 M-16, and has flown a lot of heavy guys too. Rick has built, owned and flown a lot of gyros - he attributes the Magni performance on such low HP to efficient rotors! But, I'd say a good part of it is the low frontal profile of the aerodynamic tandem configuration . the Magni useful load is a bit over 600 Lbs and it can cruise, fully loaded, at 85+ mph at about 80% power on the 912. You could probably set the prop pitch for better cruise, but I have mine set to the takeoff end.
PS: If you would like to discuss the Magni in more detail, please email me directly - I'm not comfortable promoting the Magni on an RAF forum!
01-31-2004, 07:51 AM
I can second Greg's comments on the Magni M-16. I have flown with Rick in his M-16. Comparing it with my SnoBird Tandem with a 115 hp Hirth and flown with Skywheels, Rotordyne and lastly Sportcopter blades. I would say the M-16 vastly outperforms the SnoBird.
The only area where performance with the SnoBird might be better, is the initial climb rate after take off. Everything else I would say is better in the M-16. The take off roll is shorter, cruise is much faster (by about 30mph). Control response is much smother. Engine is "much" quiter. Fuel consumption is much less. And the Magni is very comfortable to fly.
So even though my gyro weighs less and I have an extra 7-9 hp (the two fans for engine cooling take about 3 h.p. each). I would say the Magni M-16 performs very well on Rick's 912.
02-01-2004, 04:58 AM
Besides the streamlining of the enclosure, what do you contribute the better performance to? What prop & pitch setting are you using on the Snobird?
Please explain "initial climb" as compared to any other climb rate.
I sure would like to see some pictures of your Snobird.
Of the 3 rotors that you have used which performed best? Are we saying that the Magni blades are the most efficient?
02-02-2004, 08:34 AM
Chris, I have a Warp Drive 68" prop. Don't know the pitch. I have it set for a max 6400 rpm on climb out.
Initial climb is after take off. By a seat of the pants feel. I would say I could make it up faster to about 200'. Around that point the momentium slows down. So I have to lower the nose to keep the same climb A/S. The magni as I recall takes off in a little flatter additude. So I may not be comparing "apples" to "apples".
Greg G. would be a better person to say why the Magni performs better over the SnoBird.
Again I can't comment on the efficency of the Magni blades. Way beyond my scope of expertese. Plus I never tried them on my SnoBird.
The smoothest blades so far are the Sportcopter blades. I think I still liked the handling of the Sky Wheels just slighty better than the Sportcopter. I never could get the Sky Wheels stick shake free. As for the Rotordynes. Never liked them, cause the stick shake was always sooo bad. After trying to tweek them for several years I finally gave up and bought the Sportcopter blades. Best investment I made.
So if anyone is looking for a set of 28" rotordyne blades let me know.
I have some low res. pictures on my web site at:
click on photos.
02-22-2004, 07:06 AM
I am starting my classes for Private Pilot on Monday after reading for months on your forums.
The first thing I did this weekend was to download
the FAA Handbooks, in particular the Rotorcraft.
What I read there was :
"A power pushover can occur on some gyroplanes
that have the propeller thrust line above the center
of gravity and do not have an adequate horizontal
stabilizer. In this case, when the rotor is
unloaded, the propeller thrust magnifies the pitching
moment around the center of gravity. Unless a
correction is made, this nose
pitching action could become self-sustaining and
irreversible. An adequate horizontal stabilizer
slows the pitching rate and allows time for recovery."
Gentelmen, this is an official FAA document, so why are we discussing this topic at all ????
Why FAA is not sticking to it's own recomedations and allows RAF flying ????
Can anybody explain it to me ???
05-13-2012, 02:30 AM
Nostalgic stab talk......
vBulletin® v3.8.4, Copyright ©2000-2013, Jelsoft Enterprises Ltd.