The RL10E-1 is a modern version of the RL-10 family of rocket engines, the first of which flew in 1962 as the RL10A-1. The latest varient features a 3D-printed copper thrust chamber, reducing the number of parts in that area by 98%. The engine uses liquid oxygen and liquid hydrogen and has a specific impulse of 460.9s, and 24,120 lbf in a vacuum. Two of these engines are used in the upper stage of ULA's Vulcan rocket. The engines are produced by L3Harris (Aerojet Rocketdyne)
