Your top speed example is actually a little low. The OS 40/46 LA, or TT 42 GP powered trainers typically hang around at ~50 mph, but good BB 46 powered trainers usually hit closer to 70 mph in level flight with an 11-5 or 11-6 prop (an 11-7 is just a little too much for best power from a healthy 46). Even a large trainer can get close to 70 mph --- a Nexstar, for example, with brakes & droops removed, hits very close to 70 mph with an 11-5. prop. My Superstar hot rod with full span (unclipped) wings & a TT 46 Pro, has been measured @ 75 mph in level flight with an 11-6 prop.