Author Topic: Aerojet vs. Dynetics LRB's for SLS.  (Read 55893 times)

Offline Lobo

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Aerojet vs. Dynetics LRB's for SLS.
« on: 08/30/2013 06:10 pm »
I was am not so much wondering about the pro's and con's of these two possible LRB's, as not much has been released about the Aerojet ones.  My question is more to do with Aerojet bying PWR.

I was watching a video of the D4H launch two days ago, and noticed that when the narrator was describing the D4H he mentioned "Aerojet Rocketdyne RS-68" and "Aerojet Rocketdyne RL-10B".

So, Aerojet Rocketdyne would be making the AJ-1E6, and would be making a new F-1B?  So...how does that effect Dynetics/PWR concept of an F-1B booster vs. Aerojet's concept of an AJ-1E6 booster?

Seems like the competition just bought the engine supplier away from Dynetics?
Would there be a possible merger of the two into a single LRB proposal?  An Aerojet-Rocketdyne/Dynetics proposal?

I might have posted this on the Dynetics booster thread, but that's been locked by a moderator, and I didn't see any explaination as to why.  Usually the last post before a lock is a mod saying why they are locking it.
Anyone know why that thread was locked?

And anyone know what the buyout of PWR by Aerojet means for SLS LRB's?

Additionally, it looks like Dynetics is building a test tank.  Is that at MSFC they are doing that?  Their L2 paper said they'd use the FSW tooling at MSFC to make their tanks, so I'm assuming that?


Offline edkyle99

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #1 on: 08/30/2013 07:52 pm »
And anyone know what the buyout of PWR by Aerojet means for SLS LRB's?
Aerojet Rocketdyne controls RD-180, the "AJ" derivatives of NK-33, RL10, RS-68, RS-25, J-2X, and anything F-1 related.  In other words, this company controls access to primary liquid propulsion for every U.S. launch vehicle except Falcon 9 and the Minotaur/Taurus/Pegasus series.   Why NASA would also want to hand this company the keys to the SLS boosters is beyond me.

 - Ed Kyle

Offline Hyperion5

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #2 on: 08/30/2013 08:39 pm »
And anyone know what the buyout of PWR by Aerojet means for SLS LRB's?
Aerojet Rocketdyne controls RD-180, the "AJ" derivatives of NK-33, RL10, RS-68, RS-25, J-2X, and anything F-1 related.  In other words, this company controls access to primary liquid propulsion for every U.S. launch vehicle except Falcon 9 and the Minotaur/Taurus/Pegasus series.   Why NASA would also want to hand this company the keys to the SLS boosters is beyond me.

 - Ed Kyle

Oh I don't think it's "beyond" you, Ed.  They may have a near-monopoly position, but you can't deny either of their LRBs would provide substantially greater performance than any ATK solid rocket booster.  That's before we even get to the major handling advantages of an all-liquid setup, which would ease the burden on NASA's crawler significantly.  Besides this, you also have potential economies of scale ATK cannot offer if the Atlas V & Antares were to someday switch over to the new AJ-1-E6 engine.  Then there's the fact that LRBs would allow NASA to set up offices in the VAB again, something they haven't had since just before the Shuttle.  You may cringe at their near-monopoly position, but you can't deny either LRB they could offer would definitely have its advantages in performance, ground safety and convenience over what ATK is offering. 

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #3 on: 08/30/2013 10:26 pm »
I've been thinking a lot about that same thing, Lobo. I have to wonder if there are contracts PWR had with Dynetics that cannot be broken by AJ-contracts that guarantee Dynetics access to the F-1 line technology and right to enter the advanced competition, regardless of whether PW sold Rocketdyne to another entity or not. Lawyers for big firms like these are pretty good at loading up these contracts with tons of legalese guarantees like that (as well as loading up extra costs). So AJ may not be able to prevent the F-1B from going forward, even if it wanted to. In fact, this could bode well for AJR; normally one company would not be allowed two differing entries in a competition. This way the AJR lawyers can point to these contracts which may be the loophole that allows this conglomerate corporation to have two entries in the competition. From one point of view, AJR has twice as many opportunities to win as ATK. A win by either liquid is a win for AJR. What I don't see them doing is trying to integrate the two systems as a hybrid. That won't work. My own supposition is that they would allow each of the 2 teams to do its best.
 
As for performance, F-1B looks to be much simplified (< 100 parts!), gas generator, and lots of raw thrust. AJ-1E6 will have higher Isp, but some don't like the KeroLox staged combustion on a human launcher. IF the liquid booster were ever used with a modified DUUS as the US in a single stick configuration to launch Orion in a 1.5 launch architecture, AJ-1E6 might be more versatile in the ability to use 3 or 4 engines on the big rocket booster version while using only 2 on the single sttick version. Of course if that single stick version were completely ruled out, having only 2 engines on the booster for the big rocket might well be preferred to 3 or 4. With 4 AJ-1E6 on each booster, SLS would launch with 12 engines burning, 13 if they ever increased to 5 on the core. That may be more than they want to do.
« Last Edit: 08/30/2013 10:51 pm by TomH »

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #4 on: 08/30/2013 10:35 pm »
And anyone know what the buyout of PWR by Aerojet means for SLS LRB's?
Aerojet Rocketdyne controls RD-180, the "AJ" derivatives of NK-33, RL10, RS-68, RS-25, J-2X, and anything F-1 related.  In other words, this company controls access to primary liquid propulsion for every U.S. launch vehicle except Falcon 9 and the Minotaur/Taurus/Pegasus series.   Why NASA would also want to hand this company the keys to the SLS boosters is beyond me.

 - Ed Kyle

Interesting.

Well, I guess that reduces the horse race from 3 contendors to just two, ATK and AJR (AeroJet-Rocketdyne).

I'd guess that NASA would only be handing the keys over to them if their submittal is superior to ATK's...and ATK has a pretty strong case as their would be the booster with probably the least amount of infrastructure change. 

But, the issue of the overal health to SLS of having that one near-monopoly have the booster is more of a side issue.  I'm more curious about what this might mean for an LRB option for SLS.
Might the two be consolidated into -either- an F-1B booster, -or- an AJ-1E6 booster?
Or would they still offer two different boosters, with two different sets of pro's and con's, and let NASA decide which of their two proposals they want (if they don't go solid).

I work in an industry where I often see a parent company which owns different subsidiary companies which have competing product lines.  And while they can compete with each other, normally over time, I see the lines consolidated so the parent company doesn't have "children" competing with themselves.  And there will be some standardization, or one line will be outright folded into another.
That's what got my wondering about this.

Aerojet could now put the kaibosh on F-1B, if they want to promote their AJ series kerolox engines.  I would think that the more likely because the AJ series is already used by one LV, where F-1B is not. 
However, Aerojet could hedge their bets and allow Dyentics to compete in the booster competition with the F-1B...and if they get it, then the money still goes into their pocket to develop and produce the F-1B.
They could then also develop the AJ-1E6 as a single engine replacement for the two AJ-26's on Antares.  If there's paying customers for both, they probably don't care.

But, if they wanted to standardize their engines, could they pull F-1B form Dynetics, and stick wtih AJ-1E6 on a Teledyne core?  Effectively killing the Dynetics proposal...unless Dynetics can approach SpaceX about making an SLS booster with a large cluster of Merlin engines, or a smaller cluster of Raptor engines...or something...
A cluster of 25 M1D's one a 5.5m Dynetics core would have about the same power as four F-1B's, but the plumbing might be prohibitive. 

Yet, Dynetics is already bending metal on a test tank...so they seem to be moving right ahead with this.

I dunno.  Confusing...




Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #5 on: 08/30/2013 11:01 pm »
Aerojet could now put the kaibosh on F-1B, if they want to promote their AJ series kerolox engines.

My guess is they can't. When Corporation A buys Corporation B, it typically must legally honor all contracts previously signed by Corporation B (unless there are bankbuptcy or other issues-which there are none that I know of). As I said above, a corporation like Dynetics is going to have lawyers good enough to put those kinds of conditions in contracts it signed with PWR, guaranteeing access to F-1B technology. I am pretty sure that Dynetics is the lead corporation of the F-1B project anyway; PRW was not. And thus Dynetics would still have all the rights it had before.

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #6 on: 08/30/2013 11:56 pm »
Aerojet could now put the kaibosh on F-1B, if they want to promote their AJ series kerolox engines.

My guess is they can't. When Corporation A buys Corporation B, it typically must legally honor all contracts previously signed by Corporation B (unless there are bankbuptcy or other issues-which there are none that I know of). As I said above, a corporation like Dynetics is going to have lawyers good enough to put those kinds of conditions in contracts it signed with PWR, guaranteeing access to F-1B technology. I am pretty sure that Dynetics is the lead corporation of the F-1B project anyway; PRW was not. And thus Dynetics would still have all the rights it had before.

True, but I've definately seen a parent company force changes on a subsidiary against their will over time.  THis could be too large of a change though, so you could be right.

They could see about partnering directly with Dynetics though.  No idea where Teledyne is on a booster core, but Dynetics seems to be in the thickof things.  Maybe we'd see a Dynetics-AJR F-1B powered booster?
As a sole liquid competator to ATK's solids?
They could opt to do something like that, or work a deal with Dynetics to use the AJ-1E6 instead?  If it requires less development (not sure it would) then it could be a deal.
Or, just ask NASA which why they'd "prefer", GG or staged combustion.  And then offer a Dynetics-Aerojet booster that used whatever engine NASA preferred.  They'd hedge their bet that way.

Offline spectre9

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #7 on: 08/31/2013 01:28 am »
If you had to quantify the level of nefarious activity of ATK and Aerojet Rocketdyne one would barely register while the other would be off the chart.

Offline woods170

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #8 on: 08/31/2013 12:27 pm »
And anyone know what the buyout of PWR by Aerojet means for SLS LRB's?
Aerojet Rocketdyne controls RD-180, the "AJ" derivatives of NK-33, RL10, RS-68, RS-25, J-2X, and anything F-1 related.  In other words, this company controls access to primary liquid propulsion for every U.S. launch vehicle except Falcon 9 and the Minotaur/Taurus/Pegasus series.   Why NASA would also want to hand this company the keys to the SLS boosters is beyond me.

 - Ed Kyle
ATK will play that card and that's why advanced boosters for SLS will remain solid IMO. My prediction is that IF we ever see advanced boosters on SLS, they will be the 'black knights'.

Offline newpylong

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #9 on: 08/31/2013 01:04 pm »
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.


And anyone know what the buyout of PWR by Aerojet means for SLS LRB's?
Aerojet Rocketdyne controls RD-180, the "AJ" derivatives of NK-33, RL10, RS-68, RS-25, J-2X, and anything F-1 related.  In other words, this company controls access to primary liquid propulsion for every U.S. launch vehicle except Falcon 9 and the Minotaur/Taurus/Pegasus series.   Why NASA would also want to hand this company the keys to the SLS boosters is beyond me.

 - Ed Kyle

Offline edkyle99

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #10 on: 08/31/2013 03:18 pm »
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s.

 - Ed Kyle

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #11 on: 08/31/2013 06:44 pm »
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s.

 - Ed Kyle

Respectfully, that does not mean they can't and don't know how.

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #12 on: 08/31/2013 06:57 pm »
And anyone know what the buyout of PWR by Aerojet means for SLS LRB's?
Aerojet Rocketdyne controls RD-180, the "AJ" derivatives of NK-33, RL10, RS-68, RS-25, J-2X, and anything F-1 related.  In other words, this company controls access to primary liquid propulsion for every U.S. launch vehicle except Falcon 9 and the Minotaur/Taurus/Pegasus series.   Why NASA would also want to hand this company the keys to the SLS boosters is beyond me.

 - Ed Kyle
ATK will play that card and that's why advanced boosters for SLS will remain solid IMO. My prediction is that IF we ever see advanced boosters on SLS, they will be the 'black knights'.

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. 
« Last Edit: 08/31/2013 10:57 pm by TomH »

Offline joek

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #13 on: 08/31/2013 11:11 pm »
Excuse me if I'm missing something, but this discussion seems a bit premature?  AFAICT SLS Block 1A with SRBs will be flying through the early 2020's and possibly mid-to-late 2020's.  Given a nominal five year lead (?) that suggests a decision is several-to-many years in the future, and a great deal can change between now and then.

Offline spectre9

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #14 on: 08/31/2013 11:54 pm »
Launch 2 could come up to around 2019 if SLS gets a funding boost after the first launch in 2017.

ATK is only contracted for the first 2 flights.

Booster competition will start in 2015.

Quote
These new contracts are funded under an NRA risk mitigation effort and acquisition. There will be a future competition for design, development, testing and evaluation for the SLS advanced booster. This future competition is planned for 2015 and will be acquired through a separate solicitation. The 2015 competition will not be limited to awardees announced in this NRA. Successful offerors to this NRA are not guaranteed an award for any future advanced booster acquisition.

http://www.nasa.gov/home/hqnews/2012/oct/HQ_12-339_SLS_Awards_Contract.html

New boosters might be late meaning ATK might sell another set or two but they will not get a bulk deal on the old solids.

If "competition" actually means competition liquids should be a very good chance of winning the contract.

Offline edkyle99

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #15 on: 08/31/2013 11:56 pm »
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s.

 - Ed Kyle

Respectfully, that does not mean they can't and don't know how.

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
« Last Edit: 08/31/2013 11:59 pm by edkyle99 »

Offline spectre9

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #16 on: 09/01/2013 12:00 am »
I was just about to comment that the booster comp isn't limited to those in the current round which means SpaceX can enter.

Beat me to it Ed  8)

Offline clongton

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #17 on: 09/01/2013 12:19 am »
If you had to quantify the level of nefarious activity of ATK and Aerojet Rocketdyne one would barely register while the other would be off the chart.

Oh boy ain't that the truth!
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I started my career on the Saturn-V F-1A engine

Online oldAtlas_Eguy

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #18 on: 09/01/2013 12:53 am »
Excuse me if I'm missing something, but this discussion seems a bit premature?  AFAICT SLS Block 1A with SRBs will be flying through the early 2020's and possibly mid-to-late 2020's.  Given a nominal five year lead (?) that suggests a decision is several-to-many years in the future, and a great deal can change between now and then.

From the stand point of how long to develop an LRB, use the SLS core development time as a guide. Also note the engines aready exist and do not require any development. Start FY2012 to first launch 2017 is ~6 years once the engines are well defined and exist, now add 3 years to do engine development to a point where the rest of the booster can be more fully developed. Thats 9 years development cycle for a LRB. If it is supposed to fly in mid 2020's then a NLT contract for engine development would start FY2016 if not earlier in FY2015.

Online oldAtlas_Eguy

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #19 on: 09/01/2013 01:00 am »
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s.

 - Ed Kyle

Respectfully, that does not mean they can't and don't know how.

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

Kero/LOX is not the only LRB fuel combo choice. The MCT SpaceX engine speculation may have an interesting implication. A higher performance LRB and possibly a reusable one as well. Wouldn't that be something to see pop up in a Advamced Booster compitition in 2017/2018. Give SpaceX 5 years to develop a new engine and there could be some interesting things happen.

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?

Offline Lurker Steve

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #40 on: 09/03/2013 08:23 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?

The advanced boosters will have more thrust than a Atlas V or Delta IV core. Remember the other liquid competition is either 3 x AJ1E6 or 2 X F-1B on each side.

These are not your normal EELV-class boosters. With proper avionics, they could be a D4H / FH replacement as a single stick. But of course, the market for that size LV is rather small.


Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #41 on: 09/03/2013 11:15 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.

I thought there was a Atlas Phase 2 Heavy and an FX-Heavy concept that each would have had pretty good LEO performance.  The AVP2-Heavy had over 70mt to LEO with a 5m hydrolox upper stage...not a very big stage.

A hydrolox core is needed for a sustainer type of design, like Ariane V, STS, and SLS.  The core is basically a ground lit upper stage.  Otherwise, you need a large upper stage to get the payload to orbit.
That's what the S-II was.
But...I don't know that a GG kerolox engine like the F-1 has to do a short burn.  That's why I was thinking a crossfed tri-core heavy with Dynetics boosters.  It would be a little akin to the S-1D/Saturn V-B.  Except dumping whole booster cores rathan than an engine ring.  Perhaps the center core could have a modified MPS to mount just a single F-1B as that'd be ample power at booster-sep.  The boosters themselves for their weight and size will be very overpowered...because they are designed to be boosters for a sustainer core, with raw power and short burn time. 
Take that core, put a single F-1B on it, put two SLS boosters on each side of it, but a DUUS on it with four MB-60's, and you have something that'd probably throw a lot fo mass to LEO. 
Wouldn't even really need crossfeed then.  Throttle down that central engine shortly after takeoff, and let the side boosters burn full and burn themselves out, then throttle up and there should be enough fuel for quite a long burn after booster sep.  Assuming the side boosters burn for 150s, the central core with a single F-1B could burn for like 300s before staging.  That's quite a long burn.
Those big GG kerolox engines dosn't have the best isp, but the Saturn V-B was supposed to throw over 20mt to LEO with no upper stage.  So a crossfed tri-core heavy with a  single F-1B engine on the central core might be able to do that or better.  More lift off thrust with the B vs. the original, and the fact you are jettisoning 2/3 of your tankage, as well as 4 of your 5 engines.
Put the DUUS on top of that and you probably get a very heavy LEO capability, although it might not have much left for an EDS burn.
You also have a common booster core, with the only difference being two MPS's, a booster and a central core.

So, will the SLS core be more, less, or about the same expense as a Dynetics core?  That's the question as to if this would be desirable.  Also, the tri-core heavy needs an EDS as the 2nd stage probably won't get to LEO with enough fuel to send much mass BLEO. 
And with the inertia of an existing program, there probably won't be a lot of deisre to modify the ML and VAB platforms for this.  Especially if Downix is correct and the SLS core actualy will be very automated and just a fraction of the people and overhead of the ET. 
So I don't know it would be desirable...but...I think it -could- be done.
Way back during the ESAS study would have been the time though.

 

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #42 on: 09/03/2013 11:40 pm »
This thread made me think about something additional.

Aerojet owns Rocketdyne, so they own the rights to the RD-180 now?

RD-180 would very directly compete with the AJ-1E6, even moreso than the F-1B.

I understand existing contracts must be honored, but again, I've also seen parent companies force changes to susidiary companies to streamline and standardize competing lines after mergers and buy outs.
I could very much see someoneone thinking they don't need two engines so close together in performance, and might negotiate a change to Atlas V to take the AJ-1E6 engine.  Perhaps make it a good enough of a deal to make it worth ULA's while to do so.  Essentially sell a block of AJ-1E6's at a cheap enough cost to cover the modification costs to Atlas.
Or just tell ULA they must change after the existing contracts are filled.

How could/would that work, anyone know?

I have no clue what sort of deal/contracts there would be that would allow that or prevent that.

Offline Downix

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #43 on: 09/04/2013 05:19 pm »
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s.

 - Ed Kyle
Other than the RS-27A you mean.
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Offline MP99

Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #44 on: 09/04/2013 05:23 pm »
This thread made me think about something additional.

Aerojet owns Rocketdyne, so they own the rights to the RD-180 now?

RD-180 would very directly compete with the AJ-1E6, even moreso than the F-1B.

I understand existing contracts must be honored, but again, I've also seen parent companies force changes to susidiary companies to streamline and standardize competing lines after mergers and buy outs.
I could very much see someoneone thinking they don't need two engines so close together in performance, and might negotiate a change to Atlas V to take the AJ-1E6 engine.  Perhaps make it a good enough of a deal to make it worth ULA's while to do so.  Essentially sell a block of AJ-1E6's at a cheap enough cost to cover the modification costs to Atlas.
Or just tell ULA they must change after the existing contracts are filled.

How could/would that work, anyone know?

I have no clue what sort of deal/contracts there would be that would allow that or prevent that.

That's RD AMROSS - not sure if transfer of that to Aerojet is approved by Russian govt yet?

Cheers, Martin

Offline Downix

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #45 on: 09/04/2013 05:23 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.
Slightly better performing actually. If it were not for the human-rating issue, the Delta CBC would have been used in the AJAX writeup. Ironic that issue has since been shelved.
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Offline Lars_J

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #46 on: 09/04/2013 05:24 pm »
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s.

 - Ed Kyle
Other than the RS-27A you mean.

When was the last RS-27A (or RS-27) built?

Offline Downix

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #47 on: 09/04/2013 05:27 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?
Thrust to Weight ratios. Raw thrust is meaningless if the weight increases too much.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline Downix

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #48 on: 09/04/2013 05:35 pm »
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s.

 - Ed Kyle
Other than the RS-27A you mean.

When was the last RS-27A (or RS-27) built?
Last one I found on record was in 2006.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline Proponent

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #49 on: 09/04/2013 06:06 pm »
Very simple. Whoever has the best, most cost effective proposal get's it. If that is AR, so be it. They don't exactly produce junk. Sometimes monopolies do have the best product, sometimes not.
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s.

 - Ed Kyle
Other than the RS-27A you mean.

It wasn't all new; it was minor modification of an existing engine.

Offline edkyle99

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #50 on: 09/04/2013 06:07 pm »
Aerojet Rocketdyne builds good hydrogen/oxygen engines (RL10, RS-68), but it hasn't built a main propulsion kerosene/LOX engine in roughly a decade, it hasn't developed an upgraded high-thrust kerosene/LOX engine model since the late 1980s, and it hasn't developed an all-new high thrust kerosene/LOX rocket engine since the early 1960s.

 - Ed Kyle
Other than the RS-27A you mean.
The final RS-27A acceptance test was performed at Santa Susana on March 3, 2006.  This was also the last engine tested at Santa Susana.  That was about three weeks before SpaceX launched its first Falcon 1.  In the 7.5 years since then, Rocketdyne (PWR/Aerojet-Rocketdyne) has not fired up a single high thrust kerosene/LOX engine on the ground while SpaceX has flown 60 such engines (though not all fired) and tested who-knows-how-many on the ground.

 - Ed Kyle
« Last Edit: 09/04/2013 06:17 pm by edkyle99 »

Offline Lurker Steve

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #51 on: 09/04/2013 06:42 pm »
Ed, How much ORSC experience is there in Hawthorne ?? How much larger do you think it's possible to extend the basic Merlin design ? Have you heard of any NEW kerosene engines being developed at Hawthorne ?

At least Aerojet has experience working with the AJ26 / NK-33, including making the old engines flight ready and test firing them at Stennis. Who manufactured the new parts that needed to be replaced because of corrosion ?

Offline a_langwich

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #52 on: 09/04/2013 06:53 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.
Slightly better performing actually. If it were not for the human-rating issue, the Delta CBC would have been used in the AJAX writeup. Ironic that issue has since been shelved.

How has it been shelved?  Are there any plans to launch people on a Delta?  I thought both CST-100 and DC were looking at Atlas?

Offline Downix

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #53 on: 09/04/2013 08:50 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.
Slightly better performing actually. If it were not for the human-rating issue, the Delta CBC would have been used in the AJAX writeup. Ironic that issue has since been shelved.

How has it been shelved?  Are there any plans to launch people on a Delta?  I thought both CST-100 and DC were looking at Atlas?

Part of the ULA common booster program is resulting in systems being shared between Atlas and Delta, which means human-rated systems replacing non-human-rated in many areas. In addition, the RS-68A is close to being human-rated, and with the DCUS being used for the iCPS, realistically Delta could be used for human flight, should we wish to put in the effort, within 2 years.

Atlas is cheaper, however, so it will still be the commercial launch vehicle of choice.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #54 on: 09/04/2013 10:36 pm »
How has it been shelved?  Are there any plans to launch people on a Delta?  I thought both CST-100 and DC were looking at Atlas?


I know Boeing really wanted to put CST-100 on Delta, as Delta was more "their" launcher, to go with their spacecraft.
There's lots of concept art showing CST-100 on Delta.  Even some as recent as that CST-100 open house presser Boeing had a month or two ago.  It still showed it on Delta.

Assuming Boeing would have known that the upgrades in the works to Delta during CST-100 development for RS-68A and systems standardization would have resulted in a Delta that would have been similarly man-ratable to Atlas, was the switch to Atlas based on cost? Or performance?

Offline quanthasaquality

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #55 on: 11/08/2013 05:40 pm »
Since the Aerojet booster is to have 4, 1.1 million pound engines, couldn't the Pyrios booster engines later be upgraded from 1.8 million pounds, to 2.2 million pounds.

The Aerojet booster is to have 4.4 million pounds of thrust. The ATK booster is expected to produce more than the 3.5 million pounds of thrust of the 5 segment RSRM. The Dynetics booster is to have only 3.6 million pounds of thrust. Couldn't the Dynetics booster engines later be made larger, with more fuel, and 4.4 million pounds of thrust. New and improved booster, with 22% more thrust! The 4 engine SLS core, was made with upgrades in mind!

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #56 on: 11/08/2013 05:53 pm »
Since the Aerojet booster is to have 4, 1.1 million pound engines, couldn't the Pyrios booster engines later be upgraded from 1.8 million pounds, to 2.2 million pounds.

The Aerojet booster is to have 4.4 million pounds of thrust. The ATK booster is expected to produce more than the 3.5 million pounds of thrust of the 5 segment RSRM. The Dynetics booster is to have only 3.6 million pounds of thrust. Couldn't the Dynetics booster engines later be made larger, with more fuel, and 4.4 million pounds of thrust. New and improved booster, with 22% more thrust! The 4 engine SLS core, was made with upgrades in mind!

The only info I've seen on the Aerojet booster actaully only has three 1.1Mlbf AJ-1E6's, not four.  I thought it'd have four, but there's an SLS paper out there that shows some concept art for the Aerojet boosters and it shows and talks about three of them.  That's 3.3Mlbs of thrust, and a much better ISP than F-1B's.  So they actually should have a little better capacity than the Pyrios boostes.
As it looks like Aerojet -should- be getting the license to import and sell Russian built RD-180's, it's possible that they could put three or maybe four of those on the booster, giving it 2.8Mlbf and 3.7Mlbf thrust respectively, and shelve the whole AJ-1E6 development altogether.



Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #57 on: 11/08/2013 10:43 pm »
Same here. I thought I'd heard four, but then the paper someone (was it Steven?) pulled up recently showed three engines per booster, each with twin nozzles for a total of six nozzles per booster.

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #58 on: 11/09/2013 01:52 am »
Same here. I thought I'd heard four, but then the paper someone (was it Steven?) pulled up recently showed three engines per booster, each with twin nozzles for a total of six nozzles per booster.

Yes, the paper Steve posted on the thread about AJ-1E6 progress is the one I was thinking of.  That's about all I've seen on the Aerojet booster. 
You don't need as much fuel if the ISP of the engine is higher, which means less mass and less thrust needed to get it off the pad and moving.

If AJ-1E6 had the same ISP as the NK-33, the three RD-180's with their higher ISP might get pretty clos eto four AJ-1E6's, even though they have less thrust.  The boosters wouldn't need quite as much propellant mass.

Offline Hyperion5

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #59 on: 11/09/2013 02:21 am »
Same here. I thought I'd heard four, but then the paper someone (was it Steven?) pulled up recently showed three engines per booster, each with twin nozzles for a total of six nozzles per booster.

Yes, the paper Steve posted on the thread about AJ-1E6 progress is the one I was thinking of.  That's about all I've seen on the Aerojet booster. 
You don't need as much fuel if the ISP of the engine is higher, which means less mass and less thrust needed to get it off the pad and moving.

If AJ-1E6 had the same ISP as the NK-33, the three RD-180's with their higher ISP might get pretty clos eto four AJ-1E6's, even though they have less thrust.  The boosters wouldn't need quite as much propellant mass.

I remember us having this discussion back on an SLS thread a year or so ago.  Lobo was lamenting the relative lack of thrust on the Aerojet booster.  Then I ran across an article talking about there being four of those engines on the Aerojet boosters.  Downix said I'd gotten that detail right and now here we are, and suddenly the Aerojet boosters have only 3 engines.  Either they've changed the design or perhaps the source is wrong.  I'll have to dig up that post and find the link. 

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #60 on: 11/10/2013 03:09 am »
Check out the AJ1E6 thread at

http://forum.nasaspaceflight.com/index.php?topic=32622.57

The drawings I posted that I extracted from some NASA presentations clearly show three dual chamber AJ1E6 engines per core. My simulations also show these boosters can get 132.6 t into LEO with an SLS core with four RS-25D engines and an upper stage with four MB-60 engines. Pyrios F-1B powered boosters gets slightly less at 129.5 t. Check out my SLS Trajectory Simulation thread for all the gory details. :-)
« Last Edit: 11/10/2013 03:09 am by Steven Pietrobon »
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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #61 on: 11/10/2013 06:27 am »
Same here. I thought I'd heard four, but then the paper someone (was it Steven?) pulled up recently showed three engines per booster, each with twin nozzles for a total of six nozzles per booster.

Yes, the paper Steve posted on the thread about AJ-1E6 progress is the one I was thinking of.  That's about all I've seen on the Aerojet booster. 
You don't need as much fuel if the ISP of the engine is higher, which means less mass and less thrust needed to get it off the pad and moving.

If AJ-1E6 had the same ISP as the NK-33, the three RD-180's with their higher ISP might get pretty clos eto four AJ-1E6's, even though they have less thrust.  The boosters wouldn't need quite as much propellant mass.

I remember us having this discussion back on an SLS thread a year or so ago.  Lobo was lamenting the relative lack of thrust on the Aerojet booster.  Then I ran across an article talking about there being four of those engines on the Aerojet boosters.  Downix said I'd gotten that detail right and now here we are, and suddenly the Aerojet boosters have only 3 engines.  Either they've changed the design or perhaps the source is wrong.  I'll have to dig up that post and find the link.

I think then I was thinking that the AJ-1E6 would have 1Mlbs of thrust total, which seemed perhaps a bit light.  But Aerojet in that paper Steve referenced has a 550klb AJ-500, and so a 1.1Mlb AJ-1E6, so three of them were 3.3Mlbs.  An extra 300klbs of thrust. 

Now it's got me curious as to what three RD-180's would do.  If the AJ-1E6 had the lower ISP of the NK-33 (unknown, Aeojet's modifications could increase it's ISP to that similar to RD-180) then three RD-180 with better isp and less propellant mass (so the stack is lighter) might be ok with three RD-180's at a little under 3Mlbs of thrust.


Offline Blackstar

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #62 on: 11/25/2013 09:24 pm »
http://thespacereview.com/article/2410/1


Burning thunder
by Dwayne Day

In early January, almost forty years since the last F-1 rumbled, the woods surrounding NASA’s Marshall Space Flight Center were shaken by a thunderous roar. NASA engineers were not testing a rocket engine but only a part of one, something called a gas generator, which is a device that burns propellant to produce hot exhaust gases to spin a turbine that then spins a pump that pumps fuel and oxidizer into a thrust chamber where it ignites to produce the exhaust that powers a rocket. The gas generator is in many ways similar to a rocket engine, and it has to be fired on a rocket test stand. This gas generator was from a Saturn F-1 engine, the first time one had been fired in over three and a half decades. The gas generator alone was almost a third of the thrust of a Merlin 1C rocket engine for the Falcon 9 launch vehicle. That confirms what many in the rocket engine field have known for a long time: the F-1 was a monster.

And now some people are hoping for the F-1 to make a comeback.

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #63 on: 12/24/2013 08:31 am »
Any chance of conformal tanks and hydrogen peroxide as the oxidizer for either an Aerojet or Dynetics LRB that is optimized for cost?

Lightweight conformal tanks might allow for more propellant and maybe a fly back option.


"Abstract — The use of high density hydrogen peroxide/kerosene liquid rocket boosters (LRB) for the Space Shuttle is investigated as a replacement for the existing solid rocket boosters (SRB). It is shown that hydrogen peroxide/kerosene outperforms both solids, LOX/Kero, and LOX/LH2 as a general booster propellant due to its high density and moderate exhaust speed. With the same propellant mass and size as that of the current SRB’s, computer simulations indicate that payload mass can be increased by a third from 24,950 kg to 33,140 kg for a 28.45°, 203.7 km circular orbit. Recovery of the boosters is performed at
sea."

From: High Density Liquid Rocket Boosters for the Space Shuttle  By Steven S. Pietrobon, Member, BIS    Published in the Journal of the British Interplanetary Society, vol. 52, pp. 163–168, May/June
1999.
Available at: http://www.thefullwiki.org/Bristol_Siddeley_Gamma

Edited.
« Last Edit: 12/24/2013 08:50 am by HappyMartian »
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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #64 on: 12/25/2013 08:00 am »
Any chance of conformal tanks and hydrogen peroxide as the oxidizer for either an Aerojet or Dynetics LRB that is optimized for cost?

Yes. Buckleys and none. :-) The US does not have experience with large keroxide (a term for kerosene/hydrogen peroxide propellants invented by Lobo) engines, while there is plenty with kerolox. So when a choice is made, its nearly always for kerolox. The British were building up this experience with their Black Knight and Black Arrow launch vehicles, but when they pulled out of the launch business in the early 1970's, this experience was lost.

You know all those troubles that SpaceX has had with LOX? What was the main cause of the problem? Its the cryogenic temperatures that makes things stick. Thus, if a launch provider ever wants to have true reliability where they always launch on time, I believe keroxide is the best solution for the first stage (upper stages are a different story). Its higher impulse density also implies that it has greater performance than kerolox for the same volume first stage.
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Offline HappyMartian

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #65 on: 12/25/2013 11:37 am »
Any chance of conformal tanks and hydrogen peroxide as the oxidizer for either an Aerojet or Dynetics LRB that is optimized for cost?

Yes. Buckleys and none. :-) The US does not have experience with large keroxide (a term for kerosene/hydrogen peroxide propellants invented by Lobo) engines, while there is plenty with kerolox. So when a choice is made, its nearly always for kerolox. The British were building up this experience with their Black Knight and Black Arrow launch vehicles, but when they pulled out of the launch business in the early 1970's, this experience was lost.

You know all those troubles that SpaceX has had with LOX? What was the main cause of the problem? Its the cryogenic temperatures that makes things stick. Thus, if a launch provider ever wants to have true reliability where they always launch on time, I believe keroxide is the best solution for the first stage (upper stages are a different story). Its higher impulse density also implies that it has greater performance than kerolox for the same volume first stage.


If hydrogen peroxide is reliable as a large rocket engine coolant and propellant, then efficient, risk minimized, reusable "keroxide" rocket boosters should be quite doable and significantly improve the LEO payload capability of the advanced versions of the SLS.

Since "true reliability" and timely cost effective performance are crucial issues for the human-rated SLS and other current and future human-rated launchers used by the American space industry, it appears that a very high NASA/Air Force/space industry priority should be for developing a large "keroxide" rocket engine that would enable lightweight conformal composite material based lifting body shaped fly back SLS boosters and new or modified first stages for various launchers.

Research on such a large "keroxide" rocket engine for boosters and launcher first stages needs to be funded ASAP.

The Aerojet LRB, Dynetics LRB, and Dark Knights competition should logically be postponed until the development results of the large "keroxide" rocket engine project are obvious to Congress, the space industry, and the American taxpayers.

Any corrections or additions to these ideas about the basic importance of carefully investigating the feasibility and actually building and testing a large American "keroxide" rocket engine prior to holding the SLS booster competition are welcome. 


Edited.
« Last Edit: 12/25/2013 01:27 pm by HappyMartian »
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Offline BigDustyman

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #66 on: 12/26/2013 12:46 am »
I wondering if there might be environmental problems seeing as everybody's talking about safer fuels and as I recall hydrogen peroxide in purer form is very corrosive, correct me if I'm wrong on that

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #67 on: 12/26/2013 03:30 am »
HappyMartian, I agree with you. This is something that NASA could perform research on, but as kerolox is "good enough" it doesn't get funded. One aspect is staged combustion keroxide. This is a little simpler as only the HTP needs to be decomposed first in the "preburner" after it passes through a catalyst, like platinum coated mesh. There will be zero carbon deposits as the hydrogen peroxide decomposes into H2O and O2.

As HTP (high test peroxide) is a strong oxidant it will oxidise with many materials (effectively corrosion), just like any other strong oxidant like LOX and N2O4. There is extensive experience in industry on containing HTP and choosing materials for the container. Some container materials need to be pretreated.

We're getting a little sidetracked here, so it may be best to take further discussion on using keroxide to the technical discussion forum.
« Last Edit: 12/26/2013 03:40 am by Steven Pietrobon »
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Offline Archibald

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #68 on: 12/26/2013 11:14 am »
That discussion should continue there.
http://forum.nasaspaceflight.com/index.php?topic=33280.30

Steve, I'm very intrigued by that staged combustion thing. Keroxide (great name!) specific impulse is around 310 - 320 but I wonder, could staged combustion bring it to 350 ? That would make a huge difference...
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Offline HappyMartian

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #69 on: 12/26/2013 11:37 am »
That discussion should continue there.
http://forum.nasaspaceflight.com/index.php?topic=33280.30

Steve, I'm very intrigued by that staged combustion thing. Keroxide (great name!) specific impulse is around 310 - 320 but I wonder, could staged combustion bring it to 350 ? That would make a huge difference...


Archibald, maybe instead at:

Any speculation as to what engines may be included in the proposals submitted for liquid versions of the SLS advanced boosters?  Upgraded single RD-170 or RD-171, a pair of RD-180s, built by Glushko or under U.S. license? Will PWR pull out the F-1A; will it be upgraded? Will SpaceX offer a Falcon of any type with Merlin II? Other ideas?
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Offline newpylong

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #70 on: 03/31/2014 05:31 pm »
http://www.dynetics.com/news/377

Dynetics Meets Milestone on Advanced Booster Work

Offline redliox

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #71 on: 04/04/2014 09:43 am »
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 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.

Considering how the average firecracker and SRB share some basic principles...yeah I can't help getting images of a swarm of rocket scientists fleeing the VAB the day a SRB malfunctions.  Still, despite being potential bombs in tin cans, they only caused grief for ill-fated Challenger, not so much the production floor.  If ATK does win the advanced competition, they should teach their boosters some new tricks befitting a next-gen solid.

The liquid boosters at least wouldn't be explosive until fueled at the launch pad as you imply Lobo.  More chances to evolve and tweak performance too.  Aside from streamlining a solid all you can otherwise do is pack it with more flamboyant firecracker material (putting it bluntly of course).

http://www.dynetics.com/news/377
Dynetics Meets Milestone on Advanced Booster Work

Sweet news there!  A stable full-scale tank will certainly give merit to liquid boosters.
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Offline clongton

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #72 on: 04/04/2014 08:53 pm »
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 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.

Considering how the average firecracker and SRB share some basic principles...yeah I can't help getting images of a swarm of rocket scientists fleeing the VAB the day a SRB malfunctions.  Still, despite being potential bombs in tin cans, they only caused grief for ill-fated Challenger, not so much the production floor.  If ATK does win the advanced competition, they should teach their boosters some new tricks befitting a next-gen solid.

The liquid boosters at least wouldn't be explosive until fueled at the launch pad as you imply Lobo.  More chances to evolve and tweak performance too.  Aside from streamlining a solid all you can otherwise do is pack it with more flamboyant firecracker material (putting it bluntly of course).

The SRB's served safely inside the VAB for more than 30 years without a single issue. Unlike "firecrackers" the SRB's are NOT explosive; there is insufficient oxydizer in the mix to support anything other than rapid burning.  They have to be ignited, which cannot be done accidentally. By their nature they are considered to be "potentially" explosive, but in terms of practical matters they are not. You can bang on them with hammers, shoot high power rifle slugs thru them, even shoot them thru and thru with machine guns. They won't explode. Ammonium Percolate is not explosive in the form used for the SRB's. They have to be ignited and that is only possible at the launch pad.


Did you ever watch closely the Challenger explosion? The SRB's did not explode, even while the hydrogen and LOX filled ET was doing exactly that right next to them. They continued to fly until detonated by the Range Safety Officer.

And they can't "malfunction" inside the VAB. Malfunction means operating incorrectly and inside the VAB they are not operating at all. They are not even "functioning". They are just sitting there doing nothing.
« Last Edit: 04/04/2014 08:55 pm by clongton »
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Offline redliox

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #73 on: 04/04/2014 09:29 pm »
Did you ever watch closely the Challenger explosion? The SRB's did not explode, even while the hydrogen and LOX filled ET was doing exactly that right next to them. They continued to fly until detonated by the Range Safety Officer.

And they can't "malfunction" inside the VAB. Malfunction means operating incorrectly and inside the VAB they are not operating at all. They are not even "functioning". They are just sitting there doing nothing.

Correction regarding Challenger: the O-ring leak effectively blowtorched a hole into the ET.  The vehicle already exploded by the time the range officers destroyed the SRBs.  The damage was done.

I acknowledged they haven't been a danger while just sitting on the production floor.  However, the VAB no longer has active offices inside it because the threat remains that the SRBs are inherently fueled versus liquid boosters that are empty until safely on the launch pad.  And the imagery of fleeing rocket scientists refers to the fact of IF something went wrong; had engineers anticipated ice damage in Florida Challenger's fate could have been different, but 90% of the time ice doesn't even exist in Florida.

Not wanting to distract from the main topic here: point is liquid boosters are safer to handle, factory floor and elsewhere, than solids.  ATK is a good company but hoping liquids win out.
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Offline strangequark

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #74 on: 04/04/2014 09:46 pm »
Correction regarding Challenger: the O-ring leak effectively blowtorched a hole into the ET.  The vehicle already exploded by the time the range officers destroyed the SRBs.  The damage was done.

I acknowledged they haven't been a danger while just sitting on the production floor.  However, the VAB no longer has active offices inside it because the threat remains that the SRBs are inherently fueled versus liquid boosters that are empty until safely on the launch pad.  And the imagery of fleeing rocket scientists refers to the fact of IF something went wrong; had engineers anticipated ice damage in Florida Challenger's fate could have been different, but 90% of the time ice doesn't even exist in Florida.

Not going to get into a debate on the safety of solids, because I don't have the energy. However, I did want to relay that the general advice given to people working in the VAB was "If something catastrophic happens with the SRB, don't bother running, because you'll just die tired."

Offline Lars_J

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #75 on: 04/04/2014 11:01 pm »
And they can't "malfunction" inside the VAB. Malfunction means operating incorrectly and inside the VAB they are not operating at all. They are not even "functioning". They are just sitting there doing nothing.

Your story does not seem to mesh with the safety precautions taken in the VAB when dealing with solids. Perhaps the precautions were excessive, but the point remains that an element that comes pre-packaged with the propellant *and* oxidizer is always going to be more risky than one that contains neither at the time of handling.

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #76 on: 04/05/2014 02:17 am »
Your story does not seem to mesh with the safety precautions taken in the VAB when dealing with solids. Perhaps the precautions were excessive, but the point remains that an element that comes pre-packaged with the propellant *and* oxidizer is always going to be more risky than one that contains neither at the time of handling.

I could be wrong, but I thought part of the safety precautions had to do with the extreme toxicity of the propellant and the need for absolutely no trace of it to escape into the air or floor???

In any case, SRBs are off topic for this thread.
« Last Edit: 04/05/2014 02:18 am by TomH »

Offline Space Ghost 1962

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #77 on: 04/05/2014 02:38 am »
To finish the off topic SRB hazard issue:

The primary hazard is accidental ignition of SRB segment(s) during assembly, said ignition occurring asymmetric to the intended burn profile, and without seal integrity, nozzle installation, or control system. It breaks apart and something(s) shoots around the VAB bringing down the building and catching fire.

Other issue is the hideous, horrible, toxic dust that is awful to passivate, worse to work through. End of RSRB hazard story.

The other reason to prefer LRBs is that they weigh less, you might get four around a HLV core on a crawler, and your IMLEO will always be better, which if you do a HLV has to be important. They are just an effective cheat.

None of this matters as to why Ares/SLS uses them. They are used like on STS because they are there and are good enough to scare Russia and China from thinking / daring to compete with the US at heavy lift. E.g. not to bring down total end-end fixed, operations or development cost, but because they know we can do it and they can't - a HLV "bronx cheer". "Simple!"

A rational HLV for space exploration would never use these things. Congress doesn't fund rational space exploration HLV, only space cadets think so. They fund national security threats to scare off others. End of story.

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #78 on: 04/12/2014 11:59 am »
If Russia stops exporting RD-180s to the US in retaliation for sanctions, and so US production of the engines is started for national security reasons, wouldn't that change things a lot? There would be a desire to find other uses for the engine to share the costs among and it would save NASA the cost and trouble of developing a new liquid engine, making the liquid option more attractive relative to solids as well. Four RD-180s per booster should be enough to get to 130 tons with four RS-25s in the core.

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #79 on: 04/12/2014 04:49 pm »
If Russia stops exporting RD-180s to the US in retaliation for sanctions, and so US production of the engines is started for national security reasons, wouldn't that change things a lot? There would be a desire to find other uses for the engine to share the costs among and it would save NASA the cost and trouble of developing a new liquid engine, making the liquid option more attractive relative to solids as well. Four RD-180s per booster should be enough to get to 130 tons with four RS-25s in the core.

Already discussed here:

http://forum.nasaspaceflight.com/index.php?topic=33327.0

Nevertheless, post is off topic for this thread which is specific to F-1B vs. AJ-1E6

If you want to compare each against all others, the discussion goes here:

http://forum.nasaspaceflight.com/index.php?topic=27714.0
« Last Edit: 04/12/2014 04:52 pm by TomH »

Offline Prober

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #80 on: 04/24/2014 04:54 pm »
And they can't "malfunction" inside the VAB. Malfunction means operating incorrectly and inside the VAB they are not operating at all. They are not even "functioning". They are just sitting there doing nothing.

Your story does not seem to mesh with the safety precautions taken in the VAB when dealing with solids. Perhaps the precautions were excessive, but the point remains that an element that comes pre-packaged with the propellant *and* oxidizer is always going to be more risky than one that contains neither at the time of handling.

enough :D   solids have their place, look at Orbital and their use in Antares.
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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #81 on: 04/24/2014 10:17 pm »
enough :D   solids have their place, look at Orbital and their use in Antares.

They provide a decent kick at a low price, and are capable of being stored in a launch ready condition for extended periods of time, but thanks to their fuel load, they're very unsafe relative to empty metal tubes. I don't think there's much good in maintaining SRBs for manned launch vehicles beyond subsidizing the solid rocket fuel industries who also supply ballistic missiles to the United States and its allies.
« Last Edit: 04/24/2014 10:22 pm by RotoSequence »

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #82 on: 04/24/2014 10:33 pm »
Discussion of SRBs is OT for this thread. Please note the thread title and move the discussion to an appropriate location.

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #83 on: 04/24/2014 11:39 pm »
I'm curious how hard Aerojet Rocketdyne is still pushing on the three options of AJ1E6, F-1B, and RS-25 rework.  The RS-25 work has money in hand and as much certainty as there can be in this industry, so I imagine it is secure.  The F-1B has risk reduction money in hand, so I imagine they are working towards those deliverables (was that a powerpack built?  just a GG? built and tested?  flow-tested or hot fired?). 

Soo...what does Aerojet Rocketdyne have for AJ1E6?  Wasn't there a risk reduction contract for it?  If so, what was the deliverable for that?  And the tanking/stage for the AJ1E6 boosters was going to be built by Aerojet?  Have they announced completed milestones for that structure like Dynetics did for the Pyrios?

I wonder what Orbital's choice of a production engine for Antares will mean for all this.  Also, though the chances of domestic RD-180 production seem to have receded for now, the RD-180 is a potential wildcard (could substitute for AJ1E6, I'd think).

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #84 on: 04/25/2014 12:35 am »
There's been a pretty good bit of speculation about how AJ's purchase of Rocketdyne affects this. Some speculate one company can't have two entries; others say the F-1B is under Dynetics' control, and thus allowed as a separate entity. Dynetics has released a fair amount of publicity re. their efforts. They test fired the GG of an F-1A, but not the power pack. They've said nothing that I know of re. actually fabricating anything. AJ has said virtually nothing about anything that they've done in regard to AJ-1E6 other than giving it a name and stating the heritage engine it would be based on. I can't address Anteres. There was a thread re. using four RD-180s per booster.

This thread is specifically to address F-1B vs. AJ-1E6.

There is a dedicated thread to discuss RD-180 on SLS advanced boosters:

http://forum.nasaspaceflight.com/index.php?topic=33327.0

There is a dedicated thread to discuss all possible liquid entries for SLS advanced boosters:

http://forum.nasaspaceflight.com/index.php?topic=27714.0

There is a dedicated thread to discuss ATK Dark Knight Advanced Solids:

http://forum.nasaspaceflight.com/index.php?topic=30862.0

Offline a_langwich

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #85 on: 04/25/2014 02:04 am »
According to this, http://www.nasa.gov/home/hqnews/2012/oct/HQ_12-339_SLS_Awards_Contract.html#.U1m8a1cXK_E

NASA awarded 3 advanced booster risk reduction contracts (at that point--one more was awarded later, listed below):  ATK; Dynetics for F-1B major components including powerpack fabrication and test, plus metallic cryo tank fabrication; and Northrop Grumman for composite cryo tanks.

According to http://www.nasa.gov/home/hqnews/2013/feb/HQ_13-054_Aerojet_SLS_Boosters.html , Aerojet got $23M to
Quote
reduce the risk and improve technical maturation of a liquid oxygen and kerosene oxidizer-rich staged-combustion engine. The company will fabricate a representative full-scale 550,000-pound thrust class main injector and thrust chamber, and prepare to conduct a number of tests measuring performance and demonstrating combustion stability.

I'm sure all this is mentioned in some thread, maybe this one though I didn't see it, but I thought it might be useful to throw it out again, with the nasa.gov references.

Aerojet tested a heritage gas generator, which I think you were indicating by saying F-1A, but not one they've built.

Would Northrop Grumman's composite cryo work figure in a separate booster bid (what engine)?  Do we know anything about the non-engine part of Aerojet's design?  I don't see a lot on Aerojet Rocketdyne's website about structures...might they contract that out to Northrop Grumman?  (Doesn't ATK do a lot of composite structures...be a prime on one contract proposal and a sub on another?)  I suppose Aerojet could use Boeing/LM/ULA production for the tank as well.
« Last Edit: 04/25/2014 02:15 am by a_langwich »

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #86 on: 04/25/2014 02:55 am »
These are good questions, questions I'd like to have answered as well. Maybe something that Chris might want to pursue in an update article.

I doubt SpaceX is interested, but a Raptor entry would be interesting. It could at least give them some extra research money.

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #87 on: 04/25/2014 05:45 pm »
These are good questions, questions I'd like to have answered as well. Maybe something that Chris might want to pursue in an update article.

I doubt SpaceX is interested, but a Raptor entry would be interesting. It could at least give them some extra research money.

Yea, on one hand, SpaceX could get that extra R&D money from a Raptor based SLS booster contract.

On the other hand, although they won't say it, I'm sure Elon is hoping his Raptor powered BFR being available and relatively inexpensive may help cause SLS cancellation.  So probably counter productive to present a proposal for SLS that helps it's cost and performance.  I think rather than wanting a piece of the pie...they are shooting for the -whole- pie.

My guess is the latter, so I'd be surpised if Elon starts making noise about wanting to enter the booster competition.  Even though he is developing an engine that would be great for it. 

Offline baldusi

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #88 on: 04/25/2014 08:06 pm »
Look. SpaceX has two cards that depend on demonstrating usability. The big one is designing a reusable BFR and thus making SLS obsolete after the four initial launches. But the second is very interesting anyways. It would seem that Falcon Heavy inaugural flight will demonstrate something about returnable boosters. Thus, they could enter the full competition with the ace of spades. Demonstrated reusable technology. And their Raptor demonstration might even go in that direction. But knowing SpaceX, they would only do that if they kept all the ownership on the boosters.
But let's be frank, if SpaceX demonstrates just reusable boosters, the Advanced Booster competition will have a taste of obsolete.

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #89 on: 04/25/2014 09:55 pm »
But let's be frank, if SpaceX demonstrates just reusable boosters, the Advanced Booster competition will have a taste of obsolete.

There is one reason I doubt Raptor boosters could be used on SLS: ISP Density of CH4 in relation to VAB door width. With the core having only 4 main engines, and with EUS being smaller than the J-2X LUS, the difference in the 130mt payload must come from potent boosters. 5.5m is the max width for boosters in relation to the VAB doors. I don't know if that volume of CH4 at its ISP density would be enough total thrust. Then subtract prop needed for RTLS, and 130mt seems exceedingly difficult.

Look. SpaceX has two cards that depend on demonstrating usability. The big one is designing a reusable BFR and thus making SLS obsolete after the four initial launches.

Agreed. Which would mean that the program failed not for the reasons so many critics posit, but because superior technology was developed by someone else and thus the fabled heritage technology was swept away by the tide of progress. I would not at all be surprised if your scenario is exactly the way history unfolds.

Offline baldusi

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #90 on: 04/25/2014 10:16 pm »
isp density is an idiotic measure. You care about pmf, isp and T/W. Your performance is not a straight multiplication. And then you have to measure it within the SLS performance requirements. Having great T/W of the stack is the important part, since the core is very efficient. It's true that the width is a limitation, not so much height. And you can look at the Dynetic proposal that's very T/W positive with moderate isp, vs the Aerojet with great isp and reasonable T/W. SpaceX could put three Raptors and have excellent isp and T/W, and then compensate with the re-usability margins. In any case, offering a reusable booster that reduces launch cost by 20% (or whatever the boosters cost to an SLS launch) and probably very low development cost, could well make the difference.

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #91 on: 04/25/2014 11:02 pm »

There is one reason I doubt Raptor boosters could be used on SLS: ISP Density of CH4 in relation to VAB door width. With the core having only 4 main engines, and with EUS being smaller than the J-2X LUS, the difference in the 130mt payload must come from potent boosters. 5.5m is the max width for boosters in relation to the VAB doors. I don't know if that volume of CH4 at its ISP density would be enough total thrust. Then subtract prop needed for RTLS, and 130mt seems exceedingly difficult.


CH4 is only like 19% less dense than RP-1, and that applies to only the fuel tank.  The LOX tank would be the same size.  It could just be a little longer, use common bulkhead and still be 5.5m wide.  I don't think there'd be any problem there. 
Also, if comparing to the Pryios boosters, the difference would even be less than 19% because the high ISP Raptors need less fuel and oxydizer to get the same performance.  I would think an Adavnced booster with 3 Raptor engines would be a little longer than an Aerojet booster, but pretty close in length to the Pyrios booster.

As for extra fuel for RTLS, there's no current Advanced booster requirement for reuse, so a SpaceX entry wouldn't -need- that.  If the advanced booster soliticitation eventually included reusability, then all entrants would need more fuel, not just SpaceX.  They could offer a RTLS booster as a means of getting a really low price.  But then they'd run into issues of how to land it.  F9 has 9 engines with a central one.  One would assume BFR would have a similar configuration for Raptors and perform in the same way.  If you have a MLV size booster, with 3 Raptors, how do you land it?  A "Mini-Raptor" in the middle or something, but there'd have to be such an engine developed, and so far SpaceX hasn't indicated that's the case.  So not sure how they'd approach a reusable booster.


Agreed. Which would mean that the program failed not for the reasons so many critics posit, but because superior technology was developed by someone else and thus the fabled heritage technology was swept away by the tide of progress. I would not at all be surprised if your scenario is exactly the way history unfolds.

Elon will never say it because he doesn't want to make any enemies in Congress or NASA, but there's no way he isn't ultimately angling for that.  How could you not if you were going to build a HLV in the same class (initially) as SLS?
The officially line is their BFR is going to Mars and NOT to compete with SLS.  And they won't deviate from that...until it's time to.

And that's why I would anticipate SpaceX does not pursue the Advanced booster competition.
Besides, they'd have to come up with a new 5.5m core diameter tooling, that won't help with their Falcon or BFR LV's.  So also not much incentive there to jump in and possibly help SLS survive longer.

Edited: to correct the referenced quotes.
« Last Edit: 04/25/2014 11:44 pm by Lobo »

Online Steven Pietrobon

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #92 on: 04/28/2014 07:37 am »
CH4 is only like 19% less dense than RP-1, and that applies to only the fuel tank.  The LOX tank would be the same size.

LCH4 has a density of 0.4239 kg/L while RP-1 has a density of 0.8 kg/L. Thus, LCH4 is 47% less dense than RP-1. However, methalox at a 3.6 to 1 oxidiser to fuel mixture ratio (MR) is 19% less dense than kerolox at a 2.8 MR.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline baldusi

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #93 on: 04/28/2014 04:00 pm »

CH4 is only like 19% less dense than RP-1, and that applies to only the fuel tank.  The LOX tank would be the same size.

LCH4 has a density of 0.4239 kg/L while RP-1 has a density of 0.8 kg/L. Thus, LCH4 is 47% less dense than RP-1. However, methalox at a 3.6 to 1 oxidiser to fuel mixture ratio (MR) is 19% less dense than kerolox at a 2.8 MR.
Rule of thumb, for staged combustion, CH4 requires 30% more volume than RP-1. Which if you scale a tank in 3D mean an 9% longer dimensions. And the general 10extra seconds or so of isp usually mean very similar performance. Of course Russians and SpaceX appear to calculate that if you design the SC CH4 cycle taking advantage of the characteristics, like using the expander cycle for something, and thinking in terms of reusability, the CH4 is superior.
BTW rocket engine with more restarts lowers development and certifications cost. You might need as little a 10 engines for development vs 100s.

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #94 on: 04/28/2014 04:34 pm »
CH4 is only like 19% less dense than RP-1, and that applies to only the fuel tank.  The LOX tank would be the same size.

LCH4 has a density of 0.4239 kg/L while RP-1 has a density of 0.8 kg/L. Thus, LCH4 is 47% less dense than RP-1. However, methalox at a 3.6 to 1 oxidiser to fuel mixture ratio (MR) is 19% less dense than kerolox at a 2.8 MR.

Ok, thanks for the clarification Steve.  I used your number of 19%, but didn't realize you meant total comparitive propellant volume, and not just the fuel comparitive volume.

Offline Lobo

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #95 on: 04/28/2014 04:37 pm »

CH4 is only like 19% less dense than RP-1, and that applies to only the fuel tank.  The LOX tank would be the same size.

LCH4 has a density of 0.4239 kg/L while RP-1 has a density of 0.8 kg/L. Thus, LCH4 is 47% less dense than RP-1. However, methalox at a 3.6 to 1 oxidiser to fuel mixture ratio (MR) is 19% less dense than kerolox at a 2.8 MR.
Rule of thumb, for staged combustion, CH4 requires 30% more volume than RP-1. Which if you scale a tank in 3D mean an 9% longer dimensions. And the general 10extra seconds or so of isp usually mean very similar performance. Of course Russians and SpaceX appear to calculate that if you design the SC CH4 cycle taking advantage of the characteristics, like using the expander cycle for something, and thinking in terms of reusability, the CH4 is superior.
BTW rocket engine with more restarts lowers development and certifications cost. You might need as little a 10 engines for development vs 100s.

Interesting.  So do you mean a Raptor methalox booster would be about 9% longer than a comparitive RP-1 staged combustion booster like an RD-180 powered booster or an AJ-1E6 powered booster?  Or that given Raptor's extra performance, it would mean the boosters would be similar in size?

Also, roughly, assuming 5.5m diameter for both, how would a Raptor powered booster compare lengthwise to the Dynetics F-1B booster?

Offline baldusi

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #96 on: 04/29/2014 03:02 am »

Interesting.  So do you mean a Raptor methalox booster would be about 9% longer than a comparitive RP-1 staged combustion booster like an RD-180 powered booster or an AJ-1E6 powered booster?  Or that given Raptor's extra performance, it would mean the boosters would be similar in size?

Also, roughly, assuming 5.5m diameter for both, how would a Raptor powered booster compare lengthwise to the Dynetics F-1B booster?
They are width limited with SLS boosters, so it would need 30% extra length to have the same propellant mass. But, this is a booster application. You need to analyze the whole stack. SLS core has amazing propulsion, but the pmf might not be that good at first. You only care about the whole stack T/W, but it might have maximum G limitations (STS was <= 3G).
But in general, NASA is very cautious wrt staged combustion engines. And those are usually more expensive. What I mean is that the F-1B is less efficient than a SC engine, but can have more thrust.

Offline TomH

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Re: Aerojet vs. Dynetics LRB's for SLS.
« Reply #97 on: 04/30/2014 10:30 pm »
What I mean is that the F-1B is less efficient than a SC engine, but can have more thrust.

Maybe our primary two mertric should be $/newton and $/Kg to destination (LEO/GSO/TLI/TMI).

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