ABOUT MERLIN 1D
The Merlin 1D is a gas-generator cycle engine developed by SpaceX, powering the first stage of the Falcon 9 and Falcon Heavy launch vehicles. It burns RP-1 kerosene and liquid oxygen, achieving remarkable thrust-to-weight ratio through simplified design and manufacturing innovations. Nine Merlin 1D engines power each Falcon 9 first stage, enabling propulsive landing and reuse.
Image: SpaceX
PERFORMANCE
| Thrust (Sea Level) | 845 kN (190,000 lbf) kN |
| Thrust (Vacuum) | 981 kN (220,500 lbf) kN |
| ISP (Sea Level) | 282 s s |
| ISP (Vacuum) | 311 s s |
| Chamber Pressure | 9.7 MPa (1,410 psi) bar |
| Mass | 470 kg |
| Thrust-to-Weight | 179 |
| Throttle Range | 57–100% |
| Restart Capable | Yes (multiple) |
THRUST CONVERSIONS (VACUUM)
| Kilonewtons | 981.0 kN |
| Pounds-force | 220,538 lbf |
ENGINE CYCLE
Gas Generator
A gas generator cycle taps off a small portion of propellants to drive turbopumps via a separate combustion chamber. The turbine exhaust is dumped overboard, making it less efficient but simpler and more reliable. Used by the Merlin, F-1, and RS-27.
PROPULSION
| Propellant | RP-1 |
| Oxidizer | LOX |
| Engine Cycle | Gas Generator |
| Mixture Ratio | 2.36:1 |
| Flow Rate | ~300 kg/s kg/s |
PHYSICAL
| Dimensions | 0.92 m diameter × 3.0 m length |
| Combustion Chambers | 1 |
| Nozzle Expansion Ratio | 16:1:1 |
GENERAL
| Manufacturer | SpaceX |
| Country | United States |
| Status | Active |
| First Flight | May 27, 2026 |
VARIANTS (3)
- Merlin 1D
- Merlin 1D+
- Merlin 1D Full Thrust
VEHICLES USING MERLIN 1D (2)
ENGINE LINEAGE
Merlin 1C→Merlin 1D→Merlin 1D+ (upgraded variant)
⚖ PROPELLANTS
🏢 MANUFACTURER
