to their lower cost, typically have less displacement than purpose-built light aircraft engines and develop peak power at high revolutions per minute (rpm), typically above 4,000 rpm. Traditional aircraft engines, where the propeller is most commonly fastened directly to the engine crankshaft, develop peak power near the peak safe and efficient speed for the propeller—2,500 to 3,000 rpm. This speed is considered the typical maximum rpm for a single-engine aircraft propeller due to the need to keep the propeller tip speed below the speed of sound. Factory-certified aircraft engines have also used reduction units integral to their design. The Cessna 175 used a geared unit which is part of the Continental GO-300 engine while the Helio Courier and several Beechcraft twins, among others, used the geared Lycoming GO-435 and GO-480. Many light sport aircraft use engines from Rotax such as the Rotax 912 which incorporates a geared reducer. See also Ultralight References Notes Bibliography Flight No. 1935, Volume XLIX, 24 January 1946. Gunston, Bill. Development of Piston Aero Engines. Cambridge, England. Patrick Stephens Limited, 2006. Guttery, T.E. The Shuttleworth Collection. London: Wm. Carling & Co, 1969. Propellers Mechanisms (engineering)