Product overview: Liquid Oxygen/Kerosene Rocket Engine

The AJ26 is an oxidizer-rich, staged-combustion, oxygen kerosene engine that achieves very high performance in a lightweight, compact package. It was orginally known as the NK-33 engine designed to launch the N1 Russian Rocket on lunar missions.

The simple design and unique technological approach eliminates exotic materials and complex manufacturing processes, making the engines easy to operate and maintain. The dual AJ26 main engine system provides Orbital Sciences Corporation’s AntaresTM vehicle with better performance at a more affordable cost than existing engines in its thrust class.

The engine was designed by renowned gas turbine design bureau, JSC Kuznetsov, located southeast of Moscow. Aerojet Rocketdyne modernized a gimbal block for thrust vectoring capability, gimbaling feedlines, new wiring harnesses and electrical circuitry, electromechanical valve actuators and instrumentation.


Antares Main Engine System (MES)


Twin AJ26-62 Pump Fed engines



Thrust, Vacuum

377,000 lbf (each)

Thrust, Sea Level

338,000 lbf (each)

Specific Impulse, Vacuum

331 seconds

Specific Impulse, Sea Level

291 seconds

Vehicle Mixture Ratio


Engine Chamber Pressure

2278 psia

Weight (Dry)

2722 lbm

Vacuum Thrust/Weight


Overall Length

148 in