Natural laminar flow experiments on modern airplane surfaces

摘要: Flight and wind-tunnel natural laminar flow experiments have been conducted on various lifting nonlifting surfaces of several airplanes at unit Reynolds numbers between 0.63 x 10 to the 6th power/ft 3.08 power/ft, Mach from 0.1 0.7, surface leading-edge sweep angles 0 deg 63 deg. The tested were selected provide relatively stiff skin conditions, free significant roughness waviness, smooth modern production-type airframes. observed transition locations typically occurred downstream measured or calculated pressure peak for test conditions involved. No discernible effects due waviness any tested. None heights exceeded empirically predicted allowable waviness. Experimental results consistent with spanwise contamination criteria observed. Large changes in flight-measured performance stability control resulted loss by forced transition. Rain boundary layer caused stick-fixed nose-down pitch-trim two effect was flight through low-altitude liquid-phase clouds. These observations indicate importance fixed-transition tests as a standard testing procedure