Author Topic: Space Launch System (SLS) Q&A  (Read 18349 times)

Offline clongton

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Re: Space Launch System (SLS) Q&A
« Reply #40 on: 08/11/2017 12:18 PM »
  Seeing that Project Constellation was looking at 6 RS-68 engines for the core, which would have been less expensive and more powerful than RS-25, how did SLS get to looking at 4-6 RS-25 engines?
Was it merely ablative(RS-68) vs. regenerative nozzle(RS-25) cooling?

Thank you In Advance.

It was determined that the RS-68 would not survive the thermal environment of the proximity to the SRBs long enough to even reach MECO. Providing a regen nozzle for the RS-68 was not an option per USAF sources. Therefore the RS-68 was dropped from consideration and replaced with the RS-25, the next best option.
« Last Edit: 08/11/2017 12:19 PM by clongton »
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Offline whitelancer64

Re: Space Launch System (SLS) Q&A
« Reply #41 on: 12/05/2017 03:49 PM »
Is the Mobile Launcher Platform for the SLS called MLP-4?

*edit* it looks like it's called ML-1. Back to the old Apollo nomenclature, I guess.
« Last Edit: 12/06/2017 03:47 PM by whitelancer64 »
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Offline Hog

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Re: Space Launch System (SLS) Q&A
« Reply #42 on: 12/11/2017 05:39 PM »
Is there any Composite Overwrapped Pressure Vessels(COPV) used on SLS?
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Offline brickmack

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Re: Space Launch System (SLS) Q&A
« Reply #43 on: 12/11/2017 06:58 PM »
iCPS/DCSS uses a bunch of them for pressurant and attitude control propellant. EUS will use them as well, though its looking like they may go with IVF for those systems and only need a couple COPVs for storing high-pressure boiloff gas. AFAIK the core stage will use COPVs for pre-ignition tank pressurization as well, the same as on the Shuttle.

Offline Markstark

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Re: Space Launch System (SLS) Q&A
« Reply #44 on: 12/12/2017 02:08 AM »
Is there any Composite Overwrapped Pressure Vessels(COPV) used on SLS?
There are several COPVs in the Engine Section of the Core Stage. 5 big helium tanks used for pneumatic valve operations in flight. Some COPVs for hydraulic fluid used in the TVC system as well.


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Offline Caleb Cattuzzo

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Re: Space Launch System (SLS) Q&A
« Reply #45 on: 02/22/2018 05:03 PM »
Could (ignoring the politics) the SRB's be replaced with 4 falcon 9 boosters?I was doing the math and 4 falcon 9 boosters would have just as much force as 2 SLS SRB's but I don't know if they would be reusable considering the speed they will be going at sep.Plus the power to weight ratio compared to SRB's.
« Last Edit: 02/22/2018 05:03 PM by Caleb Cattuzzo »
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Offline Toast

Re: Space Launch System (SLS) Q&A
« Reply #46 on: 02/22/2018 05:39 PM »
Could (ignoring the politics) the SRB's be replaced with 4 falcon 9 boosters?I was doing the math and 4 falcon 9 boosters would have just as much force as 2 SLS SRB's but I don't know if they would be reusable considering the speed they will be going at sep.Plus the power to weight ratio compared to SRB's.

No, for many reasons. Politically it would be a non-starter (and SLS is a very political beast). Plus rockets aren't LEGOTM Elements and the resultant rocket would need substantial reevaluation, plus many components would need to be redesigned. Not to mention the "why bother?" aspect. Falcon 9 excels in two domains: Reuseability and price. But neither really help here: The cost of the design change would outweigh any benefit from having cheaper boosters, and reuseability is a moot point when SLS will have a flight rate of (at most) two per year, which won't be improved by the change (since solid rockets aren't the bottleneck in SLS's flight rate).

All that said, when NASA requested proposals for boosters for SLS, there was a proposal called Pyrios using liquid-fueled boosters and redesigned F1 engines.

EDIT: Chris Bergin did an excellent article on the proposal here that has a lot more details than the Wikipedia article linked above.
« Last Edit: 02/22/2018 05:43 PM by Toast »

Offline envy887

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Re: Space Launch System (SLS) Q&A
« Reply #47 on: 02/23/2018 02:10 PM »
Could (ignoring the politics) the SRB's be replaced with 4 falcon 9 boosters?I was doing the math and 4 falcon 9 boosters would have just as much force as 2 SLS SRB's but I don't know if they would be reusable considering the speed they will be going at sep.Plus the power to weight ratio compared to SRB's.

Would require modifications to :
1) the core stage to accept thrust from 4 attach points to the thrust beam, and to avionics to control the boosters.
2) the booster structure to support the core on the ground and to lift from the top (FH boosters lift from the bottom).
3) the VAB bay and MLP for the new engine locations, new holddowns, and to supply RP-1.
4) NASA's risk assessment policy about flying 40 engines on a single rocket.

So if you change almost everything, sure. It could be done. Would it be cheaper or faster? Almost certainly not, at this point. SLS can only fly about twice a year because the entire infrastructure is set up for that and increasing that would cost tens of billions aside from the boosters. Reuse isn't worth it for 2 flights a year.

Offline Jim

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Re: Space Launch System (SLS) Q&A
« Reply #48 on: 02/23/2018 04:06 PM »
Would require modifications to :
1) the core stage to accept thrust from 4 attach points to the thrust beam, and to avionics to control the boosters.
2) the booster structure to support the core on the ground and to lift from the top (FH boosters lift from the bottom)
3) the VAB bay and MLP for the new engine locations, new holddowns, and to supply RP-1.

I would remove the SRB beam and add core support to the ML, since the thrust beam has to modified already.

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