Starting on a GP Cub 40. Kit looks good, nice wood. I saw some posts about replacing the original aileron bellcrank system with 2 servos. Is this an absolute necessity ? What kind of servo (mini or standard) and placement would you recommend ?

Thanks,

Philippe

no it's not necessary,but I don't use the bellcrank system,it opens the door for flutter,I would use one standard servo for each aileron.

Thanks. Do you install the servos in the middle of each wing, directly aligned with the control horn ?

P.

No. Install them in the same place that the bellcranks would normally go and run extensions to the center of the wing and then a 'Y' connector.

A 40 size plane really doesn't need two servos. If you don't mind doing it that way, go right ahead, but if you want to get by with just one that's fine too. But I also agree to dump the belcrank. I use Nyrod and just route it through the wing. Sheet one area between two ribs for the nyrod to exit.

Minnflyer, looks like a simple set-up. I guess I'll try it since it beats the dual servos weight wise. Any issue with the radius of the nyrod bend ?
Btw, love the Marx quote...

If I were to build my Cub again, I'd put two servos in the wing. Easier to make adjustments that way. Using the bellcrank system makes everything very inaccessible.

Phil69,for that set up I use Gold-N-Rod # 503 because it's flexible.

Phil69: I like dual servos , but the red nyrod works well. Use one of those ball & socket dual take off`s on servo, don`t anchor the push-rod too close to servo,as they have to move up & down some. Back when radios were made in U.S.A., most made a linear take off servo, this would be a good place for one, may-be someday,(big sigh goes here!) GOOD LUCK WITH YOUR CUB. big max 1935

Phil69, Just don't make the radius too tight and you won't have a problem. Add a piece of sheeting between the 2 ribs where the rod will exit about 2" or so and cap strip the rest of the rib.

Minnflyer, I looked at the kit plans and the specs on the Gold-n-rod (2.5 " min radius) and it looks like I will have to curve the rod past the spars, through the shear web, to avoid having too small of a radius, run it ahead of the spars, then bring it back through the spars again, towards the center of the wing, to the center servo.

I just hope it does not stress the wing too much. I guess I'll have to see once it is built.

P.

You shouldn't need to do all that, here's an actual size 2.5" radius. There should be plenty of room for it.

I'm having a similar problem with a min radius bend. Is there a technique for setting the bend in the outer tube? I've been thinking of trying a little heat with rod in. Any suggestions???

mickeylanding,thats how I set mine on a tight bend,then clamp every thing until the braces and epoxy sets up,thing to remember the tighter the bend the more resistance on rod movement

TerellFlyer,
Thanks for response. First project so everything is new. Having a lot of fun with it.

I use CA and accelerator. Then I don't have to clamp anything.