I added the short inboard flap segment to my Yellow Spitfire. The flaps were driven per Yellow's design, ie, with a servo hidden in each radiator and a visible push rod. If I did it again I would make it internal as on JG's Taylor airplane above. The inboard flaps are slaved to the outboard flaps via a bowden cable which is simply a flexible cable that rides inside fixed sections of tubing mounted to each flap. About the only way to make the radiators removeable would be to secure them around their perimeter with some small, flush headed screws. Good luck with it.