Fin Gaps and Body Slots of Guided Projectiles: Effects, Data Correlation and Modeling

All prior work concerned with the effect of streamwise fin-body gaps unporting effect and body slots on the fin loads of missiles and projectiles in the transonic speed regime of 0.8 or M or 1.2, has been surveyed and analyzed. All known experimental data for the gap effects have been analyzed. A correlation relation was established to predict fin normal force losses due to gaps for any fin shape, size, aspect ratio, very well with the data which span a large variation in Reynolds number, body diameter and boundary layer thickness. Although the Mach range for present model was intended to be 0.8 or M or 1.2, available data indicated its validity in the wider range of 0.7 or M or 1.6. Fifteen cases were used to validate the present gap model. The slot effect model used is that of Washington et al. Application of these two corrections to the Copperhead guided projectile was made and a reduction as large as 38 was predicted for the normal force, which was then validated by the experimental data. The present results can be used for estimating fin load losses for the fin design of guided projectiles and missiles, with accuracy of 5, over the intended Mach number range 0.8 or M or 1.2.