Low-Speed Tests on 45-deg Swept-back Wings Parts I and II

Abstract

PART I - Pressure Measurements on Wings of Aspect Ratio 5. This report contains the results of pressure measurements on three 45-deg swept-back wings with constant chord and aspect ratio 5, over an incidence range up to 10 deg. Chordwise and spanwise lift distributions are given, mostly near the centre where, on two of the wings, modifications had been made to the section shape. It was found that altering the thickness distribution in the centre did not affect the loading but that approximately straight isobars could be obtained at values of CL below about 0.1. By the incorporation of twist and camber in the central part the distortion of the lift distribution in the centre could be avoided at one particular incidence, and thus the same chordwise distribution obtained over most of the span. Twist and camber alone do not improve the isobar pattern and therefore a thickness modification would be needed to give the desired lift distribution and isobar pattern at one particular incidence. PART II - Balance and Pressure Measurements on Wings of Different Aspect Ratios. This Part contains the results of balance and pressure measurements on constant-chord wings of 45-deg sweepback. Together with wing A of Part I they provide data for aspect ratios 2, 3, 5 and infinity. The results at low CL are analysed and used to verify assumptions made in the calculation method of Refs. 2 and 3. The growth of the boundary layer and its influence on the lift, drag and pitching moment are discussed. The effect of tip vortices on lift and drag is also discussed. The stall is investigated on the wing of aspect ratio 3.