Author Topic: How should NASA evolve the SLS?  (Read 178652 times)

Offline newpylong

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Re: How should NASA evolve the SLS?
« Reply #360 on: 04/03/2013 06:23 pm »
Who is to say the other customers won't have their own fireworks?

Offline HappyMartian

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Re: How should NASA evolve the SLS?
« Reply #361 on: 04/04/2013 01:02 am »
Who is to say the other customers won't have their own fireworks?



Boosters that are affordable and make possible human single SLS launches to the Moon are perhaps important issues to evolving the SLS.

Apollo Lunar missions must have had some worrisome LOM and LOC numbers. "How can we improve those Lunar LOM and LOC numbers?" is probably a critical question for evolving the SLS.
"The Moon is the most accessible destination for realizing commercial, exploration and scientific objectives beyond low Earth orbit." - LEAG

Offline newpylong

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Re: How should NASA evolve the SLS?
« Reply #362 on: 04/04/2013 03:09 pm »
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Offline TomH

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Re: How should NASA evolve the SLS?
« Reply #363 on: 05/04/2013 02:18 am »
I think this is the first graphic I have seen with this range of vehicles. It surely gives some perspective on the size of this monster.

[I embedded it, but the image was too wide in that format, so am just posting the link. Image loads better this way with nothing else in the screen.]

http://4.bp.blogspot.com/-JjCv75NUgVI/T1tBicTZ26I/AAAAAAAAm9w/H2bB2E8sliU/s1600/IM+2012-03-10+a+las+11.53.47.png

This one shows more vehicles, but doesn't include Saturn and Nova.

http://i.imgur.com/04bh0.jpg
« Last Edit: 05/04/2013 02:33 am by TomH »

Offline llanitedave

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Re: How should NASA evolve the SLS?
« Reply #364 on: 05/05/2013 04:44 am »
That Liberty vehicle looks like about the lowest size/capacity ratio of the whole lot.
"I've just abducted an alien -- now what?"

Offline Hyperion5

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Re: How should NASA evolve the SLS?
« Reply #365 on: 05/05/2013 05:12 am »
I think this is the first graphic I have seen with this range of vehicles. It surely gives some perspective on the size of this monster.

[I embedded it, but the image was too wide in that format, so am just posting the link. Image loads better this way with nothing else in the screen.]

http://4.bp.blogspot.com/-JjCv75NUgVI/T1tBicTZ26I/AAAAAAAAm9w/H2bB2E8sliU/s1600/IM+2012-03-10+a+las+11.53.47.png

This one shows more vehicles, but doesn't include Saturn and Nova.

http://i.imgur.com/04bh0.jpg

I've seen a number of those, and unfortunately they were made before Spacex updated their plans for the Falcon 9 family.  The Falcon Heavy would be even larger than it's shown in that lineup.  Here's an example of its true size in silhouette: http://www.sen.com/uploads/misc/Evolution-of-the-rocket2.gif

The other thing that really strikes me is just how compact the Proton-M is compared with other launchers of similar mass.  It really brings home just how dense its propellants are compared to a Falcon's or a Zenit's.  I just noticed this features the old-style SLS Bloc 2 with the big J-2X US.  It'd be really interesting to see an SLS Bloc IB inserted into the comparison charts. 

Offline TomH

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Re: How should NASA evolve the SLS?
« Reply #366 on: 05/08/2013 09:18 pm »
I just noticed this features the old-style SLS Bloc 2 with the big J-2X US.  It'd be really interesting to see an SLS Bloc IB inserted into the comparison charts.

I was thinking exactly the same thing. It would be nice to see Bloc IB with solids and to see Bloc IB with Dynetic boosters as well for the contrast to each other as well as to the other vehicles.

Offline Hyperion5

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Re: How should NASA evolve the SLS?
« Reply #367 on: 05/17/2013 10:46 pm »
So, could that "while" indicate the possibility of remaining with five-segment SRB and making up for the Advanced Booster performance with the DUUS?
I think that is clear.  The presentation shows a 105 tonne capability using five-segment booster and a bigger-than-ICPS upper stage.  This is a compromise rocket that can do the mission to nowhere for the White House.  Its development would make Mars even less likely because it would stop Advanced Booster and J-2X.

 - Ed Kyle

Oh I don't know about it making Mars less likely, Ed.  It should be considerably cheaper developing just one upper stage than two, and having dual-use flexibility is a point in favor of it rather than against it in my opinion.  This DUUS is enough to turn the Energia-class SLS Bloc 1 into a Saturn V-equivalent (118 mt LEO/43 mt BEO).   An SLS Bloc 2 with DUUS & F-1B LRBs would lift 155 mt to LEO and send 61 mt BEO.  If that a rocket of that class was somehow inadequate for getting us to Mars, I'd be questioning whether the mission planners got too ambitious.  To me the SLS Bloc 1B's DUUS is the best step towards a push for Mars and certainly not a hindrance.  You know what a true hindrance looks like?  Another Congressional showdown that results in a slimmer NASA budget. 
« Last Edit: 05/17/2013 10:48 pm by Hyperion5 »

Offline Lobo

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Re: How should NASA evolve the SLS?
« Reply #368 on: 05/18/2013 12:21 am »
So, could that "while" indicate the possibility of remaining with five-segment SRB and making up for the Advanced Booster performance with the DUUS?
I think that is clear.  The presentation shows a 105 tonne capability using five-segment booster and a bigger-than-ICPS upper stage.  This is a compromise rocket that can do the mission to nowhere for the White House.  Its development would make Mars even less likely because it would stop Advanced Booster and J-2X.

 - Ed Kyle

Oh I don't know about it making Mars less likely, Ed.  It should be considerably cheaper developing just one upper stage than two, and having dual-use flexibility is a point in favor of it rather than against it in my opinion.  This DUUS is enough to turn the Energia-class SLS Bloc 1 into a Saturn V-equivalent (118 mt LEO/43 mt BEO).   An SLS Bloc 2 with DUUS & F-1B LRBs would lift 155 mt to LEO and send 61 mt BEO.  If that a rocket of that class was somehow inadequate for getting us to Mars, I'd be questioning whether the mission planners got too ambitious.  To me the SLS Bloc 1B's DUUS is the best step towards a push for Mars and certainly not a hindrance.  You know what a true hindrance looks like?  Another Congressional showdown that results in a slimmer NASA budget. 

Yea, I think the thought here might be, if we are going to upgrade to avanced boosters anyway (which must be done, as there's only enough 5-seg parts for maybe 10 pairs), Then rather than try to beef up the core with two upper stages, and adding another RS-25 to the bottom, just make the Advanced boosters powerful enough to get you there without it.  I've always thought it's kinda of a waste to utilize a sustainer core platform, but not let the sustainer core burn all the way to disposal orbit.  If you need a 2nd stage to orbit, why aren't we making the core kerolox and putting F-1X's on it?  And then making a true 2-stage to orbit platform and toss out the idea of SRB's and then later Advanced boosters all together?  Make a slimmer Saturn V then.
But, if we are going to use those impressive and expensive RS-25's on a sustainer stage, then let them do their job and push for the whole ascent (disposal orbit).  Just make the advanced boosters bigger if you want more performance.   No matter which is chosen, they must be designed new anyway, just specify they must have enough performance to get SLS with a DUUS what they want, and if ATK's composite boosters can't get there, then they can't, and LRB's can fight it out.

Putting a new J2X 2nd stage on a sustainer core platform just never seemed to make sense to me.


Offline TomH

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Re: How should NASA evolve the SLS?
« Reply #369 on: 05/18/2013 12:24 am »
The answer is the booster competition has not started.

It's only an engineering demonstration and risk reduction at this time.

Point taken, but only 4 risk reduction contracts were issued, and that round was closed. ATK for solid advanced boosters, Dynetics and AJ for RP1 Advanced Boosters, and Northrop Grumman for composite tanks. The only talk of RS-68 is from an unnamed secondhand source. No corporation has publicly stated that they are considering RS-68 or any H2 engine. HydroLox just doesn't have the ISP density for that kind of initial thrust. (DIV and DIVH are not in this class.)

Offline TomH

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Re: How should NASA evolve the SLS?
« Reply #370 on: 05/18/2013 12:27 am »
Yea, I think the thought here might be, if we are going to upgrade to avanced boosters anyway (which must be done, as there's only enough 5-seg parts for maybe 10 pairs), Then rather than try to beef up the core with two upper stages, and adding another RS-25 to the bottom, just make the Advanced boosters powerful enough to get you there without it.  I've always thought it's kinda of a waste to utilize a sustainer core platform, but not let the sustainer core burn all the way to disposal orbit.  If you need a 2nd stage to orbit, why aren't we making the core kerolox and putting F-1X's on it?  And then making a true 2-stage to orbit platform and toss out the idea of SRB's and then later Advanced boosters all together?  Make a slimmer Saturn V then.
But, if we are going to use those impressive and expensive RS-25's on a sustainer stage, then let them do their job and push for the whole ascent (disposal orbit).  Just make the advanced boosters bigger if you want more performance.   No matter which is chosen, they must be designed new anyway, just specify they must have enough performance to get SLS with a DUUS what they want, and if ATK's composite boosters can't get there, then they can't, and LRB's can fight it out.

Putting a new J2X 2nd stage on a sustainer core platform just never seemed to make sense to me.

Bingo, on every point. And your mention of a slimmer Saturn V reminds me that Hyperion5 has asked several times whether it wouldn't be easier to resurrect that LV. F-1A with J-2S could have been done, F-1B with J-2X if they insist on the most modern upgrades. S-IVB was a great dual use US with Saturn I-B.

We do know they've said the 5th core engine is out. But who knows, wouldn't be the first time they've changed their minds. That would, however, give the ATK boosters the ability to hit 130 mt with the full sized US.

Personally, I wonder whether the core + Dynetics Boosters + iCPS wouldn't hit the 130 mt mark (that's Block IB but with Dynetics boosters swapped in, or its Block IA using Dynetics boosters and iCPS added). I don't remember anyone ever running the calculations on that and posting them here. Anyone care to run that through Schillings?
« Last Edit: 05/18/2013 12:45 am by TomH »

Offline notsorandom

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Re: How should NASA evolve the SLS?
« Reply #371 on: 05/18/2013 05:35 am »
The answer is the booster competition has not started.

It's only an engineering demonstration and risk reduction at this time.

Point taken, but only 4 risk reduction contracts were issued, and that round was closed. ATK for solid advanced boosters, Dynetics and AJ for RP1 Advanced Boosters, and Northrop Grumman for composite tanks. The only talk of RS-68 is from an unnamed secondhand source. No corporation has publicly stated that they are considering RS-68 or any H2 engine. HydroLox just doesn't have the ISP density for that kind of initial thrust. (DIV and DIVH are not in this class.)
You are correct that there was the risk reduction awards and that none of the awards went to hydrolox propulsion. However the advanced booster competition is years away. By then there will likely be other bidders. There has been talk of including the RS-68 in the trade space.

Offline spectre9

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Re: How should NASA evolve the SLS?
« Reply #372 on: 05/18/2013 10:28 am »
Who really knows if enough hydrolox to get a 130mt payload into orbit can fit through the VAB doors.

Perhaps really tall boosters can be made.

Lets not forget that 5.49m F-1B boosters + a large upper stage goes well beyond the 130mt requirement.

I'm not sure there is a definitive answer yet.

Offline deltaV

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Re: How should NASA evolve the SLS?
« Reply #373 on: 05/18/2013 04:06 pm »
Who really knows if enough hydrolox to get a 130mt payload into orbit can fit through the VAB doors.

Perhaps really tall boosters can be made.
The suitability of hydrolox boosters was discussed in one of the booster threads. IIRC it was determined that sufficiently large boosters would fit. Presumably the NASA people considering RS-68 boosters have also done those back of the envelope calculations. This update thread is not a good place for discussing possible boosters. [Posts were moved by mods.]
« Last Edit: 05/19/2013 03:04 pm by deltaV »

Offline Hyperion5

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Re: How should NASA evolve the SLS?
« Reply #374 on: 05/18/2013 04:33 pm »
Who really knows if enough hydrolox to get a 130mt payload into orbit can fit through the VAB doors.

Perhaps really tall boosters can be made.

Lets not forget that 5.49m F-1B boosters + a large upper stage goes well beyond the 130mt requirement.

I'm not sure there is a definitive answer yet.

Oh you could definitely get enough hydrolox up top to fling 130 mt to LEO and still fit through the VAB doors.  Boeing said that while the RL-10 powered DUUS upper stage-equipped Bloc 2 could launch 155 mt to LEO, one with a single J-2X could launch 178 mt, a 23 mt difference. Given the SLS Bloc IB is already capable of lifting 118 mt payloads to LEO, I'm fairly confident the J-2X US could lift at least 12 more mt to LEO.  The SLS Bloc I in manned layout is 318 feet tall, and I've heard estimates that the SLS Bloc IB may be around 340 feet tall in its manned layout.  I would expect that an SLS with a single J-2X DUUS would come in at around 350-360 feet tall.  That should not be a problem for NASA given it's roughly the same height as the Saturn V. 

Offline Lobo

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Re: How should NASA evolve the SLS?
« Reply #375 on: 05/19/2013 01:54 am »
Who really knows if enough hydrolox to get a 130mt payload into orbit can fit through the VAB doors.

Perhaps really tall boosters can be made.

Lets not forget that 5.49m F-1B boosters + a large upper stage goes well beyond the 130mt requirement.

I'm not sure there is a definitive answer yet.

Oh you could definitely get enough hydrolox up top to fling 130 mt to LEO and still fit through the VAB doors.  Boeing said that while the RL-10 powered DUUS upper stage-equipped Bloc 2 could launch 155 mt to LEO, one with a single J-2X could launch 178 mt, a 23 mt difference. Given the SLS Bloc IB is already capable of lifting 118 mt payloads to LEO, I'm fairly confident the J-2X US could lift at least 12 more mt to LEO.  The SLS Bloc I in manned layout is 318 feet tall, and I've heard estimates that the SLS Bloc IB may be around 340 feet tall in its manned layout.  I would expect that an SLS with a single J-2X DUUS would come in at around 350-360 feet tall.  That should not be a problem for NASA given it's roughly the same height as the Saturn V. 

Yea, I think part of the misconception of hydrolox boosters is that they don't need to burn as long as Delta IV cores do, with is about 250 seconds.
And certainly not as long as sustainer cores that burn all the way to orbit, or most of the way like STS, SLS, Araine 5, H-IIB, etc. 
Big solids will burn around 120 seconds, and kerolox boosters like the Dynetics ones will probably burn about 150 seconds.  The Hydrolox SLS core with those great performing RS-25's can take it from there.  So even though hydrolox boosters with RS-68's will have great impulse, you probably won't be burning them for nearly as long as Delta IV.  Probably more like 150 seconds.  I think I saw a post around here awhile back that someone posted some hydrolox LRB's replacement for Shuttle SRB's.  I think they were only about 5m wide and burned for about 150 seconds if I recall.

So, that's a bit over half the burn time of Delta IV.  So you could almost put two RS-68's on a Delta IV core and make an LRB out of it and have 125 seconds of burn time with both engines burning.  (that would probably be under powered, but just as an example).

Also, the stack really only needs all of that thrust to get off the pad and start ascent.  So a two or two RS-68 booster only needs all the juice for a short time, then they can throttle back, and then start shutting down engines. (on each side at the same time)
A three engine 5.5m LRB, maybe a bit longer than Delta IV, could start with all three burning at max, then shut one engine down after X seconds, and the 2nd engine down after Y seconds, and then that nice high ISP RS-68 (high for a booster) burn for maybe 170 seconds before separation or something?  Or 150 might be all that's needed.  Again, there's four RS-25's with the best performance that can take it from there.

Someone with more knowledge than I can probably flesh that out better, but keep in mind, max thrust is really only needed to break inertia off the pad.  In short order the amount of thrust needed to keep accelerating starts falling off.  That's why the SRB's have a tapered propellent load so they automatically throttle themselves down.
I'd guess the Dynetics boosters will have to throttle down and/or Shutdown engines prior to separation because the acceleration would get very high very quickly at full thrust with those beasts.

I think you'd have a hard time making a first stage booster hydrolox and 5.5m wider that'd burn for as long as a Delta IV, but that's not what you are trying to do.
« Last Edit: 05/19/2013 01:55 am by Lobo »

Offline BrightLight

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Re: How should NASA evolve the SLS?
« Reply #376 on: 07/02/2013 10:47 pm »
I don't know if this has been posted elsewhere but
http://www.aviationweek.com/Article.aspx?id=/article-xml/awx_07_01_2013_p0-592975.xml&p=1
The article claims that Boeing has produced a small diameter, 2.4 m test tank that is 30% lighter than Li-Al alloy tanks.
For the Shuttle external tank, LH2 tank as a model for SLS, the new composite tank would be 163,985 lbs, more than 70,000 lbs lighter than the 234,265 Li-Al tank.  To me that's a huge improvement.

Offline TrueBlueWitt

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Re: How should NASA evolve the SLS?
« Reply #377 on: 07/02/2013 11:09 pm »
I don't know if this has been posted elsewhere but
http://www.aviationweek.com/Article.aspx?id=/article-xml/awx_07_01_2013_p0-592975.xml&p=1
The article claims that Boeing has produced a small diameter, 2.4 m test tank that is 30% lighter than Li-Al alloy tanks.
For the Shuttle external tank, LH2 tank as a model for SLS, the new composite tank would be 163,985 lbs, more than 70,000 lbs lighter than the 234,265 Li-Al tank.  To me that's a huge improvement.

It also says they're working on a 5.5m tank to test.

Why specifally 5.5m? What potential application would this match up best with?  ACES?  SLS usage? Liberty?

Offline TomH

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Re: How should NASA evolve the SLS?
« Reply #378 on: 07/03/2013 12:43 am »
It also says they're working on a 5.5m tank to test.

Why specifally 5.5m? What potential application would this match up best with?

That's the diameter of Dynetics proposed advanced liquid booster for SLS. Perhaps Dynetics might sub-contract with Boeing for the tanks.

Offline Lobo

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Re: How should NASA evolve the SLS?
« Reply #379 on: 07/03/2013 01:56 am »
It also says they're working on a 5.5m tank to test.

Why specifally 5.5m? What potential application would this match up best with?

That's the diameter of Dynetics proposed advanced liquid booster for SLS. Perhaps Dynetics might sub-contract with Boeing for the tanks.

That's also one of the diameters they are considering for the SLS DUUS LOX tank...which Boeing will be building...

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