Tag: burp test

J-2X Progress: Getting All Spun Up

If you go back through the J-2X Development Blog articles, you’ll find one about the “Burp Test” that we conducted last July on J-2X development engine E10001.  In that case, we ran a very short test where we activated the helium spin start system and we ignited the main chamber, very briefly, before we shut down the whole thing.  Well, here we are about six months later and we’re doing the equivalent thing on the J-2X PowerPack Assembly 2 (PPA2).  Here is a video of the test:

 

Testing at night is always so much more dramatic.

For the PPA2, there is no main chamber to light, so this entire test was primarily focused on exercising the helium spin start system.  The flames that you see are from flare stacks necessary to get rid of the hydrogen used in the test.  Remember, the PPA2 is primarily a test article for turbomachinery and the gas-generator turbine-drive system.  It doesn’t make thrust.  All of that hydrogen that gets pumped by the fuel turbopump has to be disposed of in a controlled manner other than in the production of thrust.  So, we burn it off.  The liquid oxygen is disposed of as well, but it doesn’t require anything quite so gaudy as flare stacks.

Interestingly, when hydrogen burns, it usually burns clear.  The whole orange-flame thing is not something I entirely understand, but it always looks that way at night.  There’s some propane in the flame used as kind of like a pilot light, but not enough to cause that much color.  It could be that burning hydrogen at such a low mixture ratio (i.e., not enough oxygen immediately available so you get afterburning effects) is the cause of this as compared to the usual white hot rocket engine exhaust.  It’s also possible that it’s stuff in the air or somehow water vapor effects, or disassociation effects, but I honestly don’t know.  Any ideas from anyone else?  I’d love to hear some theories.  I do know that if you’re standing anywhere where you can see the flame, you can feel the heat radiating from it.  It’s quite an impressive experience.

Beyond exercising the helium spin start system, what this test also did is prove out the test stand subsystems, the test stand and test article control systems, demonstrates that the gobs and gobs of instrumentation is hooked up, working properly, and feeding back reasonable data, and that the proper procedures are in place to conduct a safe test.  Every facet listed is a big, big deal and has to work in conjunction with everything else. 

The folks at the Stennis Space Center — civil service, support contractors, and prime contractors alike — all deserve kudos for pulling this off successfully and, really, with minimal technical issues.  Way to go guys!  This test is yet another in a long string of demonstrations of the power of collaboration and the overall dedication and excellence of the J-2X team.  We’re now ready to step into the meat of the test series and start putting the hardware through its paces.  This is going to be exciting!  Go J-2X!

J-2X Progress: Pardon Me

I’ve lived in the South for about 20 years now.  Over that time, I’ve heard and learned all kinds of quirks of regional dialect and colloquial sayings.  I’m quite sure that I’ve even picked up a few myself.  Oh well.  One particular expression shared with me by a former training partner in the gym was a compliment.  She told me that I had good “home training.”  That is a shorthand way of saying that my parents taught me to have good manner. 

With that in mind, and in consideration of what we’ve been calling the first hot-fire test of J-2X development engine E10001 (i.e., the “burp test”), I respectfully and bashfully declare:


 

In the early evening of Thursday, 14 July, E10001 generated a burst of ignition and thrust with something like a 30,000 pounds of force — enough to toss five or six crew-cab pickup trucks into the air.  That’s one heck of a burp.  Yep, we were successful.  NASA Stennis Space Center in Mississippi, coordinating with the Upper Stage Engine office at the NASA Marshall Space Flight Center and with Pratt & Whitney Rocketdyne in Los Angeles, California conducted a full-duration, 1.9-second test.  Here is a picture of what a burp that big looks like:

 


 

Here are a couple of pictures of the engine prior to the test.  These are taken from a deck inside the test stand basically looking down on the engine.  The nozzle extends through the deck to the next level below.

 



 

You’ll note that there’s some misty fog hanging around the engine in those pictures.  While it is true that most of the time you can almost see the thickly humid air of southern Mississippi in July, this is something different.  This fog is being created by the presence of cryogenic propellants in the lines.  These lines are so cold that they effectively condense water in the air around them, even at a distance, to create a fog.  Here are some close-up frosty pics of lines chilled down prior to test:

 

 

Out of one end comes smoke and fire while the other end is frosty cold.  This is a good illustration of the broad span of environments that exist within a rocket engine.

So, what’s next?

As exciting at this brief test was, what we didn’t do is light the gas generator and get the turbomachinery up to full speed.  That’s the goal for the next test.  In addition to spinning up the turbopumps with helium and lighting the propellants in the main chamber, as we did for the burp test, we’ll take the next step in the start sequence and light off the propellants in the gas generator.  This will provide the turbopumps with the power necessary to reach mainstage, steady-state operation.  And that — those initial few seconds of mainstage —  will be our first glimpse at genuine engine operation like that which will propel spacecrafts into orbit and then outwards across our solar system.