Merlin 1D is the kerosene-burning engine that lifts SpaceX's Falcon 9 and Falcon Heavy rockets.
spacex-merlin-1d SpaceX designs and builds the Merlin 1D for its Falcon rockets. It burns kerosene with liquid oxygen, and each sea-level engine pushes with 845 kilonewtons (190,000 pounds of force). Nine of them lift a Falcon 9 first stage, and SpaceX lands and reuses that stage. Twenty-seven lift a Falcon Heavy. A vacuum version powers the second stage.
Milled copper alloy lines the chamber and the nozzle and gives a large safety margin against heat. The injector sprays the propellants into the chamber. It is a pintle design, first used in the Apollo-era Lunar Module landing engine. On the vacuum version, the bell-shaped nozzle is made of niobium sheet alloy.
Nine Merlin 1D engines lift the Falcon 9 first stage, which SpaceX lands and reuses. The engines launch NASA crew and cargo to the International Space Station and commercial satellites to orbit.
The thrust chamber and nozzle are regeneratively cooled: propellant flows through their walls and carries heat away. The liner is milled copper alloy. On the vacuum version, a thin niobium nozzle extension is radiatively cooled, so it gives off heat as radiation instead.
SpaceX says the pintle injector gives the engine inherent combustion stability. The turbopump, the machine that forces propellant into the engine, has a single shaft joining the oxygen pump, the fuel pump and the turbine, and it spins at roughly 30,000 rpm. A gas generator burns a small flow of propellant to drive that turbine.
The whole engine swivels on a gimbal to steer the rocket, and on the first stage the actuators run on high-pressure kerosene, so no separate hydraulic system is needed. TEA-TEB, a fluid that ignites by itself, starts the engine. Triple-redundant computers control each engine.
Falcon 9 chills its engines before launch. After ignition the first stage stays on the pad until automated monitors confirm that each engine is running normally. If anything is off, the engines shut down on their own, and in flight the vehicle software can shut down a failing engine.
The Merlin Vacuum powers the second stage and delivers 981 kilonewtons in vacuum. Its nozzle is fixed rather than folding out, and two redundant igniters let it restart in flight. A later version has a shorter nozzle extension that gives up some performance and uses less material.
The milled liner of the thrust chamber and nozzle. SpaceX does not name the grade.
Thin sheet forming the bell-shaped, radiatively cooled nozzle extension of the Merlin Vacuum.
The Merlin 1C powered the first Falcon 9, and the Merlin 1D follows it. The original Merlin 1A drew on NASA's Fastrac engine. The 1D's pintle injector was borrowed from the Apollo Lunar Module's landing engine, and its gas generator is like the one in Rocketdyne's F-1. A Falcon 9 first stage carries nine Merlin 1Ds and a Falcon Heavy 27, and each rocket adds one Merlin Vacuum. Barber-Nichols built the turbopump of an earlier Merlin.
SpaceX
9 Merlin 1D on the first stage
single Merlin Vacuum (MVac) with a fixed 165:1 nozzle
SpaceX
27 Merlin 1D on the first stage: nine on the centre core and nine on each of the two side boosters
single Merlin Vacuum on the upper stage shared with Falcon 9
Lockheed Martin
Falcon 9 first stage burns nine Merlin engines (2010 page; Block 5 flights use the Merlin 1D family, linked to the catalog hub)
Grumman / NASA
pintle injector first used in the Lunar Module landing engine
SpaceX drew on the Fastrac design and technology for the original Merlin 1A
Merlin 1C powered Falcon 9 v1.0: nine first-stage engines plus one vacuum engine
designed and produced the turbopump of the earlier Merlin (more than 100,000 lbf sea level class); the source does not say who builds the 1D turbopump
designs and manufactures its own Merlin engines (first and second stage)
Aerojet Rocketdyne
copper alloy. Here: Chamber and nozzle liner. There: Additively manufactured copper-alloy thrust chamber (test article).
niobium sheet alloy. Here: Radiatively cooled nozzle extension. There: RL10A-4 extendible nozzle.
SpaceX says little about what the engine is made of. It does not name the copper alloy, the grade of the niobium, or the metals in the turbopump, injector, manifolds and valves. Nor does it name any outside supplier for the current engine.
What is written above is built from these numbers and quotes. Each row links to the page it was taken from. Get all of it as JSON, or ask our MCP server.
| What | Value |
|---|---|
| Sea-level thrust | 845 kN (190,000 lbf) |
| Cycle | Gas generator |
| Propellants | Kerosene and liquid oxygen |
| Engines per vehicle | 9 on Falcon 9 first stage; 27 on Falcon Heavy |
| Vacuum thrust of the Merlin Vacuum (second stage) | 981 kN (220,500 lbf) |
| Throttle range, first stage (sea level) | 190,000 lbf to 108,300 lbf |
| Throttle range, second stage | 220,500 lbf to 140,679 lbf |
| Restart capability | yes on both stages |
| Engines flown per launch | 10 on Falcon 9, 28 on Falcon Heavy |
| Thrust-to-weight claim | highest of any boost engine ever made (SpaceX claim) |
| Turbopump shaft speed | about 30,000 rpm |
| Chamber pressure | 9.7 MPa (1,410 psi) |
| Development and first flight | developed 2011 to 2012, first flight 2013 |
| First flight of the first-generation Merlin Vacuum (Merlin 1C-based) | 4 June 2010, first Falcon 9 flight (second stage) |
| Propellants (NASA description) | kerosene and liquid oxygen |
Each material named in the sources: where it is used here, which other products use it, and its key numbers when its material page exists.
Used in 1 partChamber and nozzle liner
Used in 1 partRadiatively cooled nozzle extension
Only the chamber liner (copper alloy) and the Merlin Vacuum nozzle extension (niobium alloy) have a stated material; other parts are listed with no material. Components, suppliers and links were added from public sources. A material is left blank where no source states it.
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| Chamber and nozzle liner“use a milled copper alloy liner that provides large heat flux margins” | copper alloy (grade not stated)copper-alloy | — | — |
| Outer jacket / structural shell“The regeneratively cooled nozzle and thrust chamber use a milled copper alloy liner” | Not said | — | — |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| Pintle injector“A pintle injector provides inherent combustion stability.” | Not said | — | — |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| Turbopump (single shaft for LOX pump, fuel pump and turbine)“The engine features a reliable turbopump design with a single shaft for the liquid oxygen pump, the fuel pump, and the turbine.” | Not said | — | — |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| Radiatively cooled nozzle extension“The bell shaped Merlin Vacuum nozzle is made out of niobium sheet alloy” | niobium sheet alloyniobium-alloy | — | Merlin Vacuum engine, second stage |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| Merlin 1D sea-level variant (M1D, first stage)nine per Falcon 9 first stage, 27 on Falcon Heavy“Nine SpaceX M1D engines power the Falcon 9 first stage with up to 845 kN (190,000 lbf) thrust per engine at sea level” | Not said | — | Supplier: SpaceX |
| Merlin Vacuum variant (MVac, second stage)single upper-stage engine with a fixed vacuum nozzle“A single Merlin Vacuum (MVac) engine powers the second stage, using a fixed 165:1 expansion nozzle.” | Not said | — | Supplier: SpaceX |
| Shorter Merlin Vacuum nozzle extension (later variant)trades some performance for less material“This new nozzle extension is shorter and, as a result, decreases both performance and material usage.” | Not said | — | — |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| Gas generator (open cycle)burns a small flow of propellant to drive the turbine instead of staged combustion“The engine uses a gas generator cycle instead of the more complex staged combustion cycle.” | Not said | — | — |
| Gimballing turbine exhaust duct (Falcon 9 v1.0 Merlin Vacuum)provided second-stage roll control on the first Falcon 9 version“Turbine exhaust duct (gimbal)” | Not said | — | — |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| Engine gimbal (pitch and yaw)steers the thrust vector“Pitch, yaw Gimbaled engines Gimbaled engine/nitrogen gas thrusters” | Not said | — | — |
| Thrust-vector-control actuators driven by high-pressure RP-1no separate hydraulic fluid system“the first stage thrust vector control system pulls from the high-pressure rocket-grade kerosene system” | Not said | — | — |
| Engine computers (triple-redundant)control each engine“SpaceX uses a triple-redundant design in the Merlin engine computers.” | Not said | — | — |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| TEA-TEB pyrophoric igniterstarts the engine with a hypergolic fluid“SpaceX's Merlin engines use pyrophoric igniters with a hypergolic fluid called triethylaluminum-triethylborane, or TEA-TEB.” | Not said | — | — |
| Dual redundant igniters (Merlin Vacuum)added reliability for in-flight restart“the engine contains dual redundant triethylaluminum-triethylborane (TEA-TEB) pyrophoric igniters” | Not said | — | — |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| Octaweb engine mountarranges the nine first-stage engines and carries their thrust“The booster stage has 9 engines, arranged in a configuration that SpaceX calls Octaweb.” | Not said | — | — |
| Individual engine bayeach engine sits in its own metal bay“each engine is housed within its own metal bay to isolate it from neighboring engines” | Not said | — | — |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| Engine controller (ignition sequence)commands the engine start sequence“Engine controller commands engine ignition sequence to start” | Not said | — | — |
| Engine chill-down before launchchills the engines ahead of ignition“Falcon 9 begins engine chill prior to launch” | Not said | — | — |
| Pad hold-down and automated engine monitorsfirst stage is held after ignition until engines are verified“the first stage is held on the ground after engine ignition while automated monitors confirm nominal engine operation” | Not said | — | — |
| Autonomous safe shutdownstops the engines if any off-nominal condition is detected“An autonomous safe shutdown is performed if any off-nominal condition is detected.” | Not said | — | — |
| Engine-out vehicle management softwareshuts down failing engines in flight“System-level vehicle management software controls the shutdown of engines in response to off-nominal engine indications” | Not said | — | — |
| Part | Material | Finish and standard | Made by |
|---|---|---|---|
| SpaceX engine test stands, McGregor, Texasacceptance and qualification testing of Merlin engines“spent months reviewing data from Merlin engine tests performed at the SpaceX test facility in McGregor, Texas” | Not said | — | — |
No turbopump, injector, manifold, jacket or valve materials stated. No standards or grades. More detail: SpaceX publishes no Merlin bill of materials: turbopump housings, gas generator, manifolds, valves, igniter hardware and the actuator hardware have no stated alloys. No supplier is named for the Merlin 1D beyond SpaceX itself; Barber-Nichols is named only for the earlier Merlin turbopump (more than 100,000 lbf class). The hydraulic actuator, gimbal and engine-computer hardware is described only in general terms. The 2025 user guide quotes the engine designation 'M1D' and 'MVac'; the exact first-flight date of the Merlin 1D (Falcon 9 v1.1, 2013) comes from Wikipedia and the Spaceflight Now article, not from a SpaceX document. Quotes from the Falcon User's Guides (2025 and 2009) were machine-checked against the PDF text; quotes from NASA web pages, Spaceflight Now, Barber-Nichols and Wikipedia came through a text extractor and were not machine-checked. The chamber-pressure figure is a Wikipedia statement that cites Aviation Week; the F-1 gas-generator similarity is a Wikipedia statement that cites a textbook. More detail: SpaceX publishes no Merlin bill of materials: turbopump housings, gas generator, manifolds, valves, igniter hardware and the actuator hardware have no stated alloys. No supplier is named for the Merlin 1D beyond SpaceX itself; Barber-Nichols is named only for the earlier Merlin turbopump (more than 100,000 lbf class). The hydraulic actuator, gimbal and engine-computer hardware is described only in general terms. The 2025 user guide quotes the engine designation 'M1D' and 'MVac'; the exact first-flight date of the Merlin 1D (Falcon 9 v1.1, 2013) comes from Wikipedia and the Spaceflight Now article, not from a SpaceX document. Quotes from the Falcon User's Guides (2025 and 2009) were machine-checked against the PDF text; quotes from NASA web pages, Spaceflight Now, Barber-Nichols and Wikipedia came through a text extractor and were re-checked in a second fetch pass but not against a saved copy of the page. The chamber-pressure figure is a Wikipedia statement that cites Aviation Week; the F-1 gas-generator similarity is a Wikipedia statement that cites a textbook.
Collected from public pages and documents, checked 4 Nov 2026.
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