Author Topic: SLS General Discussion Thread 2  (Read 224238 times)

Online RonM

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Re: SLS General Discussion Thread 2
« Reply #360 on: 03/28/2016 03:59 PM »
What will be the steady state SLS flight rate?

SLS Block 2 will be 50% more massive than shuttle.

Shuttle launched on average about 4 times a year. So SLS should launch at least 2 to 3 times a year.

But I have heard on many occasions that SLS will be launched once every two years, or maybe but unlikely once a year.

This does not make sense to me. Why would the SLS launch rate be so low?


The SLS lacks payloads.

BTW, the shuttle flight rate was much higher in the 90's when it had payloads other than the ISS.

Yes, lack of payloads.

Congress is more than happy to pay for the development of SLS and Orion, but they don't seem willing to actually do anything with them other than a couple of test flights and maybe the Europa mission. Unless there is more money coming soon, and I doubt that, expect SLS to be cancelled by the mid twenties.

If the program was funded, NASA wants a minimum of one flight per year and SLS production could handle two flights per year.

Offline ThereIWas3

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Re: SLS General Discussion Thread 2
« Reply #361 on: 03/28/2016 07:01 PM »
I love this, from a ABC News item about the auditor's report on the SLS launch control software being behind schedule and over budget:

Quote
The software won't be ready until fall 2017, instead of this summer as planned, and important capabilities like automatic failure detection, are being deferred.

Yes, let's defer the safety features.  What could possibly go wrong?
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Online A_M_Swallow

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Re: SLS General Discussion Thread 2
« Reply #362 on: 03/29/2016 12:49 AM »
What will be the steady state SLS flight rate?

SLS Block 2 will be 50% more massive than shuttle.

Shuttle launched on average about 4 times a year. So SLS should launch at least 2 to 3 times a year.

But I have heard on many occasions that SLS will be launched once every two years, or maybe but unlikely once a year.

This does not make sense to me. Why would the SLS launch rate be so low?

By this trend, next generation rocket system with the same mass as shuttle will be launched once a decade.


The other big difference is that the Space Shuttles were reusable vehicles where as the SLS are expendable vehicles. This may makes a big cost difference. The 6 Space Shuttles (including Enterprise) were repaired and used again. Each SLS will be used once and thrown away.

Offline RocketGoBoom

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Re: SLS General Discussion Thread 2
« Reply #363 on: 04/22/2016 04:13 PM »
SLS and Orion are crowding out other areas of the NASA budget.

http://spacenews.com/senate-bill-cuts-other-nasa-programs-to-fund-sls-and-orion/

Quote
The bill provides $19.306 billion for NASA, an increase of more than $280 million from the administration’s request for fiscal year 2017 released in February. However, NASA’s exploration account, which includes SLS and Orion, is increased by nearly $1 billion from the request.

That increase includes about $840 million for the SLS, to $2.15 billion, and $180 million for Orion, to $1.3 billion. Exploration ground systems to support SLS and Orion also see a $55 million increase, although research and development activities are cut by more than $80 million.

The increase in exploration funding means that most other major NASA accounts suffered cuts from the administration’s request in the bill. Science, aeronautics, space technology and space operations were cut by a combined $660 million from the request. The aeronautics account suffered the largest cut on a percentage basis, seeing its request for $790 million cut by nearly 25 percent.

Within the $5.4 billion provided to science, $200 million less than the request, planetary science suffered the largest cut, of more than $160 million. The bill and report did not specify a funding level for a mission to Europa, although it did state it “remains supportive” of such a mission. The bulk of the support for a Europa mission, and the enhanced funding it has received in recent years, has come from the House.


Offline RotoSequence

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Re: SLS General Discussion Thread 2
« Reply #364 on: 04/22/2016 05:23 PM »
Maybe Congress intends to fund the development of payloads as part of a piecemeal, step by step approach once they've finished building the launch vehicle? They do seem to be in an awfully big hurry to build this rocket and make sure it's absolutely ready and on schedule, even though it has basically nothing to do. It's vexing.  :o
« Last Edit: 04/22/2016 05:26 PM by RotoSequence »

Offline Star One

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Re: SLS General Discussion Thread 2
« Reply #365 on: 04/22/2016 07:09 PM »
Maybe Congress intends to fund the development of payloads as part of a piecemeal, step by step approach once they've finished building the launch vehicle? They do seem to be in an awfully big hurry to build this rocket and make sure it's absolutely ready and on schedule, even though it has basically nothing to do. It's vexing.  :o

My thinking entirely. Has it escaped their notice that a launcher has to actually have something to launch in the first place.

Offline Zed_Noir

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Re: SLS General Discussion Thread 2
« Reply #366 on: 04/22/2016 07:52 PM »
Maybe Congress intends to fund the development of payloads as part of a piecemeal, step by step approach once they've finished building the launch vehicle? They do seem to be in an awfully big hurry to build this rocket and make sure it's absolutely ready and on schedule, even though it has basically nothing to do. It's vexing.  :o

My thinking entirely. Has it escaped their notice that a launcher has to actually have something to launch in the first place.

Rationality and Congressional Critters? ::) The Critters is fine with the current setup, since the R&D dollars goes to certain Congressional districts. Getting something operational don't matter to them, otherwise several SLS payload should be bending metal already.

Offline spacenut

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Re: SLS General Discussion Thread 2
« Reply #367 on: 04/22/2016 08:50 PM »
Well if the ATK/Orbital EELV rocket is developed using SLS solid components, strap on solids used for Vulcan, this should cut some manufacturing costs for the SLS.  How much we don't know.  Keeping assembly line work going is better than starting and stopping constantly. 

I think the original Ares I  & V concepts were fine using off the shelf parts.  All the money spent on 5 segment booster development, J2X development, etc went nowhere and built nothing.  All that money could have been spent developing the SSME as a air start engine, the only real development needed.  Then the existing 4 segment boosters would have been fine.  It would have been a lot cheaper.  Then after their development and getting into service, develop the composite boosters for improved performance.  It has been what 10-12 years and still no big rocket?  The EELV and reusable markets have made great strides in the same length of time.  Still water over the dam. 

When is SLS supposed to fly?  By the time it does Vulcan, Falcon Heavy, maybe even a metholox upper stage for Falcon Heavy, and a new EELV solid, and maybe even BO's New Sheppard reusable vehicle could be flying, all combined with in orbit refueling and evolved SEP propulsion would make SLS obsolete as far as overall costs to operate. 

Offline edkyle99

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Re: SLS General Discussion Thread 2
« Reply #368 on: 04/27/2016 09:41 PM »
Who knows if it will be built, but the video is awesome.
"If"?  It already is being built.

 - Ed Kyle

A bill is not paid until the cheque has cleared.

Block 0 SLS is in a race with Falcon Heavy and Vulcan Heavy. Definitely an "If" until Block 1A with its very heavy payload flies.
They are building Block 1 right now.  (Block 0 was an undeveloped concept.)  It will lift about 2.5 times more mass to escape velocity than an all-expendable Falcon Heavy and probably 6 times more than an all-recoverable Falcon Heavy. 

Block 1B is the next SLS, with the EUS upper stage that has been designed.  NASA has already ordered engines for that new upper stage and it looks like Block 1B will take over after only one or two Block 1 flights.  Block 1B is probably going to be able to boost 4 times more to escape than an all-expendable Falcon Heavy and 10 times more than an all-recoverable Heavy.

Vulcan Heavy is a concept that is not currently planned to be developed.  Vulcan-ACES will be powerful enough to do the EELV Heavy missions currently done by Delta 4 Heavy, but ACES is a few years down the road.  It will roughly match Falcon Heavy performance beyond LEO.

 - Ed Kyle 
« Last Edit: 04/27/2016 09:47 PM by edkyle99 »

Online Johnnyhinbos

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Re: SLS General Discussion Thread 2
« Reply #369 on: 04/28/2016 01:56 AM »
The six year old in me wonders if I can lick the giant beaters...

I've been in that room. I think if you tried you'd see a lot of folks hitting the floor real quick! (Kidding - all mixing operations are controlled remotely from a bunker...)
« Last Edit: 04/28/2016 01:58 AM by Johnnyhinbos »
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Offline TomH

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Re: SLS General Discussion Thread 2
« Reply #370 on: 04/28/2016 04:16 PM »
Block 1.....will lift about 2.5 times more mass to escape velocity than an all-expendable Falcon Heavy and probably 6 times more than an all-recoverable Falcon Heavy.

And the actually pertinent questions are:
On what timeline?
At what price per kg?
Why are you so conveniently leaving out MCT?

I was an SLS believer at one time too............But then I'm far more of a realist than I am a believer.

Offline edkyle99

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Re: SLS General Discussion Thread 2
« Reply #371 on: 04/28/2016 05:01 PM »
Block 1.....will lift about 2.5 times more mass to escape velocity than an all-expendable Falcon Heavy and probably 6 times more than an all-recoverable Falcon Heavy.

And the actually pertinent questions are:
On what timeline?
At what price per kg?
Why are you so conveniently leaving out MCT?

I was an SLS believer at one time too............But then I'm far more of a realist than I am a believer.
NASA is working to a constrained budget on SLS and Orion, so whatever that is determines the "price".  The schedule is published.  Orion is the time constraint, not SLS.  MCT is a concept. SLS is being built, with quite a bit of flight hardware already complete.

Ed Kyle

Offline CNYMike

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Re: SLS General Discussion Thread 2
« Reply #372 on: 04/28/2016 05:49 PM »
Who knows if it will be built, but the video is awesome.
"If"?  It already is being built.

 - Ed Kyle

Let me rephrase: the next administration could cancel it, then it's anybody's guess what comes next.  Trump is the wild card; who knows what he'll do?  Ten seconds of pandering to MSFC people isn't enough. 

Yes, it is being built.  Yes, it can fly.  Then again, NASA could be terminated and US space privatized completely.  We won't know until next year. 

FYI, I don't want the current manned programs canceled because we'd go through the same kind of mess that got us here in the first place.  But you can't count on whoever takes the white house to make that much sense.  And I'm not ruling Trump out until the first Wednesday in November. 

Hope that clears things up.
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Offline Coastal Ron

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Re: SLS General Discussion Thread 2
« Reply #373 on: 04/28/2016 08:59 PM »
SLS is being built, with quite a bit of flight hardware already complete.

The question has never really been "Can we build an HLV?", and so far Congress has been willing to appropriate the funds to develop such a system and get it ready for flying payloads that require it's unique capabilities.

The question has always been whether a government-owned HLV is needed or required at this point in history.  And so far the answer to that is not a resounding "Yes", but just a dribble of interest and money from Congress as a whole.

Unfortunately a dribble of support won't support the need to launch the SLS at the minimum safe flight cadence of no-less-than every 12 months, so there is a point coming very soon where having a government-owned transportation system but not having enough demand for it's unique capabilities must be reconciled...
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 Ben the Space Brit

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Re: SLS General Discussion Thread 2
« Reply #374 on: 04/29/2016 08:57 AM »
I think that the posters above are correct to emphasise that the question is 'should', not 'could'. Don't get me wrong, I'm a BFR fan-boy. I love these huge creatures. However, there is no point building The Rocket That Ate NASA if it never serves any significant purpose in the space program. I'd feel a lot more confident about SLS and its future if the following criteria were met:

1) Flight rate > 2/year;

2) Waiting list of payloads or fully-described, funded and in development missions that require its unique capabilities;

3) Any payload at all (i.e. human-ready Orion) that is expected to fly in < 5 years.

Right now, EM-1 is giving me uncomfortable Ares-I-X flashbacks.

You see... SpaceX are talking about a program of Red Dragon missions, mostly intended to gather data on and then prove all-propulsive Martian landings... starting NET 2018. When the first Dragon has pads down and is relaying data back from the Martian surface, things are going to get a lot more interesting on the Space, Science and Competitiveness Subcommittee, especially if the Gentleman from Texas is nursing a bruised ego and wants to prove himself again.
« Last Edit: 04/29/2016 08:59 AM by Ben the Space Brit »
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Online A_M_Swallow

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Re: SLS General Discussion Thread 2
« Reply #375 on: 04/29/2016 04:45 PM »
NASA could give a grant to a university professor to write a study showing how SLS could be used to build a lunar village. It does not matter if the SLS takes the habitats to lunar orbit or delivers say the rovers to a SEP tug waiting in LEO.

Providing the self funding holds out ULA and Masten should have the ability to land payloads of 5-10 tonnes on the Moon within 5 years. See Lunar_CATALYST. In about 15 years they plan to land 25 tonne payloads.

Offline ncb1397

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Re: SLS General Discussion Thread 2
« Reply #376 on: 04/29/2016 05:14 PM »
SLS is being built, with quite a bit of flight hardware already complete.

The question has never really been "Can we build an HLV?", and so far Congress has been willing to appropriate the funds to develop such a system and get it ready for flying payloads that require it's unique capabilities.

The question has always been whether a government-owned HLV is needed or required at this point in history.  And so far the answer to that is not a resounding "Yes", but just a dribble of interest and money from Congress as a whole.

Unfortunately a dribble of support won't support the need to launch the SLS at the minimum safe flight cadence of no-less-than every 12 months, so there is a point coming very soon where having a government-owned transportation system but not having enough demand for it's unique capabilities must be reconciled...

Is it really 12 months? why not 13 months or 11 months? Seems like a nice round number that happens to coincidentally coincide with the earth's orbit around the sun. If we are going to use calendars as arbitrary technical limitations, why not the Mars year - 687 days? I would like to point out that Apollo Soyuz test project was launched on a Saturn 1B 16 months after the previous Saturn 1B...and didn't explode.

Offline Coastal Ron

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Re: SLS General Discussion Thread 2
« Reply #377 on: 04/29/2016 05:47 PM »
Is it really 12 months? why not 13 months or 11 months? Seems like a nice round number that happens to coincidentally coincide with the earth's orbit around the sun.

When there are a lot of unknowns, you have to try to make assumptions.  From an NSF article:

"Although payloads are yet to be announced, Mr. Gerstenmaier confirmed the flight rate has to be once a year as a minimum requirement, in response to a question from Bejmuk – who had assumed SLS would only launch once every two or three years.

Mr. Gerstenmaier noted that “repetitive cadence is necessary” as the reason SLS will launch every year.
"

However it would be a whole host of reasons that they have used to distill down to an assumption of once per year, meaning any one of those assumptions could change - either for better or worse.  But you wouldn't know if it was for the worst unless you experienced a failure of some sort, which is a condition that NASA would rather not have.

Quote
I would like to point out that Apollo Soyuz test project was launched on a Saturn 1B 16 months after the previous Saturn 1B...and didn't explode.

And no doubt it could be that NASA could launch the SLS every 5 years and it would not explode.  But the cost of that one flight every 5 years would likely be enormous, for many reasons.

So it really does come down to cost - what is the overall cost associated with running a unique transportation system?  And what would be the cost to not have it?

Those are the questions that have not fully been asked and answered, but will have to be soon since the SLS manifest is virtually empty prior to it becoming operational...
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 notsorandom

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Re: SLS General Discussion Thread 2
« Reply #378 on: 04/29/2016 06:34 PM »
SLS is being built, with quite a bit of flight hardware already complete.

The question has never really been "Can we build an HLV?", and so far Congress has been willing to appropriate the funds to develop such a system and get it ready for flying payloads that require it's unique capabilities.

The question has always been whether a government-owned HLV is needed or required at this point in history.  And so far the answer to that is not a resounding "Yes", but just a dribble of interest and money from Congress as a whole.

Unfortunately a dribble of support won't support the need to launch the SLS at the minimum safe flight cadence of no-less-than every 12 months, so there is a point coming very soon where having a government-owned transportation system but not having enough demand for it's unique capabilities must be reconciled...

Is it really 12 months? why not 13 months or 11 months? Seems like a nice round number that happens to coincidentally coincide with the earth's orbit around the sun. If we are going to use calendars as arbitrary technical limitations, why not the Mars year - 687 days? I would like to point out that Apollo Soyuz test project was launched on a Saturn 1B 16 months after the previous Saturn 1B...and didn't explode.
The gap between Apollo 7 and Skylab 2 was even greater, 4 years 7 months and 14 days. Similarly the Delta II has some pretty big gaps in its recent launch history. The gap between Delta flight 357 and 367 is 2 years 8 months and 4 days. There is an almost 2 year gap between the last Delta II flight and the next one.

I can understand the desire to keep a regular launch cadence so the program's personnel have regular practice. However at least looking at these two rockets the gaps do not appear to present significant reliability issues. The professionals who work in this industry appear to be capable of reliably launching at any cadence. Accordingly I don't think the issue of launch cadence as it relates to reliability should be a factor the decision to continue or cancel the program. There are many pros and cons to the SLS program that are way more important than this hypothetical concern.

Offline spacenut

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Re: SLS General Discussion Thread 2
« Reply #379 on: 04/29/2016 07:35 PM »
Where do you get SLS getting 2.5 times the LEO payload vs FH?  FH expendable, like SLS will be, is supposed to get 53 tons to LEO.  I thought SLS is or was to be between 95-105 tons to LEO in current configuration.  Spun wound composite boosters might get it to 115-120, but from what I understand, not 130.  For greater than 130 tons, wouldn't they have to add a 5th engine on the core and a larger upper stage say with J2x?  Now that Falcon has full thrust in their rocket, this will change the boosters LEO ability.  The Raptor upper stage engine is supposed to be developed in the next 18-24 months.  This may greatly increase FH's payload.  SLS is certainly not 2.5 times the proposed FH. 

Someone several years ago suggested the 40-60 ton payload range, using EELV's in heavy versions, in space docking, assembly, and refueling, would be all we needed have a viable moon or Mars program.  Also, with several vendors, no real downtime if one of the competitors had a failure.  No need for billions spent on SLS or $/kg cost. 

We seem to have vendors who leach off the government with constant delays and cost overruns.   

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