How to Choose the Right Prop for My RC Airplane

Nitro and gas engines

• 1

  Refer to the engine manufacturer's recommendations. Nitro and gas engines have been designed to use a specific range of props. Going outside of this range can damage the engine by increasing loads (with a larger prop) or exceeding the acceptable RPM range (smaller prop).

• 2

  Decide if your plane needs more thrust or more speed. 3-D planes need a lot of thrust but not a lot of speed to perform well. These planes benefit from a prop with a larger diameter and smaller degree of twist. War birds like speed, and they do better with a smaller prop with a larger degree of twist.

• 3

  Select a multi-bladed prop if your plane is a scale representation of a real plane. Some RC airplanes are never meant to be flown; they are built and entered into static display competitions. The airplane needs to be historically correct. If the real airplane flew with a four-blade prop, then your model needs to have one, too, or the judges will deduct points from your plane's overall score.

Electric motors

• 4

  Select a prop that will not exceed the motor's capacity. If your motor is rated to 10 amperes and draws 9.5 amperes with an 8 x 6 prop, that's OK. However, if the amperage draw exceeds the motor's rating, then you will damage or destroy the motor.

• 5

  Select a "slow-fly" prop for trainers and mild sport planes. The "slow-fly" props have a larger blade profile; they turn slower but move more air. Speed props have a small blade profile and turn much faster; these work well on planes that crave speed.

• 6

  If your plane has landing gear, then measure the distance between the ground and the motor's spindle. This clearance gives you a frame of reference. Your prop should always have at least one inch of ground clearance; otherwise, you risk breaking the prop on a rough landing. If you need more clearance, try installing larger wheels on the landing gear.