Physicists have long known that raindropsat high speedspack a dangerous wallop. But their effect on aircraft remained mainly a theoretical problem until jets started flying at the speed of sound. After passing through rain squalls at a supersonic clip, new jet fighters returned to base peppered with pits and abrasions. U.S. Air Force engineers have now begun to reckon with rain.
Last year Convair's propulsion-engineering laboratory was assigned to test the raindrop effect. On a U.S. Navy firing range outside San Diego, Convair's engineers developed a simple but effective experiment. To approximate supersonic flight, test pellets of aircraft materials (e.g., light metals,...