A STUDY OF SEVERAL FACTORS AFFECTING THE STABILITY CONTRIBUTED BY A HORIZONTAL TAIL AT VARIOUS VERTICAL POSITIONS ON A SWEPTBACK-WING AIRPLANE MODEL

摘要

A study was made In the Langley 19-foot pressure tunnel to determine the effects of fuselage afterbody shape, split flaps, and variations in the span of the leading—edge flaps on the stability contributed by the horizontal tail to an airplane with the wing leading edge swept back 42. Supplementary tests were made to determine some of the characteristics of the air flow in the vicinity of the tail, the wing being equipped with 0.575—span leading—edge flaps and 0.5—span split flaps. All data were obtained at a Reynolds number of 6.8 x 106.nAn analysis of the air—flow surveys in the vicinity of the horizontal tail indicates that, at high angles of attack, the variation of downwash with angle of attack over the outer part of the tail span is such that the tail contribution to the pitching moment is stabilizing for the position below the extended wing—chord plane and destabilizing for the positions above the extended wing—chord plane. The air—flow surveys indicate that 20° negative dihedral would eliminate the destabilizing Influence of the tail located at 16 percent of the wing semi span above the extended wing-chord plane by placing the tail in a region of favorable downwash throughout the angle-of-attack range.