Abstract:

ESDU 79022 gives graphs for the base drag on axisymmetric bodies with at least three diameters of constant diameter section upstream of the boat-tail, at zero incidence, with a turbulent boundary layer and no jet efflux. The graphs were obtained by a correlation of experimental test data drawn from the literature. The data are limited to boat-tail angles of less than 10 degrees and graphs plotting the base drag coefficient, based on body maximum cross-sectional area, against boat-tail diameter ratio and boat-tail angle are given for Mach numbers of 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0. For values of Mach numbers between 1 and 1.5 interpolation with the data at Mach 1 in ESDU 78041 is recommended. At subsonic speeds the base and boat-tail drags are given respectively by ESDU 76033 and ESDU 77020, at transonic speeds by ESDU 78041, and ESDU Aero B.S.02.03.02 gives supersonic boat-tail drag.