Merlin | 1г—1

: The initial version used an expendable ablatively cooled carbon-fiber nozzle. It flew only twice on the Falcon 1 (2006–2007).

: An upgraded variant of the 1A with a more powerful turbine; it was never used on a flight vehicle before SpaceX shifted to regenerative cooling. Merlin 1Г—1

: The first to feature a regeneratively cooled nozzle and combustion chamber. It powered the first privately developed rocket to reach orbit (Falcon 1 Flight 4) and early Falcon 9 flights. : The initial version used an expendable ablatively

: Based on the Apollo Lunar Module landing engine, this provides excellent stability and allows for deep throttling. Merlin 1Г—1