LOW-SPEED CHARACTERISTICS OF A 45° SWEPTBACK WING OF ASPECT RATIO 8 FROM PRESSURE DISTRIBUTIONS AND FORCE TESTS AT REYNOLDS NUMBERS FROM 1,500,000 TO 4,800,000

摘要

Results are presented of an investigation in the Langley 19-foot pressure tunnel of the longitudinal characteristics of a wing having 45° sweepback of the quarter-chord line, an aspect ratio of 8, a taper ratio of 0.4-5, and NACA 631A012 airfoil sections parallel to the plane of symmetry. The results were obtained from force measurements through a Reynolds number range from 1,500,000 to 4,800,000 and pressure-distribution measurements at Reynolds numbers of 1,500,000 and 4,000,000. The effects of fences and leading-edge roughness on the characteristics of the wing were investigated by means of force and pressure-distribution measurements at a Reynolds number of 4,000,000.nThe results of the investigation indicated that the wing pitching-moment variations were caused by section-lift variations cm the outboard portions of the wing and not by section pitching-moment variations. The wing pitching-moment curve changed from a stable slope at zero lift to an unstable slope at fairly low lift coefficients and became progres¬sively more unstable as maximum lift was approached. The changes in pitching-moment-curve slope were due to separation on the outboard section which first caused a reduction in section-lift-curve slope and finally caused a loss in section lift. The section pitching-moment variations became more stable as the wing maximum lift was approached.