Hello everyone, A buddy gave me an old top wing plane with a foam semi-symmetrical wing but he extended the wing 2" on each tip. The
extensions however were sanded with a flat bottom profile. It was never flown so
the question is how will it fly? Will the flat bottom ends make it unstable?
It has full length ailerons. What can I expect.

Thanks, Sam D

It won't make any practical difference. The stability of the airplane depends on where the CG is, not on the airfoil used. Generally if the CG on a standard wing is around 30 percent of the wing chord aft of the leading edge the airplane will be stable.

Thanks, I guess I'll get it ready to fly. I was concerned the wing had some built in bad habits. I think the extra 4 inches of wing will make it glide in slower, its a 1/2A racer that originally had a 32" wing, it will fly on
2 channels with a WOT .061 Norvel.

See Ya

Should work fine as long as the thumbs work. I have done much worse and survived:-) at times the airplane didn't though come to think about it. Just kidding.

Report back and send a photo if you can.

The only think you might want to check is to make sure the AOA of the tip sections isn't somehow higher than the rest of the wing. If it is, you have wash-in, which could lead to some interesting stall handling.

Since he starts with a semisymmetrical wing, hopefully it is just sanded flat with the leading edge and TE at the same place. If it was glued on with angle of attack at the tip it would indeed be interesting, not tragic but you would have to watch the airspeed and nose up tendency.

As Montague said, the normal selection of airfoils (if mixed) would have the flat bottom in the center section and some symmetrical outboard to take care of tip stalling.

It would be nice to see a photo of the wing.