ABOUT RL-10
The RL-10 is a versatile cryogenic upper stage engine built by Aerojet Rocketdyne, known for its exceptionally high specific impulse and proven reliability over six decades of service. First flown in 1963, it has powered the Centaur upper stage through hundreds of missions. The RL-10 uses an expander cycle, where hydrogen heated by the combustion chamber walls drives the turbopump.
Image: Aerojet Rocketdyne
PERFORMANCE
| Thrust (Sea Level) | N/A (upper stage) kN |
| Thrust (Vacuum) | 110 kN (24,729 lbf) kN |
| ISP (Sea Level) | N/A s |
| ISP (Vacuum) | 465.5 s s |
| Chamber Pressure | 3.96 MPa (575 psi) bar |
| Mass | 168 kg |
| Thrust-to-Weight | 67 |
| Throttle Range | Limited (variant dependent) |
| Restart Capable | Yes (multiple) |
THRUST CONVERSIONS (VACUUM)
| Kilonewtons | 110.0 kN |
| Pounds-force | 24,729 lbf |
ENGINE CYCLE
Expander
The expander cycle uses heat from the combustion chamber walls to vaporize fuel, which then drives the turbopumps. No propellant is wasted, making it very efficient for upper stages. Used by the RL10.
PROPULSION
| Propellant | Liquid Hydrogen (LH₂) |
| Oxidizer | LOX |
| Engine Cycle | Expander |
| Mixture Ratio | 5.88:1 |
| Flow Rate | ~24 kg/s kg/s |
PHYSICAL
| Dimensions | 1.02 m diameter × 2.32 m length |
| Combustion Chambers | 1 |
| Nozzle Expansion Ratio | 84:1 (RL-10C-1):1 |
GENERAL
| Manufacturer | Aerojet Rocketdyne |
| Country | United States |
| Status | Active |
| First Flight | April 17, 1963 |
VARIANTS (5)
- RL-10A
- RL-10B-2
- RL-10C-1
- RL-10C-1-1
- RL-10C-3
VEHICLES USING RL-10 (3)
- Centaur
- Delta Cryogenic Second Stage
- SLS Exploration Upper Stage
ENGINE LINEAGE
RL-10→RL-10C-X
⚖ PROPELLANTS
