J-2S vs RLX vs RS-68r+

PurduesUSAFguy · 2006-02-03 17:11:14

RS-68 and J-2 are two great engines that would go well together. With the ablatives, you don't even need channel-wall--thought that shouldn't be too hard to copy if need be.

If (hopfully) when NASA goes with the RS-68 I would expect an eventual evolution to a regenerative nozel, the only thing Boeing needs is a firm order to develop them.

GCNRevenger · 2006-02-03 22:35:21

If Boeing can make the RS-68 "R" model without substantial development cost or time, then swell, but if not then we ought to stick with the ablative model. I am not so sure we ought to trust Boeing to deliver on the improved model, so if the SSME is dropped then NASA ought to plan Moon vehicle masses based on the regular model RS-68, with the "R" model being an upgrade.

Yang Liwei Rocket · 2006-03-20 01:35:18

We're not going to get past the "NIH" problem, because:
-It will still be made in Russia, which would still have veto power over our space program as a weapon.
-It will still be a Russian engine, even if its built here, with the associated image & political damage to NASA.
-NASA needs the engine fast, Russia may not even be able to build them soon, much less be validated in time.
-If Congress permits NASA to abandon SSME, then NASA should just use J-2S and RS-68; forget RD-0120.
The J-2S engine coupled with the bigger five segment booster is a viable alternative to SSME for the CEV launcher, especially since NASA was planning on developing both engines later anyway. The RS-68, with its superior thrust and comperable Isp at sea level, will not cause a signifigant reduction in payload of the big HLLV either, and is available off-she-shelf, no modification required.
Edit: Looking more into how complicated the SSME is, I think abandoning it entirely is looking like a better deal by the minute.

I see your point

SpaceNut · 2006-03-20 08:56:30

Futher details on SSME vs RS68 NASA Eyes Alternative to Shuttle Main Engine for Heavylift

The RS-68 engine can produce more total thrust than the SSME, but the RS-68 has a much lower specific impulse, making it something of a fuel hog.
One possible solution for keeping an RS-68-powered rocket from growing too tall, even for the 52-story Vehicle Assembly Building at Kennedy Space Center, would be to build it wider and add an extra stage.

GCNRevenger · 2006-03-20 09:26:24

Futher details on SSME vs RS68 NASA Eyes Alternative to Shuttle Main Engine for Heavylift
The RS-68 engine can produce more total thrust than the SSME, but the RS-68 has a much lower specific impulse, making it something of a fuel hog.
One possible solution for keeping an RS-68-powered rocket from growing too tall, even for the 52-story Vehicle Assembly Building at Kennedy Space Center, would be to build it wider and add an extra stage.

Yay! NASA talking some sense for once!

"While human-rated and highly reliable, the reusable SSMEs are expensive to manufacture. NASA and its contractors are looking at whether an expendable version of the SSME could be produced more cheaply, but NASA officials have privately expressed doubts about just how much cost can be squeezed out of the roughly $50 million per copy engine.

The RS-68, at roughly $14 million per copy, is cheaper to manufacture, but it does not have the SSME’s track record...

...Sources familiar with the Exploration Systems Architecture Study trade analysis that recommended the SSME as the best choice for the heavy-lift rocket, said that while the RS-68 might be cheaper to build, it also offers less performance and would have to be human-rated before trusting it to launch Moon- and Mars-bound hardware worth billions of dollars.

Although the heavy-lifter is expected to enter service around the middle of the next decade as a dedicated cargo launcher, Dumbacher said NASA wants to preserve the option of eventually using the heavy-lifter to launch humans."

Lets see here NASA...
$250M for SSME
$56-70M for RS-68

Can it really possibly cost more then saving $200M on every SDV flight to knock some heads in Michoud to build the tank a few dozen centimeters wider? You are going to redo the launch table at KSC anyway, scoot the SRB clamps out a little further and cut a few feet of concrete out of the flame trench.

And is man rating really worth it? We won't be sending humans to the Moon by direct flight until we at least have a base, and even the big 125MT payload isn't enough to go directly to Mars as Bob Zubrin calls for in MarsDirect. About the only drawback of not man-rating is losing the ability to go direct to the Moon once return fuel is available there, but this is some time down the road, isn't the assured savings of hundreds of millions a year worth the risk that RS-68 can't be man-rated? Even if it can't be, it will cost about as much to launch crews on TheStick seperatly as it would have cost to send them direct with SSME.

Its good that they are talking seriously about getting rid of the SSME, since this is a signifigant "sentimental" and political symbol of the way things used to be done, perhaps being done away with because it is technically not worthwhile. This is kind of a big deal, NASA is talking about trading engines despite engineer and congressional whining to save big money!

The SSME is one of the most complex pieces of engineering ever built by man, and it is not very likly that it can be substantially simplified. If you start throwing away turbopumps, regenerative nozzles, building less fancy combustion chaimbers, etc then the engine won't have any better performance then RS-68.

Commodore · 2006-03-20 09:46:10

Between the much lower cost, and the potential for a wider payload faring, its there really a downside to this?

If they really want to man-rate the engine, they can do it on a Delta-4H. Which would actaully be handy should we ever have issues with the Stick or want to launch more people in less time. Should we ever get a serious Moon base, were going to want to put more than 6 people into orbit at a time to man it. Though a Falcon-9 would probably be more budget friendly.

GCNRevenger · 2006-03-20 10:01:58

Between the much lower cost, and the potential for a wider payload faring, its there really a downside to this?
If they really want to man-rate the engine, they can do it on a Delta-4H. Which would actaully be handy should we ever have issues with the Stick or want to launch more people in less time. Should we ever get a serious Moon base, were going to want to put more than 6 people into orbit at a time to man it. Though a Falcon-9 would probably be more budget friendly.

The current model is already capable of launching 10m diameter payloads, so faring size isn't an issue I don't think. About the only problem is possibly losing the ability to go directly to anywhere, and perhaps the loss of a few tonnes of payload. Michoud was built to make 10m Saturn-V stages, so if they can't make a 9m Shuttle tank, then Griffin needs to take a trip to Lousiana' with a truck load of pink slips.

No, even if we do "get serious" about a Moon base, NASA won't need more then six people. Mining companies might, but if they are going to mine the Moon, they are going to need a cheaper way to get there then VSE ships anyway. In that case, Falcon-IX or Kistler KH-1 are probobly the best bet.

Commodore · 2006-03-20 10:42:52

The other "downside" mentioned was the requirement to retool the VAB and other support facilities becuase the existing shuttle hardware would be unusable. But if we are going to save $200mil a flight on the engines alone, I would think it would pay for itself many times over its lifetime.

GCNRevenger · 2006-03-20 10:51:47

I think that goes without saying

It was rebuilt to go from the 10m Saturn-V to the 8.4m Shuttle, how hard can it be to go to a 9m Shuttle-based tank?

PurduesUSAFguy · 2006-03-20 12:20:46

I think that goes without saying
It was rebuilt to go from the 10m Saturn-V to the 8.4m Shuttle, how hard can it be to go to a 9m Shuttle-based tank?

Might be really easy if you want to go real big and adopt a 10m diameter tank, since I suspect that much of the Saturn handling hardware is likley still in place.

SpaceNut · 2006-03-20 12:24:56

But even when we do make the changes to build the SDV HLLV tanks it is more than possible that this would interupt construction of the standard size ET. Also this premissed on using not only the RS-68 but also the 5 segment SRB as well. This combination would not only need wind tunnel testing for aerodynamics but would cost an addition billion or so and possibly 4 years to first flight use.

GCNRevenger · 2006-03-20 13:17:12

So what if Michoud and KSC can't handle SDV and Shuttle tanks simultainiously, Michoud ought to be done building Shuttle tanks by 2008-2009 and Shuttle ends in 2010, which is years before the SDV is supposed to go into production.

The basic shape of the main tank, payload faring, and solid rocket boosters are not exactly that complex, I don't see how wind tunnel testing would take much longer then for the smaller SSME-powerd rocket. And why would it take an additional billion dollars? Did you pull that number out of thin air? Even if it did, NASA would still save money by going with RS-68 in the long run.

publiusr · 2006-03-23 15:39:34

Very true. What's more--even the EELV salesmen were pushing widebody varients of their lvs, that would probably cost the same in new tooling as CaLV--but still be far less capable (30-40 tons per five RS-68 "Delta V" vs. 100 tons or so for CaLV).

Perhaps four RS-68s might surround one of the STS SSMEs when the orbiters are thankfully retired.

GCNRevenger · 2006-03-23 15:47:42

"30-40 tons per five RS-68 "Delta V""

Thats not true, its closer to 60MT, and each of those Shuttle SRBs costs about as much as two RS-68's.

A mixture of RS-68 and SSME would help in theory, but it wouldn't work in practice. Control systems for two completly different engines, and if one engine is unavailable, then neither will fly. Trying to strike a middle ground is the wrong idea, RS-68 was made with trading cheaper engines for bigger fuel tanks versus SSME, and so that is what NASA might just have to do.

publiusr · 2006-03-23 16:04:22

That sounds reasonable enough--and would save money in keeping all the CaLV fittings standardized. I just hope we can get CaLV under contract before a future administration kills it.

SpaceNut · 2006-06-05 19:50:59

$50m contract for moon engine development

NASA has awarded a contract worth $50 million to Pratt & Whitney Rocketdyne for the development, testing and evaluation of the J-2X engine.
The contract with the Californian company runs from June 2 through to November 30, surrounding the Systems Requirements Review scheduled for September and a Systems Design Review in October.

SpaceNut · 2006-08-11 20:25:33

I am wondering if the RS-68 can be air started/ restarted as a second stage for the CLV if the pretest of the 4 segment booster was used with the extra segment plus dummy payload weight for the CEV stage plus as proposed.

If so we can short cut by a considerable amount of design and use the Delta IV medium placed on top of the SRB as a means to do this pretest.

GCNRevenger · 2006-08-11 21:38:15

No, RS-68 is not a practical second-stage engine:

~RS-68 has tripple the thrust of J-2
~RS-68 has 16sec less Isp
~RS-68 weighs 7MT versus J-2's 1.4MT (the biggie)

Just figuring out how to attach RS-68 to the first stage will wipe out development savings if in addition to the J-2 model.

publiusr · 2006-08-17 10:42:12

It looks as though this J-2 will use channel wall like the larger RD-0120 from the Energiya Core block.

SpaceNut · 2006-12-12 22:37:54

Here are the references that I have found with detail data on the J2-X engine.

Ares I making good progress - Davis

NASASpaceflight.com: What is the expected performance P&W have been able to assure NASA of (274,500lb thrust, 448s vac Isp?), and do you have any idea what performance figures they are hoping to achieve (295,000lb thrust, 452s vac Isp)?
Davis: NASA engineers and project personnel have worked closely with PWR in designing the concept engine and setting the requirements. We are planning for a 294klbf engine at 448 sec Isp (minimum) / 452 sec (nominal) for the later lunar missions. This could come in the form of a 274klbf capability initially for LEO missions with a later modification for 294klbf or possibly just go directly to 294klbf - design and developmental testing will determine the final approach in the next year.

NASA develops two versions of J-2X engine for Ares boosters I and V

It has been a while and other than a prelimanary test not much else has occured.

SpaceNut · 2006-12-21 22:09:58

Volvo Aero in collaboration with PWR and NASA on the return to the moon

PWR has chosen Volvo Aero for its extensive experience in development and manufacturing of rocket nozzles.
PWR selected Volvo Aero because of the technologies Volvo Aero has developed for actively and passively cooled nozzle extensions in close collaboration with the Swedish National Space Board (SNSB). The lead theme in the development of new technologies at Volvo Aero has been to combine as simple as possible designs with robust manufacturing processes thus enabling a high reliability at a low product cost.
“The Vulcain 2 film cooling technology was developed on a requirement from ESA to increase performance at a lower cost. For the J-2X engine this will enable a light weight design with maximized performance at a minimum of lead time and cost,” he adds.

SpaceNut · 2007-02-16 07:08:54

Development of the J-2X engine, Jim Snoddy Manager MSFC (PDF 8MB)
The Constellation Program selected the Pratt & Whitney Rocketdyne J-2X engine to power the Ares I Upper Stage Element and the Ares V Earth Departwe Stage.This paper narrates the evolution of that decision; describes the performance capabilities expected of the J-2X design, including potential commonality challenges and opportunities between the Ares I and Ares V launch vehicles; and provides a current status of J-2X design, development, and hardware testing activities. This paper also explains how the J-2X engine effort mitigates risk by building on the Apollo Program and other lessons lived to deliver a human-rated engine that is on an aggressive development schedule, with its first demonstration flight in 2012.
More about the J-2X than you probably want to know. Lots of details.

Nasa sure does make alot of documents....

cIclops · 2007-02-16 07:37:06

Yeah lol, if you could pile them all up you wouldn't need to build a space elevator.

cIclops · 2007-04-18 22:52:07

Paul Coffman is currently working on J-2X for Pratt Whitney Rocketdyne and also worked on the original J-2.
In the Space Show Coffman discusses the J-2X and improvements in rocket engines since Apollo

SpaceNut · 2007-08-19 20:21:26

Back a while ago the Boeing and Lockheed camps united and this may be just a bit of fall out from that action.

Pratt & Whitney Machinists Reject Contract; Job Growth, Insurance Reasons For Rejection

the company's lack of commitment to add jobs in Connecticut and a proposed 60 percent increase in health insurance premiums for workers.
The new contract included pay increases of 3.5 percent for each of the three years, retroactive to July 1, and a $3,000 signing bonus. The current contract expires Dec. 2.
Beside the pay raises, the company offered a $3,000 ratification bonus to employees and said it would match half that amount if workers put the money into their retirement savings plans.
Pratt & Whitney Rocketdyne Inc., a subsidiary, announced in June a $1.2 billion NASA contract to design and develop rocket engines for the next generation spacecraft that would eventually send astronauts back to the moon.

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#51 2006-02-03 17:11:14

Re: J-2S vs RLX vs RS-68r+

#52 2006-02-03 22:35:21

Re: J-2S vs RLX vs RS-68r+

#53 2006-03-20 01:35:18

Re: J-2S vs RLX vs RS-68r+

#54 2006-03-20 08:56:30

Re: J-2S vs RLX vs RS-68r+

#55 2006-03-20 09:26:24

Re: J-2S vs RLX vs RS-68r+

#56 2006-03-20 09:46:10

Re: J-2S vs RLX vs RS-68r+

#57 2006-03-20 10:01:58

Re: J-2S vs RLX vs RS-68r+

#58 2006-03-20 10:42:52

Re: J-2S vs RLX vs RS-68r+

#59 2006-03-20 10:51:47

Re: J-2S vs RLX vs RS-68r+

#60 2006-03-20 12:20:46

Re: J-2S vs RLX vs RS-68r+

#61 2006-03-20 12:24:56

Re: J-2S vs RLX vs RS-68r+

#62 2006-03-20 13:17:12

Re: J-2S vs RLX vs RS-68r+

#63 2006-03-23 15:39:34

Re: J-2S vs RLX vs RS-68r+

#64 2006-03-23 15:47:42

Re: J-2S vs RLX vs RS-68r+

#65 2006-03-23 16:04:22

Re: J-2S vs RLX vs RS-68r+

#66 2006-06-05 19:50:59

Re: J-2S vs RLX vs RS-68r+

#67 2006-08-11 20:25:33

Re: J-2S vs RLX vs RS-68r+

#68 2006-08-11 21:38:15

Re: J-2S vs RLX vs RS-68r+

#69 2006-08-17 10:42:12

Re: J-2S vs RLX vs RS-68r+

#70 2006-12-12 22:37:54

Re: J-2S vs RLX vs RS-68r+

#71 2006-12-21 22:09:58

Re: J-2S vs RLX vs RS-68r+

#72 2007-02-16 07:08:54

Re: J-2S vs RLX vs RS-68r+

#73 2007-02-16 07:37:06

Re: J-2S vs RLX vs RS-68r+

#74 2007-04-18 22:52:07

Re: J-2S vs RLX vs RS-68r+

#75 2007-08-19 20:21:26

Re: J-2S vs RLX vs RS-68r+

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