The electric-pump-fed engine is a

bipropellant rocket A liquid-propellant rocket or liquid rocket uses a rocket engine burning liquid propellants. (Alternate approaches use gaseous or solid propellants.) Liquids are desirable propellants because they have reasonably high density and their combusti ...

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ge ...

in which the fuel pumps are electrically powered, and so all of the input propellant is directly burned in the main combustion chamber, and none is diverted to drive the pumps. This differs from traditional rocket engine designs, in which the pumps are driven by a portion of the input propellants. An electric cycle engine uses electric

pump A pump is a device that moves fluids (liquids or gases), or sometimes Slurry, slurries, by mechanical action, typically converted from electrical energy into hydraulic or pneumatic energy. Mechanical pumps serve in a wide range of application ...

s to pressurize the propellants from a low-pressure fuel tank to high-pressure

combustion chamber A combustion chamber is part of an internal combustion engine in which the air–fuel ratio, fuel/air mix is burned. For steam engines, the term has also been used for an extension of the Firebox (steam engine), firebox which is used to allow a mo ...

levels, generally from to . The pumps are powered by an

electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

, with electricity from a battery bank. Electrical pumps had been used in the secondary propulsion system of the Agena upper stage vehicle. As of December 2020, the only rocket engines to use electric

propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...

pump systems are the Rutherford engine, ten of which power the

Electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

rocket, and the Delphin engine, five of which power the first stage of Astra Space's Rocket 3. On 21 January 2018, Electron was the first electric pump-fed rocket to reach orbit. In comparison to turbo-pumped rocket cycles such as staged combustion and

gas generator 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. The term often refers to a device that uses a ...

, an electric cycle engine has potentially worse performance due to the added mass of batteries, but may have lower development and manufacturing costs due its mechanical simplicity, its lack of high temperature turbomachinery, and its easier controllability.

References

{{spacecraft propulsion Combustion Rocket engines Rocket engines by cycle Spacecraft propulsion Thermodynamic cycles

See also

References