Author Topic: 3 Ares V design papers - 2x Review/J2-X  (Read 3492 times)

Offline CuddlyRocket

3 Ares V design papers - 2x Review/J2-X
« on: 02/11/2007 07:06 AM »
A New Heavy-Lift Capability for Space Exploration: NASA’s Ares V Cargo Launch Vehicle

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070002794_2007001555.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070002798_2007001569.pdf

Development of the J-2X Engine for the Ares I Crew Launch Vehicle and the Ares V Cargo Launch Vehicle: Building on the Apollo Program for Lunar Return Missions

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070002803_2007001610.pdf

(This is the same paper as in the equivalent Ares I thread.)

Offline JIS

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Re: 3 Ares V design papers - 2x Review/J2-X
« Reply #1 on: 02/13/2007 11:27 AM »
Really interesting. This confirms that Ross was wrong. Only one J-2X engine with two versions. J-2XD (derated) could be used for Ares1 initially with heritage J-2 turbines. In case of smooth J-2X production it can be used even for initial ISS Ares 1 increasing performance above baseline.
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Offline Jim

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Re: 3 Ares V design papers - 2x Review/J2-X
« Reply #2 on: 02/13/2007 12:07 PM »
Quote
JIS - 13/2/2007  7:27 AM

Really interesting. This confirms that Ross was wrong. Only one J-2X engine with two versions. J-2XD (derated) could be used for Ares1 initially with heritage J-2 turbines. In case of smooth J-2X production it can be used even for initial ISS Ares 1 increasing performance above baseline.

How was Ross wrong?

Offline JIS

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Re: 3 Ares V design papers - 2x Review/J2-X
« Reply #3 on: 02/13/2007 12:26 PM »
Couple of months ago we had discussion about J-2X. He said that two paralel production lines will be needed.
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Offline meiza

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Re: 3 Ares V design papers - 2x Review/J2-X
« Reply #4 on: 02/13/2007 01:19 PM »
The J-2 doc is good, it answers a lot of questions and clears confusion.
I've learned the following:
J-2 was the engine used in the Saturn Ib and V. It had gas generator powered turbopumps.
J-2S was a development with turbopumps powered by tapoff from main combustion chamber. This was simpler than J-2 but not test flown. I gather from the document that it used mk 29 type turbopumps.

Now, when making VSE a reality, NASA chose NOT to pursue J-2S because it was too unproven.
J-2SD was a J-2S with some differences, that are not very well stated. This was abandoned too.

J-2+ was used in the X-33 aerospike at the turn of the millennium.  It used existing mk 29 turbopumps (of the J-2S I presume) but new injector, chamber and nozzle. It was abandoned too.

What was chosen was J-2X, an advanced development of the J-2. It will use gas generator to power the turbopumps, like J-2 did. The GG exhaust will go to the nozzle to improve thrust. It will use mk 29O and mk 29F turbopumps from the X-33 project, but these will be updated as needed. What is interesting about the gas generator: "The gas generator will use a J-2 design for the 274,000 pounds-of-thrust engine (which will be discussed later) and a Rocketdyne RS-68 engine design for the
294,000 pounds-of-thrust model."
The nozzle will be modern.

So from all this I gather: J-2X will be using:
-gas generator derived from J-2 or RS-68
-turbopumps from J-2S (mk 29), that were also used in X-33
-injector somewhat similar to J-2 (but I guess it's mostly a new development), using coaxial elements
-new combustion chamber and nozzle.

The main questions were technology readiness level and thus schedule.

So, to sum it up: the GG cycle is from J-2, the pumps are from J-2S (which was tapoff cycle).

I wonder if I got it right now. It's on pages 5 and 6 in the pdf.

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