“All-weather” operational requirements have added considerably to aircraft and missile design problems as the effects of various meteorological hazards, predominantly rain, are aggravated by high speed flight. The problem of rain erosion is reviewed with regard to the functional requirements of the components, the flight plan of the vehicle and the occurrence of rain over the geographical terrain of operation. The factors affecting rain erosion characteristics such as type of material, surface finish, shape of component, speed and rainfall intensity are discussed and empirical data derived. The influences on the problem of radar limitation in rain, the probability of rain occurrence and the effect of wind and wind-shear are mentioned. Details given of equipment for the simulation of rain erosion are concerned principally with the R.A.E. “whirling arm” and rocket runway high speed sled techniques. Correlation of test results from these facilities and flight tests are briefly discussed.

Degree of erosion of a material is defined in relation to the particular application of the material and details are given of the characteristics of numerous materials, both metals and non-metals. The utilisation of these materials for such applications as radomes, transparencies, high temperature materials, de-icing systems are briefly discussed together with methods of extending the rain erosion “life” of materials by design or by use of protective coatings.