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Author Topic: NASA Space Launch System (SLS)  (Read 69208 times)

Offline Johnbr

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« Last Edit: September 14, 2011, 03:39:30 pm by flateric »

Offline RyanC

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Re: NASA Space Launch System (SLS)
« Reply #1 on: September 14, 2011, 04:58:15 pm »
So after two years of delays caused by Mr. Obama cancelling Constellation, we get...
 
...essentially the 2005 ESAS version of Ares V, with SSMEs for the core stage and an External Tank Diameter core stage; but now painted shiny white and black to try and get Apollo-era cachet.
 
NASA quickly realized how stupid throwing away $50 million dollar engines designed for reuse between 50 flights was back during Constellation; and they switched to RS-68, which was developed out of a 1980s/1990s effort to develop a simplified expendable SSME.
 
But then the fools at DIRECT started coming out of the woodwork, claiming that the ablative nozzle of the RS-68 would never work on Ares V with the heat from the SRBs....
 
...Never mind that they had base heating problems in Apollo, specifically the Saturn V base heating environment was so severe that each F-1 engine had to be covered in about 1,000+ pounds of insulation to work.
 
Later plans to ground launch S-II stages with SRB boosters (look, Ares V forty years early!), ran into this problem of base heating from SRBs, albeit with the J-2s. Their solution was to design a heat shield that would prevent the J-2s from being fried by the SRB heat.
 
Anyway, it gets so much better.
 
Where will the SSMEs come from for the Obama [tm] version of Constellation?
 
Link
 
Quote
NASA’s three retired Space Shuttle orbiters are set to donate their entire Main Propulsion Systems (MPS) to the opening salvo of Space Launch System (SLS) Heavy Lift Launch Vehicles (HLV).

I'm sure the museums who paid $50~ million for each Orbiter are loving the fact that they will get defaced artifacts with no SSMEs, but in fact replica SSMEs in the back.
Ultimately, I predict that SLS will be within schedules and budgets for about a year. Maybe it'll actually run a bit ahead of schedule; as:
 

 
  • A lot of tough/costly work on 5-Seg and J-2X was done under CxP, providing immediate boost to appearances of viability for SLS.
  • The program would be in that phase of development that is cheapish
However, winter 2012; issues will unexpectedly arise, and the program will be restructured and then killed after a pretty hefty cost increase/overrun on the scope of what occured to JWST.
 
Mainly I think due to the programmatic costs inherent in redesigning and rechecking everything when you go from the 3 x SSME boattail in the 70 ton version that will fly first, to the 5 x SSME base for the next spiral.
 
Some more minor points:
 
Why will this rocket with many of the same elements as Ares V, be affordable when Ares V wasn't according to Obama?
 
How will they affordably recreate the workforce, which was already laid off by this point? (A lot of shuttle related workers were laid off in late August).
 
It's just a way for Obama to get certain Senators off his butt, and to defuse the use of NASA as a weapon against him in 2012 in certain very important states.
 
Once he's re-elected, he can quietly let SLS die when it cost-implodes in Winter 2012/Spring 2013.
« Last Edit: September 14, 2011, 05:00:58 pm by RyanCrierie »

Offline RyanC

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Re: NASA Space Launch System (SLS)
« Reply #2 on: September 14, 2011, 06:40:59 pm »
From
SAE 660442: Adaptation of the Saturn S-II for Ground-Launch Stage
 
Quote
A new base protection heat shield must be developed for the ground launch application of the S-II stage. This heat shield must be capable of in-flight separation when used in configurations in which the 120 in. solid motors operate prior to ignition of the J-2 engines.
 
The present S-II stage is provided with a heat shield which attaches to the J-2 engine below the turbine exhaust manifold (located on the nozzle at an area ratio e = 14:1). This shield is suspended from the thrust structure by a series of tubular struts.
 
The primary requirement for the new heat shield is to provide protection for the base of the thrust structure and LO2 tank, the equipment mounted on the stage thrust structure, and the J-2 engine nozzle, thrust chamber, and systems.
 
The current heat shield is 272 in. in diameter and does not provide protection to the lower portion of the J-2 engine nozzle.
 
Therefore, to provide protection for the base of the stage during solid motor firing, it is proposed to increase the heat shield diameter to close out these exposed areas.
 
It is anticipated that the base pressures experienced during liftoff will be substantially higher than the design values of the existing heat shield.
 
Two design concepts developed during the study for providing protection from the new base environment are illustrated in Fig. 6.
 
In the first approach (configuration A), the flexible curtain currently used to surround the J-2 engine nozzle is extended to protect the full length of the nozzle. Protection inside the nozzle is achieved with a diaphragm or cover placed over the exit area. The diaphragm is designed to separate from the engine prior to ignition. The load-carrying capability in the main body of the base heat shield is increased.
 
This improvement was necessary to counteract the higher base pressures and increased heat loads. As shown, the heat shield is also extended to approximately 396 in. in diameter. Access panels through the heat shield are included to facilitate assembly, maintenance, checkout, and repair procedures.
 
Configuration B forms a complete closeout of the boat tail area of the S-II stage. The heat shield is supported at the periphery of the interstage structure. Externally mounted crossbeams are provided to support the heat shield at four points. This method of mounting the support structure is necessary to:
 
1. Provide a simple method of releasing the heat shield prior to ignition of the J-2 engines.
 
2. Minimize redesign and relocation of equipment within the stage.
 
3. Achieve clearance between the existing engine nozzles and the structure. (During prelaunch checkout of the stage, it will be required to fully gimbal the liquid engines, thereby restricting the envelope for the heat shield support structure.)
 
In the configuration B design, protection to the engine and nozzles during S-II stage firing will be provided by a second heat shield.   This inner heat shield is identical to that currently utilized in the S-II stage. The following limited S-II stage system modifications will be required:
 
1. Jettisonable base protection system.
2. Elimination of the current ullage rocket-motor system.
3. Release of the strap-on solid motors.

Offline blackstar

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Re: NASA Space Launch System (SLS)
« Reply #3 on: September 14, 2011, 06:51:25 pm »
But then the fools at DIRECT started coming out of the woodwork, claiming that the ablative nozzle of the RS-68 would never work on Ares V with the heat from the SRBs....

They had no influence.

Offline blackstar

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Re: NASA Space Launch System (SLS)
« Reply #4 on: September 14, 2011, 06:56:27 pm »
Why will this rocket with many of the same elements as Ares V, be affordable when Ares V wasn't according to Obama?
 
How will they affordably recreate the workforce, which was already laid off by this point? (A lot of shuttle related workers were laid off in late August).
 
It's just a way for Obama to get certain Senators off his butt, and to defuse the use of NASA as a weapon against him in 2012 in certain very important states.
 
Once he's re-elected, he can quietly let SLS die when it cost-implodes in Winter 2012/Spring 2013.

Keep in mind (you probably know this) that Obama canceled this rocket before. The only reason that NASA made the announcement today is because the Senate put the rocket back into the authorization bill. NASA leadership--representing the president--does not want it. They dragged their feet on producing a design. And the only reason that the SSMEs are back in there is because Congress pushed for them.

I've read a couple of news articles on this so far that I hope will be edited before they are final, because neither one of them mentioned that this is the same rocket that was announced five years ago, and neither mentioned that the only reason NASA is doing this is because of a few members of the Senate. So some additional money will be pumped to the proper states, but this is not a development program in any real sense.

The only thing that will change the current impasse is a change in political leadership, either in the White House, Congress, or both.

Offline RyanC

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Re: NASA Space Launch System (SLS)
« Reply #5 on: September 14, 2011, 07:09:51 pm »
Keep in mind (you probably know this) that Obama canceled this rocket before.

And nothing has substantiatively changed between that rocket (Ares V) and this one, other than the clock being reset back to 2005; when Ares V was ET diameter and used SSMEs.
 
Quote
And the only reason that the SSMEs are back in there is because Congress pushed for them.

I believe the law called for STS elements to be used where practicable. That was a huge escape clause which went unused.

Offline Byeman

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Re: NASA Space Launch System (SLS)
« Reply #6 on: September 14, 2011, 07:36:54 pm »

 
But then the fools at DIRECT started coming out of the woodwork, claiming that the ablative nozzle of the RS-68 would never work on Ares V with the heat from the SRBs....
 
...Never mind that they had base heating problems in Apollo, specifically the Saturn V base heating environment was so severe that each F-1 engine had to be covered in about 1,000+ pounds of insulation to work.
 

Actually the fool is the one made the above post.  F-1 and J-2 are not the same as the RS-68  with an ablative nozzle

Offline Byeman

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Re: NASA Space Launch System (SLS)
« Reply #7 on: September 14, 2011, 07:41:20 pm »

 1.  I'm sure the museums who paid $50~ million for each Orbiter are loving the fact that they will get defaced artifacts with no SSMEs, but in fact replica SSMEs in the back.

Ultimately, I predict that SLS will be within schedules and budgets for about a year. Maybe it'll actually run a bit ahead of schedule; as:
 


1.  They are never going to get them as whole.  That was a going in condition.    And they are not "defaced" not all artifacts are complete in museums.

2.  Yes, you are the great know it all.


Offline RyanC

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Re: NASA Space Launch System (SLS)
« Reply #8 on: September 14, 2011, 08:24:24 pm »
Actually the fool is the one made the above post.  F-1 and J-2 are not the same as the RS-68  with an ablative nozzle

The Saturn approach to such base heating issues encountered during development was to brute force their way through, whether with thermal insulation applied to the engines directly (F-1) or using a mixture of an extended heat shield and thermal cocoons (J-2 for S-II Ground Launch concept), rather than declaring such issues were impossible to surmount.
 

Offline RyanC

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Re: NASA Space Launch System (SLS)
« Reply #9 on: September 14, 2011, 08:27:21 pm »
1.  They are never going to get them as whole.  That was a going in condition.    And they are not "defaced" not all artifacts are complete in museums.

There's a big difference between safing something for museum display, such as removing explosive bolts or squibs (which they had to do for the NASM's Do-335), or fabricating reproduction parts because the originals were lost somewhere or had deteriorated too badly for restoration purposes (Enola Gay, which sat outside for quite a long time), and deliberately taking major historical components of a valuable historical artifact and deliberately destroying them to save a couple bucks of money. (Removing all the orbiter SSME/MPSes so they can be expended on SLS Block I flights)

Offline Byeman

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Re: NASA Space Launch System (SLS)
« Reply #10 on: September 14, 2011, 09:26:52 pm »
1.  They are never going to get them as whole.  That was a going in condition.    And they are not "defaced" not all artifacts are complete in museums.

There's a big difference between safing something for museum display, such as removing explosive bolts or squibs (which they had to do for the NASM's Do-335), or fabricating reproduction parts because the originals were lost somewhere or had deteriorated too badly for restoration purposes (Enola Gay, which sat outside for quite a long time), and deliberately taking major historical components of a valuable historical artifact and deliberately destroying them to save a couple bucks of money. (Removing all the orbiter SSME/MPSes so they can be expended on SLS Block I flights)

NASA is loaning the orbiters.  No one it buying them.  The money is for transport.  NASA loans all its hardware and sometimes goes back a retrieves hardware for reuse.  Skylab 2 donated lots of hardware for Spacelab.  Enterprise donated avionics and systems for the other orbiters.

And you are wrong about your point. 

a.  It is not a big deal that the engines are being removed, they are not the original engines.  So your "historical" point holds no water.
a.  All  shuttle engines are not being destroyed.  There are just as many non flight ones around.   
b.  Even if NASA were to not used the SSME's, they would still be removed because with the non flight ones, they would be sent to more museums.
c.  So as it is, the orbiters are going to be displayed with real nozzles but dummy powerheads and there also will be a full up engine for displace next to the orbiter.

So, a not completely intact orbiter is not a big deal, especially when it visually the same and there is an SSME for a closeup look, which is not possible in the orbiter.

  Only anal people would care about it

Offline Archibald

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Re: NASA Space Launch System (SLS)
« Reply #11 on: September 14, 2011, 11:22:15 pm »
Quote
  Skylab 2 donated lots of hardware for Spacelab


Now that's interesting. What kind of hardware ?
Conservatoire de l'Air et de l'Espace d'Aquitaine - Bordeaux - Mérignac / Dassault aviation museum
http://www.caea.info/en/plan.php

Offline blackstar

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Re: NASA Space Launch System (SLS)
« Reply #12 on: September 15, 2011, 06:15:12 am »
I hate to seem like such a killjoy, but those SSME's are never going to fly. They'll spend another 10-20 years in a warehouse before they eventually get shipped off to museums.

On Tuesday I was at a discussion about the current human spaceflight situation and one of the themes was that this may be the beginning of the end of American human spaceflight. We may be seeing the long slow death of the program. The people who were involved in the discussion were pretty knowledgeable and include names that frequently appear in the press. They were fully aware of the pending SLS announcement and they were not optimistic about its chances of ever flying.

Offline Byeman

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Re: NASA Space Launch System (SLS)
« Reply #13 on: September 15, 2011, 09:20:07 am »
Quote
  Skylab 2 donated lots of hardware for Spacelab


Now that's interesting. What kind of hardware ?

Fans, lights, crew aids, etc

Offline RyanC

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Re: NASA Space Launch System (SLS)
« Reply #14 on: September 15, 2011, 04:13:35 pm »
Quote
Skylab 2 donated lots of hardware for Spacelab.  Enterprise donated avionics and systems for the other orbiters.

Hardware that was coming back after each mission, not expended.
 
Any SSMEs given to the SLS program will end up in the vincity of 30.2 deg N 74 deg W at the bottom of roughly 16,000 feet of water.
 
And the plan for SLS is to essentially expend pretty much the entire production run of available Block II SSMEs as a stopgap to save money and development costs before the "expendable" RS-25Es become available at some fuzzy undefined future point.
 
By the way, I can't believe you missed the big point about Skylab B, regarding historical authenticity, further undercutting your point.
 
In order to get Skylab B to fit within the new National Mall building, they had to get out the torches and other cutting implements to remove bits and pieces of it so it could fit into hall 114 at the Mall building; along with opening it up so that tourists could see the interior.
 
That enabled it to be preserved in a fully climate controlled environment; as opposed to being put outside to rot, or being cut up for scrap; so the damage served a useful purpose, similar to how the US Air Force Museum saved the XC-99 from destruction by carefully cutting it up with welding torches so the plane could be reassembled and restored at some future point (it was too large to move by land).
 
The proposed destruction of the Block II SSMEs serves no real practical purpose, other than for mythical cost savings -- because once the new "expendable" SSMEs are being built (I have serious doubts on that), quite a bit of money will have to be spent integrating the SLS stack with the new engines.
 
Quote
a.  It is not a big deal that the engines are being removed, they are not the original engines.  So your "historical" point holds no water.

They're the engines that powered each orbiter's final flight; making them historic artifacts by themselves.
 
Quote
a.  All  shuttle engines are not being destroyed.  There are just as many non flight ones around.

Currently, the plan is to destroy 26% of all flight capable SSMEs ever built, and pretty much every Block II ever built.
 
But that's OK, for they will make Replica Shuttle Main Engines (RSMEs) to fool tourists.
 
Quote
b.  Even if NASA were to not used the SSME's, they would still be removed because with the non flight ones, they would be sent to more museums.

This argument makes no sense. About 46 flight ready SSMEs were built, and there are only three orbiters left, which leaves 37 to dispense to museums with nine left in the orbiters. Then there's the test/developmental SSMEs which are historic in their own right, so there's more than enough to go around to museums, even if we left the final flight engines installed in the orbiters.
 
Quote
Only anal people would care about it

You'd be surprised at how many people would care about it.