SpaceX Merlin

Merlin 1D
	Test firing of the Merlin 1D at SpaceX’s McGregor test stand
Country of origin	United States
Manufacturer	SpaceX
Application	Booster stage engine; Upper stage engine;
Associated LV	Falcon 1 · Falcon 9 · Falcon Heavy
Status	Active
Liquid-fuel engine
Propellant	LOX / RP-1
Cycle	Gas-generator
Performance
Thrust, vacuum	981 kN (221,000 lbf)
Thrust, sea-level	845 kN (190,000 lbf)
Thrust-to-weight ratio	184
Chamber pressure	9.7 MPa (1,410 psi)
Specific impulse, vacuum	311 s (3.05 km/s) [needs update]
Specific impulse, sea-level	282 s (2.77 km/s) [needs update]
Dimensions
Diameter	Sea level: 0.92 m (3.0 ft); Vacuum: 3.3 m (11 ft)
Dry mass	470 kg (1,030 lb)

Merlin is a family of rocket engines developed by SpaceX. They are currently a part of the Falcon 9 and Falcon Heavy launch vehicles, and were formerly used on the Falcon 1. Merlin engines use RP-1 and liquid oxygen as rocket propellants in a gas-generator power cycle. The Merlin engine was originally designed for sea recovery and reuse, but since 2016 the entire Falcon 9 booster is recovered for reuse by landing vertically on a landing pad using one of its nine Merlin engines.

The injector at the heart of Merlin is of the pintle type that was first used in the Apollo Lunar Module landing engine (LMDE). Propellants are fed by a single-shaft, dual-impeller turbopump. The turbopump also provides high-pressure fluid for the hydraulic actuators, which then recycles into the low-pressure inlet. This eliminates the need for a separate hydraulic drive system and means that thrust vectoring control failure by running out of hydraulic fluid is not possible.

^ ^a ^b "Falcon User's Guide" (PDF). SpaceX. April 2020. Archived (PDF) from the original on December 2, 2020. Retrieved August 1, 2020.
^ Cite error: The named reference awst20110811 was invoked but never defined (see the help page).
^ ^a ^b "Merlin section of Falcon 9 page". SpaceX. Archived from the original on July 15, 2013. Retrieved October 16, 2012.{{cite web}}: CS1 maint: unfit URL (link)
^ Mueller, Thomas (June 8, 2015). "Is SpaceX's Merlin 1D's thrust-to-weight ratio of 150+ believable?". Retrieved July 9, 2015. The Merlin 1D weighs 1030 pounds, including the hydraulic steering (TVC) actuators. It makes 162,500 pounds of thrust in vacuum. that is nearly 158 thrust/weight. The new full thrust variant weighs the same and makes about 185,500 lbs force in vacuum.

[falconguide202004-1] "Falcon User's Guide" (PDF). SpaceX. April 2020. Archived (PDF) from the original on December 2, 2020. Retrieved August 1, 2020.

[awst20110811-2] Cite error: The named reference awst20110811 was invoked but never defined (see the help page).

[spacexfalcon9Merlinpage-3] "Merlin section of Falcon 9 page". SpaceX. Archived from the original on July 15, 2013. Retrieved October 16, 2012.{{cite web}}: CS1 maint: unfit URL (link)

[quora-M1Dquestion-4] Mueller, Thomas (June 8, 2015). "Is SpaceX's Merlin 1D's thrust-to-weight ratio of 150+ believable?". Retrieved July 9, 2015. The Merlin 1D weighs 1030 pounds, including the hydraulic steering (TVC) actuators. It makes 162,500 pounds of thrust in vacuum. that is nearly 158 thrust/weight. The new full thrust variant weighs the same and makes about 185,500 lbs force in vacuum.

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