Author Topic: SLS General Discussion Thread 3  (Read 310805 times)

Offline envy887

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Re: SLS General Discussion Thread 3
« Reply #160 on: 08/08/2018 05:52 pm »
... the ET tooling would have required modification to build it (and possibly an even bigger core, to handle the difference in strength between plasma arc and friction stir welds).

It was not necessary to change anytime soon to FSW as Plasma Arc was just fine. As far as strengthening the core to the 2-stage vehicle, that was essentially just a software change that was needed to mill less material from the core airframe, making it stronger. All this was thoroughly investigated and documented at the time. So tooling changes were not required and FSW could have been phased in over time as the program continued if that direction was desired, but even that was not needed. It would have been an enhancement to use the latest welding techniques rather than the existing ones, which were working fine.

Are you talking about building DIRECT's ET-based core, or the current SLS core? The ET tooling would have required modification to build the longer SLS core, while DIRECT's ET-based core was much shorter and could have been built on the tooling as it was. At least that is my understanding, and I think it's matches what you are saying.

Offline A_M_Swallow

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Re: SLS General Discussion Thread 3
« Reply #161 on: 08/09/2018 01:26 am »
The more I think about it, the more I think it isn't intended to succeed.  If the politico's behind SLS can get the program overturned again, they can set themselves up to be able to push another set of 10-year development contracts through - and that's where they benefit the most through the jobs and federal cash disbursal.

If they do transition SLS from development to operational, then the high-value development jobs will no longer be required in Alabama and Utah, and there will be a general transition towards lower-value technician-style jobs going to Louisiana, California, Florida and back to Texas too.

But those aren't the states currently represented by the controlling folk on appropriations.  And they will not like losing jobs and federal income.  I predict they will do 'something' to protect their own back yards before the transition comes - and I don't believe LOP-G could possibly be sufficient for them.

Now would be an especially good time for some smart people to put together a comprehensive plan that would lay out a path of transition away from SLS, to enable future surface activity programs on the Moon and Mars, IMHO - plans that would still keep all that development money exactly where the appropriations folk want it, but would - for once - actually deliver some products that the program really needs instead of these "make-work" government rockets.

I've said before, landers, habs, rovers, ISRU, power, mining &  processing - there's a sh*t ton of development projects that could be undertaken if the SLS' budget were made available, and any combination of those would deliver everyone far, far better return on investment than a shiny new $2 billion/flight rocket ever will.

Ross.

It is going to be a long time before we can afford a second Moon base so the Moon base can be built in the prototyping workshops of the development laboratories.

Launching the Moon base building to lunar orbit using the SLS looks good on public plans. Something like the LOP-G would be needed to load the buildings onto a reusable lander and refuel the lander.

Offline clongton

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Re: SLS General Discussion Thread 3
« Reply #162 on: 08/09/2018 11:07 am »
Are you talking about building DIRECT's ET-based core, ...? ... while DIRECT's ET-based core was much shorter and could have been built on the tooling as it was. At least that is my understanding, and I think it's matches what you are saying.

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Offline brickmack

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Re: SLS General Discussion Thread 3
« Reply #163 on: 08/11/2018 02:59 am »
EG, the development of the tooling and vehicle falling behind.  Is it safe to assume then that once the first flight is conducted that the planned schedule will be more stable?  ~1 flight per year type deal?

Production typically has far less potential for delays than development - it's just the nature of the beast.

That presumes development actually... finishes. SLS/Orions development schedule, by years, would be reasonable if it was flying several times a year, but as it is, most flights for the first decade of operations will be unique. EM-1, first flight, everythings new. Europa Clipper, first cargo flight (not a huge amount of risk, but some). EM-2, first manned mission, first functioning ECLSS, first live LAS, redesigned ESM plumbing. EM-3, first Block 1B, first comanifested payload, probably first LOP-G mission. EM-4, first RS-25E. EM-5, possibly new EUS main engine. EM-6, new Orion Main Engine and possibly Block 2 ESM. EM-9, Advanced Boosters. All of these have major delay potential. Nevermind the usual post-flight "oh, that didn't work as planned, gotta fix that" stuff.

Online Coastal Ron

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Re: SLS General Discussion Thread 3
« Reply #164 on: 08/12/2018 08:51 pm »
EG, the development of the tooling and vehicle falling behind.  Is it safe to assume then that once the first flight is conducted that the planned schedule will be more stable?  ~1 flight per year type deal?

Production typically has far less potential for delays than development - it's just the nature of the beast.

That presumes development actually... finishes. SLS/Orions development schedule, by years, would be reasonable if it was flying several times a year, but as it is, most flights for the first decade of operations will be unique.

To a certain degree, that is true. But for some components there is some production stability for some number of flights, such as the core, the upper stage, and the SRM's.

Quote
EM-1, first flight, everythings new. Europa Clipper, first cargo flight (not a huge amount of risk, but some).

EM-2, first manned mission, first functioning ECLSS, first live LAS, redesigned ESM plumbing.

EM-3, first Block 1B, first comanifested payload, probably first LOP-G mission.

EM-4, first RS-25E.

EM-5, possibly new EUS main engine.

EM-6, new Orion Main Engine and possibly Block 2 ESM.

EM-9, Advanced Boosters.

All of these have major delay potential. Nevermind the usual post-flight "oh, that didn't work as planned, gotta fix that" stuff.

Such a nice list I thought I would make it easier to appreciate!

What that list shows is that the core section is pretty stable in configuration for most of the flights, since engine changes are not really a part of the core itself, but modular components that can be swapped out for upgraded versions without needing a change in core construction or certification.

Even the Solid Rocket Motors don't yet have a known end date, since the upgrade program for them was put on hold. And other items you list are for the payloads, not the SLS itself. And in fact I don't consider the Upper Stage part of the SLS since they are modular too.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Online docmordrid

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Re: SLS General Discussion Thread 3
« Reply #165 on: 08/14/2018 06:37 am »
... with no real mission. 

[SLS] It has missions...After that it will build Lunar Gateway.

 - Ed Kyle

According to Anatoly Zak of RussianSpaceWeb, Europe andand Japan are looking at Falcon Heavy for their large bits and HTV-X, while the US is talking about a "commercial launch vehicle" for the PPE. Page 14

https://www.nasa.gov/sites/default/files/atoms/files/nasa_fy_2019_budget_overview.pdf

After the PPE & Russian parts, and if Zak is correct, how much remains for SLS to "build"?

RussianSpaceWeb is paywalled, but Teslarati has a write-up on it,

 Link...
« Last Edit: 08/14/2018 06:52 am by docmordrid »
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Offline FinalFrontier

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Re: SLS General Discussion Thread 3
« Reply #166 on: 08/15/2018 06:41 pm »
Expect to see further delays announced either before the end of the year or early next year.
Biggest item is probably going to be flight software issues which are still not being resolved, and potentially further delays to the orion service module. We will see what happens but don't hold your breath for the ESA they have alot of internal problems related to problems with the EU itself.

Also I am still wondering about the situation with the ML's. Did that ever get resolved or is there still going to be a 4-6 month delay because of issues with crawlers/ML mods?
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Offline Ronpur50

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Re: SLS General Discussion Thread 3
« Reply #167 on: 08/17/2018 03:18 pm »
Quick observer question.  It seems from what I'm reading that a lot of the delays that SLS has faced, though ridiculous and frustrating, seem to stem from what I'll call "first flight jitters".  EG, the development of the tooling and vehicle falling behind.  Is it safe to assume then that once the first flight is conducted that the planned schedule will be more stable?  ~1 flight per year type deal?

Reading the replies to this, I still have a question.  I know the Orion for EM-2 is under construction, but has any parts for the core for the second SLS been produced yet?  I doubt we will ever see this thing in an assembly line like photo like we do of Saturn Vs.

Online Coastal Ron

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Re: SLS General Discussion Thread 3
« Reply #168 on: 08/17/2018 03:32 pm »
Reading the replies to this, I still have a question.  I know the Orion for EM-2 is under construction, but has any parts for the core for the second SLS been produced yet?

Likely not, for a couple of reasons:

A. EM-2 is planned for around 2022, ~4 years away, and it should take less than a year to build an SLS core.

B. Ideally you want to fully test your first production unit before you commit to building your second one, so waiting until EM-1 flies and they can evaluate how it did would be best.

Quote
I doubt we will ever see this thing in an assembly line like photo like we do of Saturn Vs.

You have to remember that the Apollo program had a defined end when it was started, so they knew how many rockets they would commit to building. Of course the hope was that the prime goal (land a man on the Moon and return him safely) would be accomplished before they ran out of rockets, and luckily they did.

So for the Saturn V they built them as one "batch".

For the SLS, which is supposed to be a transportation system that lasts for decades, there is no need to build ahead of the known need. So no, for the sake of taxpayer money (i.e. inventory is not an asset), we should never hope to see a bunch of completed SLS cores lying around on the factory floor.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline Markstark

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SLS General Discussion Thread 3
« Reply #169 on: 08/17/2018 04:03 pm »
Reading the replies to this, I still have a question.  I know the Orion for EM-2 is under construction, but has any parts for the core for the second SLS been produced yet?

Likely not, for a couple of reasons:

A. EM-2 is planned for around 2022, ~4 years away, and it should take less than a year to build an SLS core.

B. Ideally you want to fully test your first production unit before you commit to building your second one, so waiting until EM-1 flies and they can evaluate how it did would be best.

Quote
I doubt we will ever see this thing in an assembly line like photo like we do of Saturn Vs.

You have to remember that the Apollo program had a defined end when it was started, so they knew how many rockets they would commit to building. Of course the hope was that the prime goal (land a man on the Moon and return him safely) would be accomplished before they ran out of rockets, and luckily they did.

So for the Saturn V they built them as one "batch".

For the SLS, which is supposed to be a transportation system that lasts for decades, there is no need to build ahead of the known need. So no, for the sake of taxpayer money (i.e. inventory is not an asset), we should never hope to see a bunch of completed SLS cores lying around on the factory floor.

Core Stage 2 structures built to date:
- Forward Skirt barrel
- Engine Section barrel
- Domes for cryo tanks and some barrels
- Intertank structural assembly in work

See this L2 thread: https://forum.nasaspaceflight.com/index.php?topic=45407
« Last Edit: 08/17/2018 04:07 pm by Markstark »

Online Coastal Ron

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Re: SLS General Discussion Thread 3
« Reply #170 on: 08/17/2018 04:36 pm »
Core Stage 2 structures built to date:
- Forward Skirt barrel
- Engine Section barrel
- Domes for cryo tanks and some barrels
- Intertank structural assembly in work

See this L2 thread: https://forum.nasaspaceflight.com/index.php?topic=45407

Hadn't seen that, so was speaking generically as a scheduling professional. A couple of thoughts:

- At some point there will be years between the production of one flight unit and the next, so the question is when to insert that gap.

- If production tooling needs to be certified, then building ahead to validate the tooling (and production processes too) is not unusual. Especially when those certifying the production tooling and processes may not be around in a couple of years when the next units are being produced.

- Putting on my contractor hat, if you *think* your production contract is in danger of being cancelled, then you are motivated to produce as many units for your customer as possible. It's been known to happen...  ;)
« Last Edit: 08/17/2018 06:26 pm by Coastal Ron »
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline Ronpur50

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Re: SLS General Discussion Thread 3
« Reply #171 on: 08/17/2018 10:01 pm »

Core Stage 2 structures built to date:
- Forward Skirt barrel
- Engine Section barrel
- Domes for cryo tanks and some barrels
- Intertank structural assembly in work

See this L2 thread: https://forum.nasaspaceflight.com/index.php?topic=45407

That is what I was wondering.  Those structures would have to have some kind of lead time if the Europa Clipper will be the second launch after EM-1 with in a year or so.  And they would/should not require much redesign after a flight....I hope. And thank you for that link, I will watch that thread now!
« Last Edit: 08/17/2018 10:04 pm by Ronpur50 »

Offline Khadgars

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Re: SLS General Discussion Thread 3
« Reply #172 on: 08/23/2018 01:12 am »
Once the engine section is completed in the Fall, the core stage will start coming together quite quickly.Staying with the Block 1 for the first set of flights (4?), particularity for EM-2, burns down a lot of risk.
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Offline Robotbeat

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Re: SLS General Discussion Thread 3
« Reply #173 on: 08/23/2018 02:51 pm »
I was strongly in favor of sticking with Block 1. Designing an SLS-specific EUS at this point is a total waste when it's basically the basic same specs as Vulcan's ACES but (probably) more dry mass and less capability. The IUS shares Delta IV infrastructure and thus reduces cost and risk. And using block 1 means that EM-2 can be crewed.
« Last Edit: 08/23/2018 02:52 pm by Robotbeat »
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Offline edkyle99

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Re: SLS General Discussion Thread 3
« Reply #174 on: 08/23/2018 03:46 pm »
I was strongly in favor of sticking with Block 1. Designing an SLS-specific EUS at this point is a total waste when it's basically the basic same specs as Vulcan's ACES but (probably) more dry mass and less capability. The IUS shares Delta IV infrastructure and thus reduces cost and risk. And using block 1 means that EM-2 can be crewed.
ACES would only carry about 60-ish percent as much propellant as EUS.  ACES or Centaur 5 Long would be better than ICPS, but not as good as EUS.

New Glenn second stage is a closer match to EUS in terms of propellant load.

 - Ed Kyle
« Last Edit: 08/23/2018 03:46 pm by edkyle99 »

Online Coastal Ron

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Re: SLS General Discussion Thread 3
« Reply #175 on: 08/23/2018 03:52 pm »
ACES would only carry about 60-ish percent as much propellant as EUS.  ACES or Centaur 5 Long would be better than ICPS, but not as good as EUS.

So what? What known payload does that affect?

Optimizing for performance when you don't have any hard data on what your customers really need is a waste of money.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline edkyle99

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Re: SLS General Discussion Thread 3
« Reply #176 on: 08/23/2018 05:49 pm »
ACES would only carry about 60-ish percent as much propellant as EUS.  ACES or Centaur 5 Long would be better than ICPS, but not as good as EUS.

So what? What known payload does that affect?

Optimizing for performance when you don't have any hard data on what your customers really need is a waste of money.
The payloads are well known.  Orion and lunar platform.  That's the plan [1].  Maximizing mass toward the moon for these missions is a no-brainer.  Block 1 can do 24-25 tonnes trans-lunar.  Block 1B is about 39 tonnes.  A Block "1.5" with an ACES might only do 30 tonnes or so. 

 - Ed Kyle

[1] https://www.nasa.gov/feature/nasas-exploration-campaign-back-to-the-moon-and-on-to-mars
« Last Edit: 08/23/2018 05:49 pm by edkyle99 »

Offline meberbs

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Re: SLS General Discussion Thread 3
« Reply #177 on: 08/23/2018 06:17 pm »
The payloads are well known.  Orion and lunar platform.  That's the plan [1].  Maximizing mass toward the moon for these missions is a no-brainer.
Only if by "no-brainer" you mean not using your brain to apply critical thinking.

The plan is for LOP-G to be staffed by astronauts for a finite amount of time to do a finite amount of stuff (what useful stuff they can do is still undefined.) Given that the stuff is undefined, you cannot make statements about how much mass would actually be useful, but it is not arbitrarily large. Even if you assume there is an unlimited amount of useful stuff for them to do, (ignoring what that would be) the conclusion then is that the station should receive commercial resupply to allow it to operate continuously (and non-SLS flights to the gateway are being considered already). Once you have vehicles that can actually fly there regularly, there is then no pressure for large cargo on any Orion flights.

Offline envy887

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Re: SLS General Discussion Thread 3
« Reply #178 on: 08/23/2018 06:19 pm »
ACES would only carry about 60-ish percent as much propellant as EUS.  ACES or Centaur 5 Long would be better than ICPS, but not as good as EUS.

So what? What known payload does that affect?

Optimizing for performance when you don't have any hard data on what your customers really need is a waste of money.
The payloads are well known.  Orion and lunar platform.  That's the plan [1].  Maximizing mass toward the moon for these missions is a no-brainer.  Block 1 can do 24-25 tonnes trans-lunar.  Block 1B is about 39 tonnes.  A Block "1.5" with an ACES might only do 30 tonnes or so. 

 - Ed Kyle

[1] https://www.nasa.gov/feature/nasas-exploration-campaign-back-to-the-moon-and-on-to-mars

ACES would obviate the need for SLS entirely, so... yeah. Of course, EUS with IVF would be even more capable, but are there any 100+ tonne payloads to send to TLI?

Offline A_M_Swallow

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Re: SLS General Discussion Thread 3
« Reply #179 on: 08/23/2018 06:54 pm »
ACES would only carry about 60-ish percent as much propellant as EUS.  ACES or Centaur 5 Long would be better than ICPS, but not as good as EUS.

So what? What known payload does that affect?

Optimizing for performance when you don't have any hard data on what your customers really need is a waste of money.
The payloads are well known.  Orion and lunar platform.  That's the plan [1].  Maximizing mass toward the moon for these missions is a no-brainer.  Block 1 can do 24-25 tonnes trans-lunar.  Block 1B is about 39 tonnes.  A Block "1.5" with an ACES might only do 30 tonnes or so. 

 - Ed Kyle

[1] https://www.nasa.gov/feature/nasas-exploration-campaign-back-to-the-moon-and-on-to-mars

ACES would obviate the need for SLS entirely, so... yeah. Of course, EUS with IVF would be even more capable, but are there any 100+ tonne payloads to send to TLI?

A Bigelow habitat module masses 20-30 tonnes. Adding lander and propellant produces a payload that is nearly 100 tonne at TLI. A Moon base can have several modules including garages for the rovers, food stores, solar panes and science laboratories.

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