The wind forcefully hits your face and car windscreen while driving on a motorway. This can cause damage to solid materials at high speeds, posing a significant issue in the aerospace industry.
In the past, rain was primarily a visibility issue for propeller aircraft. However, with the advancement of jet technology, raindrops can now cause damage to paint coatings, plastic, ceramic, and metal parts. This issue is even more severe for rockets, as every raindrop can act as a liquid projectile when a spacecraft re-enters the atmosphere at high speeds.
Scientists were required to investigate the impact of raindrop erosion on the surface prior to launching fresh rockets or planes. During the 1950s, the Royal Aircraft Establishment adapted their whirling arm device, originally designed to measure pilots’ endurance against G-forces, for conducting rain erosion research.
To simulate high speeds, scientists utilized compressed gas guns to launch test objects into water droplets held in webs. They designed advanced water guns capable of shooting droplets at supersonic velocities, mimicking the experience of flying through rain at mach 5.
The top-of-the-line equipment was a track for rocket sleds located in Sandia, New Mexico. This track was used to transport nosecones, radar domes, and other components through simulated rainstorms.
These experiments provided engineers with a comprehensive comprehension of the impact of speed, droplet size, and exposure time on rain erosion, allowing them to construct accordingly.