This engine used a pintle injector first invented by Gerard W. Elverum Jr.[1][2][3] and developed by TRW in the late 1950s and received US Patent in 1972.
[5] The thrust chamber was initially developed for the Apollo Lunar Module and was subsequently adopted for the Delta expendable launch vehicle 2nd stage.
Multi-start operation is adjustable up to 55.6 kN and propellant throughput up to 7,711 kg; and the engine can be adapted to optional expansion ratio nozzles.
The shape of the nozzle extension is such that the ablative liner is retained in the exit cone during transportation, launch and boost.
The titanium head end assembly which contains the Pintle Injector and propellant valve subcomponents is attached with 36 A-286 steel 1⁄4 inch (6.4 mm) bolts.