hi
would shorting the ailerons help with the roll rate and inlargering the rudder by 1/4 to 1/2 help in knife egdes,any other ideas would be great its a enlarge chipmunk 80" wing with a 35 dle thanks

If by helping you mean to slow the roll rate down, perhaps. Shorter as in end to end or shorter front to back? Either way, wouldn't a shorter span move less air? Just my thoughts.

shorter in lenght ,thanks

Shorter ailerons would probably reduce the roll rate. Increasing rudder area should help knife edge ability but there are other factors involved here. Fuselage shape and area distribution can affect knife edge ability as much as rudder area. Within reason, increasing rudder area will increase its efficiency meaning you get the same effect with less throw and less drag. Be sure you have adequate servo torque available on all surfaces.