Pressure-fed engine

Source: Wikipedia, the free encyclopedia.
Pressure-fed rocket cycle. Propellant tanks are pressurized to directly supply fuel and oxidizer to the engine, eliminating the need for turbopumps.

The pressure-fed engine is a class of rocket engine designs. A separate gas supply, usually helium, pressurizes the propellant tanks to force fuel and oxidizer to the combustion chamber. To maintain adequate flow, the tank pressures must exceed the combustion chamber pressure.

Pressure fed engines have simple plumbing and have no need for complex and occasionally unreliable

hypergolic
, they burn on contact; non-hypergolic fuels require an igniter. Multiple burns can be conducted by merely opening and closing the propellant valves as needed. If the pressurization system also has activating valves, they can be operated electrically, or by gas pressure controlled by smaller electrically operated valves.

Care must be taken, especially during long burns, to avoid excessive cooling of the pressurizing gas due to

Descent Propulsion System was unusual in storing its helium in a supercritical but very cold state. It was warmed as it was withdrawn through a heat exchanger from the ambient temperature fuel.[1]

This is a diagram of the pressure fed, reusable Orbital Manouevering System pod, of which there were two on either side of the shuttle’s stabiliser. It was used on the Space Shuttle orbiter (or simply Space Shuttle) for orbital insertion, manoeuvring the orbiter in space, and the deorbit burn. The AJ10-190 engines could be reused for up to 100 missions.
Diagram of an RS-25 (or Space Shuttle Main Engine), that used a twin shaft staged combustion cycle. There were three of these on the back of the orbiter. Comparing the diagram of the RS-25 to that of the Orbital Manoeuvring System (OMS), it is clear that the RS-25 engine is far more complex. The record for the most space shuttle missions an individual RS-25 engine has been used on is 19.

Spacecraft attitude control and orbital maneuvering thrusters are almost universally pressure-fed designs.[2] Examples include the Reaction Control (RCS) and the

Draco (RCS) engines on the SpaceX Dragon 2; and the RCS, ascent and descent engines on the Apollo Lunar Module.[1]

Some launcher

upper stages also use pressure-fed engines. These include the Aerojet AJ10 and TRW TR-201 used in the second stage of Delta II
launch vehicle, and the
Kestrel engine of the Falcon 1 by SpaceX.[3]

The 1960s Sea Dragon concept by Robert Truax for a big dumb booster would have used pressure-fed engines.

Pressure-fed engines have practical limits on propellant pressure, which in turn limits combustion chamber pressure. High pressure propellant tanks require thicker walls and stronger materials which make the vehicle tanks heavier, thereby reducing performance and payload capacity. The lower stages of

pump-fed liquid fuel engines instead, where high pressure ratio nozzles are considered desirable.[2]

Other vehicles or companies using pressure-fed engine:

See also

References

  1. ^ a b "LM Descent Propulsion Development Diary". Encyclopedia Astronautica. Archived from the original on 6 June 2012. Retrieved 5 June 2012.
  2. ^
    ISBN 0-89499-134-5
    .
  3. ^ "Falcon 1 Users Guide" (PDF). SpaceX. 2008-09-28. Archived from the original (PDF) on 2 October 2012. Retrieved 5 June 2012.

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Pressure-fed_engine&oldid=1178776175"