Rocketdyne J-2

J-2 is the designation for a rocket engine, which came into use in the Saturn V moon rocket. It was once the largest operated with liquid hydrogen engine of the USA, but has been surpassed with the development of the main engine of the space shuttle.

The use of J-2

Five J -2 engines were in the second stage (S- II) of the Saturn V used. In each case a J-2 engine went in the third stage (S- IVB ) of the Saturn V, the identical second stage ( S- IVB also ) of the Saturn IB for use. In studies for planned Nova rocket various configurations have been proposed, the upper stages would have been also driven by J-2 engines.

A unique characteristic of the J -2 was that it was repeatedly fired. So the third stage of the Saturn V J-2 engine was used twice during the flight. The first burning period lasted two and a half minutes and served to bring the spacecraft into orbit. After the crew had checked the correct functioning of the spaceship and the engine was capable of ignition again, the J-2 engine was again fired for 6 minutes and 30 seconds to bring the ship to the moon course, by NASA TLI (Trans Lunar Injection) mentioned.

To re- ignite the engine a longer pause was necessary to cool individual parts and for the turbo pump a sufficient amount of gaseous hydrogen to have available to start this again. The break was about 35 minutes. For the Wiederzündbarkeit has departed from the prior art ignition by hypergolic Zündmedien, an arc ignition (similar to a spark plug) has been introduced.

Was an improved version, the J -2S for the planned successor to the Saturn V Nova, developed and tested. The J -2S yielded about 10 % more thrust and improved the specific impulse slightly, but was never used.

The improved J -2X

This new variant of this engine should be used for use as part of the Constellation program, which was to replace the space shuttle after its decommissioning in 2010. The J- 2X engine should be to act in both versions of the Ares rockets as engine in the Ares I in high school, at the Ares V Earth Departure Stage only in the ( EDS). The use of three J- 2X is projected system in the upper level of Space Launch.

Development is the new engine of Whitney Rocketdyne Inc.; the contract for this was signed in July 2007. First tests with the historic J -2 engine, primarily for obtaining comparative data, took place near St. Louis at the NASA Stennis Space Center. In November 2008, there was the engine the Critical Design Review at the Marshall Space Flight Center in Huntsville, Alabama and is qualified for the flight. In the first test flight of the Ares IX it was not used. In 2011, began test runs of the new engine in complete configuration at the John C. Stennis Space Center.

Specifications

Use: Saturn IB / S- IVB second stage - an engine Use: Saturn V / S -II second stage - five engines Use: Saturn V / S- IVB third stage - an engine