Why RC Prop Choice Matters
An RC airplane propeller is a small wing that spins. It turns motor power into air movement. Diameter controls the disk area. Pitch controls how far the prop may move in one turn. RPM controls how fast both actions happen. A balanced setup gives useful thrust without overloading the motor.
Physics Behind the Estimate
This calculator uses common propeller relations. It converts inches to meters. It finds pitch speed, tip speed, disk area, torque, and an ideal static thrust value. The thrust model uses momentum theory. It assumes useful prop power equals input power multiplied by prop efficiency. Real thrust can change with blade shape, airframe blockage, altitude, and testing method.
How Builders Can Use It
Use the tool before changing prop size. Try one value at a time. A larger diameter usually increases static thrust. It can also raise current draw. A higher pitch usually increases possible speed. It can reduce climb if the motor cannot hold RPM. Check the Mach value. Keep prop tips below safe limits. Many model pilots avoid very high tip Mach numbers because noise, stress, and efficiency losses rise quickly.
Reading the Results
Thrust-to-weight ratio helps judge launch and climb. Around 0.5 may suit calm sport flying. Around 1.0 can give strong vertical performance on light models. Pitch speed shows an upper speed idea, not guaranteed flight speed. Efficiency, drag, and prop slip reduce it. Torque helps compare motor loading. The chart compares major outputs, so setup changes are easier to see.
Safety and Practical Testing
Always verify estimates with a wattmeter, tachometer, and secure stand. Stay behind the propeller arc. Inspect blades before each run. Stop testing if vibration appears. Use the CSV and PDF exports to save each setup. Compare saved records after field tests. Then choose the prop that gives the best balance of thrust, speed, temperature, and flight time.
Treat the numbers as a planning guide, not a final approval. Bench results matter more. Battery sag can lower RPM. Hot motors waste power. A worn prop can lose lift. Repeat checks after any crash, nose over, or rough landing during real field use.