Wind Tunnel Experiments of the Effect of Near-Wake Combustion on the Base Drag of Supersonic Projectiles

A series of fumers based on magnesiumstrontium peroxide was tested at the Naval Surface Weapon Centers Hypersonic Tunnel to see the effect of varying the parameters that control the rate of combustion of pyrotechnics. The parameters that were varied included spin rate, fuel content, fuel particle size, the oxidizer, and the addition of burning rate additivies calcium resinate, polyvinylchloride, oxamide, and gelatin. The base drag reductions measured for all the mixes could be approximately correlated by a single expression relating base drag reduction to the mass burning rate of the fumer mix. The base drag reduction estimated for propellant combustion gases is similar to the base drag reductions achieved with pyrotechnics. This raises the possibility of invisible fumer mixes.