Hi Charlie111, I wasn't referring to your prototype.
You're right there's a huge difference between a boat prop in water and a airplane prop in air, but fluids are fluids and the airplane prop drags the air around with it as it's forced backwards just as a boat prop does. The free flight guys used bits sticking out into the propwash to effect trim changes between power on and glide such as wing pylon height, area and fin area above and below the fuse as starters.