Author Topic: SLS General Discussion Thread 3  (Read 123646 times)

Offline FinalFrontier

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Re: SLS General Discussion Thread 3
« Reply #740 on: 04/15/2019 03:57 am »
Yes and that's one of the core problems of the past two decades but not the only one.
Solids and insistence on continued use of them has caused nothing but delays budgetary harm and safety margin erosion both in CXP and again in SLS. Solids are literally the hill on which nasa is dying right now.

Solid rocket boosters should have either remained at 4 segment for J130 style SLV and then been phased out for LRBs for BEO, or been junked to begin with after STS. They were and are an ineffecient dangerous and expensive non re-usable design.
I recall the justification at the time for keeping the five segment program from CXP and consequently having to clean sheet a new core stage for SLS was because of "national security interest" in preserving the nation's solid rocket manufacturing base. Ludicrous as nothing has been preserved and there was ultimately no national security impact the suggestion was costs for DOD would rise for procuring missile motors if a five segment nasa vehicle was not made POR and this was proven to be bunk multiple times before and after.

Five star post for Chuck because what he is describing is exactly how this sort of nonsense happened and will continue to happen.
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Offline woods170

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Re: SLS General Discussion Thread 3
« Reply #741 on: 04/15/2019 07:20 am »

The Saturn V was built specifically to meet Kennedy's Moon goal, and it had no other planned uses. They did not justify building the Saturn V because of uses after Apollo, it was built to support Apollo. Skylab was just a bonus because they cut the Moon landing portion of the program off at Apollo 17, and had three leftover rockets (2 of which are museum pieces now). So the only "demand" for Saturn V was the Apollo program. It was never intended to be used after that.
<snip>
But if Congress does NOT fund any NASA programs that REQUIRE the SLS, then that would show a lack of demand. The SLS would be unneeded, and would likely be shut down for a number of reasons (i.e. safety, cost, etc.).

Back in the Constellation Program days the Ares-1 CLV and Ares-5 HLV were needed in order to enable the lunar program. Therefore there was a real existing demand for the Ares rockets. When our team proposed the Jupiter HLV to replace the Ares LVs it was to support the Constellation Program. Therefore there was a real existing demand for the Jupiter HLV. But when Obama cancelled the Constellation Program both the Ares and Jupiter LVs were no longer needed. No justifying demand for either LV existed and both should have disappeared. But because the Ares HLV was such a valuable pork-source the Senators decided to continue the Ares HLV under a new name; SLS. But the SLS is really a rocket without a purpose. There are no missions that require it that cannot be accomplished without it. Congress has refused to fund any missions requiring the SLS only that cannot be flown on other existing rockets. There are lots and lots and lots of proposed powerpoints showing NASA doing all kinds of wonderful things with the SLS but in reality Congress is having none of it. There is no justifiable reason to continue the SLS. The SLS is nothing but a big black hole into which taxpayer money disappears by the billions.

Ares became a LV without a purpose and was cancelled.
Jupiter became a LV without a purpose and was dropped.
But corruption reared its ugly head in Congress and the pork vendor professionals that roam the hallowed halls of Congress like poltergeists in an old mansion rebranded Ares as SLS and began sucking the government teat for all it was worth. They continue to do so to this very day, sucking everything else NASA could be doing dry as a desert-baked bone.

SLS needs to just go away so NASA can do something else worthy of its heritage with all that money. If it doesn't it won't be too many more years before NASA itself becomes a government agency without a purpose because all the things it could be doing will be happening under the oversight of commercial space agencies that are operating all kinds of programs more efficiently and at much lower cost than NASA could ever even dream about in a fantasy dream.

Excellent recap Chuck.

Like Jim has been saying for many, many years: NASA needs to get out of the business of building launchers. They should focus on building payloads instead.

Unfortunately NASA, being a government agency, will do whatever its political masters demand it to do.
I just wish Obama would have given Shelby and Nelson the middle finger back in the 2011 - 2012 timeframe.
« Last Edit: 04/15/2019 07:24 am by woods170 »

Offline Steven Pietrobon

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Re: SLS General Discussion Thread 3
« Reply #742 on: 04/15/2019 10:19 am »
Stephen, have you done any simulations to see what the impact would be on SLS's performance with those upper stages?

I've done plenty! See

http://www.sworld.com.au/steven/space/sls/

By the way, my birth certificate says my name is Steven. :-)

Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Steven Pietrobon

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Re: SLS General Discussion Thread 3
« Reply #743 on: 04/15/2019 10:45 am »
5 segment SRBs were developed for the upcoming STS missions, which all of a sudden became 51.6º orbits and they clawed back 20,000 pounds of payload.  NASA instead decided to go the SLWT(Super Light Weight Tank) route that gave back 7,000 pounds of payload, which was approx. 50% of the required ISS mission.

It was the Advanced Solid Rocket Motors (ASRM) that was planned to increase the Space Shuttle's payload to ISS. This motor had only three segments, not five.

https://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster#Advanced_Solid_Rocket_Motor_%28ASRM%29_Project

https://www.flightglobal.com/FlightPDFArchive/1991/1991%20-%201869.PDF

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19920000825.pdf

A separate five segment SRB program (different to that of RSRMV) was being investigated prior to Columbia in 2003 to further increase payload beyond the SLWT Al-Li tank (introduced in 1998 and the modification chosen to increase payloads to ISS).

https://www.nasa.gov/centers/marshall/news/news/releases/2003/03-186.html
« Last Edit: 04/15/2019 10:52 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Online notsorandom

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Re: SLS General Discussion Thread 3
« Reply #744 on: 04/15/2019 02:21 pm »
I thought I remember reading somewhere that since the aluminum/lithium alloy of the SLWT was not as strong as the older aluminum alloy that the SLS core ended up being lighter if the older aluminum were used. The SLS core is so much bigger and has to take stronger loads than the STS ET that the trade worked out to favor AL rather than making the AL-LI thicker. Anyone else remember hearing something along those lines?

Online envy887

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Re: SLS General Discussion Thread 3
« Reply #745 on: 04/15/2019 02:24 pm »
Does anyone know how to find the contract modifications for the SLS SRBs? I'm interested in an updated cost per flight set, but the last contract I can find was the final STS contract, which is $142M per flight set of 4-segment RSRMs.

Offline Endeavour_01

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Re: SLS General Discussion Thread 3
« Reply #746 on: 04/15/2019 03:34 pm »
Stephen, have you done any simulations to see what the impact would be on SLS's performance with those upper stages?

I've done plenty! See

http://www.sworld.com.au/steven/space/sls/

By the way, my birth certificate says my name is Steven. :-)

Awesome. Thanks.

My bad on the misspelling. It's fixed now.
I cheer for both NASA and commercial space. For SLS, Orion, Falcon 9, Falcon Heavy, Dragon, Starliner, Cygnus and all the rest!
I was blessed to see the launch of Space Shuttle Endeavour on STS-99. The launch was beyond amazing. My 8-year old mind was blown. I remember the noise and seeing the exhaust pour out of the shuttle as it lifted off. I remember staring and watching it soar while it was visible in the clear blue sky. It was one of the greatest moments of my life and I will never forget it.

Offline Hog

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Re: SLS General Discussion Thread 3
« Reply #747 on: 04/15/2019 04:39 pm »
5 segment SRBs were developed for the upcoming STS missions, which all of a sudden became 51.6º orbits and they clawed back 20,000 pounds of payload.  NASA instead decided to go the SLWT(Super Light Weight Tank) route that gave back 7,000 pounds of payload, which was approx. 50% of the required ISS mission.

It was the Advanced Solid Rocket Motors (ASRM) that was planned to increase the Space Shuttle's payload to ISS. This motor had only three segments, not five.

https://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster#Advanced_Solid_Rocket_Motor_%28ASRM%29_Project

https://www.flightglobal.com/FlightPDFArchive/1991/1991%20-%201869.PDF

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19920000825.pdf

A separate five segment SRB program (different to that of RSRMV) was being investigated prior to Columbia in 2003 to further increase payload beyond the SLWT Al-Li tank (introduced in 1998 and the modification chosen to increase payloads to ISS).

https://www.nasa.gov/centers/marshall/news/news/releases/2003/03-186.html
Thank you for setting me straight Steven.  Each of the ASRM (Advanced Solid Rocket Motors) segments were 150 inches in diameter, 4" greater in diameter than the RSRM(Redesigned Solid Rocket Motor) that was used for the first, post STS-51L Challenger Return To Flight(RTF).  This extra 4" of diameter increased the SRMs propellant loadout by 100,000 pounds per motor.

"The ASRM motor case consists of three segments that require 11 welded factory
joints, two bolted field joints, an integral external tank attach ring, and integral
external stiffeners to resist the buckling loads induced by splashdown.
In contrast, the RSRM motor case is composed of four segments that require
three bolted field joints, seven pinned factory joints and bolted external stiffeners.
The ASRM case is essentially the same weight as that of the RSRM,
since the weight gain associated with increased diameter is offset, primarily, by the
weight reduction due to the elimination of the factory pinned joints."

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19920000825.pdf

The ASRM project was abandoned after robots and other equipment and infrastructure was already installed after 2 billion dollars was invested.  That was 1993, only a few years after the Vandenberg/Shuttle fiasco which saw 5 plus billion dollars go down the drain. Make those same mistakes a couple times and you've got yourself a full year of funding for NASA,


The  4 segment RSRM used for the majority of the STS manifest. These units output just under 3.1 million pounds thrust at approx. MET plus 20 seconds.
In essence a SLS SRB is an STS SRB with an extra segment placed directly in the middle. The segments of the motor are referred to as, starting at the bottom nozzle end. 1)Aft Segment 2)Aft-Center Segment 3) Center Segment 4)Forward Center Segment 5) Forward Segment (contains the igniter)
As the SLS is expendable, there will be no parachutes. 
 25 percent more propellant
 New nozzle design
 New asbestos-free insulation and liner configuration
 New avionics
 Improved nondestructive evaluation processes
Approx 25% more thrust or more than 3.6 million pounds thrust per motor, for 3.6 million pounds combined.
"One five-segment engineering test motor, ETM-03, was fired on October 23, 2003."

The 5 segment SLS Solid Rocket Booster, will be constructed of existing flight hardware that was used in reuseable form for STS, though for SLS usage it will be in expendable form.  Apparently there are 80 of these Space Shuttle SRB segments made of 1/2" thick DAC
"Each motor consists of five rocket motor segments, thrust vector control and an aft exit cone assembly; it is 153 feet long and 12 feet in diameter. The entire booster (including nose cap, frustum, and forward and aft skirts) will be approximately 177 feet long. Of the booster’s total weight of 1.6 million pounds, propellant accounts for 1.5 million pounds."

OmegA will be using their new filament wound cases.  The Heavy variant will feature a 4 segment first stage, called Castor 1200 with a single segment 2nd stage(Castor 300), with a liquid upper stage on top(two RL10C-5-1 engines.  IIRC The 4 segment OmegA 4 segment first stage is equivalent in height to a 5 segment STS/SLS solid rocket motor which is 177 feet long.
With the issues that have come up with building new Mobile Launchers(ML's) or modifying existing ML's, I don't see NASA going with liquid boosters, though I think the dual F-1B powered Pyrios booster(3.6 million pounds thrust per booster-2 F-1s per or 7.2 million pounds thrust per launch) would have been excellent.  With NASA wanting to preserve its multi hundred million dollar investment in the large diameter SRM facilities in Utah, I can see SLS staying with solids.  Perhaps we install a 2nd thrust beam perpendicular to the current one in the SLS core stage and add a second set of the new 4 segment filament wound solid boosters.  A major redesign for sure, but the after these 80 SRB segments are flown(10 segments per mission), enough for 8 SLS missions, a new booster solution will also be a major redesign point as well.
There just seems to be hurdle after hurdle with SLS.
Paul

Online envy887

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Re: SLS General Discussion Thread 3
« Reply #748 on: 04/15/2019 05:09 pm »
...Perhaps we install a 2nd thrust beam perpendicular to the current one in the SLS core stage and add a second set of the new 4 segment filament wound solid boosters. ...

I recall someone on here saying they had looked at this and it was too much additional weight for the crawlers, MLPs, and/or crawlerways. The SRBs are some 730 tonnes each, so 4 of them will weigh more than a fully loaded Saturn V.

Offline edkyle99

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Re: SLS General Discussion Thread 3
« Reply #749 on: 04/15/2019 05:52 pm »
They should be using 5x RS25s on that core stage. Not doing that and not having a powerful upper stage has hamstrung the whole vehicle :(

Forgive me if this has been discussed before but with recent developments I wonder if the EUS does eventually get constructed will it be the current Boeing version or something "off the shelf" like ACES or the New Glenn 2nd stage.
When Delta 4 Heavy production ends, ICPS as-is will be toast, in my opinion.  ULA will (if it wins NSSL) then have Centaur 5 or 5+ available, which would provide more capability.  If Northrop Grumman or Blue Origin win NSSL, their upper stages would be candidates that should also increase performance - not EUS performance in any of these cases, but better than ICPS.   

 - Ed Kyle
« Last Edit: 04/15/2019 05:56 pm by edkyle99 »

Online envy887

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Re: SLS General Discussion Thread 3
« Reply #750 on: 04/15/2019 06:06 pm »
They should be using 5x RS25s on that core stage. Not doing that and not having a powerful upper stage has hamstrung the whole vehicle :(

Forgive me if this has been discussed before but with recent developments I wonder if the EUS does eventually get constructed will it be the current Boeing version or something "off the shelf" like ACES or the New Glenn 2nd stage.
When Delta 4 Heavy production ends, ICPS as-is will be toast, in my opinion.  ULA will (if it wins NSSL) then have Centaur 5 or 5+ available, which would provide more capability.  If Northrop Grumman or Blue Origin win NSSL, their upper stages would be candidates that should also increase performance - not EUS performance in any of these cases, but better than ICPS.   

 - Ed Kyle

The NG upper stage should be pretty close to or better than EUS. BE-3U will have lower ISP but much higher thrust, and EUS stages low enough that thrust is still relevant. Also, Blue is using a common bulkhead so they can run a lower dry mass ratio and have more propellant.

Offline Steven Pietrobon

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Re: SLS General Discussion Thread 3
« Reply #751 on: 04/16/2019 06:32 am »
I thought I remember reading somewhere that since the aluminum/lithium alloy of the SLWT was not as strong as the older aluminum alloy that the SLS core ended up being lighter if the older aluminum were used. The SLS core is so much bigger and has to take stronger loads than the STS ET that the trade worked out to favor AL rather than making the AL-LI thicker. Anyone else remember hearing something along those lines?

The switch from Al-Li to Al was done to save $30M per flight, at a reduction of 3 t of payload (that extra 3t would cost $10,000/kg). The NSF article is a little confusing.

https://www.nasaspaceflight.com/2013/02/sls-new-buckling-standards-drops-super-light-alloy/

This statement seems to contradict that using an Al-Li tank would be lighter.

"Al-2219 is less brittle, so they can use thicker plate which can be reliably formed, and the thicker orthogrid actually results in a lighter structure overall."
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Lars-J

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Re: SLS General Discussion Thread 3
« Reply #752 on: 04/16/2019 04:25 pm »
Liquid boosters. 4 engine core. Lighter alloy core. 6 rl10b2 upper stage.

You are acting as if there are technical issues causing the SLS problem. But switching out this for that won't solve the core issues... Prime contractor rot, NASA mismanagement, and congressional encouragement.

Any one of the choices you mention would have worked. But the original SLS idea (basically Direct) should have been simple too! Virtually all the pieces were in place already.
« Last Edit: 04/16/2019 04:26 pm by Lars-J »

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