Injector

Prometheus’ injector assembly consists of two halves: upper and lower. The upper half is machined out of stainless steel and houses all of the fluid inlets for the propellants. The lower half is machined out of copper and includes the orifices the propellants will be ejected out of. 

The injector uses an unlike doublet design, which involves fuel and oxidizer streams being injected at an angle and mixing at the impingement point. Liquid oxygen flows into the injector’s inner ring at high pressures and is injected into the chamber while ethanol flows into the outer ring, where it some of it is used for boundary layer cooling and the rest is injected.