I'am getting ready to put 1/8 flap control horns in my new masterpiece . I would like to be able to tweek the later. How should I heat treat them so that I can bend them without risking tearing up the flaps? Bill
One of the most important thing in tweaking flap horns is how they are mounted in the flaps. I always use laminations of plywood epoxied onto the ends of the flaps. This is easiest to do with at least 5/16 thick flaps.
I also don't like 1/4 inch flaps because they flex too much. I do not believe in softening the flap horn material for several reasons...first if you do it it must be done before the horn is brazed onto the wire. Doing it afterwards is impossible without disturbing the brazed joint and weakening it.
When actually tweaking the flaps I always use two pieces of 3/16 in plywood, one of top of the flap and one below (actually two on each flap which makes four pieces total) to hold the flaps. the plywood pieces need only to be about two inches square. Have someone hold the airplane nose down so you can see the edges of the flaps and bend away gently and slowly holding the plywood pieces over the flap horn and the flap.
The plywood mounting pieces in the flap are laminated with three pieces of of 1/8 plywood with the center pieces slotted for the horn wire before assembly. Lamination is done with slow set epoxy.
This system is foolproof. I've used it for many years on a lot of airplanes and never had a failure...
Randy Cuberly