Interesting concept but given such vestigial rudders on the empennage, what form of prop/pitch/throttle control for yaw?
Rod
Rod
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Helicopter concept, but... 2
- Thread starter evelrod
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thruthefence
Aerospace
I'm sure they are varying the pitch on the propulsive propellers (for want of a better word)
For anti torque, adding power to the main transmission and one of the props takes a bigger "bite" of air. (or the opposite takes a smaller bite).
For yaw control, one takes a bigger bite, the opposite a little less.
All this done by those clever ones & zeros, of course.
I think this thing could do the Osprey's mission at a lot less money.
For anti torque, adding power to the main transmission and one of the props takes a bigger "bite" of air. (or the opposite takes a smaller bite).
For yaw control, one takes a bigger bite, the opposite a little less.
All this done by those clever ones & zeros, of course.
I think this thing could do the Osprey's mission at a lot less money.
MikeHalloran
Mechanical
At hover and low forward speed, differential speed and/or (more likely) differential pitch control of the tractor propellers would be essential for yaw control. I can't tell which they use. Either would probably be too sensitive at high forward speed unless the gain is reduced or clipped with increasing forward speed; I have no knowledge of the matter, but it seems possible.
No, on reflection, it seems likely. Note that the vestigial rudders don't seem to have trim tabs. Which suggests that perhaps they _are_ trim tabs. Only one short sequence toward the end of the video shows them deflected a few degrees. They don't seem to have enough 'authority', if that's the right word, to offset a thrust asymmetry; that might be of concern.
Agree, ones and zeros must be there.
I wonder if they reduce the main rotor rpm at high forward speed, too; I'd guess they'd have to, to keep the advancing tip speeds subsonic. Or maybe it doesn't really go that fast?
Mike Halloran
Pembroke Pines, FL, USA
No, on reflection, it seems likely. Note that the vestigial rudders don't seem to have trim tabs. Which suggests that perhaps they _are_ trim tabs. Only one short sequence toward the end of the video shows them deflected a few degrees. They don't seem to have enough 'authority', if that's the right word, to offset a thrust asymmetry; that might be of concern.
Agree, ones and zeros must be there.
I wonder if they reduce the main rotor rpm at high forward speed, too; I'd guess they'd have to, to keep the advancing tip speeds subsonic. Or maybe it doesn't really go that fast?
Mike Halloran
Pembroke Pines, FL, USA
evelrod,
The yaw control/anti-torque is provided by a combination of rudder and prop pitch, which can vary depending upon forward speed. During hover, the rudders are obviously not effective, so differential prop pitch would be used. At higher speeds, using the rudders as much as possible would seem to be more efficient.
There's recently been quite a bit of renewed interest in compound helicopters, like this Eurocopter X3, the Sikorsky X2, Piasecki X-49, or the AVX concept. There currently is a debate over whether compounds or tiltrotors are the best way forward. It will be interesting to see how it all plays out in the next few years.
Terry
The yaw control/anti-torque is provided by a combination of rudder and prop pitch, which can vary depending upon forward speed. During hover, the rudders are obviously not effective, so differential prop pitch would be used. At higher speeds, using the rudders as much as possible would seem to be more efficient.
There's recently been quite a bit of renewed interest in compound helicopters, like this Eurocopter X3, the Sikorsky X2, Piasecki X-49, or the AVX concept. There currently is a debate over whether compounds or tiltrotors are the best way forward. It will be interesting to see how it all plays out in the next few years.
Terry
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GregLocock
Automotive
Check out the gyrodyne. That used one forward facing airscrew on a stub wing on one side to provide both rotor torque reaction and forward thrust.
I'd love to see the tradeoff analysis on these designs.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
I'd love to see the tradeoff analysis on these designs.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
MikeHalloran
Mechanical
Thanks for teaching me something today, Greg.
Mike Halloran
Pembroke Pines, FL, USA
Mike Halloran
Pembroke Pines, FL, USA
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1
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thruthefence
Aerospace
Greg, didn't the (Fairey) Gyrodyne use reaction jets on the blade tips, thus no torque reaction?
Regarding the main rotor advancing blade going supersonic, I would thing the "wing" would provide enough lift at speed, to allow the pitch of the main rotor blades to be decreased, unloading the main rotor, and pushing the blade stall back somewhat.
Regarding the main rotor advancing blade going supersonic, I would thing the "wing" would provide enough lift at speed, to allow the pitch of the main rotor blades to be decreased, unloading the main rotor, and pushing the blade stall back somewhat.
MikeHalloran
Mechanical
Yeah, the wing should help. Like Greg said, an n-dimensional tradeoff, where n could be large.
Mike Halloran
Pembroke Pines, FL, USA
Mike Halloran
Pembroke Pines, FL, USA
Thru the Fence,
I think you meant the Fairy Rotodyne.
It was the reaction jets on the rotor tips that killed the project ( It was too noisy.), but the concept was good.
Here is a link to a video of the bird at Farnborough.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
I think you meant the Fairy Rotodyne.
It was the reaction jets on the rotor tips that killed the project ( It was too noisy.), but the concept was good.
Here is a link to a video of the bird at Farnborough.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
thruthefence
Aerospace
Exactly so.....The tip jets were shut off in cruise flight, making it a sort of super autogyro.
here's another link for those interested.
IMHO the British aerospace industry missed a bet with this thing.
here's another link for those interested.
IMHO the British aerospace industry missed a bet with this thing.
So what we have here is a repeat of the Gyrodyne using improved engines and controls 63 years later.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
GregLocock
Automotive
is the one I meant, apparently though gyrodyne can mean something else.
Why were all British helicopters of that era designed to look like cartoon characters?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
Why were all British helicopters of that era designed to look like cartoon characters?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
thruthefence
Aerospace
Thanks for that link, Greg, i had my Fairey's confused!
SAITAETGrad
New member
The Cartercopter is another of these aircraft with the rotor for low speeds and the wing for high speeds. You can see it here:
The Cartercopter has an autogyro rotor and without the tip jets turned on, the Fairey Rotodyne was the same. These types do not have torque to overcome as the rotor rotation is independent of the aircraft. The X3 has a conventional gearbox driven rotor.
You can read what Jay Carter has to say about their rotor performs at higher speeds:
The Cartercopter has an autogyro rotor and without the tip jets turned on, the Fairey Rotodyne was the same. These types do not have torque to overcome as the rotor rotation is independent of the aircraft. The X3 has a conventional gearbox driven rotor.
You can read what Jay Carter has to say about their rotor performs at higher speeds:
SAITAETGrad
New member
Reading the wiki page on the gyrodyne...I never new about the earlier version which is indeed very similar to the X3. I made the same mistake others have made in this thread...referring to either the "Jet Gyrodyne" and the Rotodyne that resulted from it.
GregLocock
Automotive
Well now I can't get it out of my head. What is the disadvantage of the gyrocopter vs a conventional helicopter?
My guess is that control of hover is more difficult, every time you yaw the thing it starts to move forwards or backwards. This could be compensated for by using the cyclic. These days that could be done by a $2 chip (with a million dollar validation program).
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
My guess is that control of hover is more difficult, every time you yaw the thing it starts to move forwards or backwards. This could be compensated for by using the cyclic. These days that could be done by a $2 chip (with a million dollar validation program).
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
Compositepro
Chemical
A gyrocopter cannot hover. It must be moving forward to drive to overhead rotor, which has no motor. I think there is a light drive shaft on it, just to get it started rotating.
The term "Gyrocopter" and "Autogyro' were both trade marked terms to describe an unpowered rorary wing aircraft
The Eurocopter, Cartercopter and Rotodyne all have powered rotors which enable true vertical flight.
I found a rather long winded article which covers these aircraft in great detail.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
The Eurocopter, Cartercopter and Rotodyne all have powered rotors which enable true vertical flight.
I found a rather long winded article which covers these aircraft in great detail.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
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