RC Propeller Pitch Speed Calculator

How it works

Loaded rpm = KV × pack volts × (1 − load drop); pitch speed (mph) = pitch (in) × rpm ÷ 1,056; real speed ≈ pitch speed × (1 − slip); tip speed = π × D × rpm ÷ 60; Mach = tip speed ÷ 1,125 ft/s

A propeller is a screw: in one revolution it would advance by its pitch if the air were solid, so pitch times rpm is the theoretical airspeed at which the blades stop producing thrust. Real aircraft fly 15–25% slower than pitch speed because the prop needs some slip to make thrust and the airframe has drag, and motors turn 10–20% below their unloaded KV × volts figure once a prop loads them. Pitch and diameter pull in opposite directions at a fixed motor power: a big low-pitch prop gives static thrust for climbing and hovering, a small high-pitch prop gives speed. Tip speed is the limit — beyond about Mach 0.7 blades become loud and inefficient, so fast setups use smaller diameters and higher rpm rather than ever-larger props.

Worked example

A 1,000 KV motor on 4S (14.8 V) turning a 10×6 prop: about 12,580 rpm under load, giving a 71 mph pitch speed and a realistic top speed near 57 mph; tip speed 549 ft/s (Mach 0.49) is fine. For 60 mph you would want roughly 6.3″ of pitch, or an 11×7 with a lower KV.

Frequently asked questions