EXPERIMENTAL STUDIES INTO HAIL IMPACT CHARACTERISTICS

A program of work to develop an understanding of hailstone impact char acteristics is described and the progress to date is presented. Patter nators and high-speed photography have been used to investigate impact characteristics on a flat plate and a spinner from a turbofan aeroeng ine. Results have shown that the approach angle of the hailstones, rel ative to the impact surface, has a significant effect on the distribut ion of ice following impact. Approach velocity of the hailstones, targ et temperature, and spinner rotation have no significant effect on the distribution. Studies into successive impacts on two adjacent surface s have shown that the angle between the two surfaces is important in d etermining the distribution of ice.