IR Materials Rain Damage Prediction And Tests Results

A comparison between G.S. Springer's theory, that predicts rain optical and rain mass degradations for different kinds of infrared materials, and the experimental results obtained by ONERA on the SAAB rain rotating arm on IR homogeneous samples is presented. The agreement between theory and experiment is rather poor. A very simple correlation between optical degradation and V, C, p (respectively : droplet impact velocity, longitudinal wave velocity and density of infrared materials) is proposed, which is in good agreement with all data obtained in the range of 200 to 300 m/s for the 9 tested materials.