accidents.. areas to avoid your advice

fara

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Don't use car or motorcycle engines in aircraft but if you do, fly every inch with a landing spot beneath you which sometimes is not that easy to do
 

fara

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My experience is flying Elas. And I have flown in very rough air sometimes. The behavior is very closed to what you have described about dominator. When I´ve found such rough conditions I always fly to hold a constant nice attitude closed to Vy, which implies a reduced power setting. It works in all the machines.

I have no experience with gyros without a proper HS in rough air.

One of the questions I´m wondering is how long can a gyro be in a very low g situation before the situation becomes unrecoverable. Flying in rough air with Ela my experience is that I´ve been in unloaded situations for a couple of seconds. But you know that in these situations my time estimation can be very wrong. Besides, I believe that the rough air is never going to produce a sustained 0g situation.

It is obvious that nobody will command a 0g maneuver but… Pilots are human beings, and all of us make mistakes…
Andy’s accident in Mallorca is something that seems not having any sense. The same that the MT accident in Germany. But things do not happen without reason, and medical issues are never a satisfactory explanation. I thing that at any moment something has been made in the controls that has degenerated in an unrecoverable situation…

Because both accidents seem to have happened after a hard sideslip I think that this maneuver has something to do. But a lot of experienced gyro pilots (me, for example) feel comfortable doing sideslip…know. I´m trying to imagine what could be wrong…

Additionally I´m trying to imagine how could develop a sustained 0g maneuver in a gyro. All my imaginations end with a broken machine pointing directly down…

ferran
Trikes have the same issue with zero G. You will have no control in that in a WSC and they do tumble forward as well but this has been figured out decades ago and unless you do an aerobatic maneuver or whip stall, you can tumble and people even today die in that regimen but they are (in a harsh sense) doing idiotic things. If you fly them within their operating limitations, they are as safe as anything else. Of course trike pilots believe there are operating limitations and they can't get away doing anything and everything they want. They fly through cold fronts and transient turbulence and come out on the other side (and there are ones with HTL as well). I have been dozens of times thrown up and out of my seat, hanging by the seatbelt only. I would guess its one second may be two at most as well but more towards the one.
IMO based on limited flight time, I did not find gyroplanes I flew as confidence inspiring in weightlessness as trikes but the number of times I experienced it in gyroplanes was limited to 2 and I am new to them so psychologically the feel is not under my skin yet either and that has to play a part as well.
 
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Vance

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My Strong Opinion About Zero Gs in a Gryoplane

My Strong Opinion About Zero Gs in a Gryoplane

IMO based on limited flight time, I did not find gyroplanes I flew as confidence inspiring in weightlessness as trikes but the number of times I experienced it in gyroplanes was limited to 2 and I am new to them so psychologically the feel is not under my skin yet either and that has to play a part as well.

In my opinion anyone experiencing a zero G event in a gyroplane lacks judgment Abid.

It is not surprising that you lack confidence and have imaginary demons about gyroplanes when you are flying with someone with such disregard for the basic principles of gyroplane flight.

I would strongly recommend not flying with that person again Abid; as they are exhibiting a lack of knowledge and an attitude that greatly enhances the chance of an unfortunate ending to a gyroplane flight.

I have experienced low G events in a gyroplane.

I have not and I am not able to imagine how to get to zero Gs for even one second in a gyroplane.

I feel you would learn a lot flying with a competent gyroplane instructor.

A few hundred hours as pilot in command of a gyroplane may relieve you of many of the fantasies you have developed imagining you understand what people have posted.

You may learn to identify those people who lack knowledge of how a gyroplane flies.

Thank you, Vance
 

Doug Riley

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How long a STABLE gyro can be kept in low/zero G without losing a critical amount of RRPM depends on the design (is this becoming a familiar theme?).

A Bensen rotor is one of the worst in this regard. It is draggy (because of lap-jointed skins, very low mass, open blade tips, gaps in the upper skin segments, lots of reflex and a sub-optimal airfoil). All of these features make this rotor lose RRPM VERY fast when the disk AOA is reduced to near zero. The only feature of the Bensen rotor that compensates a little for these shortcomings is that it is designed to operate at high RRPM (over 400). If you slow it down to increase its efficiency (by increasing pitch or lengthening the hub, as we all used to do), then you have made it really easy to lose enough RRPM in low G to prevent recovery.

At the other extreme, a rotor that holds its RPM for a relatively long time will have: an accurate NACA or other professionally-developed airfoil; as little reflex as is safe; absolutely smooth surfaces; closed blade tips; and a lot of mass (especially at the tips). There is quite a dramatic difference in RRPM retention between, for example, Skywheels and Bensens.

I think that an airframe design that makes it difficult to sustain zero G is the most important safety feature, though. If the craft noses up when G's are reduced, it will automatically increase the rotor disk AOA and therefore G loading. In effect, the frame will tend to override a sudden forward stick input or downdraft. Again, this feature is easily designed into the aircraft using negative H-stab incidence and/or a slightly low thrustline.

The opposite extreme from the frame that noses up in zero G is a frame that noses DOWN. A HTL gyro (including one that has a H-stab but the H-stab has no incidence or is too small) will nose down, at least a little, when the G's are reduced. A PPO occurs when this nosing-down reaction becomes self-sustaining. That, in turn, takes less than a second -- a fraction of the time than it would take for RRPM loss alone to become unrecoverable.

I understand that a Magni will nose down at first when the stick is thrown forward. If so, that makes sense. However, I also understand that the Magni will stop the pitch-over on its own before it progresses far at all. This also makes sense. The Magni's H-stab is large but has no incidence. The stab won't develop a nose-up force until it has acquired a negative AOA. That means the frame must rotate a few degrees nose-down before the H-stab "bites" and arrests any PPO tendency.

It would very useful if rotor manufacturers would test (and disclose!) their products' RPM decay rates at various low and zero disk AOA's at various airspeeds. But none of them does, as far as I know. The customer is left to do the "research" -- using live ammo, so to speak.
 

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Good thread.
Thanks for posting...
Man, I love this site!!!
 

fara

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In my opinion anyone experiencing a zero G event in a gyroplane lacks judgment Abid.

It is not surprising that you lack confidence and have imaginary demons about gyroplanes when you are flying with someone with such disregard for the basic principles of gyroplane flight.

I would strongly recommend not flying with that person again Abid; as they are exhibiting a lack of knowledge and an attitude that greatly enhances the chance of an unfortunate ending to a gyroplane flight.

I have experienced low G events in a gyroplane.

Thank you, Vance
Vance:
Transient weightlessness due to weather is a fact of life.
Fly in Florida in the summer afternoons where T-storms pop up in 30 minutes from what seems like harmless puffy clouds and you will too experience at least one weightless encounter for a fraction of a second.
Tampa = Sticks of Fire is the Lightning capitol of the USA, second only to Sydney, Australia to the number of lightning strikes and thunder storms.

Fly summer afternoons here and you will be zig zagging storms that pop up all around you and yes probably at least once then you will be visited by a drop that punches you up nicely for sure. I have gone around the US in open cockpit trikes a few times. My students are flying around 5 continents in trikes right now. Weather will happen. We and our machine has to handle mild to somewhat moderate weather. weightlessness is rare but not unheard of once in a year here if you fly afternoons. Hell going across the country 3 times in trikes I have had my share of that plenty. I am surprised you have not.

Enjoy a minor example of flying around afternoon t-storms by some students with Larry. We have been caught in much much much worse than that but I am not a video guy.

Pilot Country Trip in Poor Weather - YouTube
 

fara

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...

I understand that a Magni will nose down at first when the stick is thrown forward. If so, that makes sense. However, I also understand that the Magni will stop the pitch-over on its own before it progresses far at all. This also makes sense. The Magni's H-stab is large but has no incidence. The stab won't develop a nose-up force until it has acquired a negative AOA. That means the frame must rotate a few degrees nose-down before the H-stab "bites" and arrests any PPO tendency.

It would very useful if rotor manufacturers would test (and disclose!) their products' RPM decay rates at various low and zero disk AOA's at various airspeeds. But none of them does, as far as I know. The customer is left to do the "research" -- using live ammo, so to speak.
Holy crap. Someone who conceptually makes sense.
Negative incidence on the HS would also be best determined when the whole system including drag profile (addition of floats, addition of baggage cowls below the fuselage fairings) and the whole rotor system (diameter, momentum, inertia etc. etc.) is all taken into consideration. I see here people taking this rotor putting it on that one, taking this engine putting it on that frame (many times with a higher power engine than original) and taking floats and putting them on somewhere. It all has consequences which have to be taken into account and I don't think they are.
 
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Vance

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Do the math!

Do the math!

I have more than five hours in my log book in Florida.

I have not found any reason to fly near a thunderstorm or a tornado and in my opinion anyone who does is making poor aviation decisions.

In my opinion sustained zero Gs are just not going to happen in a gyroplane.

Low Gs yes; but not sustained zero Gs.

In my opinion there will never be a time when your seat belt is needed to keep you from coming out of the seat in a gyroplane.

I would love to hear from someone on this forum who was experienced a sustained zero G event in a gyroplane and how they imagine it happened.

2,000 feet per minute sink will only get you zero Gs for less than a second.

One G is 32 feet per second per second acceleration; do the math.

Thank you, Vance
 

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Fara,
I cannot but help notice that you constantly relate your scanty experiences in gyroplanes with your "vast" experience in trikes. I do not see the co-relation when you bring trikes into the picture. It may be better for our understanding if you could co-relate rotary wing aspects into the threads pertaining to gyroplanes, so that we could learn from those. After all, this is the "Rotary Wing Forum", right? I'm sure that you provide very useful trike info in a different forum.

I do believe that your efforts to sound convincing about your knowledge in rotary wing concepts is quite comical in some respects. I am reminded of William Shakespeare's "Macbeth", and the quote "it is like a tale told by an idiot, full of sound and fury, but signifying nothing".
 

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xzThis thread prompted me to think which hurt a little.

I started thinking what is zero g.


My understanding of zero g is when your acceleration is exactly equal and opposite to gravity. Acceleration greater and opposite to gravity results in positive G loading, acceleration greater and in the same direction of gravity results in negative g load.

The most obvious example is at the top of a zoom climb when the pilot commands forward stick the gyro still accelerates away from the earth but as it slows its acceleration away from Earth at some moment it will be equal and opposite to gravity and you have zero g.

For this to occur (that is decelerate in the climb) the pilot needs to reduce lift by either reducing engine thrust and/or lift. So isn't the case that zero g is the result of reducing AoA and therefore lift which can result deceleration and monetary zero g and if allowed to continue negative until terminal velocity is reached.

It may sound like semantics because you cant have one without the other but the the change in G loading is feedback from the changes in AoA. It is not that zero g condition means no lift, rather zero lift results in zero g and if no lift is added will end up being negative g.

The point I want to make with this is that "seat of your pants" flying is feedback to the pilot indicating that the AoA has changed for whatever reason. If you have the stick fixed means that the air is changing (turbulence, updrafts, downdrafts) or if the stick is moving you are commanding a higher or lower AoA.

If you are flying along and you move the stick forward and you feel yourself getting lighter you know you have just reduced lift (and rotor thrust) so that is your AoA indicator.
 

fara

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I have not found any reason to fly near a thunderstorm or a tornado and in my opinion anyone who does is making poor aviation decisions.

In my opinion sustained zero Gs are just not going to happen in a gyroplane.

Low Gs yes; but not sustained zero Gs.
Sustained zero G?? Who was talking about sustained? Did I mention sustained 0 G anywhere by mistake? Because all the discussion is about transient phenomenon and they all fall within sub second time frame. Someone commented about 2 seconds in weightlessness and I tried to -nicely- say that most likely its closer to one and in fact its less than one bt when it happens it probably has the psychological effect of making it feel much longer :).
Vance so to be clear, I have been talking about transient due to weather weightlessness and you do get it in aircraft rather rarely but fly enough and you will have it.
You are right that flying in and too close to T-storms is not a great "planned" decision.
There are scattered T-storms in this part every summer every day. No 2 ways about it. You are going to fly around these scattered storms when you fly here in the summer or you will not fly most of the summer. That is all there is to it.

Thomasant: I cannot but help notice that you constantly relate your scanty experiences in gyroplanes with your "vast" experience in trikes. I do not see the co-relation when you bring trikes into the picture.
Yes, because weather and transient moderate updrafts and downdrafts you fly through do not care if you are on Aladin's magic carpet or a gyro or a jet. Only that in a jet that is moving forward at 800 feet/sec an encounter with free fall transient for 1/3rd of a sec is going to only allow you to drop about 10 feet and in a trike or gyroplane that cruise around the same speed (gyros sometimes are even slower) that encounter would drop you for a lot more. Thankfully mild to low moderate transient weather where we would usually fly doesn't make it last even close to 1/3rd of a second but its there nontheless, admittedly and fortunately rarely.

JAL: Very expensive specially if you don't get half off discount etc. but still worth doing it once when you got some extra money. Very much fun also.
http://www.nogravity.com/
A cheaper way to experience it (without doing the parabola in your gyroplane) is
http://www.skydivecity.com/
Well at least for the first 5 seconds or so and its close to me :)
A little technical treatment
http://galileoandeinstein.physics.virginia.edu/lectures/gal_accn962.htm
Teetering rotors have their issues with this but they are also less complex and generally work but they should have limitations. Army presented papers and analysis on such topics due to historical data and to improve future designs. Hopefully some rotor/gyroplane manufacturers will use it.
 
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Vance

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Sorry Abid, I misunderstood.

Sorry Abid, I misunderstood.

Trikes have the same issue with zero G. You will have no control in that in a WSC and they do tumble forward as well but this has been figured out decades ago and unless you do an aerobatic maneuver or whip stall, you can tumble and people even today die in that regimen but they are (in a harsh sense) doing idiotic things. If you fly them within their operating limitations, they are as safe as anything else. Of course trike pilots believe there are operating limitations and they can't get away doing anything and everything they want. They fly through cold fronts and transient turbulence and come out on the other side (and there are ones with HTL as well). I have been dozens of times thrown up and out of my seat, hanging by the seatbelt only. I would guess its one second may be two at most as well but more towards the one.
IMO based on limited flight time, I did not find gyroplanes I flew as confidence inspiring in weightlessness as trikes but the number of times I experienced it in gyroplanes was limited to 2 and I am new to them so psychologically the feel is not under my skin yet either and that has to play a part as well.
It appeared to me from your post you were talking about one, maybe two second zero G events. I would refer to these as sustained.

I have yet to experience a Zero G event of any length in a gyroplane and I would not fly with someone who did.

In my opinion this person who exposed you to these two zero G events lacks skill and an understanding of how a gyroplane flies.

I try to avoid low G events in any gyroplane I fly.

I have experienced uncomanded low G events in clear air turbulence flying a gyroplane but they are generally of very short duration.

I do not share your feeling that being near a thunderstorm is a necessary part of summer flying in Florida.

Thank you, Vance
 

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I've seen several videos posted on this forum that show a gyro tumbling out of the sky.
I suspect those gyros had just experienced a momentary zero-g event! Am I wrong?

S O M E T H I N G must be causing it?
 

bryancobb

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1:00 PM to 5:00 PM

1:00 PM to 5:00 PM

...I do not share your feeling that being near a thunderstorm is a necessary part of summer flying in Florida...
Maybe if you stay on the ground between 1:00 and 5:00!
 

brett s

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Abid isn't taking into account the huge difference between a trike's wing loading & a gyro or helicopter's blade loading making a big difference in how they are affected by wind & turbulence. Another sign of little actual experience in the latter...

You don't need zero g to cause a high thrustline gyro to PPO, keep in mind what happens to cyclic authority on a teetering rotor as g load decreases - it's not an on/off switch.

I'm sure most of us have experienced transient low g in a rotorcraft due to turbulence - very short bursts, not sustained for any length of time & not a big deal on a properly designed ship.

I've been in what the FAA classifies as "severe" turbulence once in a CH-47C (in the ROK mountains right after a cold front passed), don't care to ever see it again & was damn glad we weren't in anything smaller. The metal ramp extensions were bouncing up a couple feet at times, anything not strapped down was flying around the cabin & we even had a few emergency exit lights pop out of their mounts.
 

bryancobb

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Teach me brother :)

Teach me brother :)

...You don't need zero g to cause a high thrustline gyro to PPO,...
Ok...so I thought zero-g was required. Are you saying a gyro can flip even when in normal flight maneuvers, if the prop thrust is pushing above the center of mass of the fuselage?
 

brett s

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I wouldn't call anything that involves low g a normal flight maneuver & definitely not something that should be done intentionally. But mother nature can also get you there...

As g load decreases your control authority also starts decreasing in a teetering rotor, with enough thrust & CG offset you won't need to get all the way to zero g before you're in trouble.
 

fara

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Brett
I got to say I am in awe of rotorcraft that can handle these transient weather phenomenon without getting effected much. Would you please explain for my benefit how a gyroplane or a Bell UH-1 with a teetering rotor reacts to the split second weightlessness event. We know they will eventually happen

Vance: better stay on the ground in Tampa in the height of summer.
No one went to plan and show me these weather events btw. So let's not point any fingers at people who don't exist. The gyroplane people I flew with are responsible, safe and probably better hands on pilots than I ever expect to become. They just don't waste their time on the forum and I don't blame them.

1 to 5 pm is a good rule of thumb For precaution. Nature doesn't work on that precise schedule. It helps though to be on the ground between 1 and 6 for sure.
 
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All_In

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Interesting, I've ferried 100's of new pipers from Orlando to San Diego weaved my way through many overcast thunderstorms cells dumping rain with turbulence.
Lots of negative G's in a small fixed wing wasn't very scary, just hung on an flew her the best I could. However, if it were not for the seat beat I would be banging my head on the roof from the negative G's!

I posted about the trip home from Rotors Over the Rockies fly-in (Last YR) = server turbulence for about 400 miles. Just pulled the power back and enjoyed the rock and roll ride and tried hold my altitude within 500 feet. Hard to do when your being bumped up and down by 600 feet each dump.


Question: Has anyone here ever been caught in and flown a gyroplane through similar server turbulence for any length of time and if so what was it like?
 
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