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Friday, May 1, 2009

Common RC Heli Control Configuration

Co-Axial Heli
Co-Axial helicopters use a counter-rotating twin rotor design. Two sets of blades spinning in opposite directions eliminate the need for a tail rotor and provide excellent stability making these helicopters an ideal introduction to the hobby.

Collective Pitch (CP) Heli
Collective Pitch Helicopters alter altitude by changing the blade angle using pitch servo combined with increased RPM from the motor (pitch/throttle curves decide the exact input of each variable and can be altered depending on ability).

Fixed Pitch (FP) Heli
Fixed Pitch RC Helicopters only have 4 channels and they increase in altitude by increasing power to the motor. They have curved blades to create more lift and lack the collective pitch (blade angle) method of lift. They have a very simple servo configuration making them easier to repair than a CP Heli.


Hiankun said...

Based on my knowledge, the CP helicopters don't increase their RPM with the pitching angle of main rotor. Instead, they increase the ``power output'' of the engine and hope to maintain a stable working RPM. In other words, to keep fly in almost steady RPM is one advantage of the CP helicopters.

That's what I know but I am not sure it's correct or not. Just for your reference.


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joed said...

The pitch of a CP Heli increases or decreases wrt the trottle. When the trottle is push up, it is naturally that the rpm of the motor also increases. A stable RPM of 2200 to 2500 is desired for flying especially during hovering. But if the RPM do not change while changing the pitch, I think it is really hard for the heli to fly.

Hiankun said...

Thanks to joed'e reply. You remind me something. Yes, it's the ``stable'' RPM we want, not a ``steady'' one.

joed said...

We learn everyday :)
Nice to find someone who is in the same interest group. Perhaps we should meet one day at the flying field.