RCV model engine from UK employs the idea, albeit it is a not a 100% conventional engine. If you look at the picture, you will see that the propeller is fastened on the rotating cylinder valve, which of course rotates at half the speed of the crankshaft, because we are having a 4-stroke engine.
Indeed, the RCV60-SP, which is .60 cu. in. can swing 14x14, 15x12, 16x12 2-bladed props, which are sizes of .80 and up for conventional engines!