Author Topic: Aerojet vs. Dynetics LRB's for SLS.  (Read 55907 times)

Offline clongton

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #20 on: 09/01/2013 11:45 am »
Heavy Lift is an absolute necessity for the beginning of any serious BEO exploration mission profile, but that vehicle won't see a reasonably consistent launch rate for many years to come, making it very expensive to build and use. But that level of expense can be brought down, provided the boosters chosen for it are LRBs, and those LRBs are designed to be able to function alone in combination with an upper stage as both a CLV and a general purpose LEO launch vehicle in their own right. As such they will fly far more often than the HLV they support, driving their cost per unit down and, as a result, driving down the cost of the HLV when that vehicle is employed.
« Last Edit: 09/01/2013 05:57 pm by clongton »
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Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #21 on: 09/01/2013 05:51 pm »

Respectfully, I have to disagree. The F-1B is actually not an entry by Rocketdyne; it is an entry by Dynetics. Further, those solids are the poorest choice possible on every level, regardless of how many times Chris calls them the "favorite". They have the lowest Isp. They incur high weight on the crawler. They are toxic and place limitations on VAB operations. In case of an in flight abort, they cannot have the engines turned off, and if they have to be detonated they will spew pyrotechnic debris throughout the sky, debris that would be very dangerous to the parachutes. Though the upper end of the cylinder could be blown, NASA didn't do that on STS and likely wouldn't do so on SLS. ATK has already said they can't reach the 130 mT requirement without a 5th RS-25 on the core. That would require the LUS with J-2X of Block II. NASA has said they are not going to add that 5th RS-25. They seem to want DUUS as it can do circ., TLI, and LOI burns, or a TMI burn. The advanced solids just do not meet the requirements. (I know some here think they can do the calculations better than ATK and that Dark Knights can meet the specs. I find it highly doubtful that others are right and ATK's own engineers are wrong.)

This competition needs to be decided on merit, not politics, and not by ATK playing a victim card of, "Oh poor us. Those guys have a monopoly, therefore you have to give this contract to us." That's balderdash. 

Tom,

I'm a big fan of LRB's over SRB's, but I think I need to play devil's advocate a little.

I like LRB's over advanced SRB's, but I don't know that SRB's are a -poor- choice per se.  They could be the cheapest to develop (we don't know price yet), and they will require the least amount of infrastructure change.  A source on L2 said that LRB would need a new ML, and that the existing one just cannot accommodate the propellant lines needed for LRB's.  I don't know enough about it to confirm or refute that, just saying if that -is- true, that'd be a big additional cost to going to LRB's.  I'd like to see two ML's anyway, but with a switch to LRB's, they'd actually need another ML to accommodate two SLS-LRB launches.

They do have the poorest ISP, but remember, these are boosters.  ISP isn't all that big of a hit for short burn boosts like SRB's or LRB's would do.  They are only burning for around 2 minutes or so, so thrust is the major driver for most of that boost (if I understand it correctly) and then as it goes farther along in ascent, thrust advantages is shifted over into ISP advantage, with ISP being the most important thing by the time the payload reaches orbit.
They can't be shut down in flight, but then again, I believe Orion's LAS system is over-designed to escape SRB's burning out of control.  To get above them before they are blown.  Part of the reason it's so big and heavy.  While LRB's are safer, it won't really matter to the crew I don't think from an abort standpoint, as I don't they'll redesign Orion with a smaller and lighter LAS system. (correct me if I'm wrong there)
And KSC and the VAB have been dealing with big SRB's for over 30years, so I don't think that's really a -new- problem.  And it's something they'll be set up to handle with Block 1 SLS anyway.  Although I'm sure ideally it'd be nice to not have them in the VAB.

You are right about the performance not getting to 130mt without the 5th RS-25, but I believe it would be -just- shy of 130mt without the 5th RS-25.
Pretty close.  Between 120-130mt I think.
But, according to Chris, NASA is evaluating 3 options currently.  Option #3 has the DUUS, but both Option 1 and 2 -do- have a 5th RS-25 on the core, along with a now 5m CPS and J2X 2nd stage.  So they are still officially looking at options with a 5th core engine.
(I hope they don't go that way though).

I do hope the competition is decided on merit, and not politics....but...NASA is a government agency so politics are -always- going to be a factor.

Anyway, I suppose the detailed SRB discussion is OT as this is a thread about how Aerojet's purchase of PWR will effect the two different LRB potential proposals
:-)

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #22 on: 09/01/2013 05:56 pm »

I look at it this way.  Where does the country's current top hands-on knowledge of high thrust kerosene/LOX rocket engines reside?  The answer:  not at Aerojet-Rocketdyne, but rather in the hands of some folks at Hawthorne and McGregor. 

Now a follow-up question.  Who is more likely to succeed at developing a new super-high thrust kerosene/LOX engine?  The folks who shut down their production years ago, or the folks who are building them, right now?

 - Ed Kyle

Ok Ed, I'll bite.

What might SpaceX boosters look like?  I don't think they have any known plans for a larger kerolox engine anymore, like the Merlin 2.  They've replaced that with the large methalox Raptor.
That engine is a possibility, but you are specifically referring to kerolox, not methalox, as a competing bid from SpaceX.

So what did you have in mind?
A large clusters of M1D's?  Not sure that NASA would want 25 of them on a booster core MPS.
A Merlin 2?  I think they shelved that concept in favor of the Raptor. (although I'm sure they could un-shelve it for an Advanced booster proposal?)

And what booster core would they use?  They'd need more than the Falcon core, but with a 5.5m limitation, it's most like the MCT core would be wider than that.  So are they going to develop two new core diameters?

Maybe, I just not sure how you think they'd approach this, if at all?

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #23 on: 09/01/2013 06:04 pm »
Heavy Lift is an absolute necessity for the beginning of any serious BEO exploration mission profile, but that vehicle won't see a reasonably consistent launch rate for many years to come, making it very expensive to build and use. But that level of expense can be brought down, provided the boosters chosen for it are LRBs, and those LRBs are designed to be able to function alone in combination with an upper stage as both a CLV and a general purpose LEO launch vehicle in their own right. As such they will fly far more often than the HLV they support, driving their cost per unit down and, as a result, driving down the cost of the HLV when that vehicle is employed.

As I've asked before, is there a good financial case for LV's based on the LRB's?  if so, what?  it'd compete for the very limited payload range that would be where Delta IV is now, and FH will be entering in soon.  There's only been 5 US payloads that needed that much lift in the last 10 years.
Are there commercial customers wanting that payload range?
Could an LRB-LV effectively compete with FH for them?

But...if an SLS LRB -were- to become a stand alone LV...with some sort of reasonable flight rate...I wonder what happens when someone asks why not strap 3 of them together in a heavy configuration, with crossfeed?  Would there then be much need for the SLS core then?
Especially if those booster cores were being made at MAF or MSFC anyway?

Put a DUUS on top that's modified to have four MB-60's.  THat should get a pretty good payload to LEO anyway with the 8.4m PLF.

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #24 on: 09/01/2013 06:11 pm »
Also,
Isn't NASA looking at RS-68A as a potential booster engine along with composite solids, a "large GG kerolox" engine like the F-1B, and a staged combustion kerolox, presumably the AJ-1E6?

That's an Aerojet-Rockdyne engine now too.  Would Aeroject propose that?  Or someone else?  The engine is already in production and I understand could be pretty cheap with a decent production rate.  Wouldn't need to install kerolox at 39B then AND would have commonality with EELV. 
Could even eventually see a phasing out of Atlas in the EELV program if USAF decides with SpaceX, they don't need two EELV's any more for backup.  D4 and D4H already cover everything Atlas V covers, so the line and two Atlas pads could be retired, cutting cost for ULA.  And pumping up the RS-68 production rate quite a bit of there were LRB's using like four RS-68's each.

I believe Ed posted an RS-68 LRB proposal for Shuttle with five RS-68's on a 5.5m core.

Might anything come of that option?  How might AeroJet owning PWR come into play on that?

Offline clongton

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #25 on: 09/01/2013 06:18 pm »
Strapping 3 boosters together? Unlikely. Any potential HLV replacement would need a LOX/LH2 core and Kero/LOX or Meth/LOX boosters. The boosters need to be hydrocarbon-based for their raw power in the lower atmosphere where isp is not an issue and the core needs to be LH2/LOX because it will burn most/all the way to orbit where isp is very important, thrust not so much. It's really the only way at this time to get the best of both worlds.

I suspect that whatever engine powers the LRB would eventually find its way onto the next generation Atlas, replacing the Russian engine. Either that or the LRB will replace the Atlas.
« Last Edit: 09/01/2013 06:24 pm by clongton »
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Offline Lars_J

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #26 on: 09/01/2013 06:30 pm »
Strapping 3 boosters together? Unlikely. Any potential HLV replacement would need a LOX/LH2 core and Kero/LOX or Meth/LOX boosters. The boosters need to be hydrocarbon-based for their raw power in the lower atmosphere where isp is not an issue and the core needs to be LH2/LOX because it will burn most/all the way to orbit where isp is very important, thrust not so much.

Not necessarily true... Weren't there calculations that showed that Delta IV based boosters would be just as effective (if not more) than Atlas V based boosters?

But again, we need to stop falling into the trap of optimizing for performance vs. optimizing for cost.

Offline clongton

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #27 on: 09/01/2013 06:34 pm »
But again, we need to stop falling into the trap of optimizing for performance vs. optimizing for cost.

Only to a point. Physics doesn't bow at the altar of cost.
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I started my career on the Saturn-V F-1A engine

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #28 on: 09/01/2013 08:01 pm »
They do have the poorest ISP, but remember, these are boosters.  ISP isn't all that big of a hit for short burn boosts like SRB's or LRB's would do.  They are only burning for around 2 minutes or so, so thrust is the major driver for most of that boost...

It's not just the raw thrust; it's also the T/W (thrust to weight ratio). As I understand it, those SRBs are so heavy that most of their liftoff thrust goes into just lifting themselves, and not as much of the thrust is being transferred to the thrust beam. With the KeroLox boosters, while the Isp density is high, the pure volumetric density is not (if I understand correctly) as high as the solid propellant. This means the liquids are contributing more of their thrust to the thrust beam on the core.

Those advocating HydroLox boosters are forgetting one important factor: width of the VAB doors. Due to horizontal clearance, boosters are limited to 5.5 meters. The very low density of LH requires much more volume. To get the equivalent thrust that an RP-1 booster would give, you would need boosters as wide as or wider than the core. (I know you have proposed a 8.4 m common HydroLox core, but that won't work. The core can't even support its own weight at liftoff; it depends on the structural strength of the boosters to support it from the beam.) HydroLox boosters are just not possible on SLS because they would be far too large to fit through the doors. There's also the issue of what engine you'd put on them. Six or seven RS-25s for a two minute burn; I don't think so. Eight or nine RS-68-As? I don't want to even think about the complications of that.

RP-1 is just the only fuel that makes sense for this application.

I also agree with Clongton regarding the KeroLox booster doing double duty in a single stick configuration for a 1.5 launch architecture. The core would then not need to be human rated. I also think commonality between that LV's US and DUUS should be examined carefully. If those stages could share tooling, tanking, avionics, and perhaps even MB-60 engines, even more money could be saved.
« Last Edit: 09/01/2013 08:10 pm by TomH »

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #29 on: 09/02/2013 06:56 am »

It's not just the raw thrust; it's also the T/W (thrust to weight ratio). As I understand it, those SRBs are so heavy that most of their liftoff thrust goes into just lifting themselves, and not as much of the thrust is being transferred to the thrust beam. With the KeroLox boosters, while the Isp density is high, the pure volumetric density is not (if I understand correctly) as high as the solid propellant. This means the liquids are contributing more of their thrust to the thrust beam on the core.


Assuming that's true, it would be for the steel casing boosters.  The advanced solids would have both more energetic HTPB propellant, and a lighter composite casing.  Which is the main point of the new version.


Those advocating HydroLox boosters are forgetting one important factor: width of the VAB doors. Due to horizontal clearance, boosters are limited to 5.5 meters. The very low density of LH requires much more volume. To get the equivalent thrust that an RP-1 booster would give, you would need boosters as wide as or wider than the core. (I know you have proposed a 8.4 m common HydroLox core, but that won't work. The core can't even support its own weight at liftoff; it depends on the structural strength of the boosters to support it from the beam.) HydroLox boosters are just not possible on SLS because they would be far too large to fit through the doors. There's also the issue of what engine you'd put on them. Six or seven RS-25s for a two minute burn; I don't think so. Eight or nine RS-68-As? I don't want to even think about the complications of that.

RP-1 is just the only fuel that makes sense for this application.


Huh?

See this post by Ed.

http://forum.nasaspaceflight.com/index.php?topic=31491.msg1037679#msg1037679

Seems that a 5.5m wide hydrolox LRB can feed five RS-68's.  Although, this exact booster would be a bit of a problem as the MPS diameter is wider than the core.  Not a problem for the Shuttle as the ET had not MPS to interfere with, but SLS will.  Still, apparently a 5.5m hydrolox booster with five RS-68 engines is feasible.  Not far too large to fit through the VAB doors at all.

Not saying it's the best way to go, but certainly a feasible way to go.  Be interesting to see what the projected SLS block 2B performance would be with them.

That paper also evaluates kerolox boosters with four RD-180's and RP-1/peroxide boosters.  As well as flyback boosters. 
Interesting.
Also, on page 12, it chose the RD-180 over the NK-33, and listed an "AJ-800" as a future engine development.  I'm guessing maybe even way back then in 2001 Aeroject had concepts of making a two chamber version of the NK-33, but hadn't really thought too much about increasing the thrust of each chamber yet?  As one NK-33 chamber has a vacuum thrust of almost 400klbs, so two would be almost 800klbs.  So Aerojet might have ben kicking that around fro quite some time.








Offline Oli

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #30 on: 09/03/2013 02:27 am »
Something tells me ATK will win this easily. So with liquids (F-1B) you get..

A new high-thrust kerolox engine program, 8000kn (!), that's 10x a Merlin.
A new core which must be strong enough to transfer all this raw thrust to the upper attachement.
4 additional liquid engines at launch which can fail.

With AJ-1E6 you have 6 SC kerolox engines in addition to the 4 RS-25. So in total 10 engines without engine out capability (correct me if I'm wrong about that one).
« Last Edit: 09/03/2013 02:43 am by Oli »

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #31 on: 09/03/2013 05:49 am »
Something tells me ATK will win this easily. So with liquids (F-1B) you get..

A new high-thrust kerolox engine program, 8000kn (!), that's 10x a Merlin.
A new core which must be strong enough to transfer all this raw thrust to the upper attachement.
4 additional liquid engines at launch which can fail.

With AJ-1E6 you have 6 SC kerolox engines in addition to the 4 RS-25. So in total 10 engines without engine out capability (correct me if I'm wrong about that one).

Well, if ATK wins, it will probably have more to do with cost than technical merit (or politics).  IF ATK can make the composite casings cheaply, then the infrastructure to get the segments to KSC and assemble them there will already be in place.  The SLS ML will already be set up for it.

I don't know that engine count will be a big deal, unless SpaceX proposes a booster with 25 Merlin 1D's on it or something.  Then they might start thinking that could be detrimental.

I would think you -would- have engine out capability depending on where the engine fails.  But that's the same as the stages on Saturn V, and on STS.  Any engine failure too early one them would have caused a LOM abort.

And as far as engine failures go, at least typically an engine failure of F-1B or AJ-1E6 would not be a catastrophic failure.  But an SRB failure would be fully catastrophic failure.  or a failure on the pad...or in the VAB....etc...

I think LRB's probably have the advantage over SRB's in terms of overall safety.  Dunno about reliability as F-1B, AJ-1E6, and advanced solids will all be new engines...so we won't really know until there's a track record.
If reliability is the concern, then go with an engine already proven like RD-180 or RS-68.


Offline Hyperion5

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #32 on: 09/03/2013 06:24 am »
Something tells me ATK will win this easily. So with liquids (F-1B) you get..

A new high-thrust kerolox engine program, 8000kn (!), that's 10x a Merlin.
A new core which must be strong enough to transfer all this raw thrust to the upper attachement.
4 additional liquid engines at launch which can fail.

With AJ-1E6 you have 6 SC kerolox engines in addition to the 4 RS-25. So in total 10 engines without engine out capability (correct me if I'm wrong about that one).

Well, if ATK wins, it will probably have more to do with cost than technical merit (or politics).  IF ATK can make the composite casings cheaply, then the infrastructure to get the segments to KSC and assemble them there will already be in place.  The SLS ML will already be set up for it.

I don't know that engine count will be a big deal, unless SpaceX proposes a booster with 25 Merlin 1D's on it or something.  Then they might start thinking that could be detrimental.

I would think you -would- have engine out capability depending on where the engine fails.  But that's the same as the stages on Saturn V, and on STS.  Any engine failure too early one them would have caused a LOM abort.

And as far as engine failures go, at least typically an engine failure of F-1B or AJ-1E6 would not be a catastrophic failure.  But an SRB failure would be fully catastrophic failure.  or a failure on the pad...or in the VAB....etc...

I think LRB's probably have the advantage over SRB's in terms of overall safety.  Dunno about reliability as F-1B, AJ-1E6, and advanced solids will all be new engines...so we won't really know until there's a track record.
If reliability is the concern, then go with an engine already proven like RD-180 or RS-68.



Of course, if you actually look at the stats regarding the Shuttle's SRBs, they were only at fault in one instance in 135 flights.  Once the O-ring issue was resolved I can't say I ever heard of another moment when the SRBs were ever a significant issue from a safety perspective.  My guess is aside from ground handling safety, SRBs will be neck-and-neck with LRBs in terms of flight safety risk.  They're certainly more proven, though obviously there is no engine shutdown option with solids unless you engineer something into the SRB.  I get the feeling that will not happen with ATK emphasizing the low cost of their "Black Knights". 

Offline WindnWar

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #33 on: 09/03/2013 11:42 am »
You can't base the future reliability of the "Black Knights" on Shuttle SRB's. Different grain structure, different case, means its just as new as an LRB would be, and is no more proven.

Offline Oli

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #34 on: 09/03/2013 01:35 pm »
I think the SLS program is an opportunity for developing components for a new ELV. The RL-60 engine for example would be nice to have, I heard about NASA and air force cooperating on this one. So we have...

F-1B engine for a first stage a la Falcon 9. Sounds interesting, although manufacturing such a huge engine could be expensive. With its low first stage ISP it would also require early staging and a relatively powerful second stage engine (e.g. Merlin).

AJ-1E6 as a RD-180 replacement. I think NASA does not want 6 SC kerolox engines on SLS, also manufacturing them in the US could be too expensive for an ELV.

An Ariane 6 style launcher with monolithic solids. ATK's SLS solids would share similarities with those developed for A6. Approx. the same diameter, composite casings and electrical TVC. Unfortunately the infrastructure for casting the solids would have to be set up in Vandenberg and at the Cape.

RS-68 with higher thrust. Potentially allows for getting rid of the solids on Delta IV (if that is a big cost factor). Requires a regen nozzle for SLS. Just a thought.

Edit: This may have been mentioned before in another thread, but what about adding 4 strengthened Falcon 9 cores as boosters? Does it have to be 2 boosters?

« Last Edit: 09/03/2013 02:24 pm by Oli »

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #35 on: 09/03/2013 04:15 pm »
Of course, if you actually look at the stats regarding the Shuttle's SRBs, they were only at fault in one instance in 135 flights.  Once the O-ring issue was resolved I can't say I ever heard of another moment when the SRBs were ever a significant issue from a safety perspective.  My guess is aside from ground handling safety, SRBs will be neck-and-neck with LRBs in terms of flight safety risk.  They're certainly more proven, though obviously there is no engine shutdown option with solids unless you engineer something into the SRB.  I get the feeling that will not happen with ATK emphasizing the low cost of their "Black Knights". 

I think the 5-seg boosters are heritage enough of the Shuttle boosters that you could reasonably look at the Shuttle boosters as a "flight history" to extrapolate to the 5-seg.

But the composite boosters will have 4 longer segments, new composite casings, new nose cones, new propellants, and I think somewhat different nozzles. (trying to remember from the ATK paper on them).

I think you'd be hard pressed to look at the flight record of the shuttle 4-seg boosters and extrapolate anything to these new ones.  Other than saying the manufacturer is the same, so you can expect similar quality and reliability. 
But the F-1's were pretty reliable too, and F-1B will be based on them.  And the AJ-1E6 would probably have some track record going into a booster competition visa vi the AJ-26, if the AJ-1E6 has the same combustion chamber as the AJ-26.

The Dark Knights won't have had -any- track record to point to, prior to flying on SLS for the first time.


Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #36 on: 09/03/2013 05:24 pm »
I think the SLS program is an opportunity for developing components for a new ELV. The RL-60 engine for example would be nice to have, I heard about NASA and air force cooperating on this one. So we have...

F-1B engine for a first stage a la Falcon 9. Sounds interesting, although manufacturing such a huge engine could be expensive. With its low first stage ISP it would also require early staging and a relatively powerful second stage engine (e.g. Merlin).


a la Falcon 9?  Not sure I get your comparisons there.

I agree that if NASA and USAF really can get their heads together, that SLS could have some communal benefits with EELV's.  Possibly a new ELV out of the boosters, but again, those would be a heavy-EELV class payload, and there will already be D4H and FH competing there, so I don't know if I see a commercial or government market for a single stick Dynetics or Aerojet booster.  It'd probably be too expensive to compete in the smaller payload classes again F9 and Atlas V-401 and Ariane 5's dual payload costs. 
But, SLS can have a DUUS which shares a lot in common with DCSS, and it's possible that a common DCSS might be standardized on Atlas V as well as opposed to ACES (or so I've heard).
MB-60 could be used for DUUS and Common DCSS, as the original plan was to put it on DCSS when it was developed.
Orion is being launched once by D4H, and you never know if there might not be a crewed launch of Orion on D4H some day if there's a need.  Apparently RS-68A gets Delta very close to man-ratable.
And RS-68A is being looked at as a potential booster engine for SLS along with F-1B and AJ-1E6 and Advanced solid.

So there's some commonality that might develop there.


AJ-1E6 as a RD-180 replacement. I think NASA does not want 6 SC kerolox engines on SLS, also manufacturing them in the US could be too expensive for an ELV.


I certainly think this is a potential possibility, as an AJ-1E6 would be a very similar engine to the RD-180.  ULA would need a reason to do so though.  Either USAF directs them to switch to a US-built engine if one is available for a relatively straight forward switch, or Aerojet will have to come to the table with a price that can beat the Russian price.  I'm sure the Russians want to charge more than they are under contract for now to ULA, but they might keep prices low if there's a US competator who might replace them.

Also, we will want to see what happens in 2015 and beyond.  I think that's when the USAF will accept competative bids to ULA.  SpaceX is really the only other competator I think that could bid, and they will need some vertical integration capability for at least some of those contracts, if not all.  I think 39A is in their plans for that, as well as manned launches.  But if they are able to get in there and land some USAF/DoD contracts away from ULA, then ULA will either need -more- subsidy from the government to maintain both Atlas and Delta, or USAF/DoD will need to give them the flexibility to cost cut to compete more openly. And I think we'd see a retirement of one EELV and a focus on just one.  I would guess that Atlas would be retired, and Delta would survive for a few reasons.  The main one being D4H is already flying and capable of launching from either coast.  If Delta IV is retired, AVH would need to be developed if ULA wanted to continue to compete for that heavy lift class.  Although they could get out of it (as there aren't many payloads that Atlas V-551 can't launch), I would tend to think they'd stick with the Delta and have the full range covered.
The other reason is that if NASA goes with DUUS, it would be a DCSS derivative, and might use Delta 5m tank tooling for it's LOX tank.
ULA might go with a common DCSS rather than ACES or common Centaur for Atlas, and then phasing out the Atlas booster would make more sense.

If SpaceX cannot or will not compete for those government launches, then ULA may continue to be subsidized to maintain both EELV's for government usage.  So we will see there.
But...just saying I could see a scenario where there's no need to replace the RD-180 on Atlas, as Atlas could go away. 


An Ariane 6 style launcher with monolithic solids. ATK's SLS solids would share similarities with those developed for A6. Approx. the same diameter, composite casings and electrical TVC. Unfortunately the infrastructure for casting the solids would have to be set up in Vandenberg and at the Cape.


That's possible.  Ed had several interesting concepts on just such a thing.  Probably only a possibility if NASA were to choose advanced composite SRB's for SLS.   Although, that would probably look like "Liberty" moreso than Ariane 6.  Unless ATK were to produce and qualify single segment boosters, 2-segments boosters, and/or 3-segment boosters to go along with the 4-segment advanced boosters with SLS.
Would need one or two upper stage versions of them too.  Something like the Castor 30XL.  And I think they'd probably want a hydrolox upper stage of some sort on it like Ariane 6 will have.  Where would that come from?  I doubt ULA. 
But, this would have to be a very cheap LV to really get out there and compete with Falcon 9 and FH, and it would have to have pads on both coasts and vertical integration if it wants to get government contracts.
I just don't know that I see a good economic case for it unless some current LV's are retired and replaced by it, like Ariane 5 would be by Ariane 6.  Lots of players out there now, and in the near future.


RS-68 with higher thrust. Potentially allows for getting rid of the solids on Delta IV (if that is a big cost factor). Requires a regen nozzle for SLS. Just a thought.


Well, not sure how much more thrust you can get out of RS-68 without needing to stretch the Delta IV core.  The A upgrade solved some inefficiencies so it didn't require more fuel, but I think maybe if they went for more thrust, it would burn propellant faster.  But, as I understand, the regen nozzle would allow for higher chamber pressure and better performance, without perhaps more fuel consumption.  So that would probably be the most logical RS-68 upgrade if that was deemed desirable.

But, other than for potentially an SLS hydrolox LRB, I don't think even a regen RS-68 would go on the SLS core.  It's a booster engine and the SLS core is a sustainer core.  A sustainer core really needs a sustainer engine like RS-25 or Vulcan to get the most performance.  Some on here have posted that SLS would take a pretty substantial performance hit if switched to RS-68, unless it were to mount a large J2X or MB-60 (at least 4)  upper stage and have core burnout much earlier than disposal orbit.  Make a big Delta 4 Medium+ (5,2) out of it.  Stage basically where Delta 4 does, and have maybe three RS-68R's on it.
That's be a pretty radical (and expensive) redesign to SLS though, and perhaps need core strengthening to handle the increased trhust from the core MPS.
So I don't see RS-68's going on SLS once RS-25's are designed on it.  Either RS-25E's will be developed, or SLS would be retired, and maybe we could see a "Delta 5" LV.  6.5m CCB's with three RS-68's on each.  Single stick and tri-core heavy.


Edit: This may have been mentioned before in another thread, but what about adding 4 strengthened Falcon 9 cores as boosters? Does it have to be 2 boosters?


The SLS core is being design for only two boosters.  Something like AJAX which could mount multiple CCB's would be needed instead of the current design.  Once it's design for just two boosters, that probably won't change ever.  SLS would probably be retired first. 
In the ESAS study, NASA very throroughly rejected any LV with more than two boosters.  That may or may not have changed now.  But it's probably a mute point once we have SLS.

It could be possible to have a pair of F9 v1.1 boosters on each side attached to a strongback adaptor that would transfer their power into the upper thrust beam.  But I dont' know that two F9v1.1 on each side would be powerful enough.
Aerojet is looking at 3 AJ-1E6 and each of those would have 1Mlbs each or 1.1Mlbs.  So 3Mlbs of thrust minimum, probably a little more.
Two F9v1.1 cores would have about 2.5Mlbs, and would be heavier than a single booster with a strongback adaptor and two cores rather than one.  So less thrust and a lower T/W ratio.
So not seeing that as much of a possibility.
I had a thread about using a whole FH as a booster.  Attach the whole stack to strongback adaptor on SLS.  But, most thought that was pretty unlikely for various reasons.  But that should have enough thrust and performance.  Might make for a pretty funky flame port pattern in the mobile launcher.  ;-)

« Last Edit: 09/03/2013 05:33 pm by Lobo »

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #37 on: 09/03/2013 05:31 pm »
F-1B engine........manufacturing such a huge engine could be expensive.

Dynetics has gone from >5000 parts to <100 parts/ I do not think it is the size as much as the number of parts and the complexity of forming and connecting those parts. 3-D printers for exotic alloys can be used to fashion single peices that used to take numerous man hours to fabricate in tiny pieces then put together. Sometimes it is easier to put together big pieces than it is tiny pieces. I believe these engines may be much cheaper when examined from a dollar/newton perspective.


This may have been mentioned before in another thread, but what about adding 4 strengthened Falcon 9 cores as boosters? Does it have to be 2 boosters?

Yes, it has to be 2 boosters due to the configuration of the thrust beam. 4 F9s are not enough thrust. Lobo had an entire thread about connecting 3 per side at the single attachment point using a strongback; that gets really complicated. You were just talking about too many engines. Now you're talking about 54 engines just on the boosters.

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #38 on: 09/03/2013 08:05 pm »
Yes, it has to be 2 boosters due to the configuration of the thrust beam. 4 F9s are not enough thrust. Lobo had an entire thread about connecting 3 per side at the single attachment point using a strongback; that gets really complicated. You were just talking about too many engines. Now you're talking about 54 engines just on the boosters.

Yea, that seemed like a pretty novel concept.  But ultimately it would probably be a little more complex than NASA probably wants to pursue.

The good news is, there appears to be new friction stir welding tooling at MAF and/or MSFC that can make 5.5m tanks?  Dynetics appears to be using that to make some demo tanks.  Boeing made the Ares 1 US pathfinder tank too.
So if it exists already, it's not like there would be money saved by not using it at this point.  Rather, might as well use it.  If someone can lease it or whatever to make SLS booster cores, then there's probably not much reason not to do that for an LRB option for SLS, given everything.


Offline Lars_J

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #39 on: 09/03/2013 08:10 pm »
This may have been mentioned before in another thread, but what about adding 4 strengthened Falcon 9 cores as boosters? Does it have to be 2 boosters?

Yes, it has to be 2 boosters due to the configuration of the thrust beam. 4 F9s are not enough thrust. Lobo had an entire thread about connecting 3 per side at the single attachment point using a strongback; that gets really complicated. You were just talking about too many engines. Now you're talking about 54 engines just on the boosters.

4 F9's not enough thrust? Not that I advocate using F9 boosters, but the F9v1.1 core has ~50% more thrust than an RD-180 on an Atlas V core, and ~80% more thrust than an RS-68A on a Delta IV core. How in the world is *thrust* the problem?

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