What is propeller cupping?
When the trailing edge of the blade is formed or cast with an edge curl it is said to have a cup. Cupped props will usually allow a faster top speed and more midrange efficiency by allowing more positive trim with less prop slip. Cupping benefits are so desirable that nearly all modern recreational, high-performance or racing propellers contain some degree of cup. Cupping will usually reduce full-throttle engine speed about 100 to 200 RPM below the same pitch propeller with no cup. A propeller repair shop can increase or decrease cup to alter engine rpm to meet specific operating requirements on most propellers.
