Before revision: As early as the 1940s, drop tests were conducted by lifting a carrier-based plane such as the Grumman F6F Hellcat to a height of ten feet and then dropped, simulating the impact of a landing at nineteen feet per second .
After revision: As early as the 1940s, drop tests were conducted by lifting a carrier-based plane such as the Grumman F6F Hellcat to a height of ten feet and then dropped, simulating the impact of a landing at .