The Effect of Trailing-edge Extension Flaps on Propeller Characteristics

John L. Crigler

sty 1945 · National Advisory Committee for Aeronautics

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Summary: An analysis was made to determine the effect on propeller performance of extension flaps added to the trailing edge of a propeller blade. A method of calculating the changes in the ideal angle of attack, the angle of zero lift, and the design lift coefficient of a propeller blade section having a trailing-edge extension flap was utilized to calculate the performance of a six-blade dual-rotating propeller with extension flaps varying up to 40 percent chord. The method was used to determine the angle that the flap extension must make with the chord in order to obtain a particular load distribution. Although the analysis in this report was made for a wind-tunnel propeller designed to operate at low advance-diameter ration, the method is directly applicable to any propeller section under any operating condition.