Helicopter concept, but...
Helicopter concept, but...
(OP)
Interesting concept but given such vestigial rudders on the empennage, what form of prop/pitch/throttle control for yaw?
http://www.youtube.com/embed/8ljxyDtCsaM
Rod
http://www.youtube.com/embed/8ljxyDtCsaM
Rod





RE: Helicopter concept, but...
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.
RE: Helicopter concept, but...
rmw
RE: Helicopter concept, but...
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
RE: Helicopter concept, but...
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
RE: Helicopter concept, but...
I'd love to see the tradeoff analysis on these designs.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Helicopter concept, but...
Mike Halloran
Pembroke Pines, FL, USA
RE: Helicopter concept, but...
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.
RE: Helicopter concept, but...
Mike Halloran
Pembroke Pines, FL, USA
RE: Helicopter concept, but...
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.
http://www.youtube.com/watch?v=SJqcVVnk3DM
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
RE: Helicopter concept, but...
here's another link for those interested.
http://ww
IMHO the British aerospace industry missed a bet with this thing.
RE: Helicopter concept, but...
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
RE: Helicopter concept, but...
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: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Helicopter concept, but...
RE: Helicopter concept, but...
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
RE: Helicopter concept, but...
http://www.cartercopters.com/index.html
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:
http://www.cartercopters.com/mu-1.html
RE: Helicopter concept, but...
RE: Helicopter concept, but...
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: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Helicopter concept, but...
RE: Helicopter concept, but...
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.
http:
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
RE: Helicopter concept, but...
The X3 can hover whereas the Cartercopter or Rotodyne could not. The Cartercopter can however "Kite" or hold position over the ground with sufficient wind (i.e. windspeed >= minimum airspeed). Helicopters used for heavy lift in hover usually don't have that far to go or at least don't have to go very fast. Big exceptions would be SAR rotorcraft or troop transports.
An aircraft of the style of the Cartercopter could have a significant advantage over an aircraft of the style of the X3 for missions where you are looking purely for VTOL with high speed transport. The Cartercopter conceptually is a simpler and potentially a lower maintenance aircraft as it does not have the main rotor gearbox.
RE: Helicopter concept, but...
You said;
"The X3 can hover whereas the Cartercopter or Rotodyne could not."
Wikepedia says:
""The Rotodyne performed to expectations and set a world speed record in the convertiplane category, at 190.9 mph (307.2 km/h) on 5 January 1959, over a 60 mi (100 km) closed circuit.[8] As well as being fast, the craft had a safety feature: it could hover with one engine shut down with its propeller feathered,""
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
RE: Helicopter concept, but...
The tip jets were primarily for VTOL. Otherwise, the aircraft was designed to fly with the rotor in auto-rotation.
RE: Helicopter concept, but...
The rotodynes original task was short haul, city center to city center passenger service, to avoid going to the airport, or the railway station.
There were certain factions in Great Britain that did not want to see this happen.
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