You can experiment with large fine pitch props, but then you run into other problems. Such as forward speed, engine cooling, torque and and other issues.
If we could have turned scale props on our models someone would have done so already. The closest that anyone has gotten was Byron's Purr Power system that he developed for his line of warbirds. Funny name for it as the engine was really cranking in order to produce the thrust. And it provided just enough thrust if you didn't go overboard with the model wieght. There were other prop drive systems (i.e. reduction gear or belt drive) tried and developed during the eighties. Most have been forgotten due to the improvement in engines. As well as other trends. Plus they where heavy as well.
Remember our models don't fly in scale air. [&:]