• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

FT Simple Cub Aileron Differential

#1
Does anyone have an idea of how much differential is required with the cubs wing design? I know this plane will have some serious adverse yaw with ailerons just by looking at the design. Do most people just leave the dihedral out of the 4-channel version? I just ordered one for a nice slow flyer. Thanks
 

Merv

Legendary member
#2
My buddy flys his Simple Cub without any differential, he needs a little rudder at times to overcome the adverse yaw. He has talked about adding a little differential but so far he has none. My guess, not very much.

I’ve got a scratch built Cub, no dihedral & no adverse yaw. My Cub is about the size of the Storch.
 
#3
My buddy flys his Simple Cub without any differential, he needs a little rudder at times to overcome the adverse yaw. He has talked about adding a little differential but so far he has none. My guess, not very much.

I’ve got a scratch built Cub, no dihedral & no adverse yaw. My Cub is about the size of the Storch.

I was thinking of making the wing level myself just to counteract the yaw tendency. High wings don’t need much stabilization as it is. Adverse yaw can definitely ruin the planes ability to turn at all with ailerons.
 
#6
This is what I was thinking as well. I do a lot of scratch building/designing and no these old school style planes have old school aerodynamic tendencies. When I get it together, I'll do some experimenting and see what settings work best.
 
#7
When I flew the 4-channel version with the 'standard' dihedral of the 3-channel wing, I found that doing an aileron/rudder mix overcame the adverse yaw well. Without the mix, the adverse yaw was quite extreme. I'd turn one way with the ailerons, and find myself heading off in an entirely different direction than intended.
 
#8
When I flew the 4-channel version with the 'standard' dihedral of the 3-channel wing, I found that doing an aileron/rudder mix overcame the adverse yaw well. Without the mix, the adverse yaw was quite extreme. I'd turn one way with the ailerons, and find myself heading off in an entirely different direction than intended.
Yep that is definitely a side effect of bad adverse yaw! dihedral increases the effect for sure. Thanks for the feedback
 

Merv

Legendary member
#9
There are several ways to fix adverse yaw. Yon can program a aileron to rudder mix. You can program the down the aileron to go down less than up up aileron goes up. The old school way before computer radios, move the servo horn by 1-2 splines. Instead of the horn being 90 degrees at neutral it will be off slightly either for or aft. Forward if the servos are installed in the bottom of the wing & aft if they are installed in the top,of the wing. You will need to adjust your pushrods and trim according.

Your servo horns installed incorrectly, aft when they should be for, will cause the down aileron go down more than the up goes up. It’s the extra drag from the down aileron, fighting against the turn, that is cause of the adverse yaw not the dihedral. You always want the extra drag to be on the up aileron to help pull you around a turn.