Bell/Boeing Quad TiltRotor (QTR) - Concept Of Deployment
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Bell/Boeing Quad TiltRotor (QTR) - Concept Of Deployment
YouTube - Bell/Boeing Quad TiltRotor (QTR) - Concept Of Deployment
Came across this today, first I have heard of it!!!!!
Came across this today, first I have heard of it!!!!!
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?
Very perspicacious of you GPMG, does that criterion somehow not apply to all other powered aircraft then?
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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?
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?
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.
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.
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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'
'ya canna chenge the laws o physics captain'
Last edited by GPMG; 13th Jul 2009 at 14:49.
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?
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?
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.
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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.
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.
Last edited by Tourist; 14th Jul 2009 at 15:34.
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.
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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.
