View Full Version : Bell/Boeing Quad TiltRotor (QTR) - Concept Of Deployment
tiger19
13th Jul 2009, 02:34
YouTube - Bell/Boeing Quad TiltRotor (QTR) - Concept Of Deployment (http://www.youtube.com/watch?v=zjYFhQA8mYs)
Came across this today, first I have heard of it!!!!!
I hope that the engines are 100% reliable, even when hit by enemy action.
Icare9
13th Jul 2009, 11:32
The concept has been around for many years, see Fairey Rotodyne for example.
Very perspicacious of you GPMG, does that criterion somehow not apply to all other powered aircraft then?
Ok, scenario is thus.
Aircraft is landing or taking off from an airfield and one engine fails. Single engine has a hope of gliding down, 2 has a strong posibility, and a 4 can go around and land safely (this is obviously dependant on altitude / attitude but in most cases there can be a happy outcome).
If this Quad Tiltrotor does the same, it will have it's 4 engines at an angle to provide lift as it will be going too slow for it's stubby wings to provide enough lift (also to avoid ground strike from the rotors).
So if they are all providing lift, take out one engine / rotor and it is like a leg suddenly dissapearing from a table. I would be surprised if any pilot or automatic system could find a way of reacting to this without the worst happening.
This system would also be likely to be used to land in 'hot' areas so the chances of losing an engine or ortor would be increased.
Also if this thing loses an engine in forward flight at 10'000ft, if it does continue to fly, it would provide a bit of a dilema to the pilots as to just how they would get it down.
If you feathered all rotors to provide 0% lift, the landing would be pretty hot and fast, probably a bit too much?
oxenos
13th Jul 2009, 12:43
No doubt, as with the Chinook / Belvedere type helicopter, the engines and rotors are interconnected.
Any way it seems to work for that lot Helibeds.
LowObservable
13th Jul 2009, 13:37
Prop-Rotors would be cross-shafted left and right and fore and aft.
Clearly there is some advantage over the twin in that you have 75 per cent rather than 50 per cent of power left after a single failure.
That said, my local dealer doesn't have access to the kind of chemicals that would make the QTR look sensible.
Engines may be cross connected but rotor pitch failure / general rotor failure would be pretty tough to manage.
Didn't claim to have a Eureka moment, but I would have thought that it was pretty obvious. I'm sure that the boffins at Bell have got it all covered (although the Osprey is under a bit of fire from certain quarters because of stability issues, one of which caused the death of 19 Marines).
'ya canna chenge the laws o physics captain'
racedo
13th Jul 2009, 17:58
Having capability like that do you need to spend billions on aircraft carriers ?
dead_pan
13th Jul 2009, 19:45
Given the birthing pains of Osprey, I think it is a sure-fire bet this will never fly.
If on the off-chance it ever did, anyone care to comment on whether the rotor configuration would preclude autorotation in the event of power plant failure?
Donkey497
13th Jul 2009, 20:55
Damn, the might Wocka-Wocka is deafening up close, I shudder to think how much noise & blade pressure waves would be created by a close-coupled pair of them such as this idea.
Tourist
14th Jul 2009, 07:27
Donkey,
The Osprey is very quiet, there is no reason to believe the 4 propped version would be anything different.
GPMG
"Engines may be cross connected but rotor pitch failure / general rotor failure would be pretty tough to manage"
"So if they are all providing lift, take out one engine / rotor and it is like a leg suddenly dissapearing from a table. I would be surprised if any pilot or automatic system could find a way of reacting to this without the worst happening."
All the points you make are just as true of the chinook. My big concern would be what if the tilt mechanism stuck in the forward flight position. The landing would be very fast, and very noisy as the props disintegrate in a fiesta of light and sound.
LowObservable
14th Jul 2009, 14:41
If I recall correctly, landing with the rotors forward is a last-ditch emergency option with the V-22. It avoids having to design and certificate the pivot mechanisms to the same level as primary structure.
Jolly Green
14th Jul 2009, 15:52
It's been done in the V-22. Both rotors rotate so that as the prop strikes the runway the pieces go away from the fuselage. The proprotors are designed to 'broomstraw' or disintegrate into small lightweight pieces as they impact. On an early test flight the engines wouldn't rotate so they landed in airplane configuration. Worked just as planned.
Tourist
14th Jul 2009, 16:33
I bet there was some spectacular pucker going on in the last few seconds before touchdown.:eek:
fallmonk
14th Jul 2009, 17:56
Does any one know IF the V-22 has ejection seats for crew ?
Or is it we land no matter what happens !
OFBSLF
14th Jul 2009, 19:38
Given the birthing pains of Osprey, I think it is a sure-fire bet this will never fly.
One can only hope.