Gyrocopters/Autogyros
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I actually had a long chat with Ron Jenkins of the CAA about gyros a while back. He's the sort of chief rotary licensing etc person, don't know his exact title (hope he doesn't read this!). At the time I had a PPL(A) and was close to a PPL(H) and wanted to know how many hours training I'd need for a PPL(G). Anyway, we discussed safety, and he seemed to think they were inherently OK, and that most of the accidents had been due to poor training before it was properly regulated, or poor self-build skills. I must admit what mainly put me off was trusting something with so many moving parts to someone else's DIY skills - or my own for that matter 
. But difficulty of flying didn't come into it as far as I remember, and the main snags seemed to be similar to those of the R22, ie negative g and mast bumping if you don't know what you're doing.
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Whirly
To fly is human, to hover, divine.
. But difficulty of flying didn't come into it as far as I remember, and the main snags seemed to be similar to those of the R22, ie negative g and mast bumping if you don't know what you're doing. ------------------
Whirly
To fly is human, to hover, divine.
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Check out the US accident statistics for these machines here.
These accident rates are for gyroplanes only, do not include homebuilt helicopters. As there is (in my opinion) a complete lack of regulatory control over these aircraft, the only way you can get a feel for safety in this category is to review the accident statistics.
I think that Whirly has hit the nail firmly on the head - these machines are being built by people who do not have the first clue about what they are doing. I have seen workmanship so poor on some of these pieces of equipment, that I do not understand how they ever got airborne at all. Of course, the fact that many people do not know how to operate them doesn't help matters any.
I think that a lot of them get completed then spend the rest of their lives sitting around the corner of a garage, otherwise the accident rate would be even higher!
Scary machines, just like homebuilt helicopters!
Can't get that hyperlink to work right. Sorry about the long string.
[This message has been edited by Cyclic Hotline (edited 21 June 2001).]
These accident rates are for gyroplanes only, do not include homebuilt helicopters. As there is (in my opinion) a complete lack of regulatory control over these aircraft, the only way you can get a feel for safety in this category is to review the accident statistics.
I think that Whirly has hit the nail firmly on the head - these machines are being built by people who do not have the first clue about what they are doing. I have seen workmanship so poor on some of these pieces of equipment, that I do not understand how they ever got airborne at all. Of course, the fact that many people do not know how to operate them doesn't help matters any.
I think that a lot of them get completed then spend the rest of their lives sitting around the corner of a garage, otherwise the accident rate would be even higher!
Scary machines, just like homebuilt helicopters!
Can't get that hyperlink to work right. Sorry about the long string.
[This message has been edited by Cyclic Hotline (edited 21 June 2001).]
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I’ve had a think overnight. Its surprising what the little grey cells can trawl up after sleeping on it. But I’m away from home at the moment so nothing to refer to. Sorry if this is obvious.
The fundamental difference between auto gyros and helis is that a heli’s rotor is powered whereas the gyro’s relies on airstream for rotation. Consequently air flows downwards through a heli’s rotor but passes upwards through a gyro’s. A heli’s rotor is tilted forwards in s&l flight but a gyro’s is tilted backwards. Lift is derived from the blade’s AoA to the airstream. The teetering head teeters, to adjust the blade’s AoA automatically throughout a revolution to equalise lift around the disc. If you drag the rotor blades through the air fast enough a lift component causes the forward facing blade to advance and a state of equilibrium can be achieved at circa 200 rpm.
Now any change to AoA caused by turbulence or mishandling will upset that equilibrium. The rotor head will teeter trying to maintain the appropriate AoA resulting in rotor speed fluctuations. There is no power drive to maintain rotor speed regardless as in a heli. In extreme cases, the teetering head reaches its stops. Not only does the inertia of the blade impart a shock to the mast but then insufficient AoA is generated. The distribution of lift around the disc is perturbed, exacerbating the problem. (OK SR?) This is the inherent problem of the teetering head. It appears difficult, if not impossible, to manufacture one with sufficient range for the more extreme flight conditions. In a heli, at least you have the engine to help overcome the perturbations. You’re not relying totally on inertia.
The other condition to cause the same problem is the push-over. When the rotor disc is unloaded in a bunt type manoeuvre, the AoA reduces and with it, the lift component that ensures rotation. The rotor slows. In extreme cases the AoA can become negative which positively and rapidly slows the rotor. It doesn’t need a lot to slow the rotor below a critical speed from which it does not recover its rotational speed.
What price an aircraft that shouldn’t be flown in turbulent conditions? I do think that it has been all too easy to blame the pilots’ mishandling for what appear to me to be inherent deficiencies of the concept. Certainly, not fully understood by their pilots but don’t we all rely to some extent on intrinsic good manners? I’m not saying don’t fly them but, if you choose to…… Do you have your answer now SSD? That’s enough from me. I would rather see the argument pursued by more technically knowledgeable types.
But finally,
Q. Have you ever wondered why these machines have such a low aspect ratio fin and rudder?
A. Well, sketch a blade in on a side elevation just missing the top of the rudder and see how far they are designed to go before de-capitating the rudder! One builder modified his with a taller rudder. Guess what happened?
WWW: You certainly get 12 out of 10 from me for stirring it! Can you do the same for the Instructors’ Forum?
[This message has been edited by Yogi-Bear (edited 22 June 2001).]
The fundamental difference between auto gyros and helis is that a heli’s rotor is powered whereas the gyro’s relies on airstream for rotation. Consequently air flows downwards through a heli’s rotor but passes upwards through a gyro’s. A heli’s rotor is tilted forwards in s&l flight but a gyro’s is tilted backwards. Lift is derived from the blade’s AoA to the airstream. The teetering head teeters, to adjust the blade’s AoA automatically throughout a revolution to equalise lift around the disc. If you drag the rotor blades through the air fast enough a lift component causes the forward facing blade to advance and a state of equilibrium can be achieved at circa 200 rpm.
Now any change to AoA caused by turbulence or mishandling will upset that equilibrium. The rotor head will teeter trying to maintain the appropriate AoA resulting in rotor speed fluctuations. There is no power drive to maintain rotor speed regardless as in a heli. In extreme cases, the teetering head reaches its stops. Not only does the inertia of the blade impart a shock to the mast but then insufficient AoA is generated. The distribution of lift around the disc is perturbed, exacerbating the problem. (OK SR?) This is the inherent problem of the teetering head. It appears difficult, if not impossible, to manufacture one with sufficient range for the more extreme flight conditions. In a heli, at least you have the engine to help overcome the perturbations. You’re not relying totally on inertia.
The other condition to cause the same problem is the push-over. When the rotor disc is unloaded in a bunt type manoeuvre, the AoA reduces and with it, the lift component that ensures rotation. The rotor slows. In extreme cases the AoA can become negative which positively and rapidly slows the rotor. It doesn’t need a lot to slow the rotor below a critical speed from which it does not recover its rotational speed.
What price an aircraft that shouldn’t be flown in turbulent conditions? I do think that it has been all too easy to blame the pilots’ mishandling for what appear to me to be inherent deficiencies of the concept. Certainly, not fully understood by their pilots but don’t we all rely to some extent on intrinsic good manners? I’m not saying don’t fly them but, if you choose to…… Do you have your answer now SSD? That’s enough from me. I would rather see the argument pursued by more technically knowledgeable types.
But finally,
Q. Have you ever wondered why these machines have such a low aspect ratio fin and rudder?
A. Well, sketch a blade in on a side elevation just missing the top of the rudder and see how far they are designed to go before de-capitating the rudder! One builder modified his with a taller rudder. Guess what happened?
WWW: You certainly get 12 out of 10 from me for stirring it! Can you do the same for the Instructors’ Forum?
[This message has been edited by Yogi-Bear (edited 22 June 2001).]
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Yogi,
That certainly makes sense to me, but I'm not technically minded enough to be certain. Maybe we should ask some of the more knowledgable types from Rotorheads what they think.
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Whirly
To fly is human, to hover, divine.
That certainly makes sense to me, but I'm not technically minded enough to be certain. Maybe we should ask some of the more knowledgable types from Rotorheads what they think.
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Whirly
To fly is human, to hover, divine.
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O.K. Where to start? This is my first post to this forum so I'll try not to stray. First, A properly designed gyro is both easy to fly and very safe. However, the number of properly designed gyros is small. I'll first address the turbulence issue. The stability in turbulence is determined by the point at which the rotor thrust line passes the longitudinal axis. If the rotor thrust line passes behind the longitudinal C.G. when an updraft is encountered the nose of the aircraft will lower into the new relative wind. When a downdraft is encountered, just the opposite will happen. If the rotor thrust line passes in front of the longitutinal c.g. then an updraft will cause the nose to pitch up and a down draft will cause the nose to pitch down, this is an unstable condition. The next question should be, well how do you make the rotor thrust line pass behind the c.g.? By placing the propeller thrust line at or below the vertical C.G. and installing a horizontal stabilizer. The dangerous part of flying a machine that is not stable in pitch is when the propellor thrust line is above the vertical C.G. a SIGNIFICANT nose down pitching moment is created when the aircraft approaches zero g. The rotor itself is somewhat tolerant of low G conditions as long as the time period is not excessive (more than 2 seconds, exact number depends on many factors such as blade weight and airfoil.) Machines that have a high thrust line, low vertical C.G. and no horizontal stabilizer will pitch over severly as a result of propellor thrust when the aircraft is unloaded in turbulance. This is the classic power push over. This event can happen very quickly and even quick reflexes by an experienced pilot to reduce power may not be timely enough. A gyro with centerline thrust and an adequate horizontal stabilizer are not prone to power push over, gust induced oscilation, or pilot induced oscilation.
Keep in mind that this information is abreviated. You could write volumes about the stability of the gyroplane. A good place to gather additional information about gyros is the web site http://www.rotorcraft.com they have a conference section with a couple of useful downloads. One is an excellent article written by Jean Forcade on stability of the gyroplane.
I am a gyroplane CFI in the U.S. and will be happy to answer any specific questions via email. I will be out of town intermittently and away from email for up to a week at the time. I am also the Chief Test Pilot for the CarterCopter and don't have internet access when I travel for those duties. I'll shut up for now and I apologize for the spelling. Not one of my strong points.
Keep in mind that this information is abreviated. You could write volumes about the stability of the gyroplane. A good place to gather additional information about gyros is the web site http://www.rotorcraft.com they have a conference section with a couple of useful downloads. One is an excellent article written by Jean Forcade on stability of the gyroplane.
I am a gyroplane CFI in the U.S. and will be happy to answer any specific questions via email. I will be out of town intermittently and away from email for up to a week at the time. I am also the Chief Test Pilot for the CarterCopter and don't have internet access when I travel for those duties. I'll shut up for now and I apologize for the spelling. Not one of my strong points.
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Fellow rotorheads,
A gyro cannot experience mast bumping in the same way a heli does. There is no mast to provide torque. The rotor is allowed to spin on a bearing.
Negative g is still a problem because it leads to loss of attitude control.
This is true of all teetering rotor systems.
Loss of rotor authority means that the gyro can rotate itself right into the rotor, usually chopping the tail off.
Another area of concern is PIO or pilot induced oscillation. This usually happens with low time pilots who chase the controls and wind up doing a series of porpoising manuevers that get progressively worse culminating in a tail boom strike or other catastrophe.
A horizontal stabilizer of adequate proportions can vastly improve the damping and control response and reduce the PIO danger.
Incidentally, engine failure results in more than "a gentle glide". A steep glide must be entered to maintain forward airspeed.
At the bottom, similar to a heli, a flare is entered to build energy in the rotor.
There is no collective to pull, the flare is used to cusion the touchdown.
[This message has been edited by Try_Cyclic (edited 24 June 2001).]
A gyro cannot experience mast bumping in the same way a heli does. There is no mast to provide torque. The rotor is allowed to spin on a bearing.
Negative g is still a problem because it leads to loss of attitude control.
This is true of all teetering rotor systems.
Loss of rotor authority means that the gyro can rotate itself right into the rotor, usually chopping the tail off.
Another area of concern is PIO or pilot induced oscillation. This usually happens with low time pilots who chase the controls and wind up doing a series of porpoising manuevers that get progressively worse culminating in a tail boom strike or other catastrophe.
A horizontal stabilizer of adequate proportions can vastly improve the damping and control response and reduce the PIO danger.
Incidentally, engine failure results in more than "a gentle glide". A steep glide must be entered to maintain forward airspeed.
At the bottom, similar to a heli, a flare is entered to build energy in the rotor.
There is no collective to pull, the flare is used to cusion the touchdown.
[This message has been edited by Try_Cyclic (edited 24 June 2001).]
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We weren’t overwhelmed in the mighty rush, were we?
Thank you RN and TC. The ideal configuration that RN espouses is presently unconventional in the Land of Uk. I haven’t seen one in England though I’ll bet they’re lurking somewhere. It may well be the way to go but those that fly here today have a low C of G, high thrust line, with all the accompanying deficiencies, as described.
Using the links from http://www.rotorcraft.com/ :-
A study of http://www.aircommand.com/ will indicate the new configuration. Then refer to http://www.aircommand.com/elite2706.html and notice the degree of modification between the conventional and the new Elite upgrade. I always wondered why nature configured storks and cranes that way. It seems that auto gyros are still very much in an experimental stage and the benign configuration may yet be evolving.
Dealing with the type you are most likely to buy secondhand, I cannot recommend too highly Peter Lovegrove’s articles in Pilot magazine of August and September 1971. Yes, in 1971 after a spate of fatal accidents. They describe the surprising handling problems of the type of machinery that you still see around today with graphic illustrations of the problems and their consequences. It is sobering reading and this is where we came in. A new spate of accidents is occurring as though it has never happened before. Probably, the articles are still obtainable from Pilot mag. If they can’t oblige then I can, with their permission of course. Just put your life savings in a suitably large ‘Jiffy’ bag and email me for my address!
Thank you RN and TC. The ideal configuration that RN espouses is presently unconventional in the Land of Uk. I haven’t seen one in England though I’ll bet they’re lurking somewhere. It may well be the way to go but those that fly here today have a low C of G, high thrust line, with all the accompanying deficiencies, as described.
Using the links from http://www.rotorcraft.com/ :-
A study of http://www.aircommand.com/ will indicate the new configuration. Then refer to http://www.aircommand.com/elite2706.html and notice the degree of modification between the conventional and the new Elite upgrade. I always wondered why nature configured storks and cranes that way. It seems that auto gyros are still very much in an experimental stage and the benign configuration may yet be evolving.
Dealing with the type you are most likely to buy secondhand, I cannot recommend too highly Peter Lovegrove’s articles in Pilot magazine of August and September 1971. Yes, in 1971 after a spate of fatal accidents. They describe the surprising handling problems of the type of machinery that you still see around today with graphic illustrations of the problems and their consequences. It is sobering reading and this is where we came in. A new spate of accidents is occurring as though it has never happened before. Probably, the articles are still obtainable from Pilot mag. If they can’t oblige then I can, with their permission of course. Just put your life savings in a suitably large ‘Jiffy’ bag and email me for my address!
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WWW
I suppose with all those share options and a cut of the profits from your company, a gyro may soon be parked in the garage of the WWW Towers?
PS
A bright yellow gyro flew over my place one evening last week. It looked great but did sound a bit noisy..though it was buzzing along at a fair old lick...a bit like a bee out of hell.
It was flying down the south east corner of the Stansted zone, on a track from Andrewsfield to Stapleford. Might have been doing a big circuit out of North Weald though. Could be a local enthusiast who you could contact?
[This message has been edited by Stan Sted (edited 30 June 2001).]
I suppose with all those share options and a cut of the profits from your company, a gyro may soon be parked in the garage of the WWW Towers?
PS
A bright yellow gyro flew over my place one evening last week. It looked great but did sound a bit noisy..though it was buzzing along at a fair old lick...a bit like a bee out of hell.
It was flying down the south east corner of the Stansted zone, on a track from Andrewsfield to Stapleford. Might have been doing a big circuit out of North Weald though. Could be a local enthusiast who you could contact?
[This message has been edited by Stan Sted (edited 30 June 2001).]
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General interest in gyrocopters?
Take a look at the address below. I found details of this company some 5 years ago and have followed their progress ever since. They may well be onto something big as there does seem to be a market waiting out there.
Perhaps the wider use of these fascinating aircraft is about to begin.
I hope they have the noise problem sorted though. The RAF 2000 that often flies round here sounds like a swarm of bees in a tumbledrier.
http://www.groenbros.com
ShyT
[This message has been edited by ShyTorque (edited 29 June 2001).]
Take a look at the address below. I found details of this company some 5 years ago and have followed their progress ever since. They may well be onto something big as there does seem to be a market waiting out there.
Perhaps the wider use of these fascinating aircraft is about to begin.
I hope they have the noise problem sorted though. The RAF 2000 that often flies round here sounds like a swarm of bees in a tumbledrier.
http://www.groenbros.com
ShyT
[This message has been edited by ShyTorque (edited 29 June 2001).]
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Just a quick note following your ad on PPRUNE.
The man you need is Tony Melody.
He has been building and testing these for CAA, James Bond films and all sorts. He is doing displays all over the world these days. On top of this he is a thoroughly reasonable bloke! He will be more interested in helping get you sorted out properly than helping you unload your wallet.
Please give me your contact details and I will get him to contact you. He will give you some very sound advice. If he doesn't actually sell you one he will tell you what to ovoid and probably point you in the right direction.
Wyatt
The man you need is Tony Melody.
He has been building and testing these for CAA, James Bond films and all sorts. He is doing displays all over the world these days. On top of this he is a thoroughly reasonable bloke! He will be more interested in helping get you sorted out properly than helping you unload your wallet.
Please give me your contact details and I will get him to contact you. He will give you some very sound advice. If he doesn't actually sell you one he will tell you what to ovoid and probably point you in the right direction.
Wyatt
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Gyrocopters/Autogyros
I'm glad to inform the community that today Victor Shumeiko called me from the airfield where he tested his new gyro. Vic (shining) reported that they performed first few flights carrying three full-scaled men on board. I've already posted a couple of Vic's gyro pictures, which can be seen from the http://twistairclub.narod.ru/ - then go to English news. Hope to post some
more this week.
Victor's gyro has the original design and a couple of interesting innovations in it which Vic supposes to patent.
Shown is the aircraft with two back seats (side-by-side, sure) removed for test runs. Engine is now 2.5 l injected Subaru converted in Russia. Engine showed 360 kgs thrust. Prop is 3-bladed (181 cm) composite Ukraine-made one.
Victor has build his own rotorhead and used RAf 30' rotor for current flying. We also bought Hollmann and SportCopter(new, painted) rotors to compare them - I believe it may be interesting though somebody surely did this before.
Vic also built his own hydraulic prerotator using local pump and motor. These are extremely heavy and don't last long anyway. This current system allows to prerotate up to 370-380 rrpm. The gyro weights approx. 390 kg empty though I'm sure it will become some
25-30 kg lighter soon. It was named "Okhotnik" which directly means "the hunter".
If anybody is interested in updates, please let me know via e-mail.
Here are htpp://twistairclub.narod.ru/hunter.htm - some poor photos of 3-on-board flights.
more this week.
Victor's gyro has the original design and a couple of interesting innovations in it which Vic supposes to patent.
Shown is the aircraft with two back seats (side-by-side, sure) removed for test runs. Engine is now 2.5 l injected Subaru converted in Russia. Engine showed 360 kgs thrust. Prop is 3-bladed (181 cm) composite Ukraine-made one.
Victor has build his own rotorhead and used RAf 30' rotor for current flying. We also bought Hollmann and SportCopter(new, painted) rotors to compare them - I believe it may be interesting though somebody surely did this before.
Vic also built his own hydraulic prerotator using local pump and motor. These are extremely heavy and don't last long anyway. This current system allows to prerotate up to 370-380 rrpm. The gyro weights approx. 390 kg empty though I'm sure it will become some
25-30 kg lighter soon. It was named "Okhotnik" which directly means "the hunter".
If anybody is interested in updates, please let me know via e-mail.
Here are htpp://twistairclub.narod.ru/hunter.htm - some poor photos of 3-on-board flights.
Last edited by twistair; 18th Oct 2002 at 14:44.
Would you care to cross-post to "Flight Test", I think that you might get some interest over there.
Incidentally, is that the Scimitar shaped "Kievprop" being used?
G
Incidentally, is that the Scimitar shaped "Kievprop" being used?
G
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G,
we tried KievProp, but this one is different. It's also made in Ukraine but the brand is "Donchak".
There are actually some 4-5 companies in Ukraine who is manufacturing both composite and wooden props. KievProp and Donchak seem to be the best though I still didn't test some other.
we tried KievProp, but this one is different. It's also made in Ukraine but the brand is "Donchak".
There are actually some 4-5 companies in Ukraine who is manufacturing both composite and wooden props. KievProp and Donchak seem to be the best though I still didn't test some other.
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Gyrocopters
Hello gents,
I would be very thankfull if you could give here your perception of the gyrocopters... this famous unknown..
What do you think of their safety and building, their piloting.
Have you a good or bad impression....
Would you be inclined to learn more about them or, simply to try them ?
thank you in advance.
Victor
I would be very thankfull if you could give here your perception of the gyrocopters... this famous unknown..
What do you think of their safety and building, their piloting.
Have you a good or bad impression....
Would you be inclined to learn more about them or, simply to try them ?
thank you in advance.
Victor