The .72 would just fly the WM Chipmunk. I have both, a WM Chipmunk and a older Goldberg Chipmunk. Identical in dimensions, the Goldberg OS .90 four stroke and the WM has an OS .90 two stroke. I do not retract the gear on the WM, I like the more scale looks of wheel pants (besides, Art Scholl's retractable Chipmunk used Bellanca Viking gear which retracted aft). They both fly great, certainly not 3D, but will snap and tumble well. Good luck, you will like the way it flies.

3D Flight