ORIGINAL: ptmac3
ORIGINAL: da Rock
In any case, you want the lever arm of the servo to be shorter than the lever arm of the surface. If you can. And the above starting point helps insure that result.
Why?
Why?
You're working with levers at both ends of the connecting rod.
If they're the same length, there is no multiplication of load seen by the servo. Whatever load hits the flying surface, that's the load the servo will see. And we size the servos to the model, so they're guaranteed strong enough for that load. So we give the servo the chance to do the job. And it won't take excess battery doing it. Nor will it be "blown back" or fail to give full deflection in a dive when you ask for full deflection. Those problems are silent killers that we might encounter if the surface is rigged to have more leverage than the servo.
There is an excellent chart that was published in a recent issue of one of our RC magazines. It shows the relationships and the gains/losses from different lever arms. I gotta find out which magazine and give credit because it's due.
This chart is from
MODEL AIRPLANE NEWS
July 2007 issue
"Maximum Control, Inflight Servo Tests"
Beginners should find that magazine and buy it. The article should be part of
Learning to Fly RC 101.