Mitch's Servo load calculator
Have you ever wondered what torque is required to make your control surfaces
move reliably?
Well, I found this formula on the flair products website (www.flairproducts.co.uk)
I have added this form and made a calculator for it. Simply enter the Width
and Chord (depth) of your control surface. Enter the maximum expected airspeed
of your aircraft and the maximum angle of deflection (any more than 45 degrees
is a bit pointless unless you are making airbrakes)
How to calculate
the servo power you need.
For typical ailerons the following rule of thumb works well.
Torque required (Ncm) = (Rb * Rt * Rt * V * V * Ra) / 2000000
where
Rb = aileron length in cm
Rt = aileron chord in cm
Ra = aileron travel in degrees at V
V = max. speed in m/sec.
It is important to enter realistic values for aileron travel, otherwise the
results will not make much sense.
You should also include an additional safety margin of 1/3 to allow for
friction, play and estimation error, and add even more if in doubt.
However, making this allowance is not an excuse for building inaccurately.
Mitch Mabbutt
Copyright © 2004 Mitch Mabbutt. All rights reserved.
Revised: April 11, 2004