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helicopter rotor help

helicopter rotor help

(OP)
hi,
i am working on a project to design a helicopter. Right now my task is to acquired the force required from actuators to tilt the rotor.
I have done some research and with my understanding, I am very confused on the way to get or estimate that force.
First way I tried was to use the pitching moment of my helicopter. Then, with that moment and the swash-plate dimensions, I could obtain the force needed to hold the body and the rotor in a certain position when the CG is not directly under the mask.
Other way I found is to take the moment at the shaft. When sum of the moments are equal to inertia times angular acceleration, I could get another value of force required for tilting the rotor at certain speed.

For example, first the helicopter is hovering and we need to go forward. The rotor disc are supposed to be tilted forward in order to provide forward velocity. To do that we need actuator to tile the cyclic swash-plate. At that moment I still cant imagine which part would be tilted the rotor or the body itself?
After that, i think the actuator has to provide coupling moment in which keep the body nose down in the forward flight. Otherwise there would not be any factor preventing the body to oscillate during the flight. :? :? :?

I found force value of the first method of pitching moment is quite high (30000N for 4000kg copter) and second method provides me as low as only 400N.

Therefore would really like to ask anyone or expert that could explain to me how this works. If both of my method are wrong, the alternative would also be appreciated.

RE: helicopter rotor help

In transition from hover to forward flight, the entire aircraft tilts forward.

Before that happens, the rotor cone tilts forward as the blade aoa is increased in the aft quarter of the circle. It might be more correct to say that the rotor cone gets deeper, but only at the back of the a/c.

It might be helpful to work out the forces on a single rotor blade passing over the tailcone with the cyclic stick held far forward.

There just has to be a textbook that covers the subject....

Mike Halloran
Pembroke Pines, FL, USA

RE: helicopter rotor help

Be sure & tilt your swashplate 90 degrees ahead of where you want the helicopter to go.

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