AJ-1E6 (Now AR-1) Progress Known?

[TomH]

....the main issue is that the boosters are volume limited. They can't be bigger than 5.5m, due to VAB size. So, you couldn't really put a booster much bigger than a Delta IV. You could put about 80% more propellant than a Delta IV core stage. And let's say that you add four engines (you can't fit more), that's 3Mlbf per booster. But you'd only have fuel for around 115s (back of the envelop calculation), that's even less than the SRB!...

Lobo, I told you this same thing earlier in the thread. HydroLox boosters on this beast would simply be too big. LH2 is low density and requires so much volume that the boosters would be so big the thing could not fit through the doors. It wouldn't even come close.

Edit: I see you addressed this and posted 2 minutes before I did. I don't see all that raising the booster height and flaring out as viable design. I think they want the booster to attach to the core at the top of the booster.

BTW: the thread topic regards known progress on AJ-1E6. We are getting away from that.

[Lobo]

Edit: I see you addressed this and posted 2 minutes before I did. I don't see all that raising the booster height and flaring out as viable design. I think they want the booster to attach to the core at the top of the booster.

Not saying it's the best way, just that it was feasible, unlike your post that it would be too wide. 
But remember the the booster height was an issue only in the 2001 study because this would be an STS booster replacement, and they didn't want the boosters as tall or taller than the ET.  I believe the booster height requirement for SLS Advanced boosters is actually more than these would have been.  So not an issue for SLS.
THe MPS can flair out, as the VAB doors are wide on the bottom.  That's how the STS wings got out.  Just can't be more than 5.5m higher up. 
Such a booster would just have to be designed such that the MPS and engines don't interfere with the SLS core MPS.  But that's the same for any new booster.  Dynetics gets around this by flaring out the two F-1B nozzles the other direction.  4 or 5 RS-68A nozzles might or might not be a problem to accomodate.  A Rocket scientist will have to answer that.  My guess would be that 4 RS-68's could be accomodated in by putting two pairs on each side of the core, basically where the F-1B's are on the Dynetics booster, but two RS-68's there instead of one F-1B.  Not sure if the two pairs could be moved far enough out to accomodate a 5th RS-68 right in the middle or not.  But maybe.  It'd look like the 5-engine pattern on the S-1C, but with the four outter engines squeezed together on opposite sides so they don't protrude too close to the SLS core.
Again, that's for a rocket engineer, not for me.  :-)

BTW: the thread topic regards known progress on AJ-1E6. We are getting away from that.

Good point.
Although, I think the point of the thread is the AJ-1E6 for use on the SLS boosters, which sort of by default creates discussions about the SLS booster options, in comparison and contrast.

While RS-68A's could probably be used, on a booster that would fit within the Advanced booster limitations, and it would have some potential economic advantages of cost sharing, the same might apply to the AJ-1E6, particularly if Atlas V were to consider going to it at some time (if it doesn't go away in favor of ULA supporting Delta IV only) and depending on what the future of Antares holds.  If it has limited launches for COTS only, then it probably won't have enough flight rate to cost share much with, and likely USAF contracts woudl be going over to ULA and possibly SpaceX.   Not sure if Antares would even be a player there.  So not much cost sharing with USAF unless they tell ULA they don't want them to use that Ruskie built engine any more since a fairly direct replacement is available in the market in the AJ-1E6.
But...if there could be...then I'd think AJ-1E6 could be as economical as RS-68A, and probably a better booster engine choice overall.

[Lobo]

Tom,

This discussion made me think about this:

http://forum.nasaspaceflight.com/index.php?topic=32705.msg1092057#msg1092057

Aerojet now owns the rights to RD-180 don't they?
RD-180 is almost a complete overlap of AJ-1E6.  Must more so than F-1B is with AJ-1E6.

Might that see a future most for Aerojet-Rocketdyne to phase out the procurement of the Russian made RD-180 in favor of the US-built AJ-1E6?  Which would be a similar engine.
A scenario where AJ-1E6 might be used for Atlas V and Antares would then make a very strong cost sharing and standardization case for AJ-1E6 for SLS.

[baldusi]

Aerojet now owns the rights to RD-180 don't they?

Not exactly RD AMROSS has the rights. And PWC participation (49%, I believe) has yet to be transferred to AJ parent company (the Russian government has to allow it, which is part of the ongoing political issues).
So the US could do a local RD-180, but I think they would have to do it through RD AMROSS. I guess Rocketdyne (and thus AeroJet) has the rights to the technology, though.
But remember that the AJ proposal for SLS boosters is very "risky" for NASA's risk formula. And both ULA and Orbital are commercial companies. They won't buy it because it's cool, or even because it's American. They would buy it if and only if it made business sense. Thus, the true question is: Can AJ make the AJ-1E6 cheaply enough to be competitive in current (and future) market?

[Lobo]

Not exactly RD AMROSS has the rights. And PWC participation (49%, I believe) has yet to be transferred to AJ parent company (the Russian government has to allow it, which is part of the ongoing political issues).
So the US could do a local RD-180, but I think they would have to do it through RD AMROSS. I guess Rocketdyne (and thus AeroJet) has the rights to the technology, though.
But remember that the AJ proposal for SLS boosters is very "risky" for NASA's risk formula. And both ULA and Orbital are commercial companies. They won't buy it because it's cool, or even because it's American. They would buy it if and only if it made business sense. Thus, the true question is: Can AJ make the AJ-1E6 cheaply enough to be competitive in current (and future) market?

Yes, can they make it cheaply enough to be competative?  That is the real question.  But, could Aerojet now sort of torpedo the produrement of more RD-180's to the US, even if there wasn't a problem on the Russian side?  Although problems from the Russian government would make that easier. 
How would RD-180's get here if Aerojet decided they didn't want them here?  (assuming existing contracts were met, just that new ones wouldn't be)

Could Aerojet box out the cheaper competition and not bring any more in, so as to -create- a market for the AJ-1E6?
Or could Energomash just sign a deal with a different US company to import them into the US and make them available to ULA?  Perhaps with ULA directly?  And go around Aerojet-Rocketdyne entire?

Also, is sounds like Orbital is sueing ULA for barring them from getting the RD-180, so they used the AJ-26/NK-33 instead?

If the deal was between PWR and Energomash, how could ULA bar Orbital from getting them?  I don't really understand that relationship. 
Does Orbital still want the RD-180 now that they are using AJ-26?  I'd think if they switch engines, with would be more logical to go with another Aerojet engine rather than RD-180.

Dunno...I agree companies won't buy the AJ-1E6 just because it's cool or US made, but if it make financial sense.  However, a company like ULA which is almost completely government launches, probably will do pretty much what the government wants.  I wonder if these rumblings, even if nothing comes from them ultimately, will make a few at USAF/DoD perk up and think that maybe having one of their EELV's dependant on the Russians isn't perhaps the best idea, any more than it's the best idea to be reliant on them for human space access?
Might USAF/DoD decide they don't want to support an LV that depends on a Russian supplied engine any more?  Meaning, Atlas needs to find a domestic replacement, or Atlas goes away, and Delta is standardized for all govenrment launches ULA gets?

Also, I was not aware that NASA deemed the Aerojet boosters as "risky".  Is that just becuase they are staged combustion?  Or for some other reason?

[baldusi]

How would RD-180's get here if Aerojet decided they didn't want them here?  (assuming existing contracts were met, just that new ones wouldn't be)

Difficult to say, but Rocketdyne was the local partner of RD AMROSS. And the minority, at that. Their role is mostly local support. Remember that ITAR prevents a an American engineer to actually tell to a Russian engineer what went wrong. And the Russian equivalent prevents the Russian to answer how to solve it. So each interchange has to be cleared by whoever is that handles ITAR permits.

Could Aerojet box out the cheaper competition and not bring any more in, so as to -create- a market for the AJ-1E6? Or could Energomash just sign a deal with a different US company to import them into the US and make them available to ULA?  Perhaps with ULA directly?  And go around Aerojet-Rocketdyne entire?

I think that Energomash would have to honor their contracts with RD AMROSS, and then they would have to apply again for the permits to transfer the know-how etc. Sort of non viable. But AeroJet has little say, since they don't produce the engine and they lack a majority on RD AMROSS. Overall, they might try to increase their support costs part of the price, but then they'd get into a nasty monopoly issue. Trust me, they don't like to get into anti trust problems. Specially not if DoD is the angry party.

Also, is sounds like Orbital is suing ULA for barring them from getting the RD-180, so they used the AJ-26/NK-33 instead?
If the deal was between PWR and Energomash, how could ULA bar Orbital from getting them?  I don't really understand that relationship. 
Does Orbital still want the RD-180 now that they are using AJ-26?  I'd think if they switch engines, with would be more logical to go with another Aerojet engine rather than RD-180.

First, let's remember that the NK-33 stock is limited, and Orbital might have just enough to cover the CRS contract and, may be, a couple of extra launches. And also let's remember that Kutznesov has not received the funds to actually install the necessary tooling. They currently produce aircraft turbines. So the NK-33 supply is limited and extending it would cost a fortune. So AeroJet would be happy to sell Orbital more NK-33A (or however they call them), but I'm pretty sure they will ask for a BIG number. A number big enough that they can argue that it's not a "realistic choice", or that doing it is "economically" unfeasible.
Now, the interesting part is why they are suing ULA. And the reason is that they are using anti-trust law. And the one that actually holds the alleged monopoly on DoD launches is ULA. Thus, the problem is not that RD AMROSS signed an exclusivity contract, but that ULA "forced" them to sign it using its monopoly powers to keep Orbital out of said market.

...Might USAF/DoD decide they don't want to support an LV that depends on a Russian supplied engine any more?  Meaning, Atlas needs to find a domestic replacement, or Atlas goes away, and Delta is standardized for all government launches ULA gets?

Atlas V is cheaper than Delta IV, has lower lead time and (until 2015) has better flexibility for swapping payloads. But more importantly, the EELV's program has grown so expensive that I seriously doubt that anyone would want to actually put more money. I think is more of a "we'll deal with it if it happens" situation.

Also, I was not aware that NASA deemed the Aerojet boosters as "risky".  Is that just because they are staged combustion?  Or for some other reason?

Yes, look at how they calculate risk. Staged Combustion is considered the riskiest of all. And the number of engines and thrust chambers is also the biggest. It's a statistics game, really. Gas Generator catastrophic failure is not really that bad, as SPX CRS-1 shown. And as Zenit-2 Teselin-2 #8 and NSS 8 shown, Stage Combustion failure modes can be nasty. Thus, the risk penalty on SC is huge. And again, you multiply that failure probability by the number of turbopumps. And the thrust chamber failure modes by the number of thrust chambers (including start failures). When you do it that way, the AeroJet proposal will be the most risky.
Personally, I think is an exaggeration since they should only worry about LOM and LOC, and the truth is that even a TP explosion on the AJ boosters would mean the same as an early engine shutdown on the Pyros: LOM. Remember that you have to keep the boosters depleting the propellant at the same rate, else you move your CG asymmetrically and lots of nasty things happen. And SLS is assumed to be on the limit of performance, thus, even the loss of one F-1B midflight will probably mean LOM. And STS-51L shown quite clearly what a failure on a solid booster would mean (and the advanced ones would have like 50% more pressure).
Now, let's suppose that you calculate LOC. I don't think that even a catastrophic failure like NSS 8 would mean LOC in a LRB. The engines are simply too far from the capsule, and you could shut down all orderly. That's the part that I don't like of the calculation. That and the fact that in real use, the SC cause one abort to orbit, while a SSSRB caused a LOM. And there were 3 SC vs 2 x SRB per STS flight.

[Lobo]

Thanks for all the clarifications baldusi.

The legalize of it all is quite beyond me.  :-)

[Lobo]

Yes, look at how they calculate risk. Staged Combustion is considered the riskiest of all. And the number of engines and thrust chambers is also the biggest. It's a statistics game, really. Gas Generator catastrophic failure is not really that bad, as SPX CRS-1 shown. And as Zenit-2 Teselin-2 #8 and NSS 8 shown, Stage Combustion failure modes can be nasty. Thus, the risk penalty on SC is huge. And again, you multiply that failure probability by the number of turbopumps. And the thrust chamber failure modes by the number of thrust chambers (including start failures). When you do it that way, the AeroJet proposal will be the most risky.
Personally, I think is an exaggeration since they should only worry about LOM and LOC, and the truth is that even a TP explosion on the AJ boosters would mean the same as an early engine shutdown on the Pyros: LOM. Remember that you have to keep the boosters depleting the propellant at the same rate, else you move your CG asymmetrically and lots of nasty things happen. And SLS is assumed to be on the limit of performance, thus, even the loss of one F-1B midflight will probably mean LOM. And STS-51L shown quite clearly what a failure on a solid booster would mean (and the advanced ones would have like 50% more pressure).
Now, let's suppose that you calculate LOC. I don't think that even a catastrophic failure like NSS 8 would mean LOC in a LRB. The engines are simply too far from the capsule, and you could shut down all orderly. That's the part that I don't like of the calculation. That and the fact that in real use, the SC cause one abort to orbit, while a SSSRB caused a LOM. And there were 3 SC vs 2 x SRB per STS flight.

Yea, I think that's a good point there.
First, I think any LOC calculation should be better for any LRB vs. SRB because unless it's so catastrophic that it ruptures the fuel tank, as you said, it can be shut down, and the crew craft initiates a controled abort.  But even with a situation that there's a Challenger like failure in a booster, which ruptures the core or something, you have boosters that can be shut down, rather than burning SRB's that can only be blown up...possibly showering the capsule parachute with debris. 
So I would think any LRB LOC calculation should be better than any SRB LOC calculation.
(Heck, even in the huge N-1 failures, they had unmanned Soyuz capsules on them, and it's LAS system engaged properly and would have saved the crews from those explosions...at least one or two of them did.  And you don't really get more catestrophic that one of those going up!)

Now, as for LOM, like you said, an F-1B might have a better behaved failure, but with just engines, a failure to any one engine would result in a LOM if it happened too early in ascent.  If it happened closer to LRB-sep, then perhaps the opposite F-1B on the other booster could be shut down, and separation done a little later.  There might be less chance of the engine failure and causing the whole booster to blow up, and while that's good, it's still a LOM.  And that is what the LAS system is for is to abort away from any problem, up to the entire LV going boom.
The main difference would be the LV blowing it in flight, or having it do a controlled crash into the ocean after abort.

But...even that said...the RS-25's are staged combustion too.  So SLS already has four staged combustion engines that could possible fail in a less well behaved way that a GG hydrolox engine.  So that will always be an issue with SLS.  So I think it's probably a bit of a red herring. 
But...I'm not rocket scientist either.

But...do you think that "risk" will put a thumb on the scale to favor the Dynetics booster if an LRB were to beat out ATK?
The F-1B is an awesome engine.  Just seems like the AJ-1E6 might be a little more "useful" engine all around for the US rocket industry.

[baldusi]

I simply don't know the innards of the process. In particular, we don't know who will be at NASA nor Congress by the time comes to actually make the decision. And as far as I know, even the tender is not ready, thus, the parameters are totally unknown. I was just making a point about a potential disadvantage that I see in the AJ-1E6 project.

[Lobo]

I simply don't know the innards of the process. In particular, we don't know who will be at NASA nor Congress by the time comes to actually make the decision. And as far as I know, even the tender is not ready, thus, the parameters are totally unknown. I was just making a point about a potential disadvantage that I see in the AJ-1E6 project.

Understood.  Thanks for the information.  :-)

[Lobo]

Has Aerojet released any numbers on the AJ-500 or AJ-1E6 as to what the ISP will be?  Their sea level thrust will be about 500klbs and 1000klbs respectively, but will they have the lower ISP of the NK-33?  Or will the higher chamber pressure of pumping the thrust up to 500klbs per chamber increase the ISP closer to that of the RD-180?

[TomH]

Yea, Dynetics has released a substantial amount of information re. Pyrios and ATK re their Dark Knights. We have heard almost nothing from AJ re. AJ-1E6. We don't know anything about how they are using that risk-reduction funding. Since those are public funds, aren't regular milestone reports required? I do wish some basic specs would be released. Then Steven Pietrobon could run those calculations you asked him to with some degree of accuracy. Like you, I would really like to know how this would compare with Pyrios on 4 engine core with 4 x MB-60 DUUS.

[Lobo]

Yea, Dynetics has released a substantial amount of information re. Pyrios and ATK re their Dark Knights. We have heard almost nothing from AJ re. AJ-1E6. We don't know anything about how they are using that risk-reduction funding. Since those are public funds, aren't regular milestone reports required? I do wish some basic specs would be released. Then Steven Pietrobon could run those calculations you asked him to with some degree of accuracy. Like you, I would really like to know how this would compare with Pyrios on 4 engine core with 4 x MB-60 DUUS.

Yea, thrust level is all I've seen out.  I hope they will put out some more info soon so that we can more accurate info to use, rather than so many assumptions.

It'll be interesting to see how this all shakes out.
There is a potential US market for this engine, or a US made RD-180 (which I think they will be able to make too now that Aerojet owns Rocketdyne.)  Especially if NASA is interested in ORSC engine for an advanced boosters for SLS.
Atlas V and Antares being the other two.  If Aerojet plays their cards right, they could perhaps come out with a similar US engine that could be swapped out for the RD-180 on Atlas V, swapped out for the two AJ26's on Antares, and power SLS's boosters perhaps giving a Block 2B SLS over 130mt lift capacity with no SLS core or upper stage modificaitons (other than booster interfaces, and ML modificaiton if the existing one can even be used).

I think the main hurdle will be giving ULA an offering that will require minimal modifications to Atlas V, as well as very similar performance, and at a price point competative with the Russians.   RD-180 may be more expensive in the future...depending on poltics...so that would help Aerojet's case for a domestics replacement. 
Maybe they'll blend the NK-33 tech they've been learning with the new RD-180 designs they now have through Rocketdyne, and incorporate them into an "AJ/NK-180" basically.  Same mounts and controls and such as RD-180, but with NK-33 based components too. 

Since USAF is ULA's main customer, and USAF might not mind a small price increase for Atlas V in a switch to a domestic engine, there could be an angle to help a switch even if Aerojet can't match the Russians pricing.  If they can get close...and it's US made...and since it's the USAF...I would think that would be attractive to them.

[edkyle99]

Here is my attempt at a review of the basic corporate relationships involving the various players discussed in this thread.  I've skipped some details, such as Boeing's former ownership of Rocketdyne via. its acquisition from Rockwell International.

Pratt & Whitney:  Made RL-10 and jointly owned RD-AMROSS to import RD-180 from NPO Energomash.  RD-AMROSS originally set up to import RD-180 for Lockheed Martin Atlas III, later used for Lockheed Martin (later United Launch Alliance) Atlas V.  P&W was also licensed through RD-AMROSS to produce RD-180 in U.S..  United Technologies (UTC) owned P&W and currently still retains its RD-180 rights.

Aerojet (Gencorp):  Made AJ-10 and is licensed importer of NK-33, rebranded with new controller as AJ-26.  Subsequently proposed new upgraded engines based on NK-33/AJ-26 for SLS booster.

Rocketdyne:  Original F-1, and J-2(X), SSME developer.  RS-68 is most recent development.

In 2005, UTC bought Rocketdyne to create Pratt & Whitney Rocketdyne.

In 2013, Gencorp bough PWR to create Aerojet Rocketdyne, a company that currently builds RS-68, that is rebuilding an existing RL-10 engine inventory into a common EELV type, and that holds the NK-33 license, which currently consists of reconfiguring a limited inventory of 40 year old Russian engines for Antares.  Its planned acquisition of the RD-180 license is currently in limbo, as I understand things.  If it gains RD-180 rights, it seems to me very likely that RD-180 will replace NK-33/AJ-26.

 - Ed Kyle

[Lobo]

Here is my attempt at a review of the basic corporate relationships involving the various players discussed in this thread.  I've skipped some details, such as Boeing's former ownership of Rocketdyne via. its acquisition from Rockwell International.

Pratt & Whitney:  Made RL-10 and jointly owned RD-AMROSS to import RD-180 from NPO Energomash.  RD-AMROSS originally set up to import RD-180 for Lockheed Martin Atlas III, later used for Lockheed Martin (later United Launch Alliance) Atlas V.  P&W was also licensed through RD-AMROSS to produce RD-180 in U.S..  United Technologies (UTC) owned P&W and currently still retains its RD-180 rights.

Aerojet (Gencorp):  Made AJ-10 and is licensed importer of NK-33, rebranded with new controller as AJ-26.  Subsequently proposed new upgraded engines based on NK-33/AJ-26 for SLS booster.

Rocketdyne:  Original F-1, and J-2(X), SSME developer.  RS-68 is most recent development.

In 2005, UTC bought Rocketdyne to create Pratt & Whitney Rocketdyne.

In 2013, Gencorp bough PWR to create Aerojet Rocketdyne, a company that currently builds RS-68, that is rebuilding an existing RL-10 engine inventory into a common EELV type, and that holds the NK-33 license, which currently consists of reconfiguring a limited inventory of 40 year old Russian engines for Antares. 

Thanks Ed,
The big picture with all that legaleze is always a little disorientating.

Its planned acquisition of the RD-180 license is currently in limbo, as I understand things.  If it gains RD-180 rights, it seems to me very likely that RD-180 will replace NK-33/AJ-26.

So what about all of the pomp and circumstance for the AJ26/NK-33 derived AJ-500 and AJ-1E6?  Is that a backup plan in case Aerojet-Rocketdyne don't get the RD-180 liscence? 

And do you think they'd just continue to buy the Russian RD-180 and not make it themselves?  Or make a US built one since they'd have the rights to make it?  And then just call it an "AJ-1E6" or something and drop the Russian model references totally?  (Remove the Russian letters stenciled on the nozzles and replace them with a "Made in U.S.A" stencil...etc.).

On on a side note, do you know what the ancestory and heritage the NK-33 shares with the RD-180?
I sort of assumed that the RD-170/180/190 family developed for Zenit/Energia was based on the development done on the NK-15/33 under the Soviet umbrella in the 80's.  That development of the RD family didn't reinvent the wheel on kerolox ORSC, but used existing work done previously.
But perhaps that's incorrect?
I only mention that in the context as I sort of thought the NK family was the ancestor of the RD family.  And if that were the case, would an Aerojet built dual chamber ORSC kerolox engine in the 850-1000klbs thrust range at sea level basically be both a US built RD-180 -and- a modernized dual chamber version of the NK-33?

Or are they two completely unrelated engines?

[baldusi]

As far as I know it, they are completely unrelated. In particular, after Mishin's failure at N-1, he was replaced as head of Energyia by Glushko. Kutznesov's NK-15/33 family was an offense and was forbidden, and he directed his bureau to make a superior engine to that, thus, the RD-170 was born. Knowing how much Glushko hated the NK engines, I would be surprised that they shared any technology. May be they share some metallurgy, but I don't know the details.

[Lobo]

As far as I know it, they are completely unrelated. In particular, after Mishin's failure at N-1, he was replaced as head of Energyia by Glushko. Kutznesov's NK-15/33 family was an offense and was forbidden, and he directed his bureau to make a superior engine to that, thus, the RD-170 was born. Knowing how much Glushko hated the NK engines, I would be surprised that they shared any technology. May be they share some metallurgy, but I don't know the details.

Hmmm...interesting.  Seems like a waste to reinvent the wheel just based on some perceived loss of face.  But who knows with those crazy Ruskies.  heheheh

If they really are two completely unrelated engines, it does make for a quandry with Aerojet-Rocketdyne I would think.  Aerojet has invested a fair amount of money into making the NK-33 mount US controls and whatever else they've done to make the "AJ26" out of it.  Money and knowledge and experience that would sort of just be written off if they decide to just buy Russian made RD-180's.  I think they've also promoted their future NK-33 derived, US made variants as "USA Made" engines as opposed to those Russian made engines.  Perhaps that was just something flown out there before things worked out to where they could actually buy the RD-180 outright.  But it would seem to be a reversal of PR a bit.  But I suppose if the price is right, companies of flipped and reversed on things like that before.  Buying the RD-180 outright would save the development of tooling up a production line for an AJ-1E6 or a US-built RD-180.  Although I kind of like the thought of a US made engine filling this need in the US rocket industry.  But I suppose price is key.

And Orbital sounds like they want the RD-180 for Antares (they were sueing ULA for blocking RD-AMROSS's ability to sell it to Orbital...or something like that), and obviously it's already flying on Atlas.  Which then brings up the interesting situation of an Aerojet-Rocketdyne ORSC powered option for SLS.  With no AJ-1E6, that's just leave the RD-180 as the only other kerolox option vs F-1B...which would then also be an Aerojet-Rocketdyne engine. 
I suppose that gives an opportunity for an SLS booster, Antares, and ULA to all share a common engine.  Aerojet is already selling engines to Orbital, so I'd assume they'd jump at the chance to start selling them RD-180's once the NK-33 supply ran out...if there were no legal reasons they couldn't from ULA.
Which then makes an interesting cross over to Steve Pietrobon thread about SLS trajectories.  He was going to use some RD-180 data to model an AJ-1E6 powered SLS booster.  Maybe he can just now model an SLS using four RD-180's directly?

http://forum.nasaspaceflight.com/index.php?topic=32911.msg1111260#msg1111260

[Steven Pietrobon]

OK, in my search to find out as much information on the AJ1E6 as possible, I found these two documents:

S. Crumbly, "NASA's Space Launch System: Partnering for tomorrow," ASEE Eng. Research Council, Washington, DC, USA, Mar. 2013.
http://www.asee.org/Crumbly_ASEE_Final.pdf

S. Crumbly, "NASA's Space Launch System: Partnering for tomorrow," Space & Missile Defense Symp, Huntsville, AL, USA, Aug. 2013.
http://smdsymposium.org/wp-content/uploads/2013/09/Crumbly-presentation.pdf

The only figure mentioned is a thrust of 1.1Mlbf, presumably at sea level. However, I was able to extract these three nice images which are attached. I printed these out and using the 8.4074 m diameter of the core as a reference, I obtained the following measurements:

Booster Diameter: 5.1245 m
Booster Fairing Diameter: 6.5836 m
Nozzle Diameter: 1.8340 m
Engine Area Ratio: 31.04

For the boosters, I derived the following values:

Total Propellant Mass: 721,178 kg
Dry Mass less Engine Mass: 95,279 kg (using the Pyrios booster as a reference)
Oxidiser to Fuel Mixture Ratio: 2.693

Note that I've given the derived values to four or more significant figures, but in no way should you take that to mean an accuracy to that level. Accuracy is probably around ±5% and ±20% on the dry mass estimates. Now using the RD-180 as a reference, I was able to derive the following performance figures.

Sea Level Thrust: 4,893,044 N
Nozzle Efficiency: 0.893595 (derived from USAF Isp calculation program and RD-180)
Ideal Thrust Coefficient: 1.821
Chamber Pressure: 17,665,729 Pa
Vacuum Thrust: 5,428,390 N
Vacuum Isp: 3274.5 m/s
Engine Mass: 7466.7 kg

Again, accuracy is going to be ±5%. This then gave the following derived value for the booster:

Total Dry Mass: 116,679 kg

I've used these values in a simulation of SLS, but I ran out of time during the weekend to finish the results. Preliminary information indicates a payload to a 200 km circular orbit of 132.6 t using four RS-25D engines on the core and four MB-60 engines on the upper stage.

[Steven Pietrobon]

Which then makes an interesting cross over to Steve Pietrobon thread about SLS trajectories.  He was going to use some RD-180 data to model an AJ-1E6 powered SLS booster.  Maybe he can just now model an SLS using four RD-180's directly?

http://forum.nasaspaceflight.com/index.php?topic=32911.msg1111260#msg1111260

I believe the RD-180 does not have enough thrust. It has a sea level thrust of 3827 kN, compared to 4893 kN for the AJ1E6. That's a 22% reduction. If we have 4x3827 = 15,308 kN, then that compares favourably with 3x4893 = 14,679 kN. So you would need four RD-180 engines on each booster to get the required performance.

[Lobo]

Interesting.  Thanks Steve,

Looks like they have three AJ-1E6's where I thought they said they were going to use four of them? 

I like the LEO performance! over 130mt right there.  Although the DUUS would only have two MB-60's on it.   But then again, it's not really supposed to be optimized for LEO performance anyway, but rather BLEO.  However, I would think they could build the DUUS with capability to mount four MB-60's...just in case 130mt to LEO is ever needed (unlikely).  But obviously they are evaluating four RL-10's or two MB-60's, and they are all the same size engine.  So the capability to mount four MB-60's shouldn't be hard to have in the DUUS.  Like two RL-10's on Centaur or 2 and 4 RL-10's on ACES.
It may never fly in that config, but -could- fly if needed...type of thing...