Propping an Engine for Aerobatics

Aerobatics, its all about getting the most power and thrust out of an engine. The thrust and RPM of engine has two main variables, what pitch/diameter of prop, and throttle setting. Obviouslty the second varible is always going to be full throttle to get the most thrust, but what about the prop? This is where people make mistakes and have problem, and get frusterated. People associate more pitch with more thrust witch is all wrong. More pitch gives you more speed and less thrust. Why? The propeller is actually a small, spinning wing, and as air flows over it, it produces lift, or in this case, thrust; and the flatter it is (the less pitch) the more efficient it is at producing thrust. By increasing the pitch, the prop is deflecting air instead of using it to produce thrust. These are sometimes called momentum props. So what do we want for aerobatics? High diameter, low pitch. By increasing the diameter you are allowing more blade area, and since it is like a wing by increasing the area you increase the amount of lift it produces, and since this a prop the thrust it produces.

    For a 46 the best aerobatic prop would be the APC 12.25 x 3.75 or a 12-4. Remember High Diameter Low pitch propellers are what you want to get the most thust, and thrust doesn't equal speed. Now go have some fun!

-By Darrell Nutt