Use of spike on a hemispherical body changes the ow eld and hence, the aerodynamic drag. Computational studies have been carried out to obtain the ow eld around a hemispherical body with spikes at a hypersonic Mach number of 6. The e ect of shape of spike tip and length has been studied. Laminar computations have been made adopting structured grid using commercial software FLUENT. It is observed that use of a sharp spike itself reduces the drag signi cantly. However, the use of a hemispherical

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... ead spike further reduces the drag. Contribution of di erent components towards drag indicates that the increase in length of a spike does not change the spike contribution. However, the ow eld on main body is altered, which leads to reduction in drag with change in length. The estimated maximum drag is found to be highest among all reported drag values with any spike shape and length in the literature.