ANALYSIS OF THE DRAG COMPONENTS OF THE ANGLED ARROW PROJECTILE

Numerical results have been obtained for a range of Mach numbers between 1.5 and 4.5, and comparisons made with experimental data. The estimated results are in good agreement with experimental data, but similar studies on other missiles will have to be made before it can be ascertained that the method of analysis is fully reliable. Of the drag components for the bare body, the contribution of the base pressure seems to be subject to the greatest uncertainty. In the case of wind-tunnel tests, the importance of the wave drag increases rapidly with the Mach number and contributes close to one-half of the total drag coefficient at M = 4.5. The behaviour of the base pressure drag is complicated by a strong Reynolds number effect, but its contribution drops rapidly at high Mach numbers. As the Mach number increases, the nature of the boundary layer around the missile changes from turbulent to laminar, with a corresponding drop of the skin friction coefficient, but once the boundary layer has stabilized, the contribution of the skin friction increases with the Mach number. In the case of the finned body, the base pressure drag is again a very important factor, presently intractable analytically, and for which very few experimental data are available. The increase in drag due to the presence of the fins is considerable, varying from 50 to 70 percent of the bare body drag within the Mach number range considered (1.86 to 4.50).