ESDU 96012 provides an empirical graphical method derived from a correlation of wind-tunnel data for the prediction separately of boat-tail and base pressure drag that applies at all Mach numbers up to 1.3. The method requires that there are at least three diameters of cylindrical body upstream of the boat-tail and that there is no jet efflux or base bleed. The method for base pressure drag applies for boat-tail angles (the angle made with the base) up to 45 degrees but for boat-tail drag only for boat-tail angles up to 25 degrees for subsonic Mach numbers@ 30 degrees for a Mach number of 1 and 35 degrees for supersonic Mach numbers. The method may also be used for afterbodies of parabolic profile. The total afterbody drag is the sum of the two components. The quality of fit with the experimental data is illustrated; total drag coefficient based on body maximum diameter is estimated to within 0.015. However@ because of the limited sample of data@ it is suggested that an accuracy of 0.03 should be allowed for. A worked example illustrates the use of the method.
ESDU 96012 A-2005 history
2005ESDU 96012 A-2005 Subsonic and transonic base and boat-tail pressure drag of cylindrical bodies with circular-arc boat-tails.