A free-flight investigation of wing-body junction design for a transonic swept-wing aircraft

A method of designing the body of a swept wing-body combination, to obtain favourable wing-body interference at transonic speeds, has been investigated in free flight at zero lift. Models of four different bodies, in combination with identical wings swept back 55 degrees, were flown within the range of Mach numbers between 0·8 and 1·5 at Reynolds numbers, based on wing chord, up to 10 million. The general effectiveness of each body shape was determined by measuring the total drag of each model; the local effects of each design were determined by measuring the pressure distribution in the wing-body junction. The results show that it is possible te design a body which will produce a presribed velocity distribution in the wing-body junction at a transonic design Mach number, but that it is necessary to control the velocity distribution elsewhere on the wing in order to ensure low drag. An adequate estimate of the overall wave drag is given by linear theory, provided that the Mach number is not too close to uni and the flow on the wing remains shock-free.