Rocket Engines - friznit/Unofficial-BDB-Wiki GitHub Wiki

RL20-P3

Pratt & Whitney's first proposal for a staged combustion cycle design. It was mentioned in at least one Saturn improvement study as a drop in replacement for J2 or the highly-conceptual HG-3 on Saturn II.

XLR-129

XLR-129 is a direct successor to the RL20 and has a similar powerhead where the turbos and pre-burner connect to a central chamber above the combustion chamber. However instead of a Y shape, this uses a triaxial arrangement and adds low pressure pumps/inducers upstream of the main turbos. It was originally meant for the ISINGLASS B52-launched rocket-powered boost glide spy plane and was later proposed for the shuttle programme, though it lost out there to Rocketdyne's RS25. It has a unique dual mode feature which allows it to function either with its nozzle extension retracted or extended for optimal performance at sea level or altitude.

RS-30

Rocketdyne's RS-30 resulted from a study to select an optimum configuration for a 20 klbf hydrolox topping-cycle engine (old terminology for staged combustion). While slightly less powerful than late model RL10 engines, it could serve as a drop in replacement and the extraordinarily high vacuum ISP makes the engine ideal for long duration on orbit applications, such as the IPP space tug.

MB-60

The MARC-60 Mitsubishi Aerojet Rocketdyne Collaboration (aka MB-60 or RS-73) was a proposal for future Delta IV and H2A upgrades and was briefly considered for the SLS EUS. The engine is an expander bleed design with additional boost pumps for high chamber pressure. The bleed exhaust is injected into the nozzle extension for film cooling, which recovers some ISP from the open cycle. The film cooling also allows the use of a simple sheet metal nozzle extension.

E-1

Occupying a middle ground between the H-1 and the F-1 booster engines, the E-1 is a bit of a curious use case. Originally developed for the Titan I first stage (where it would be accompanied by a pair of LR-101 verniers), it was later proposed in a 4-engine cluster for the Saturn I first stage.

M-1

Aerojet's massive M-1 was originally conceived during NASA's early Nova programme, which was setup to study a range of lunar direct ascent rocket designs. After Saturn was selected for the lunar missions, work turned to the post-Apollo era and crewed interplanetary expeditions. Several concepts from this second round of studies (also known as Nova, although largely unrelated to the earlier designs), used an uprated M-1 as a second stage engine as well as a first stage engine replacing the F-1. The engine can be switched between the vacuum model and a sea level optimised version in the editor.