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Bell unveils new VTOL concepts

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Bell unveils new VTOL concepts

Old 2nd Aug 2021, 19:14
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Bell unveils new VTOL concepts


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Old 2nd Aug 2021, 21:10
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An more informative illustration is here: https://www.helis.com/database/news/...-usaf/?noamp=1

If I understand it correctly, the idea is to have a jet propelled tilt rotor with folding blades .
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Old 2nd Aug 2021, 22:12
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I wouldn't like to be the guys doing the fatigue analysis on those rotors when in the folded position. I think the blades could be made better use of in the open position in cruise. Each blade is likely to be separately actuated and therefore could be set to minimum drag and also act as a useful lifting surface. The drag in this arrangement may not outweigh the drag in the folded arrangement.
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Old 3rd Aug 2021, 00:52
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Translation from stowed high speed flight to rotorborne flight could be interesting.
The Osprey doesn't fold it's rotors - and it transitions from a mid-speed turboprop to a helicopter by trading thrust vector for lift - right?
But this thing would transition from pure jet, through turbo-prop to helicopter.
What speed would you need to decelerate to, to be able to fully deploy (presumably) feathered rotors into the airstream, yet still support the vehicle's weight in wingborne flight?
Actuators would need to be very powerful to deploy long rotors into an airstream that would have to be fast enough to support wingborne flight at vehicle MAUW and the rotors would have to be damn stiff and strong to withstand that airload.
Is it then a gradual transition from turbojet to turboprop mode - increase in pitch - thrust from jet exhaust transitioning to propeller thrust?
Am I missing something here?
Can't quite picture how the transition between modes of propulsion would work... but then I'm no aerospace engineer.

Last edited by tartare; 4th Aug 2021 at 00:32.
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