Approximate shapes of nonlifting bodies having minimum, pressure foredrag at high supersonic airspeeds are calculated. With the aid of Newton's law of resistance, the investigation is carried out for various combinations of the conditions of given body length, base diameter, surface area, and, volume. In general, it is found, that when body length is fixed, the body has a, blunt nose;whereas, when the length is not fixed, the body has a, sharp nose. The additional effect of curvature of the flow over the surface is investigated to determine its influence on the shapes for minimum drag. The effect is to increase the blunt ness of the shapes in the region of the nose and the curvature in the region downstream, of the nose:These shape modifications have, according to calculation, only a, slight, tendency to reduce drag.nSeveral bodies of revolution of fineness ratios 3 and 5, including the calculated shapes of minimum drag for given length and base diameter and for given base diameter and surface area, were tested at Mach numbers from 2.73 to 6.28. A comparison of theoretical and experimental foredrag coefficients indicates that the calculated minimum-drag bodies are reasonable approximations to the correct shapes. It is verified, for example, that the body for a given length and base diameter has as much as 20 percent less foredrag than a cone of the same fineness ratio.
展开▼
