I built a carbon fiber tail spring for my KR-2 back in 1985 or so. It weighed about 1/4 what the steel part weighed. It was 26 layers of bi-directional cloth, with epoxy resin, layed up over a two-by-four cut with a bandsaw to the desired bend. ( I put an "s" bend in the tailspring to raise the nose slightly, and provide more tailspring to rudder clearance)
The only flaw in the final product, was that the TGT, or transition glass temperature was low (room temp), as I did not heat cure it. When I set the airframe outside in the sun, that nice black carbon fibre part heated up, and since the tailwheel was sitting sideways for a few hours, it took a permanent set, twisted that is.... It seemed to have the right "springiness" that I wanted, but it was never flown, so durability and reliability is up to you. Bill Zorc KR-2S project started in 1974....
