Live: Testing for the J-2X Upper Stage Engine

[MP99]

New post on the J-2X blog:-
http://wiki.nasa.gov/cm/blog/J2X/posts/post_1341860258235.html

Test A2J014, J-2X E10001:  It ran the full, planned 260 seconds duration.  This test represented several more "firsts" for J-2X.  This was the first time that the J-2X was started directly to secondary mode.  It was the first time that the J-2X switched, in run, from secondary mode to primary mode.  This was the first J-2X test with a stub nozzle extension that offered the opportunity to perform an in-run calibration of the facility flow meters and, in so doing, provide for a good estimation of engine performance.  It turns out that E10001 is, to our best understanding, exceeding expectations in terms of required performance.

(My highlight)

That seems to be new news - performance exceeds expectations.

Big question is when we'll start to hear actual figures.



Edit: forgot to mention another standout, a really long burn:-

Test A1J017, J-2X PowerPack-2:  It ran the full, planned 1,150 seconds duration.  That's over 19 minutes of continuous rocket engine operation and that's pretty amazing.

And was surprised to hear that SSME had gone through even longer tests than that a couple of decades ago.

cheers, Martin

[sdsds]

1150 seconds is amazing, but....

The specified propellant flow rate is (or was) 650 lbm/s; at the high end the CxP EDS would have held 253000 kg = 558000 pounds of propellant.

558000 / 650 = 858 seconds of operation was anticipated for each mission.

[MP99]

Good point.

Thinking about it, if CxP's TLI would have used low-throttle mode, the total burn time would have been even longer.

cheers, Martin

[Downix]

1150 seconds is amazing, but....

The specified propellant flow rate is (or was) 650 lbm/s; at the high end the CxP EDS would have held 253000 kg = 558000 pounds of propellant.

558000 / 650 = 858 seconds of operation was anticipated for each mission.

The original EDS design used two J-2S+ which each ran at 580 lbm/s. It held 457,884 lbm, which meant the original EDS mission would burn for just shy of 400 seconds. They also had an isp of 451, which meant it could have thrown 133,703 lbm to TLI.

[AnalogMan]

Another test firing:

J-2X Engine With Nozzle Extension Goes the Distance

NASA engineers conducted a 550-second test of the new J-2X rocket engine at Stennis Space Center in Mississippi on July 13. The J-2X engine will power the upper-stage of a planned two-stage Space Launch System, or SLS. The SLS will launch NASA's Orion spacecraft and other payloads, and provide an entirely new capability for human exploration beyond low Earth orbit. Designed to be safe, affordable and flexible for crew and cargo missions, the SLS will continue America's journey of discovery and exploration to destinations including nearby asteroids, Lagrange points, the moon and ultimately, Mars.

The test, conducted on the A-2 Test Stand, continued a series of firings to gather critical data for engine development. This was the first flight-duration test of the engine's nozzle extension, a bell shaped device to increase engine performance.

Operators collected data about the nozzle extension's performance in conditions that simulated heights up to 50,000 feet. Additionally, operators introduced different propellant pressures at startup to test how the engine reacted. The J-2X is being developed by Pratt & Whitney Rocketdyne for NASA’s Marshall Space Flight Center in Huntsville, Ala. It is the first liquid oxygen and liquid hydrogen rocket engine rated to carry humans into space to be developed in 40 years.

http://www.nasa.gov/mission_pages/j2x/j2x_july13_1.html

[spectre9]

Nice steam cloud but would be nice to see what this nozzle extension looks like.

[Prober]

Nice steam cloud but would be nice to see what this nozzle extension looks like.

you want the nozzle, I want the video...hhehhe

[AnalogMan]

Nice steam cloud but would be nice to see what this nozzle extension looks like.

you want the nozzle, I want the video...hhehhe

Video is here (but no views of the nozzle!):
http://www.nasa.gov/multimedia/videogallery/index.html?media_id=148375021

[spectre9]

Watched the whole way through and the vid cuts before the engine stops.

If it did stop there was no clear cut off that I saw.

[renclod]

... would be nice to see what this nozzle extension looks like.

it looks like this

[AnalogMan]

J-2X Powerpack Assembly II test firing at Stennis planned for today.

Stand:                   A-1
Planned duration:   1500 seconds (25 minutes)
Target test time:     3:00 - 5:00pm CDT

Will include the following:

• LOX and Fuel Inlet Duct Fuel Isolation Valve (FIV) Survey
• LOX System Helium Injection Evaluation
• FTP H-Q Excursion (head-flow rates)
• OTP Cavitation Runs
• FTP Nozzle Resonance
• FTP Cavitation Run

-------------------------
Update

Actual Test Start Time: 16:47 CDT
Actual Duration:           1350.5 seconds (22.5 minutes)

[catdlr]

From: NASA/SSC

"A Summer of Records for Engine Testing

As Olympic athletes converge on London with dreams of winning gold in the 2012 Summer Olympic Games, NASA is also setting records while testing the J-2X powerpack at the Stennis Space Center. The first time was June 8, when engineers went the distance and set the Test Complex A record with a 1,150-second firing of the developmental powerpack assembly. On July 24, engineers surpassed that record with a 1,350-second test of the engine component on the A-1 Test Stand at Stennis. The powerpack is a system of components on the top portion of the J-2X engine. On the complete J-2X engine, the powerpack feeds the thrust chamber, which produces the engine fire and thrust. The advantage of testing the powerpack without the thrust chamber is to operate over a wide range of conditions to understand safe limits.

The July 24 test specifically gathered data on performance of the liquid oxygen and fuel pumps during extreme conditions. The test data provides critical information for continued development of the turbopump for use on the J-2X engine, the first human-rated liquid oxygen and liquid hydrogen rocket engine to be developed in four decades. The J-2X is being built by Pratt & Whitney Rocketdyne for NASA’s Marshall Space Flight Center in Huntsville, Ala.

The J-2X engine will power the upper-stage of a planned two-stage Space Launch System, or SLS. The SLS will launch NASA's Orion spacecraft and other payloads, and provide an entirely new capability for human exploration beyond low Earth orbit. Designed to be safe, affordable and flexible for crew and cargo missions, the SLS will continue America's journey of discovery and exploration to destinations including nearby asteroids, Lagrange points, the moon and ultimately, Mars. "

http://www.nasa.gov/multimedia/imagegallery/image_feature_2316.html

[RyanC]

There's an interesting blogpost on the J-2X blog; along with the comments to it:

http://blogs.nasa.gov/cm/blog/J2X/posts/post_1338829889472.html

Tidbits of note:

RS-25 SSME and J-2X teams are basically one and the same; they form the Liquid Engines Element of the SLS program.

J-2X is pulling almost staged combustion performance from a gas generator cycle engine.

J-2X Gas Generator is based upon RS-68 experience, since the original J-2 GG would not work anymore for the requirements pushed on J-2X.

J-2X Valves are more akin to RS-25 SSME valves due to the higher flowrates and pressures.

Etc. It's basically a brand new 2005-2008 engine rather than an updated J-2; about the only thing in common is the J-2 name, the gas generator cycle, and maybe a few other bits somewhere on the engine.

They also mentioned having to change alloys because of OSHA requirements for Beryllium; something any F-1 restart would have to deal with.

Another minor note is that SSME startup is very long, six seconds vs three for J-2X, due to the need to balance out starting up four turbopumps and a complicated staged combustion cycle, vs J-2X's two turbopumps and simpler GG cycle.

You know, given that J-2X is about a ton lighter than the latest block SSME; is only couple ISP less efficient than the SSME, and puts out nearly 300 klbf vacuum, against 488 klbf; would it really be a big loss if SLS core was switched to J-2X?

You would lose some payload to orbit, due to gravity/drag losses, and the slightly lower ISP of the J-2X; but you'd win out by simplifying ground support operations which would have to support only a single hydrolox engine instead of two; which goes double for the spare parts pile to support launch operations, etc.

[sdsds]

http://www.nasa.gov/multimedia/imagegallery/image_feature_2316.html

Did this phrase cause anyone else concern? "The test data provides critical information for continued development of the turbopump for use on the J-2X engine."

Hadn't they better be essentially complete on turbopump development?!? Are there any changes other than "tuning" the engine that can be accommodated at this point in the overall program?

[edkyle99]

You know, given that J-2X is about a ton lighter than the latest block SSME; is only couple ISP less efficient than the SSME, and puts out nearly 300 klbf vacuum, against 488 klbf; would it really be a big loss if SLS core was switched to J-2X?

They would have to develop a sea-level variant of J-2X to make it work.  The main change would be to dispense with most of the nozzle extension.  Such an engine would have much lower thrust and specific impulse at sea-level compared to RS-25, and would also result in lower vacuum ISP.  SLS would lose performance, maybe a lot of performance, but possibly with money savings resulting.

I think that J-2 variants have been studied for such an application in the past. 

 - Ed Kyle