Radio Control Airplane Prop,s
Radio Control plane propellers are generally 2, 3 or 4 blade. The high rotating speeds do not allow props with blade counts of more than 4 to be efficient enough to be practical.
The rc prop works by rotating a airfoil (blade) through the air causing a difference in pressure between the forward and rear surfaces of the blades creating a vacuum in front of the prop which pulls it forward. The blade rotation is also forcing air from the back of the blade rearward, adding thrust into the mix. For the techies there is lots of info on airfoils and how they work here.
Prop size is measured by diameter and pitch.
Diameter meaning, length of a 2 blade prop or width of circle scribed by the tips in rotation.
Pitch is a number referred to that a prop would move forward per revolution. Example a 6 pitch would move forward 6 inches per revolution.
Pitch can be seen as a gear in a auto. Low pitch number equals low gear, more power less speed. High pitch number the opposite.
RC Propellers are made from a few different materials, wood, and a variety of plastics and composites.
In general, stiffer props are more efficient but easily broken. Plastic composite are more flexible, less efficient but more durable.
Motor manufactures list a selection of props for each of there engines.
It is important to match prop, engine and airframe. Choosing a prop that allows the engine to operate in the power band is the first step.
Narrowing the choice to one that works with the airframe is the final step.
There is a thousand variables in air frames, making it next to impossible to make a chart to reflect them all. Picking the best prop for each plane can only be accomplished by trial.
A prop chart for glow engines can be found here. It is a good starting point for testing.