The Conical Shock Wave Formed by a Cone Moving at a High Speed

This paper gives an account of investigations which have been carried out in continuation of word already described by G. I. Taylor and the present writer (1933). In our former paper we developed a method for calculating the air flow and pressure in the neighbourhood of a cone and gave the results of numerical calculations which had been made for cones having semi-vertical angles of 10, 20 and 30°. These calculations were checked by obtaining surface pressure measurements on cones in a high-speed wind channel and by obtaining photographs of conically headed bullets in flight. The results of both experimental investigations were in satisfactory agree­ment with our calculations. In addition the photographs showed that, at speeds for which no mathematical solution was found possible, the shock wave was no longer conical and was detached from the apex of the cone. Part I of the present paper deals with the results of further photographic investigations which were arranged for when our earlier programme was nearing completion. At that time the Research Department, Woolwich, were developing a method of taking photographs of medium-sized projectiles in Flight, and it appeared that such photographs would give a more satisfactory means of checking the calculations than had been possible with the photographs of small bullets. With this object in view the Ordnance Committee requested that photographs should be obtained showing two-pounder projectiles in flight. The results obtained from these new photo­graphs are reviewed below, and a brief description is given also of the experimental methods used at the Research Department.