Author Topic: SLS General Discussion Thread 3  (Read 76619 times)

Offline Verio Fryar

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Re: SLS General Discussion Thread 3
« Reply #400 on: 02/11/2019 03:48 pm »
The corestage should be using 5x RS-25 engines as originally planned - not 4x as now.

Yes, the original plan was five RS-25's on the core, five segment HTPB solid boosters and dual J-2S+ powered upper stage. Payload to LEO was 146.6 t! This slide says this is a future growth version, but the version chosen in the final report is the one below. Unfortunately, they also recommended the Ares-I and it went downhill from there.
How a 5 x RS-25 version could fix the problems of SLS? IMO the exorbitant cost and low flight-rate are the main problems. I can't see how a bigger SLS could help with them.

Offline Khadgars

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Re: SLS General Discussion Thread 3
« Reply #401 on: 02/11/2019 03:58 pm »
Remember Congress has not fully funded ANY programs that require the SLS, and we are just a mere 3 years away from when the SLS is supposed to be operational - and it normally takes at least 7 years to build small planetary robotic hardware

It really doesn't take that long.

Most everyone thinks and hopes that the SLS will be used for HSF missions, so my point was that non-HSF mission, which are far less complex, can take 7 years or more. The Mars rovers have taken that long, and the human-rated Orion spacecraft will have taken 18 years by the time it is fully certified to fly crew.

In our modern times, HSF certified hardware has always taken far long to get ready for launch than planned, meaning that the SLS may not actually fly any payloads for years. Congress is already unhappy with the now $10B JWST, so I would not expect them to be thrilled with programs that start at $10B and don't launch for a decade or more.

Not funding payloads for the SLS will just continue to exacerbate the problem the SLS will have when it's ready to be operational - and there will be nothing to launch. At some point someone is going to notice that situation is just a couple of years away, and that will force Congress and the President to do something - either fund payloads quickly and fully, or debate whether the SLS is needed at all.

Either way, Congress has to finally review the SLS program.
18 years  is literally insane. About $20 billion spent before the first crewed launch!! >:( Think of the crewed Lander they could have made for that money...

These posts are so numerous that they do not serve any purpose.  I would respectfully request users refrain from them unless there is a specific point being made that hasn't been issued countless times before.

« Last Edit: 02/11/2019 09:58 pm by Khadgars »

Offline MATTBLAK

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Re: SLS General Discussion Thread 3
« Reply #402 on: 02/11/2019 10:31 pm »
I thought this was an SLS discussion thread; you know - where we discuss the pros and cons of most things SLS? If that's not done, how can there be an actual discussion...
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Offline Lar

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Re: SLS General Discussion Thread 3
« Reply #403 on: 02/12/2019 04:39 pm »
There has to be a place to discuss the technical stuff without rehashing why[1]  SLS is a colossal waste of time, money and engineering talent over and over again. We have other threads for that.

So yeah, cool it on the SLS sux here. There are surely interesting technical things to discuss.

1 - er, I mean whether.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
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Offline clongton

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Re: SLS General Discussion Thread 3
« Reply #404 on: 02/12/2019 07:29 pm »
I thought SLS was essentially all NASAís idea under the concept of DIRECT /Jupiter.  Simple safe soon.  How did Congress generate the SLS idea?
https://www.nasa.gov/pdf/361841main_14%20-%20DIRECT_HSF_Commission.pdf
Initial cost estimates were way off.

SLS is decidedly *not* DIRECT/Jupiter. In fact the only thing they share is long distance optics - they *LOOK* similar.
SLS is everything that Jupiter was specifically designed to avoid. :(
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Khadgars

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Re: SLS General Discussion Thread 3
« Reply #405 on: 02/13/2019 03:59 pm »
I thought SLS was essentially all NASAís idea under the concept of DIRECT /Jupiter.  Simple safe soon.  How did Congress generate the SLS idea?
https://www.nasa.gov/pdf/361841main_14%20-%20DIRECT_HSF_Commission.pdf
Initial cost estimates were way off.

SLS is decidedly *not* DIRECT/Jupiter. In fact the only thing they share is long distance optics - they *LOOK* similar.
SLS is everything that Jupiter was specifically designed to avoid. :(

I really loved the Jupiter design, it was as brilliant as it was elegant imo.  We can say that it moved NASA away from the 1.5 architecture that used the stick and Ares V  :P
« Last Edit: 02/13/2019 04:08 pm by Khadgars »

Offline spacenut

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Re: SLS General Discussion Thread 3
« Reply #406 on: 02/18/2019 02:29 am »
Jupiter 130 used existing hardware.  SLS went to larger 5 segment solids (extra money), they redesigned the SSME to RS-25  to lower costs but they had to basically rebuild the engine (extra money).  They stretched the tank (extra money) to use 4 engines instead of three.  All of this cost extra and delayed the introduction of the SLS. 

All Direct Jupiter 130 was to move the 3 SSME's from the orbiter to the bottom of the existing shuttle tanks and use the same solids, and pop Orion on top.  Not a whole lot of work.  Going to 5 segments and 4 engines made a whole new rocket. 
« Last Edit: 02/18/2019 02:31 am by spacenut »

Offline Coastal Ron

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Re: SLS General Discussion Thread 3
« Reply #407 on: 02/18/2019 03:10 am »
SLS is decidedly *not* DIRECT/Jupiter. In fact the only thing they share is long distance optics - they *LOOK* similar.
SLS is everything that Jupiter was specifically designed to avoid. :(
Iím unclear what the functional differences are between Direct and SLS?  Obviously the projected costs to develop SLS and Direct are off by 5x.

You're asking the right person that questions, since clongton (i.e. Chuck Longton) was on the Direct Jupiter team.

Quote
So this seems to ripple into other attempts to get to the moon without SLS.  All of the sudden, seems like everyone else has to rush to do what was originally planned for the direct launcher for less.

"Everyone" doesn't have the same motivation to go to our Moon as the U.S. Government (and U.S. motivation is fuzzy too), and the Senators that defined the SLS really didn't have a specific use case for the SLS - there was no defined need for an HLLV at that time.

And really the use case for the SLS is diminished when there are other transportation systems the U.S. Government can use, especially when they are partially reusable or fully reusable ones. And though Direct would have reused Shuttle infrastructure and designs, it would not have lead to a reusable launch vehicle.

I don't think we're seeing a "rush" to get to our Moon...
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 woods170

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Re: SLS General Discussion Thread 3
« Reply #408 on: 02/18/2019 06:26 am »
Jupiter 130 used existing hardware.  SLS went to larger 5 segment solids (extra money), they redesigned the SSME to RS-25  to lower costs but they had to basically rebuild the engine (extra money).  They stretched the tank (extra money) to use 4 engines instead of three.  All of this cost extra and delayed the introduction of the SLS. 

All Direct Jupiter 130 was to move the 3 SSME's from the orbiter to the bottom of the existing shuttle tanks and use the same solids, and pop Orion on top.  Not a whole lot of work.  Going to 5 segments and 4 engines made a whole new rocket. 

Additionally: DIRECT would have used the then-existing tooling for building the core stage, using the basic design of the ET. Only the LOX tank would be re-designed, with a newly-designed boat-tail section added to house the MPS.
SLS however went with a completely new design for the core stage, using completely different tooling. The only thing DIRECT and SLS have in common is the diameter of the core stage which, in both cases, is the same as the diameter of the shuttle ET. Other than that no commonality between SLS and the original shuttle ET remains. Even the isolation foam on the outside of the core stage has been completely re-developed. Thrust-beam the same? Nope, completely re-designed.
Umbilical plates the same? Nope, completely re-designed.
And the list goes on and on and on...
For all intents and purposes SLS is a completely new rocket, with no shuttle heritage remaining. Even the RS-25 engines have been significantly upgraded from their original STS SSME design (new valves, new controller,  TPS added to the bells, etc.
The SRB's have an additional segment, as well as using a new internal profile and a new formula for the solid propellant. The TVC system has been replaced with a newer design and the avionics are a new design too.
« Last Edit: 02/18/2019 06:31 am by woods170 »

Offline clongton

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Re: SLS General Discussion Thread 3
« Reply #409 on: 02/18/2019 03:31 pm »
While I will never tire of walks down memory lane wrt the DIRECT days, it is decidedly off topic for this thread and I would ask that we leave the discussion there. People come here to discuss SLS so let's do that. Anyone that wants to dig deeper into DIRECT should go to the DIRECT website which we continue to maintain. Everything is there; designs, white papers, baseball cards, artwork, videos, member profiles, cost breakdowns, IMS, etc. It's all there for your edification.
http://www.directlauncher.org/

We now return you all to your regularly scheduled SLS thread.
« Last Edit: 02/18/2019 03:35 pm by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

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