Some observations of the flow over a delta-winged model with 55-deg leading-edge sweep, at Mach numbers between 0.4 and 1.8

Abstract

A delta-winged model, with 54.8-deg leading-edge sweep and a 6 per cent thick RAE 101 section, has been tested in the Royal Aeronautical Establishment (Bedford) 3-ft Wind Tunnel. The results of lift and pitching moment measurements at Mach numbers from 0.70 to 1.02 and from 1.42 to 1.82 are presented and discussed with the aid of surface oil-flow observations. The Reynolds number of the tests was between 2.2 and 3.3 x 10power6. At Mach numbers up to at least 1.07 a leading-edge-separation vortex sheet formed on the wing at incidence. An interaction between the vortex sheet and the wing upper-surface shock wave at Mach numbers just below 1.0 caused unsteadiness of the forces on the model and a pitch-up. At Mach numbers from 1.42 to 1.82 the flow was attached at the leading edge, and an oblique shock lay across the upper surface of the wing.