Ollie and Bank to Turn. You are right up to a point. I'm not arguing with the basics of the drag to thrust balance. That's a given.

But the prop can only spin so fast and the pitch can only do so much.

The current world speed record is 215 mph. I seem to recall the latest ducted fan fun fly models doing speed passes close to that speed or even faster. Certainly they exceed that speed by a good factor in a dive. I seem to recall seeing reports of 240 mph speeds from ducted fan scale jet models. Without getting into a lot of research I will suggest that these models can do this argely because they don't have a prop to slow them down.

A few years back the world speed record was held by a glider because it didn't have the props of the day to slow it down.

Obviously a clean airframe is all part of the equation but to ignore the aerodynamics and efficiencies of the prop is to only look at half the picture.

None of this takes away from the interesting discussion in this thread though. There's lots of good info here. But it just seemed to me that Dusteater is looking for a "quick" speed fix without doing the homework first. So I offered a suitable option along with reminding you folks about one of the main speed limiting factors in any propellor driven airplane.