The Effect of a Rear-Mounted Disc on the Drag of a Blunt-Based Body of Revolution

Abstract

Summary Experiments have shown that the drag of a body of revolution with a blunt base can be substantially reduced by mounting behind the body a disc of rather smaller diameter than the body. With a single disc the base drag was reduced by about 35 per cent and with two discs a reduction of 55 per cent was obtained. When the cavity between the body and the best single disc was filled in to form a solid boat-tailed afterbody there was an even greater reduction of drag. A single disc mounted nearer to the body than the position giving low drag gave a large increase of drag with severely unsteady flow. The nature of the flow in both the low-drag and high-drag régimes is discussed.