Uncontrolled Roll on Full Flaps

[TY2068]

Does the plane have a slight tendency at all to roll left in straight and level flight with no flaperon set ?

[avidflyer]

When setting the flaperons, it is helpful to clamp a stick on each flaperon bottom the same distance out from the fuselage. Have the end of each stick project back the same distance from the flaperons. 18" - 24" is fine. With the aircraft level side to side, and the joy stick centered, ends of both sticks should be at the same height. You should also have the same amount of travel up and down at the ends of each stick when the joy stick is all the way to the right, and all the way to the left. The nice thing about using the sticks is it magnifies the differences between the two sides, and gives you something to measure to. JImChuk

[ppilotmike]

On flutter, have you removed the flaperons and verified that the "mass balance" weights truly balance the flaperons. I would suspect the uncontrolled roll is due to a rigging problem, Jims post is a good way to check that.

[kitfoxjim]

As I recall many years ago, when I did the rigging on my Model 2 (90-91) there was a possibility that one of the aileron push rods could go over centre if the flap handle was not limited in travel. Went back to look at the manual rigging instructions but that section is now missing.
I would suggest looking at the aileron mixer assembly while deploying full flaps as there may be this over centre condition.
The aileron push rod could be too short but the best cure would be to limit flap handle travel.
Jim

[Guy Buchanan]

Two possibilities for uncontrolled role. Miss-rigging, which you seem to have eliminated, and un-symmetric stall. It's possible that one of your flaperons is stalling. It's also slightly possible you're getting a partial stall on one wing, though I'm not really seeing how that would happen. As for the stalled flaperon, the most likely culprit would be a bad airfoil, possibly a kink or other hard edge on the top of the leading edge somewhere. It wouldn't have to be the entire flaperon. I can't remember if the 3 flaperons were symmetric but if they weren't you'd want to check to make sure they weren't installed upside down.

[avidflyer]

The Kitfox 1 to 3 model flaperons all have flat bottoms. Also, it would be pretty near impossible to install them up side down. JImChuk

[HighWing]

I am likely revealing my age, but back in the really olden days when these puppies were being actively built, it was common practice to put an Adel Clamp on the sloping tubing next to the flap handle that limits the flap function of the flaperons to 20 degrees only. I don't remember if the uncontrolled roll was the gremlin, but I did it on my first IV and the one I fly now. Never an issue.