Author Topic: Nozzle Extension study of the J-2 and J-2S engines  (Read 16633 times)

Offline Downix

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While doing research on the J-2S+ from the ESAS report, I ran across a very interesting report put out by Goodyear, which was studying vacuum optimized nozzle extensions for the J-2 series of engines.  In it, they had a plethora of data of performance curves, expansion ratios, etc.  Studying the nozzle they designed for the J-2S, I realize that the final capability of the J-2S w/ the nozzle extension designed by Goodyear in the 1970's matched almost perfectly with the J-2S+ within the ESAS report, only a few kg of thrust and a half isp difference by my calculations.  In addition, the J-2S w/ nozzle extension matches the physical dimensions of the J-2X we have today.  So upon request, putting the document on here for everyone to enjoy.  I know I have enjoyed this insight into the J-2 evolution.
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Offline Blackstar

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #1 on: 05/12/2011 05:27 pm »
A couple of years ago I saw a few North American Aviation studies of uprated S-II stages for the Saturn V.  NAA built the S-II and so naturally they were always looking for opportunities to upgrade it and sell more of them.  One surprise was that some of the documents listed other upgrades for the J-2 engine.  I think there was a J-2T proposal, and also a J-2X proposal.  These designations were ca 1966, so they probably bore no correlation to later versions of this engine with similar designations.

I don't know if those were NAA designations, or if Rocketdyne had also proposed those variants of the J-2.  Anyway, my point is that during Apollo there were proposals to get more performance out of the J-2.  Of course, the same is true of the F-1.

Offline Downix

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #2 on: 05/12/2011 05:41 pm »
A couple of years ago I saw a few North American Aviation studies of uprated S-II stages for the Saturn V.  NAA built the S-II and so naturally they were always looking for opportunities to upgrade it and sell more of them.  One surprise was that some of the documents listed other upgrades for the J-2 engine.  I think there was a J-2T proposal, and also a J-2X proposal.  These designations were ca 1966, so they probably bore no correlation to later versions of this engine with similar designations.

I don't know if those were NAA designations, or if Rocketdyne had also proposed those variants of the J-2.  Anyway, my point is that during Apollo there were proposals to get more performance out of the J-2.  Of course, the same is true of the F-1.
The J-2X from back then is mentioned in this report as well, it was a sub-scale working model of the J-2 used for developing add-on technologies, such as the nozzle.  The J-2T was an aerospike version of the J-2, and it hit full prototype stage.  The idea behind the J-2T was to be able to turn the S-II into a much more capable launcher, with the J-2T on the second stage.  It shared 90% of the parts with the J-2S on the first stage of the proposal. The J-2T know-how of course was carried over to the X-33 aerospike program (which itself was based on the sub-scale J-2X of the 1960's I discovered, not the full-sized J-2S as often reported, and the production version for Venturestar would have used the full sized versions of the parts)
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Offline Prober

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #3 on: 05/12/2011 06:21 pm »
While doing research on the J-2S+ from the ESAS report, I ran across a very interesting report put out by Goodyear, which was studying vacuum optimized nozzle extensions for the J-2 series of engines.  In it, they had a plethora of data of performance curves, expansion ratios, etc.  Studying the nozzle they designed for the J-2S, I realize that the final capability of the J-2S w/ the nozzle extension designed by Goodyear in the 1970's matched almost perfectly with the J-2S+ within the ESAS report, only a few kg of thrust and a half isp difference by my calculations.  In addition, the J-2S w/ nozzle extension matches the physical dimensions of the J-2X we have today.  So upon request, putting the document on here for everyone to enjoy.  I know I have enjoyed this insight into the J-2 evolution.

Keep the info coming.....good find!    I did have problems with the ver i downloaded from this site so i looked it up.  The link:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730011573_1973011573.pdf

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Offline renclod

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #4 on: 05/12/2011 07:45 pm »
After going through 33% of the report, I don't understand if this Airmat *extendable* nozzle extension is useable for re-start.

Using the search function with "start", "loiter" gives nada.

Two issues:

1/ Ice forming inside the (4-inch wall thickness) nozzle extension after first cutoff. How to thermaly condition the extension, while loitering in LEO, if the object is a flapping in the ... vacuum. Especially with multiple engines. Is it sensitive to iced wall ?

2/ Assymetric loads on the nozzle wall at ingnition = restart. This Airmat thing must be hold in tension, otherwise it collapses under compression loads (it's in the paper). The initial deployment is controled,  from a known shape; but a re-start is different.

Will read forward to 100%, I promise.

edit. Finished. There's nothing about restartability. If anything, this report shows how *not* to build an extendable/deployable nozzle extenson. But cool nontheless.

« Last Edit: 05/12/2011 10:11 pm by renclod »

Offline Downix

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #5 on: 05/12/2011 11:39 pm »
After going through 33% of the report, I don't understand if this Airmat *extendable* nozzle extension is useable for re-start.

Using the search function with "start", "loiter" gives nada.

Two issues:

1/ Ice forming inside the (4-inch wall thickness) nozzle extension after first cutoff. How to thermaly condition the extension, while loitering in LEO, if the object is a flapping in the ... vacuum. Especially with multiple engines. Is it sensitive to iced wall ?

2/ Assymetric loads on the nozzle wall at ingnition = restart. This Airmat thing must be hold in tension, otherwise it collapses under compression loads (it's in the paper). The initial deployment is controled,  from a known shape; but a re-start is different.

Will read forward to 100%, I promise.

edit. Finished. There's nothing about restartability. If anything, this report shows how *not* to build an extendable/deployable nozzle extenson. But cool nontheless.

Indeed, a lot of lessons learned from this.  The modern RL-10B-2 nozzle demonstrates a lot of the lessons from this have been learned. 

This does at least show where the ESAS likely got the performance numbers for the J-2S+ from.
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Offline robertross

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #6 on: 05/13/2011 12:15 am »
While doing research on the J-2S+ from the ESAS report, I ran across a very interesting report put out by Goodyear, which was studying vacuum optimized nozzle extensions for the J-2 series of engines.  In it, they had a plethora of data of performance curves, expansion ratios, etc.  Studying the nozzle they designed for the J-2S, I realize that the final capability of the J-2S w/ the nozzle extension designed by Goodyear in the 1970's matched almost perfectly with the J-2S+ within the ESAS report, only a few kg of thrust and a half isp difference by my calculations.  In addition, the J-2S w/ nozzle extension matches the physical dimensions of the J-2X we have today.  So upon request, putting the document on here for everyone to enjoy.  I know I have enjoyed this insight into the J-2 evolution.

Oh thanks for posting it!

Offline Downix

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #7 on: 05/13/2011 12:36 am »
Did even more digging, and found other information:

J-2S in 1972:
Chamber Pressure: 1215 psia
Thrust: 1,178.8 kN
ISP: 436 w/o nozzle extension, 452 w/ nozzle extension

J-2S+ in ESAS report:
Chamber Pressure: 1246 psia
Thrust: 1,221 kN
ISP: 451

J-2X w/ J-2S tap-off cycle:
Chamber Pressure: 1219 psia
Thrust: 1,218.8 kN
ISP: 455s

J-2X w/ RS-68 derived gas generator: (current J-2X calculated)
Chamber Pressure: 1380 psia
Thrust: 1,307.8
ISP: 442
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Offline EE Scott

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #8 on: 05/13/2011 12:48 am »
Did even more digging, and found other information:

J-2S in 1972:
Chamber Pressure: 1215 psia
Thrust: 1,178.8 kN
ISP: 436 w/o nozzle extension, 452 w/ nozzle extension

J-2S+ in ESAS report:
Chamber Pressure: 1246 psia
Thrust: 1,221 kN
ISP: 451

J-2X w/ J-2S tap-off cycle:
Chamber Pressure: 1219 psia
Thrust: 1,218.8 kN
ISP: 455s

J-2X w/ RS-68 derived gas generator: (current J-2X calculated)
Chamber Pressure: 1380 psia
Thrust: 1,307.8
ISP: 442

Very interesting.  Does anybody know if there is any chance that the J-2X contract can be altered toward a higher isp/lower thrust version?  Or would this just set the project back too far?
Scott

Offline Downix

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #9 on: 05/13/2011 01:21 am »
Did even more digging, and found other information:

J-2S in 1972:
Chamber Pressure: 1215 psia
Thrust: 1,178.8 kN
ISP: 436 w/o nozzle extension, 452 w/ nozzle extension

J-2S+ in ESAS report:
Chamber Pressure: 1246 psia
Thrust: 1,221 kN
ISP: 451

J-2X w/ J-2S tap-off cycle:
Chamber Pressure: 1219 psia
Thrust: 1,218.8 kN
ISP: 455s

J-2X w/ RS-68 derived gas generator: (current J-2X calculated)
Chamber Pressure: 1380 psia
Thrust: 1,307.8
ISP: 442

Very interesting.  Does anybody know if there is any chance that the J-2X contract can be altered toward a higher isp/lower thrust version?  Or would this just set the project back too far?
They changed it to the gas generator to reduce the time to develop, as well as to increase thrust and try to save Ares I.  To change it now would delay the engine. However, it is a drop in replacement, and could be added back in, a Block II if you will.

Addendum, switching back also lightens the engine, going from 2,516 kg to 2,472 kg.  I also have realized that a lot of the documentation for the J-2X erroneously uses the earlier tap-off cycle information rather than the current iteration, or uses the higher specification of the two.

The original tap-off information from 2006 had the isp at 448, for instance, with the gas generator version at 236.  The 2007 update listed a performance upgrade for the engine which improved the isp for both the tap-off and gas generator versions, bringing them to the numbers I have above.
« Last Edit: 05/13/2011 02:20 am by Downix »
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Offline Prober

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #10 on: 05/13/2011 01:26 am »
After going through 33% of the report, I don't understand if this Airmat *extendable* nozzle extension is useable for re-start.

Using the search function with "start", "loiter" gives nada.

Two issues:

1/ Ice forming inside the (4-inch wall thickness) nozzle extension after first cutoff. How to thermaly condition the extension, while loitering in LEO, if the object is a flapping in the ... vacuum. Especially with multiple engines. Is it sensitive to iced wall ?

2/ Assymetric loads on the nozzle wall at ingnition = restart. This Airmat thing must be hold in tension, otherwise it collapses under compression loads (it's in the paper). The initial deployment is controled,  from a known shape; but a re-start is different.

Will read forward to 100%, I promise.

edit. Finished. There's nothing about restartability. If anything, this report shows how *not* to build an extendable/deployable nozzle extenson. But cool nontheless.
 
 

What type of nozzle extention does SpaceX use on the upper stage?
 
It glows in orbit but is simple and works.
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Offline robertross

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #11 on: 05/13/2011 01:50 am »
What type of nozzle extention does SpaceX use on the upper stage?
 
It glows in orbit but is simple and works.

Niobium IIRC

Offline Proponent

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #12 on: 05/13/2011 04:04 am »
A couple of years ago I saw a few North American Aviation studies of uprated S-II stages for the Saturn V.  NAA built the S-II and so naturally they were always looking for opportunities to upgrade it and sell more of them.  One surprise was that some of the documents listed other upgrades for the J-2 engine.  I think there was a J-2T proposal, and also a J-2X proposal.  These designations were ca 1966, so they probably bore no correlation to later versions of this engine with similar designations.

The J-2T, by the way, was aerospike version (T = toroidal) of the J-2 intended for growth versions of the Saturn V.  It appears to have been desired not for its altitude-compensating characteristics (the S-II being ignited at altitude anyway), but for for its reduced length, which allowed greater tank stretches without raising the roof of the VAB.

What I wonder is why the J-2T never appears to have been considered for the ground-launched versions of the S-II (e.g., the INT-17).  Then its natural altitude-compensation would have come in handy.
« Last Edit: 05/13/2011 04:44 am by Proponent »

Offline Prober

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #13 on: 05/13/2011 05:33 am »
A couple of years ago I saw a few North American Aviation studies of uprated S-II stages for the Saturn V.  NAA built the S-II and so naturally they were always looking for opportunities to upgrade it and sell more of them.  One surprise was that some of the documents listed other upgrades for the J-2 engine.  I think there was a J-2T proposal, and also a J-2X proposal.  These designations were ca 1966, so they probably bore no correlation to later versions of this engine with similar designations.

The J-2T, by the way, was aerospike version (T = toroidal) of the J-2 intended for growth versions of the Saturn V.  It appears to have been desired not for its altitude-compensating characteristics (the S-II being ignited at altitude anyway), but for for its reduced length, which allowed greater tank stretches without raising the roof of the VAB.

What I wonder is why the J-2T never appears to have been considered for the ground-launched versions of the S-II (e.g., the INT-17).  Then its natural altitude-compensation would have come in handy.

Kind of interesting you bring up the (T = toroidal).  I've had a star shape in the SS solids in my head.  Do the solid motor engineers know something the liquid guys don't?
 
 
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Offline Proponent

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #14 on: 05/13/2011 05:39 am »
I don't see any connection between the shape of a solid-propellant grain and an aerospike.

Offline STS-200

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #15 on: 05/13/2011 09:16 am »
J-2S in 1972:
Chamber Pressure: 1215 psia
Thrust: 1,178.8 kN
ISP: 436 w/o nozzle extension, 452 w/ nozzle extension

Many thanks for posting the file.

Thought I'd attach a couple of refs to the standard J-2S, just in case folks haven't come across them.
First file is huge and quite specific to the Saturn V, although there some good details on the engine at the start.
Second (smaller summary file) suggests that the ground tests showed the J-2S performed somewhat better than the specification.

http://hdl.handle.net/2060/19690072871
http://hdl.handle.net/2060/19690073042

(Search NTRS for "J-2S improvement study" if the links don't work).
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Offline Downix

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #16 on: 05/13/2011 03:49 pm »
Very nice, going over them now.

I'll admit, studying the history of the J-2 has given me new respect for the PWR engineers behind the J-2X, and I'm seeing more in common than I used to.
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Offline clongton

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #17 on: 05/15/2011 11:53 pm »
Nice find Downix. Keep it coming.
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I started my career on the Saturn-V F-1A engine

Offline simonbp

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #18 on: 05/16/2011 10:10 pm »
J-2X w/ J-2S tap-off cycle:
Chamber Pressure: 1219 psia
Thrust: 1,218.8 kN
ISP: 455s

Interesting, I hadn't realized that the move to RS-68 turbomachinery had made such a difference.

Just for comparison that's better Isp than RL-10A-4-2 (@ 451s), but still below the nozzle-extended RL-10B-2 (@ 464s), though all three are pretty darn similar. More to the point, the thrust is equal to 11x RL-10B-2 or 12.3x RL-10A-4-2. If you need the thrust, I can't imagine J-2X being twelve times more expensive than RL-10A-2.

Offline Downix

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Re: Nozzle Extension study of the J-2 and J-2S engines
« Reply #19 on: 05/16/2011 11:44 pm »
J-2X w/ J-2S tap-off cycle:
Chamber Pressure: 1219 psia
Thrust: 1,218.8 kN
ISP: 455s

Interesting, I hadn't realized that the move to RS-68 turbomachinery had made such a difference.

Just for comparison that's better Isp than RL-10A-4-2 (@ 451s), but still below the nozzle-extended RL-10B-2 (@ 464s), though all three are pretty darn similar. More to the point, the thrust is equal to 11x RL-10B-2 or 12.3x RL-10A-4-2. If you need the thrust, I can't imagine J-2X being twelve times more expensive than RL-10A-2.
Right.  The tap-off is also simpler/cheaper to build.
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