RThe wind blows into my face. When you drive on the highway, you hit the windshield of your car with even more force. At high speeds, raindrops can wear away solid materials, which is a significant concern in the aerospace industry.
For propeller aircraft, rain was primarily a visual problem, but in the jet era, aircraft were susceptible to raindrops, which eroded paint coatings and damaged plastic, ceramic, and even metal parts. For rockets, the problem was even worse. For a spacecraft re-entering the atmosphere at high speed, every droplet is a liquid bullet.
Engineers needed to study the effects of raindrop erosion on the ground before flying new rockets and aircraft. In the 1950s, the Royal Aircraft Institute repurposed a swing-arm rig that had been used to test pilots' resistance to G-forces to study rain erosion.
To achieve faster speeds, the researchers used a compressed gas gun to fire the test article into water droplets suspended in the web. They developed an extreme water gun that fires water droplets at supersonic speeds to simulate flying through the rain at Mach 5.
The most advanced equipment was a rocket sled truck in Sandia, New Mexico, which carried nose cones, radar domes, and other components through simulated storms.
These tests have enabled engineers to fully understand how velocity, droplet size, and exposure time affect rain erosion and are now building accordingly.
