ESDU 00028 presents a graphical method for estimating the pressure and Mach number distributions on boat-tails with length/maximum diameter ratio up to 5 at zero angle of attack for Mach numbers from 1.5 to 4. The graphs, each for a value of Mach number (1.5, 2, 3 or 4), present theoretical results obtained using the method of characteristics. For conical boat-tails, pressure coefficient and Mach number are plotted against non-dimensional distance along the body for boat-tail angles of 2, 4, 6, 8 and 10 degrees. For circular-arc boat-tails they are plotted against non-dimensional distance along the body for various values of the ratio of the arc radius to body cross section maximum radius. The graphs for circular-arc boat-tails also apply to parabolic-arc boat-tails and for both types the boat-tail angle is defined as the local angle at the boat-tail/base junction. Equations and graphs for the boat-tail angle in terms of the boat-tail dimensions are provided for both conical and circular-arc bodies, and for the latter case an equation and graph gives the ratio of the arc radius to body cross section maximum radius in terms of the other dimensions. The effect of boundary layer on the use of the results is discussed. The method applies when there is a jet efflux, provided the base pressure is below that at the end of the boat-tail; conditions for that to occur may be predicted using ESDU 00017 for the case of conical boat-tails. A worked example illustrates the use of the method. For boat-tails with length/maximum diameter ratio greater than 5 data are presented in ESDU Aero B.S.05.03.01.