Rain Impact Damage to Supersonic Radomes

The research described has been directed toward a better understanding of raindrop damage to vehicles traveling at very high velocities with emphasis upon the erosion of ceramic-type radomes. An accelerator capable of impacting targets with short water jets at speeds up to Mach 5 is described. The validity of using high-speed liquid jets to simulate raindrop impact is demonstrated. Topics covered include: drop energy-crater volume relations; oblique and multiple impacts; erosion rates; internal fracturing and spallation caused by stress waves; radome coatings; information from rocket sled tests; a theoretical analysis of the cratering process; motion of raindrops in the supersonic shock layer; probability modeling of erosion; and spatial and temporal variations of pressure exerted on the target surface by liquid impacts.