Estimate Propeller's Static Thrust Last updated: November 17, 2023 Copyright © 2004 - 2024, rcplanes.online  RPM The recommended prop P/D (Pitch/Diameter) ratio for sport models is 1/2 to 1/1. With a too large pitch, the prop becomes inefficient at low forward speed and high rpm, as when during the take-off and/or climbing. (you may need to hand-launch the plane). Whereas a propeller designed for greatest efficiency at take-off and climbing (with small pitch and large diameter) will accelerate the plane very quickly from standstill, but will give less top speed. The graph below shows Thrust & Drag vs Speed for 3 props with different P/D ratios. The plane reaches max level flight speed when the Thrust becomes equal to Drag. The prop with P/D ratio of 1/2 yields higher thrust at low airspeed, but gives lower top airspeed. Whereas the prop with P/D ratio of 1/1 yields lower thrust at low airspeed, but gives higher top speed. to MAIN PAGE