Author Topic: SLS General Discussion Thread 2  (Read 419610 times)

Offline RonM

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Re: SLS General Discussion Thread 2
« Reply #1260 on: 01/23/2018 01:40 pm »
A reusable system doesn't make economic sense if it only flies once or twice per year. The R&D cost would make it more expensive than an expendable rocket. How many boosters and cores will be lost in testing? Could have used those for missions.

Offline AncientU

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Re: SLS General Discussion Thread 2
« Reply #1261 on: 01/23/2018 02:48 pm »
Changing direction so completely also doesn't make sense.
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Offline UltraViolet9

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Re: SLS General Discussion Thread 2
« Reply #1262 on: 01/23/2018 03:46 pm »

Between FH, NG, NA, and BFR, US industry already has one reusable heavy lifter near first launch, another in development, and two larger ones in design, split between two competitors.  There's little technical or programmatic need for the government to pursue a fifth heavy lifter, reusable or otherwise.

NASA's launch development effort needs to be redirected to be more rational and less redundant, not even more redundant and irrational than it already is.
 

Offline Coastal Ron

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Re: SLS General Discussion Thread 2
« Reply #1263 on: 01/23/2018 04:33 pm »
SLS
4 RS-25's ($55M each) $220M
2 SRB's ($30M each) $60M
Tank Core $75M
Avionics $25M (rad hard, commonality with EUS)
= $380M

I forgot to check your estimate on the Tank Core, and that is way off too. As a point of reference, here is what NASA had negotiated as prices for the Shuttle ET & SRM's near the end of the program:

External Tank (ET): last contract - $2.94B for 17 units = $173M/ea
Solid Rocket Motors (SRM): last contract - $2.4B for 35 refurbished flight sets = $69M/set

That totals to $241.5M for each Shuttle flight, where you are estimating $135M for each SLS flight for the same hardware elements. I think you are off by a significant amount.

As for the RS-25, though NASA is using existing engines for the first four flights, it has already awarded a $1.16B pre-production contract to Aerojet Rocketdyne that produces no flight units, but prepares AR to produce flight units. Assuming the SLS flies at least nine times (4 w/existing engines, 5/new engines), that would mean this contract alone would account for $55M of engine cost, and that doesn't count the cost of producing the new engines themselves (which would be a separate contract).

Costs do drop over time as more units are produced, but there are limits to how much they can drop.

For instance, for the SLS core the cost of the aluminum will not drop below the current market price because the amount of aluminum the SLS uses is not very significant compared to the total market need, so volume purchasing won't matter. And pretty much everything on the SLS is low-volume production, meaning except for the core units that everything else will be produced on production lines that will only run intermittently, which doesn't allow for much cost reduction - even if production is doubled.

But just updating the ET and SRM costs to reflect a number I think is more realistic, I come up with:

SLS
4 RS-25's ($55M each) $220M
2 SRB's ($50M each) $100M
Tank Core $200M
Avionics $25M (rad hard, commonality with EUS)
= $545M

And that would just be the piece-part costs, not the final assembled cost. YMMV
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 Ronsmytheiii

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Re: SLS General Discussion Thread 2
« Reply #1264 on: 01/23/2018 04:54 pm »
So was wondering why SLS kept the clean-pad design of the Ares I ML and tower vs moving the FSS to the Pad surface like Shuttle. The clean pad made sense for Ares as you had two separate LVs, but with SLS after EM-1/only Block 1A flight the vehicle should have a fixed height for umbilicals. By removing the Tower from the ML you free up a lot of space and most importantly weight on it.

because it would increase pad time.  integration off pad with the umbilical tower makes more sense like Atlas V and Falcon 9.  The upper stages and spacecraft need to be checked  out with the umbilicals.  Spacecraft need to be connected to GSE once attached to the rocket.
Shuttle umbilicals were at the tail.  LH2 vent was the only connection at the pad.

Thank you for the informed feedback Jim.

Offline oldAtlas_Eguy

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Re: SLS General Discussion Thread 2
« Reply #1265 on: 01/23/2018 08:28 pm »
SLS
4 RS-25's ($55M each) $220M
2 SRB's ($30M each) $60M
Tank Core $75M
Avionics $25M (rad hard, commonality with EUS)
= $380M

I forgot to check your estimate on the Tank Core, and that is way off too. As a point of reference, here is what NASA had negotiated as prices for the Shuttle ET & SRM's near the end of the program:

External Tank (ET): last contract - $2.94B for 17 units = $173M/ea
Solid Rocket Motors (SRM): last contract - $2.4B for 35 refurbished flight sets = $69M/set

That totals to $241.5M for each Shuttle flight, where you are estimating $135M for each SLS flight for the same hardware elements. I think you are off by a significant amount.

As for the RS-25, though NASA is using existing engines for the first four flights, it has already awarded a $1.16B pre-production contract to Aerojet Rocketdyne that produces no flight units, but prepares AR to produce flight units. Assuming the SLS flies at least nine times (4 w/existing engines, 5/new engines), that would mean this contract alone would account for $55M of engine cost, and that doesn't count the cost of producing the new engines themselves (which would be a separate contract).

Costs do drop over time as more units are produced, but there are limits to how much they can drop.

For instance, for the SLS core the cost of the aluminum will not drop below the current market price because the amount of aluminum the SLS uses is not very significant compared to the total market need, so volume purchasing won't matter. And pretty much everything on the SLS is low-volume production, meaning except for the core units that everything else will be produced on production lines that will only run intermittently, which doesn't allow for much cost reduction - even if production is doubled.

But just updating the ET and SRM costs to reflect a number I think is more realistic, I come up with:

SLS
4 RS-25's ($55M each) $220M
2 SRB's ($50M each) $100M
Tank Core $200M
Avionics $25M (rad hard, commonality with EUS)
= $545M

And that would just be the piece-part costs, not the final assembled cost. YMMV
Ok my intent was what was the lowest possible current estimate with the realization that reality would be a larger number. Then for SLS 1B add the costs for the EUS of not less than $120. But if the SLS tank is $200M vs my $75M then the EUS tank would be another $20M for $40M vs the one in the $120M estimate of $20M. So the new number would be $140M for EUS added to the $545 of the basic SLS gives a cost for manufacture of the SLS 1B of $665M.

Add to that the $800M/year for the operations and maintenance contract.

This gives the new budgets for the two cases of:
1 launch per year > $1.465B
2 launches per year > $2.13B

If the $800M is funded as a seperate line and then a max cap for operations and development of SLS of $1.5B that is $1.33B for the manufacture for 2 launches per year leaving only $170M for costs margins or some development upgrades work.

Offline AncientU

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Re: SLS General Discussion Thread 2
« Reply #1266 on: 01/23/2018 09:23 pm »
Orion atop that vehicle would be estimated at approximately a billion each ($972M per reference below, p31).

Assume both missions include Orion (other payloads, if ever funded, won't be cheaper), so baseline is:
1 launch per year > $2.465B
2 launches per year > $3.13B
« Last Edit: 01/23/2018 09:26 pm by AncientU »
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Offline oldAtlas_Eguy

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Re: SLS General Discussion Thread 2
« Reply #1267 on: 01/23/2018 11:33 pm »
Orion atop that vehicle would be estimated at approximately a billion each ($972M per reference below, p31).

Assume both missions include Orion (other payloads, if ever funded, won't be cheaper), so baseline is:
1 launch per year > $2.465B
2 launches per year > $3.13B
2 Launches per year > $4.13B

(2 Orion's)

A BTW is that the max Congress may be willing to spend is probably $3.5B total per year. So funding 2 launches per year is questionable. NOTE $3.5B is 18% of NASA's budget.
« Last Edit: 01/23/2018 11:39 pm by oldAtlas_Eguy »

Offline Robotbeat

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Re: SLS General Discussion Thread 2
« Reply #1268 on: 01/24/2018 01:34 am »
A reusable system doesn't make economic sense if it only flies once or twice per year...
...you've got that backwards. The point of the reusable system would be so you can afford to fly more than once or twice a year.

The idea was to do something like this during a later refresh of the SLS design, i.e. along with the proposed flyback boosters.

And likely the core would land down-range.

It costs like a billion dollars to build an SLS. It may make sense to add some auxiliary engines, grid fins, and legs to enable down-range landing and reuse. (Would also need to change the insulation. But the engines and thrust structure and hydraulics, etc, could remain the same.)
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Offline oldAtlas_Eguy

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Re: SLS General Discussion Thread 2
« Reply #1269 on: 01/24/2018 01:53 am »
A reusable system doesn't make economic sense if it only flies once or twice per year...
...you've got that backwards. The point of the reusable system would be so you can afford to fly more than once or twice a year.

The idea was to do something like this during a later refresh of the SLS design, i.e. along with the proposed flyback boosters.

And likely the core would land down-range.

It costs like a billion dollars to build an SLS. It may make sense to add some auxiliary engines, grid fins, and legs to enable down-range landing and reuse. (Would also need to change the insulation. But the engines and thrust structure and hydraulics, etc, could remain the same.)
But you loose 30-40% of performance. So an SLS 1B at 110mt LEO payload as expendable (being generous) would become a 66-77mt LEO payload. So it's complete reason for being disappears just to be able to have some reusability of the S1 stages.

An SLS 2 as reusable would be 80-90mt. So the level of redesign to get back to a performance level of 100mt would require the SLS to be something completely different.
« Last Edit: 01/24/2018 01:56 am by oldAtlas_Eguy »

Offline spacenut

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Re: SLS General Discussion Thread 2
« Reply #1270 on: 01/24/2018 01:55 am »
What would be cool is to have 6m boosters based on F9 for say 17 Merlin engines with another ring of 8 around the original 8 (A F17 booster).  These could replace the solids and be able to land for reuse.  Then as someone said, add another RS-25 to the core for a 5 engine core.  Then have an upper stage with say 4 BE-3U's.  I think this could get you 150-175 tons to LEO and using one BE-3U's could get a fairly large deep space probe going.  Boosters would be reusable not just dumped in the ocean. 

Of course rockets aren't Lego's, but, this could be some future upgrade. 

Offline MATTBLAK

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Re: SLS General Discussion Thread 2
« Reply #1271 on: 01/24/2018 02:00 am »
Orion atop that vehicle would be estimated at approximately a billion each ($972M per reference below, p31).

Assume both missions include Orion (other payloads, if ever funded, won't be cheaper), so baseline is:
1 launch per year > $2.465B
2 launches per year > $3.13B
With fully expendable Falcon Heavy now claimed to have 63 tons to LEO capability; that mission architecture could be improved.
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Offline Cheapchips

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Re: SLS General Discussion Thread 2
« Reply #1272 on: 01/24/2018 11:53 am »
As a cost saving, I don't know at what point SLS could switch to carbon tanks. It would save a good % of that 200m structure cost.

NASA/Boeing finished successful testing of a 5.5m hydrogen tank under flight loads in 2016.  The research was specifically aimed at lowering costs and improving payloads of SLS class rockets. The production techniques should scale fairly easily to 8.4 meters.

It'll probably be another bit of great work from NASA & partners than doesn't see active service.  :-\

If you are going to have a disposable rocket, tanks manufactured mostly by a robot would seem the perfect way to go.

https://www.compositesworld.com/articles/nasaboeing-composite-launch-vehicle-fuel-tank-scores-firsts
« Last Edit: 01/24/2018 02:13 pm by Cheapchips »

Offline envy887

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Re: SLS General Discussion Thread 2
« Reply #1273 on: 01/24/2018 01:20 pm »
A reusable system doesn't make economic sense if it only flies once or twice per year...
...you've got that backwards. The point of the reusable system would be so you can afford to fly more than once or twice a year.

The idea was to do something like this during a later refresh of the SLS design, i.e. along with the proposed flyback boosters.

And likely the core would land down-range.

It costs like a billion dollars to build an SLS. It may make sense to add some auxiliary engines, grid fins, and legs to enable down-range landing and reuse. (Would also need to change the insulation. But the engines and thrust structure and hydraulics, etc, could remain the same.)
But you loose 30-40% of performance. So an SLS 1B at 110mt LEO payload as expendable (being generous) would become a 66-77mt LEO payload. So it's complete reason for being disappears just to be able to have some reusability of the S1 stages.

An SLS 2 as reusable would be 80-90mt. So the level of redesign to get back to a performance level of 100mt would require the SLS to be something completely different.

Partially reusable SLS would need liquid boosters that can land downrange, so the payload hit depends mostly on the specs of those boosters. Using New Glenn boosters as LRBs would greatly increase the payload at the same time as allowing recovery. I estimate 136 t to LEO and 53 t to TLI, both with EUS.

Without a larger upper stage than EUS I don't think there is any hope of recovering the core stage, but bigger boosters would allow a couple of RS-25s to be removed (saving ~$114M per flight) while still having much greater payload than SLS 1B.

Offline RonM

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Re: SLS General Discussion Thread 2
« Reply #1274 on: 01/24/2018 02:04 pm »
A reusable system doesn't make economic sense if it only flies once or twice per year...
...you've got that backwards. The point of the reusable system would be so you can afford to fly more than once or twice a year.

The idea was to do something like this during a later refresh of the SLS design, i.e. along with the proposed flyback boosters.

And likely the core would land down-range.

It costs like a billion dollars to build an SLS. It may make sense to add some auxiliary engines, grid fins, and legs to enable down-range landing and reuse. (Would also need to change the insulation. But the engines and thrust structure and hydraulics, etc, could remain the same.)
But you loose 30-40% of performance. So an SLS 1B at 110mt LEO payload as expendable (being generous) would become a 66-77mt LEO payload. So it's complete reason for being disappears just to be able to have some reusability of the S1 stages.

An SLS 2 as reusable would be 80-90mt. So the level of redesign to get back to a performance level of 100mt would require the SLS to be something completely different.

Partially reusable SLS would need liquid boosters that can land downrange, so the payload hit depends mostly on the specs of those boosters. Using New Glenn boosters as LRBs would greatly increase the payload at the same time as allowing recovery. I estimate 136 t to LEO and 53 t to TLI, both with EUS.

Without a larger upper stage than EUS I don't think there is any hope of recovering the core stage, but bigger boosters would allow a couple of RS-25s to be removed (saving ~$114M per flight) while still having much greater payload than SLS 1B.

How much time and money would that redesign take? Not feasible.

Best thing to do would be to continue with SLS as is. If SpaceX, Blue, and others fail to get their giant rockets flying by 2025, NASA will have SLS. If a cheaper commercial option it comes along, then it will be time to cancel SLS.

IMO, the best idea so far is to modify SLS to build an upper stage that can be refueled in LEO. Then massive payloads can be sent BEO. Might give SLS something to do worth its high cost.

Offline oldAtlas_Eguy

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Re: SLS General Discussion Thread 2
« Reply #1275 on: 01/24/2018 02:04 pm »
A reusable system doesn't make economic sense if it only flies once or twice per year...
...you've got that backwards. The point of the reusable system would be so you can afford to fly more than once or twice a year.

The idea was to do something like this during a later refresh of the SLS design, i.e. along with the proposed flyback boosters.

And likely the core would land down-range.

It costs like a billion dollars to build an SLS. It may make sense to add some auxiliary engines, grid fins, and legs to enable down-range landing and reuse. (Would also need to change the insulation. But the engines and thrust structure and hydraulics, etc, could remain the same.)
But you loose 30-40% of performance. So an SLS 1B at 110mt LEO payload as expendable (being generous) would become a 66-77mt LEO payload. So it's complete reason for being disappears just to be able to have some reusability of the S1 stages.

An SLS 2 as reusable would be 80-90mt. So the level of redesign to get back to a performance level of 100mt would require the SLS to be something completely different.

Partially reusable SLS would need liquid boosters that can land downrange, so the payload hit depends mostly on the specs of those boosters. Using New Glenn boosters as LRBs would greatly increase the payload at the same time as allowing recovery. I estimate 136 t to LEO and 53 t to TLI, both with EUS.

Without a larger upper stage than EUS I don't think there is any hope of recovering the core stage, but bigger boosters would allow a couple of RS-25s to be removed (saving ~$114M per flight) while still having much greater payload than SLS 1B.
Small problem in using 7m diameter NG as boosters. The pad can only handle a vehicle that is 21m wide. 2 7m wide NG boosters and the 8.4m core is 22.4m. It will not fit.

Offline spacenut

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Re: SLS General Discussion Thread 2
« Reply #1276 on: 01/24/2018 02:30 pm »
So 6m wide side boosters could fit, barely. 

How many Merlins could fit a 6m wide booster? 
Then is the thrust enough to meet or exceed the solids capabilities? 
Would NASA help pay for such a booster? 
Would or could they make the core to handle either 4 or 5 engines depending on payload? 
Would a 500 lb thrust AR-1 booster be able to land to not be dependent on SpaceX?
Would a BE-4 or Raptor based booster be better for reuse? 

I know SLS hasn't flown yet, and because of this, it may be cancelled if New Glenn gets flying, Vulcan gets flying, and FH gets flying.  Lot of heavier payloads could be assembled in orbit and get a moon centric program going without SLS at a lower cost.  To me making SLS work at a lower cost would mean ditching the solids and using reusable boosters, or eventually going with a 10-12m reusable booster. 
« Last Edit: 01/24/2018 02:31 pm by spacenut »

Offline mike robel

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Re: SLS General Discussion Thread 2
« Reply #1277 on: 01/24/2018 04:39 pm »
All these schemes ignore you would need a new MLP to mount the booster along with new swing arms and launch pad tankage.

Very likely it would require the VAB internal structures and doors to be redesigned, unless these LRBs were the same size and shape as the current SRBs and the new SLS took up the same envelope as the old SLS.  New LRBs would require the core to be redesigned to accept the new boosters.

This would be hideously expensive and delay any meaningful follow on missions (a not very precise unit of measure) for a very long time.

As big a fan boy of boosters [as I am] (in sometimes outlandish configurations  - see my Saturn V models elsewhere on the thread) [I find ]this is a somewhat silly and unrealistic discussion.
« Last Edit: 01/24/2018 06:57 pm by mike robel »

Offline envy887

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Re: SLS General Discussion Thread 2
« Reply #1278 on: 01/24/2018 05:16 pm »
A reusable system doesn't make economic sense if it only flies once or twice per year...
...you've got that backwards. The point of the reusable system would be so you can afford to fly more than once or twice a year.

The idea was to do something like this during a later refresh of the SLS design, i.e. along with the proposed flyback boosters.

And likely the core would land down-range.

It costs like a billion dollars to build an SLS. It may make sense to add some auxiliary engines, grid fins, and legs to enable down-range landing and reuse. (Would also need to change the insulation. But the engines and thrust structure and hydraulics, etc, could remain the same.)
But you loose 30-40% of performance. So an SLS 1B at 110mt LEO payload as expendable (being generous) would become a 66-77mt LEO payload. So it's complete reason for being disappears just to be able to have some reusability of the S1 stages.

An SLS 2 as reusable would be 80-90mt. So the level of redesign to get back to a performance level of 100mt would require the SLS to be something completely different.

Partially reusable SLS would need liquid boosters that can land downrange, so the payload hit depends mostly on the specs of those boosters. Using New Glenn boosters as LRBs would greatly increase the payload at the same time as allowing recovery. I estimate 136 t to LEO and 53 t to TLI, both with EUS.

Without a larger upper stage than EUS I don't think there is any hope of recovering the core stage, but bigger boosters would allow a couple of RS-25s to be removed (saving ~$114M per flight) while still having much greater payload than SLS 1B.
Small problem in using 7m diameter NG as boosters. The pad can only handle a vehicle that is 21m wide. 2 7m wide NG boosters and the 8.4m core is 22.4m. It will not fit.

SpaceGhost1962 looked at triple 8.4 m setups and thought they were feasible. I'm not sure what pad changes they would entail, perhaps he can elaborate.


Offline Coastal Ron

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Re: SLS General Discussion Thread 2
« Reply #1279 on: 01/24/2018 10:14 pm »
As a cost saving, I don't know at what point SLS could switch to carbon tanks.

Likely never, since the production line is set up for building using aluminum.

Quote
It would save a good % of that 200m structure cost.

Maybe, but maybe not. Keep in mind that the SLS was designed to use aluminum, so building an SLS out of carbon fiber (or anything other than aluminum) means that you're essentially designing a brand new rocket. That would cost many $Billions and take many years.

Quote
NASA/Boeing finished successful testing of a 5.5m hydrogen tank under flight loads in 2016.

IIRC NASA did a test of building the Orion spacecraft frame out of carbon fiber, and found that there wasn't any real different in cost or weight, so they stuck with aluminum. If such a trade study were done for the SLS the same could be found (but such a study will never be done).

Quote
The research was specifically aimed at lowering costs and improving payloads of SLS class rockets. The production techniques should scale fairly easily to 8.4 meters.

Not sure we know what the Blue Origin New Glenn will be built out of, but we already know the SpaceX BFR & BFS will be built out of carbon fiber. But they are being designed from the start to use those materials.

Quote
It'll probably be another bit of great work from NASA & partners than doesn't see active service.  :-\

Sometimes R&D does not result in an intended use, but that doesn't mean it wasn't a successful experiment. Sometimes understanding why something is not worth pursuing is as good as understanding that it should be pursued.

Quote
If you are going to have a disposable rocket, tanks manufactured mostly by a robot would seem the perfect way to go.

https://www.compositesworld.com/articles/nasaboeing-composite-launch-vehicle-fuel-tank-scores-firsts

Actually the current tank manufacturing process is already automated. Read more about it on the wonderful link below...  ;)

https://www.nasaspaceflight.com/2017/05/sls-core-stage-recovering-weld-pin-change/
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

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