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Old 20th May 2005 | 22:39
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Chiplight
 
Joined: Jul 2001
Posts: 68
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From: CT, USA
Cyclic Control by Pulsed Torque

This has got to be one of the most interesting ideas I've seen in a while.


The R/C helicopter in the attached photos has no swashplate and no control rods at all. Also, no servos, yet it has full control of roll, pitch, yaw and collective thrust- cyclic control is achieved by pulsed torque to the main electric motor. The pulse is timed correctly using an optical sensor and sensor plate that rotates with the main rotor. Yaw control is simpler, with just changes to the tail motor speed.

I'll admit that I had to look at this thing for a long time before I comprehended it.
The motor is pulsed on and off in different parts of the rotor's cycle. This causes the fixed pitch rotor to create more thrust during that portion of the cycle that the motor is driving it. Control inputs take effect 90 degrees later in the cycle, just like with ordinary swashplate control.

Collective thrust is controlled by varying the duty cycle of the pulses to the motor.

There are two gyros: one is yaw-axis for tail, and the other a "free gyro" which is two-axis for cyclic.
A video in japanese is available on this page http://www.nanorc.com/revolutor.php
more pics here
http://www.vassfamily.net/heli/tech.html

Last edited by Chiplight; 21st May 2005 at 02:58.
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