// PROPULSION SYSTEMS AND ENGINE TECHNOLOGY TERM

Gas Generator

A gas generator is a core component in some rocket and jet engines that acts like a small, secondary engine. It burns a small amount of fuel to produce hot gas, which is then used to power the turbines that drive the main fuel pumps.

TECHNICAL DEFINITION

In aerospace propulsion, a gas generator is a combustion device within a gas-generator cycle (or open cycle) liquid-propellant rocket engine that burns a fraction of the propellant to produce a hot gas stream, which powers the turbopump assembly turbine before being exhausted.

BACKGROUND

A gas generator is a device for generating gas. A gas generator may create gas by a chemical reaction or from a solid or liquid source, when storing a pressurized gas is undesirable or impractical.

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SYNONYMS & ALIASES

  • GG
  • pre-burner
  • powerpack
  • turbine driver
  • precombustor
  • monopropellant gas generator

USAGE NOTE

The performance of a gas-generator cycle engine is characterized by its exhaust being dumped overboard, which is simpler but less efficient than a staged combustion cycle.

DEVELOPERS

Organizations developing technology related to Gas Generator.

  • Aerojet Rocketdyne

    A subsidiary of L3Harris Technologies, Aerojet Rocketdyne has a long history of developing gas-generator cycle engines, including the RS-68 used on the Delta IV Heavy launch vehicle and the F-1 engines that powered the Saturn V.

  • SpaceX

    SpaceX develops the Merlin engine family, which powers the Falcon 9 and Falcon Heavy rockets. The Merlin engine is a prominent modern example of a gas-generator (or open-cycle) rocket engine, known for its reliability and reusability.

  • ArianeGroup

    A joint venture between Airbus and Safran, ArianeGroup is the prime contractor for Europe's Ariane launchers. They develop and produce the Vulcain engine, a gas-generator cycle cryogenic engine that powers the main stage of the Ariane 5 and Ariane 6 rockets.

  • NPO Energomash

    A leading Russian rocket engine manufacturer, Energomash is known for its high-performance engines. While famous for staged-combustion cycles, they also produce renowned gas-generator cycle engines like the RD-107/108 family, which has powered Soyuz rockets for decades.

  • Indian Space Research Organisation (ISRO)

    India's national space agency develops its own launch vehicles and propulsion systems. The Vikas engine, a key component of the PSLV and GSLV rockets, is a liquid-fueled engine that operates on a gas-generator cycle.

  • Firefly Aerospace

    An American aerospace firm developing small and medium-lift launch vehicles. Their Reaver 1 engine, which powers the first stage of their Alpha rocket, uses a gas-generator cycle and is designed for low-cost manufacturing and operation.

  • Relativity Space

    Known for its focus on 3D-printed rockets, Relativity Space develops the Aeon engine family. Their Aeon R engine, designed for the reusable Terran R rocket, is a gas-generator cycle engine that burns liquid oxygen and liquid methane.

  • Rocket Lab

    While their Rutherford engine uses a unique electric pump-fed cycle, Rocket Lab is developing the Archimedes engine for their larger Neutron rocket. Archimedes is designed as a reusable gas-generator cycle engine fueled by liquid oxygen and methane.

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