Flight Determination of Partial-Span-Flap Parasite Drag With Flap Deflection

摘要

Level-flight performance testswere conducted on a typical light general aviation single-engine retractable aircraftnwith partially and fully extended partial-span single-slotted flaps in both gear-up and gear-extended configurations.nA parabolic variation in the aircraft equivalent parasite drag area with flap deflection was observed for bothnconfigurations. A linear relation was discovered between the aircraft equivalent parasite drag area and the square ofnthe flap deflection angle for both configurations. This result suggests that level-flight performance tests in the stowednand fully extended flap configurations will yield adequate data for estimating performance for intermediate flapndeflections. A similar linear relation was confirmed for an NACA 23012 airfoil equipped with a single-slotted flatnusing classical NACA wind-tunnel data. The flight tests showed that the aircraft equivalent parasite drag areanincreased by a factor of 1.16 at 10u0001n, by 1.81 at 20u0001n, and by 3.14 at a full flap deflection of 32u0001nin the gear-upnconfiguration.With the gear extended, the equivalent parasite drag area increased by a factor of 1.14 at 10u0001n, by 1.29nat 20u0001n, and by 1.67 at the 32u0001nfull flap deflection. The results are expected to be typical for similar aircraft.