Quote Originally Posted by MYR View Post
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Anyway, it is sure that аt above 2700/2900 rpm we are compelled to use little diameter propellers, so it is rather difficult to use the available power, because little propellers don't blow a lot of air around the cowlings.
Au contraire. Presumably you weren't being literal about the need for blowing air around the cowl, as that is not a meaningful measure of prop performance. In any case, lots of direct drive engines with high RPM's and smaller dia. props do just fine, like the Jabiru's, which perform well on many different airframes.

Ron