Flow Visualisation, Pressure Measurements and Numerical Calculations on Spike-Tipped Bodies

The requirements imposed by EADS Deutschland GmbH for the design of a new high velocity missile V/SHORADS (Very/Short Range Air Defence System) are the reduction of drag and to obtain reliable information from the opto-electronic embedded sensors at even high angles of attack. The aim of our investigation is to find new spike geometries and to optimise these to reach high angles of attack without losing the drag reduction effect well-known for small angles of attack. Flow visualisation pictures taken with differential interferometry are shown. A classical disk spike geometry is compared with a new spherical spike and the advantages of the latter are discussed. For equal diameters and lengths the disk spike proves to be more efficient below 8° whereas the sphere spike is more efficient beyond this angle of attack. Pressure measurements are presented and compared to the numerical calculations.