Second Of Four Planned J-2X Generator Trials Wraps Up
Engineers at NASA's Marshall Space Flight Center in Huntsville,
AL have completed a series of tests on a key component of the J-2X
engine which will power the upper stage of the upcoming Ares I
rocket.
The test on August 15 was the last of 20 in this series,
concluding the second of four planned sets of tests on the J-2X's
workhorse gas generator, the driver for the turbopumps which start
the engine.
The gas generator test program is designed to demonstrate the
component's performance, durability and combustion environment, and
to reduce risk in the design, fabrication and operation of flight
hardware. The third phase of testing will begin in July 2009. The
J-2X's workhorse gas generator is fabricated by Pratt and Whitney
Rocketdyne of Canoga Park, CA.
The primary objectives achieved in this series of tests were to
regulate ignition timing and address stability issues in the gas
chamber. During engine start, a pressurized helium system begins to
turn the turbopumps, which draw liquid hydrogen and liquid oxygen
propellants into the system. The propellants flow into the
generator's combustion chamber, where they are sparked into life by
pyrotechnic igniters installed in the side of the main combustion
chamber.
Once combustion is initiated, hot gases flow into the turbine.
The combustion gas provided by the generator drives the
turbomachinery, which delivers high pressure propellants to the
main injector during the J-2X burn. This testing allows engineers
to address stability issues that can arise during operation of the
combustion chamber and will allow engineers to develop a clean
design for the J-2X engine.
Beginning in 2015, the Ares I rocket will carry the Orion crew
capsule and as many as six astronauts and small payloads to the
International Space Station. During the first two-and-a-half
minutes of flight, the first stage booster will power the vehicle
to an altitude of about 189,000 feet, or 36 miles, at a speed of
Mach 4.8. After its propellant is spent, the reusable booster will
separate, and the upper stage's J-2X engine will ignite -- powering
the Orion to low Earth orbit at an altitude of about 425,328 feet,
or roughly 80 miles.
The workhorse gas generator test series is an essential step in
development of the J-2X engine. More than 50 tests have been
performed on the generator to date. This generator was manufactured
to be more durable than the actual generators slated for use in the
J-2X engine, allowing it to withstand numerous tests.
The J-2X is an upgraded variant of the storied J-2 rocket
engine, which powered the second stage of the Saturn V moon
rocket.