Looking for help with placement of aileron servos...

[DavidHyams]

I am building a pair of electric speed 400 DD Herr Eng J-3 Cubs with 48" wing span and I'm planning to add barndoor type ailerons. I am going to use a pair of GWS 9 gram servos to control the aileron surfaces and I'm looking for advice on the location for the servos.

I assume that it is desirable to keep the servos as close to the fuse as possible to prevent tip heavy turns and far enough out on the wing to distribute pressure evenly accross the aileron control surface. The Cubs wing struts connect with the wing about 2/3 distance from the fuse. So my big question, should I place the servos inside or outside the wing struts and why.


Thanks

[Don Sims]

David,
Thank you for the post! I'm moving it to modeling science. My opinion is what difference would it make if you placed them where they are on the end closest to the wing in this case? Possibly a straight connection about one inch from the fuse end of the aileron. There shouldn't be a huge amount of stress on the servo with a speed 400... Just my opinion, we'll see what the pros have to say!
Don

[DavidHyams]

Thanks, I'll look for more followup in assigned category. The idea of keeping weight towards the fuse came from an article on mounting cameras onto wings.

In order to reduce aileron servo loading, I have reduced the size of the ailerons from the actual aircraft design by about 1/3. I like to fly low and slow on three bladed props, not much into aerobatics, just bush hopping, so I desire steady wings in a breeze, not rolls.

I will be installing a single axis gyro inline to the aileron servos to provide automated roll control as well as a gyro on the elevator to control pitch. All this to get smoother videos...

A current Beaver Films video production. Oh yea, my wife strongly suggests that I mention the video was made in conjuction with Foamie Productions( the wife, kids, and pets ).

http://www.anemone.com/RCFlights/Marymoor.wmv

Once again thanks

[DBCherry]

David,
If you're not concerned about rolling the plane as quickly as possible, then it won't matter how far out on the wings you mount the servos.
With one servo out in each wing panel, the plane will still balance laterally. If you were looking for fast rolls, then I'd say keep them close to the fuse. (Besides, a little extra weight out towards the tip should help reduce the tendency to roll in a gust - more inertia for the wind to overcome.)
I'd place them 1/3rd to 1/2 of the way out to minimize induced twist on the aileron surfaces, but I doubt you'd be able to tell the difference when flying slowly and gently.
Just my 2 cents.
Dennis-