Saturday, March 10, 2012

Idea: Helicopter with the blades extendeding from the outer edge of a lens shaped lifting body

I was today walking with a dog and it occurred to me that with a fly by wire system a helicopter which would have blades outside of a circular lifting body and that would have a pusher prop (cruise prop) on top of the said flat lifting body in a pivoting pylon with thrust vectoring, could possibly fly stable and avoid the not that good things of a helicopter and be more efficient VTOL craft than a conventional helicopter. The bearing on the outer ring would possibly though be some sort of a challenge. On a big one, the outer ring could be not connected to the inner ring at all, but it could actually use maglev technique to levitate in a hole without physical contact with the bearing. This could come with too heavy weight penalties, so not sure if it would be feasible. So this is just a out of the box thinking idea because I have always felt that there is something wrong with helicopters, I have never really liked how they look like and how they function, there must be a better way to do that.

Cyclic system could be hidden inside the center section so that it would not cause drag like on a helicopter where there are lots of mechanical parts directly in the airflow causing drag. In cruise the plane would be a gyrocopter rather than a helicopter because it would have positive angle of attack unlike helicopter which cruises at negative angle of attack (and only blades have positive angle of attack).

I would like to try this as RC-model, but the challenge would be to fabricate such a large and yet lightweight bearing that would be size of the craft itself. The outer shell with the bearing would have a gear tooth that would be driven with a pinion gear that would be connected to the engine. This would also function as gear reduction drive. In addition to the ring drive to takeoff and landing, there would need to be a generator for driving the pylon mounted thrust vectoring prop that would be run with an electric motor.

The shape of the lifting body would be a suboptimal airfoil because it would need to be symmetrical and have both sharp leading edge and trailing edge but. This kind of craft would be naturally unstable but it could be artificially stabilized with software.


Robb Greathouse said...

Darpa was working on something like that with retracting blades.

The idea of the lifting body is interesting. Perhaps the disc could be the aircraft during flight. Not having to have the blades to fly might reduce stress on bearing and make it easier to build.

Totally different structure. Why aren't we seeing lifting bodies in the homebuilt airplane market? It seems like they would be easier to construct.

Serg said... - interesting software for airfoil/wing/flap system design