October 21, 2007
Thank You, Captain Obvious

Metal suit not same for NASA's J-2X engine- al.com

The J-2X is going beyond the needs of the Saturn moon rockets. To loft the Apollo capsule, the Saturn rocket's upper stages had to generate 230,000 pounds of thrust.

"This one has to generate more than 290,000 pounds of thrust," said Mike Kynard, J-2X program manager. "Not only is the J-2X going to be more powerful, it's going to be different. Time has seen to that. This engine has its roots in Apollo, but we aren't just lifting their work. It's almost a new engine."

Duh. Isn't that what we were all saying when NASA decided to quote-"resurrect"-unquote the J-2 instead of modifying the SSME as originally planned (or adapting another in-production LOx/LH2 engine)?

Here again, we see the "Stick" mentality at work: forego what seems to be a more reasonable solution involving enhanced existing hardware on the grounds that the enhancement will be "too expensive" and "take too much time", in favor of using heritage technology in a new way...only to have that approach later fall prey to realities that should have been apparent from the start, resulting in the designing of hardware whose "heritage" is limited to a superficial resemblance.

Posted by T.L. James on October 21, 2007 08:48 PM | TrackBack



"it's almost a new engine"...

so, why don't build the (better) "J-2Y" ?

read about my idea of a "J-2Y" on ghostNASA


Posted by: GM at October 22, 2007 08:46 AM

The SSME and RS-68 were ill-suited as both
are ground start engines.

The J-2 was the only big engine that had an airstart

It's a pity they broke many of the best features of the J-2
to conceive of the J-2X

Posted by: anonymous at October 22, 2007 01:02 PM

There really is only one solution ax AresI now and go with direct launcher.
Direct launcher uses Existing RS-68s or SSMEs there are no air start events.

This would push J2X development requirements to when the EDS flies or you can just use a cluster of two to four RL60s in place of the one J2X on the EDS.
The RL60 is an upgraded RL10 it can perform restarts be made to throttle etc just like the RL10 and unlike the J2X it's not a paper engine.

Lastly even the smallest version of direct launcher still can lift over 132,000lbs so if needed even this version can perform a lunar mission in just three launches.
One change needed might be switching to storable propellants or adding more insulation to the LSAM tanks.

Posted by: Membrane at October 23, 2007 09:40 PM