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earthgoodboy
27th Jun 2012, 06:16
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.

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.
thanks

baby spanner
27th Jun 2012, 23:09
i cant help with the maths... however for anyone else to they need more information...

what weight are the blade
how long are they
how many are there?

earthgoodboy
28th Jun 2012, 04:24
the mass of the blade is yet unknown. I should let it be a variable for now.
and my helicopter is coaxial, its gonna be 2 blades on each rotor, each blade is 6m in length.

Also my CG would be lean forward about 30 cm. And assuming there is no lift from the tail.

Nf stable
29th Jun 2012, 07:55
I'm reading this, thinking that you're trying to tilt the whole disk forcefully with the actuators, rather than feather the blades and let the aerodynamics do the tilting. Maybe I'm picking you up wrong...