Author Topic: SLS General Discussion Thread 2  (Read 424726 times)

Offline Robotbeat

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Re: SLS General Discussion Thread 2
« Reply #1280 on: 01/25/2018 02:27 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....
...this isn't accurate. The core has a bunch of extra performance, and this would be done concurrently with upgrading the flyback boosters.

Additionally, being able to fly a good 5-10 times per year would make up for a minor loss in performance.
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Offline AncientU

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Re: SLS General Discussion Thread 2
« Reply #1281 on: 01/25/2018 08:01 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....
...this isn't accurate. The core has a bunch of extra performance, and this would be done concurrently with upgrading the flyback boosters.

Additionally, being able to fly a good 5-10 times per year would make up for a minor loss in performance.

Availability around 2030-2035... price tag, gazillions.
It would have to fly twice daily to make up for the costs by then.
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Online envy887

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Re: SLS General Discussion Thread 2
« Reply #1282 on: 01/25/2018 08:10 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/

Blue is doing friction stir welding in their New Glenn plant, so the main tanks are probably Al or Al-Li alloy like Falcon and SLS. They are also doing auto CFRP layup, likely for interstages and fairings like many other vehicles.

Offline cebri

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Re: SLS General Discussion Thread 2
« Reply #1283 on: 02/13/2018 06:33 pm »

Offline catdlr

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Re: SLS General Discussion Thread 2
« Reply #1284 on: 02/14/2018 12:08 am »
Inside SLS: Outfitting The World’s Most Powerful Rocket


NASA's Marshall Space Flight Center
Published on Feb 13, 2018


Find out why NASA’s new deep-space rocket, the Space Launch System (SLS) is more than just big and beautiful. For the world’s most powerful rocket, it takes a lot of “guts.” Engineers have built all the giant structures that will be assembled to form the first SLS rocket, and now they are busy installing and outfitting the rocket’s insides with sensors, cables and other equipment.  The rocket’s insides including its incredible flight computers and batteries will ensure SLS can do the job of sending the Orion spacecraft out beyond the Moon farther than any human-rated space vehicle as ever ventured. Learn how the SLS core stage components are being outfitted for the first SLS mission, Exploration Mission-1.

https://www.youtube.com/watch?v=RO2onNNbovA?t=001

Tony De La Rosa

Offline speedevil

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Re: SLS General Discussion Thread 2
« Reply #1285 on: 02/14/2018 01:18 am »
Inside SLS: Outfitting The World’s Most Powerful Rocket

$100000 fastners? That's where the money's been going!
Thanks.

Offline joek

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Re: SLS General Discussion Thread 2
« Reply #1286 on: 02/14/2018 02:27 am »
$100000 fastners? That's where the money's been going!

No, 100,000 fasteners.  But you knew that, didn't you?  Let's  give it a break please.  Plenty of things to complain about SLS; that's not one of them.

Offline ArbitraryConstant

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Re: SLS General Discussion Thread 2
« Reply #1287 on: 02/14/2018 06:20 am »
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.)
I think this is what AncientU was trying to get at when suggesting a clean sheet, because there's fewer steps from a clean sheet to an RLV than from SLS to an RLV. There simply isn't any way to broach any of the changes or assumptions necessary for what you describe without creating a situation where it cascades into other modifications that make sense once you grant the initial mod, and pretty soon you end up with something completely unrecognizable.

Let's try this thought experiment using implications from what you've suggested.

* flyback boosters
* so the boosters need to be liquids
* hydrocarbon is needed for sufficient thrust, engine can be AR-1 or BE-4
* but if the core lands downrange it needs engines that can air start which RS-25 can't, RS-68 can't handle the thermas, so we add BE-3
* except now this thing has three different first stage engines and two different fuels
* air start is required for flyback so RS-25 is eliminated
* so now the core either gets 30-40 BE-3's or switches to hydrocarbon and uses AR-1/BE-4
* wait a minute, if we switch the core to hydrocarbon we don't even need boosters anymore

See? You can't do it. As soon as you grant even the most minimal assumptions necessary for SLS reusability, the entire thing converges on a BFR/NA single stick hydrocarbon design and it is no longer recognizable as SLS anymore. Which would be fine except the SLS isn't a political reality if it isn't the SLS.

Offline MATTBLAK

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Re: SLS General Discussion Thread 2
« Reply #1288 on: 02/14/2018 06:34 am »
Landing the SLS corestage is a no go. Flyback boosters are feasible and desirable and would go a long way towards cutting costs. But the up front development costs of Flyback boosters would be steep. ATK reckons they could deliver the 'Dark Knights' Super Solid Boosters for cheaper than the current 5 segment SRBs. I'd believe it when I see it.

If this monster must be expendable - make the payload worth the expense of ditching the hardware. It's been calculated by smart people - one of them on this website - that uprating the Corestage to 5x RS-25 engines, plus the Dark Knights and higher thrust engines on the Exploration upper stage would push this booster's capability to a fair bit more than 120 metric tons into Low Earth Orbit. If this must be a 'Pork Rocket' - please make it a strong and lean porker. I mean nothing pejorative about that...
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Offline Refleks

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Re: SLS General Discussion Thread 2
« Reply #1289 on: 02/14/2018 07:43 am »
If you google "Ares Mars Direct" you get a concept from the early 90's of a heavy lifter based on the STS, foreshadowing the more recent Ares V / SLS systems, but with one main difference: the RS25's are housed on a lifting body and mounted on the side of the fuel tank similar to how the Shuttle was.   This would allow the excellent RS25s to be returned for reuse, saving money.

I do realize NASA is going the direction of expending the RS25s, and eventually opting for expendable new-builds, and my question is, what is the rationale behind this versus a return vehicle?  The RS25s are high performance and complex,  it's hard to believe the cost benefit analysis suggests that expendable versions with the same performance would be that much cheaper (unless they're opting for lower-performance / less complex expendable engines)

Since the STS system was capable of lifting ~110 tons to LEO, the resulting vehicle should still be a 100t class lifter even with the engine return glider.

Another question I've always wondered is, would it be feasible for SLS to incorporate four Falcon 9 type boosters in a configuration similar to Energia (in lieu of two higher thrust SRBs)?  How about four SRBs, if it's not man rated?

Offline Coastal Ron

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Re: SLS General Discussion Thread 2
« Reply #1290 on: 02/14/2018 02:21 pm »
I do realize NASA is going the direction of expending the RS25s, and eventually opting for expendable new-builds, and my question is, what is the rationale behind this versus a return vehicle?

The short answer is that the concept and design for the SLS was not entirely up to NASA. The SLS was created out of the cancellation of the Constellation program, where Congress designated that the SLS should take over the work already started for Ares I/V, plus try and utilize parts of the soon-to-end Shuttle program.

So the requirements that NASA was given did not include reusability, nor any cost goals that might have led to the use of certain technologies or techniques. Here is the law Congress wrote that created the SLS:

Quote
SEC. 302. SPACE LAUNCH SYSTEM AS FOLLOW-ON LAUNCH VEHICLE TO THE SPACE SHUTTLE.
(a) UNITED STATES POLICY.—It is the policy of the United States that NASA develop a Space Launch System as a follow- on to the Space Shuttle that can access cis-lunar space and the regions of space beyond low-Earth orbit in order to enable the United States to participate in global efforts to access and develop this increasingly strategic region.
(b) INITIATION OF DEVELOPMENT.—
(1) IN GENERAL.—The Administrator shall, as soon as prac- ticable after the date of the enactment of this Act, initiate development of a Space Launch System meeting the minimum capabilities requirements specified in subsection (c).
(2) MODIFICATION OF CURRENT CONTRACTS.—In order to limit NASA’s termination liability costs and support critical capabilities, the Administrator shall, to the extent practicable, extend or modify existing vehicle development and associated contracts necessary to meet the requirements in paragraph (1), including contracts for ground testing of solid rocket motors, if necessary, to ensure their availability for development of the Space Launch System.
(c) MINIMUM CAPABILITY REQUIREMENTS.—
(1) IN GENERAL.—The Space Launch System developed pursuant to subsection (b) shall be designed to have, at a minimum, the following:
(A) The initial capability of the core elements, without an upper stage, of lifting payloads weighing between 70 tons and 100 tons into low-Earth orbit in preparation for transit for missions beyond low-Earth orbit.
(B) The capability to carry an integrated upper Earth departure stage bringing the total lift capability of the Space Launch System to 130 tons or more.
(C) The capability to lift the multipurpose crew vehicle.
(D) The capability to serve as a backup system for supplying and supporting ISS cargo requirements or crew delivery requirements not otherwise met by available commercial or partner-supplied vehicles.
(2) FLEXIBILITY.—The Space Launch System shall be designed from inception as a fully-integrated vehicle capable of carrying a total payload of 130 tons or more into low-Earth orbit in preparation for transit for missions beyond low-Earth orbit. The Space Launch System shall, to the extent practicable, incorporate capabilities for evolutionary growth to carry heavier payloads. Developmental work and testing of the core elements and the upper stage should proceed in parallel subject to appro- priations. Priority should be placed on the core elements with the goal for operational capability for the core elements not later than December 31, 2016.
(3) TRANSITION NEEDS.—The Administrator shall ensure critical skills and capabilities are retained, modified, and devel- oped, as appropriate, in areas related to solid and liquid engines, large diameter fuel tanks, rocket propulsion, and other ground test capabilities for an effective transition to the follow- on Space Launch System.
(4) The capacity for efficient and timely evolution, including the incorporation of new technologies, competition of sub-ele- ments, and commercial operations.

And without new requirements given to NASA, there is no need to make changes at this point.
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Offline spacenut

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Re: SLS General Discussion Thread 2
« Reply #1291 on: 02/14/2018 03:00 pm »
I saw on YouTube where someone figured using 4 F9's on the core and got I think about 130-150 tons to LEO.  However, a lot of infrastructure would have to be reworked to do this.  It would be cheaper to operate than the solids, and partly reusable.  Don't know how many billions would be needed to rework the infrastructure to handle this.  The VAB, the transporter, and even the flame trenches.  The core would also have to be reworked, thus basically a new rocket again.

I thought it was a good idea as two F9's could be used for lighter payloads and 4 for heavier payloads. 
« Last Edit: 02/14/2018 03:02 pm by spacenut »

Offline Coastal Ron

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Re: SLS General Discussion Thread 2
« Reply #1292 on: 02/14/2018 08:21 pm »
I saw on YouTube where someone figured using 4 F9's on the core and got I think about 130-150 tons to LEO.

Other than the Europa mission, which could fly on an existing launcher, the only currently forecasted use for the SLS and Orion at this point is the Deep Space Gateway. And I don't think that dearth of payloads and missions is because the SLS isn't big enough, or we haven't spent enough money on it yet.

So while thinking up costly ways to mutate the SLS may be fun, it really belongs in realm of fantasy - or for NSF, the "Advanced Concepts" section.

My $0.02
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Offline MATTBLAK

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Re: SLS General Discussion Thread 2
« Reply #1293 on: 02/14/2018 10:06 pm »
With sadness; I'd say we'll never see liquid boosters for SLS. The Dark Knights solids should present no major challenges and money for fancy boosters would be better spent on payloads or optimizing the upper stage.
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Offline Hog

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Re: SLS General Discussion Thread 2
« Reply #1294 on: 02/16/2018 06:11 pm »
If you google "Ares Mars Direct" you get a concept from the early 90's of a heavy lifter based on the STS, foreshadowing the more recent Ares V / SLS systems, but with one main difference: the RS25's are housed on a lifting body and mounted on the side of the fuel tank similar to how the Shuttle was.   This would allow the excellent RS25s to be returned for reuse, saving money.

I do realize NASA is going the direction of expending the RS25s, and eventually opting for expendable new-builds, and my question is, what is the rationale behind this versus a return vehicle?  The RS25s are high performance and complex,  it's hard to believe the cost benefit analysis suggests that expendable versions with the same performance would be that much cheaper (unless they're opting for lower-performance / less complex expendable engines)

Since the STS system was capable of lifting ~110 tons to LEO, the resulting vehicle should still be a 100t class lifter even with the engine return glider.

Another question I've always wondered is, would it be feasible for SLS to incorporate four Falcon 9 type boosters in a configuration similar to Energia (in lieu of two higher thrust SRBs)?  How about four SRBs, if it's not man rated?
The expendable RS-25s will actually be of higher RPL than the:
16 "HERITAGE" (RS-25 Block II) 104.5% rpl/2188kn/491,881lbs. thrust with a service life of 55 starts/27,000 seconds and ISP of 450.2secs, which have now been converted to:
16-"ADAPTATION RS-25" using 109%rpl/2281kn/512,789lbs. thrust good for 6 starts/2500 seconds of runtime with an ISP of 450.7 secs
leading to the future
"RESTART RS25" 111%rpl/2321kn/521,782 lbs. thrust for 4 starts/1700 seconds of runtime with an ISP of 450.8 secs  of which the low hanging fruit for cost reductions were chosen and are now being hotfired culminating in a 33% reduction in RS25 cost.

With direction towards "RS25 BLOCK IV" upgrade plan to enact some of the "higher risk, higher payoff" cost reduction strategies that were deferred from the "RESTART RS25" initiative", with hotfire testing targets of 115%rpl(which would be approx. 2404kn/540,441lbs. thrust vac. using RESTART numbers)
I am thinking that the data gained from the RS25 Block-III SSME Upgrade Project from the turn of the century, isn't being lost.  There are many aspects of it that are being mirrored in the current "RESTART RS25" effort, the major difference is of course reusability. The higher RPLs and safe affordable-REUSEABLE-SSME did NOT mix.(erosion)  Block-II SSME allowed 111%rpl for Contingency Aborts ONLY(do or die as Mr Hale says), intact Aborts allowed for 109%.. A 120% Power Level(PL) is mentioned with nominal operation at 104.5% RPL.  (120%rpm would be 2509kn/564,046lbs. thrust vac.)

 We'll see what the reduced "deep" throttling (down to 80%) and disposable requirements allow for future "Block IV" testing.


I have included the 2000 Block III SSME Upgrade Project Overview.
Paul

Offline su27k

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Re: SLS General Discussion Thread 2
« Reply #1295 on: 02/17/2018 02:22 am »
If you google "Ares Mars Direct" you get a concept from the early 90's of a heavy lifter based on the STS, foreshadowing the more recent Ares V / SLS systems, but with one main difference: the RS25's are housed on a lifting body and mounted on the side of the fuel tank similar to how the Shuttle was.   This would allow the excellent RS25s to be returned for reuse, saving money.

The engines are housed in a side mounted pod, but I don't think it was ever planned to be recovered and reused. In fact I don't think any Shuttle Derived Heavylift has plans for engine reuse, probably because their envisioned flight rate is too low.

Offline Robotbeat

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Re: SLS General Discussion Thread 2
« Reply #1296 on: 02/17/2018 03:14 am »
If you google "Ares Mars Direct" you get a concept from the early 90's of a heavy lifter based on the STS, foreshadowing the more recent Ares V / SLS systems, but with one main difference: the RS25's are housed on a lifting body and mounted on the side of the fuel tank similar to how the Shuttle was.   This would allow the excellent RS25s to be returned for reuse, saving money.

The engines are housed in a side mounted pod, but I don't think it was ever planned to be recovered and reused. In fact I don't think any Shuttle Derived Heavylift has plans for engine reuse, probably because their envisioned flight rate is too low.
There were concepts for recovering the side pod.


EDIT: from this NASA Spaceflight article:
https://www.nasaspaceflight.com/2010/06/sd-hlv-assessment-highlights-post-shuttle-solution/
Quote
“A notional extensibility approach for operational vehicles using this hybrid concept is shown (in the graphic – left). The advantages include reducing the number of changes to the launch pad and also providing for easier detachment of the propulsion modules when used in conjunction with the recovery module concept presented (see reference in Sidemount overview).”
« Last Edit: 02/17/2018 03:41 am by Robotbeat »
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Offline Proponent

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Re: SLS General Discussion Thread 2
« Reply #1297 on: 02/19/2018 05:58 am »
Other than the Europa mission, which could fly on an existing launcher....

By the way, is everyone here aware that the administration's proposed FY 2019 NASA budget recommends moving Europa Clipper from SLS to a commercial launch vehicle?

Offline woods170

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Re: SLS General Discussion Thread 2
« Reply #1298 on: 02/19/2018 06:55 am »
Other than the Europa mission, which could fly on an existing launcher....

By the way, is everyone here aware that the administration's proposed FY 2019 NASA budget recommends moving Europa Clipper from SLS to a commercial launch vehicle?

The president's budget proposal is DOA. When US Congress is finished with it ISS will stay in orbit until (at least) 2028 and Europa Clipper will still be assigned to launch on SLS.

Offline Proponent

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Re: SLS General Discussion Thread 2
« Reply #1299 on: 02/22/2018 06:34 am »
By the way, is everyone here aware that the administration's proposed FY 2019 NASA budget recommends moving Europa Clipper from SLS to a commercial launch vehicle?

The president's budget proposal is DOA. When US Congress is finished with it ISS will stay in orbit until (at least) 2028 and Europa Clipper will still be assigned to launch on SLS.

I think that's quite possible, but it's nonetheless significant that the Trump administration takes the view that flying Europa Clipper on SLS 1) costs more than it's worth, and 2) causes scheduling problems, given SLS's very low production rate (left unmentioned, however, is the questionable wisdom of entrusting an extremely expensive, one-of-a-kind payload to EUS on its very first flight).

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