Also, when trying to compare full-scale prop efficiencies to our R/C, the full-scale warbirds that swung a Hamilton Standard, or Curtis Electric for that matter, were equipped with automatically adjustable-pitch props. The Hamilton's being hydraulic and the Curtis' being mostly electric. As the variables on flight changed, such as speed, angle of attack, etc, so did the pitch of the blades to keep the engine in its proper power band. Our little engines have to contend with fixed-pitch props which are a compromise between thrust and speed.

Jesse