engineers at Stennis Space Center may conduct a brief hot-fire test of the first J-2X development upper-stage rocket engine next week, after installing it in historic Test Stand A2 at the Mississippi facility on June 11.
“We’re going to drop propellants on the engine and make sure that we get expected chill-down procedures,” says Mike Kynard, J-2X project manager at. “We’ll make sure the pumps are properly conditioned and things like that, and we’re actually thinking if that goes without a hitch, we might go ahead and run a short start test.”
While that 1.9-sec. test – tentatively scheduled for June 21 – would be the first with actual ignition in the engine, it would be followed by a second 7-sec. hot-fire test about a week later that should produce the calibration data needed for a series of full-duration evaluations during the summer.
“That test is going to be our first main-stage test,” Kynard says of the 7-sec. trial, noting that the engine will be set up cautiously to avoid running too hot. The J-2X project has scheduled 10 tests during the summer, with a week to 10 days between them for data analysis and adjustments to the engine and instrumentation. Each of the 10 is scheduled to run the full 500 sec. the engine would fire in a heavy-lift launch mission.
Originally developed as the upper-stage engine in the Ares I crew launch vehicle, the J-2X has been tentatively selected as the upper-stage engine for the heavy-lift Space Launch System (SLS) that Congress has orderedto develop as a government-owned capability to send humans beyond low Earth orbit. In the tentative design for the SLS, NASA chose a vehicle that would use one or two of the 300,000-lb.-thrust liquid-oxygen/liquid-hydrogen engines in its upper stage, with a throw-away version of the Space Shuttle Main Engine powering the main stage and twin solid-fuel boosters based on the Ares I first stage as strap-ons.
However, that design has not won final approval from NASA’s senior managers, and meetings are under way at agency headquarters this week to consider alternatives. Those include a vehicle with more space shuttle heritage, and one that would use a hydrocarbon-fueled main-stage engine in lieu of the solid-fuel strap-ons.
The J-2X development at Stennis – designated engine No. 10,001 – is the first complete version of the powerplant assembled by Pratt & Whitney Rocketdyne, using funding originally appropriated for the Ares I. Presumably the testing will continue with SLS funding if the engine is selected for the heavy lifter.
Kynard says plans are in place for early-altitude start-testing with a clamshell enclosure at Test Stand A2 at Stennis while work on the new A3 altitude stand built for the J-2X is completed.