RE: planning some quick build around 55 AX
The Contender is late Sixties/early Seventies aerodynamics and building technology. If you're not an oldster that built one many years ago and who just wants one out of nostalgia, I'd forget about it. By today's standards the Contender is heavy and its rudder authority is atroscious and lacking force. What little force there is will yaw to the right, but will roll the model to the left when right rudder is given. That sucks. There are no fixes with that model.
It was revolutionary when it came out and taught a lot of us something new about flying and aerodynamics. Today it is just revolting.
Ed Cregger