Author Topic: SLS: Higher payload without second stage  (Read 18703 times)

Offline spacenut

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Re: SLS: Higher payload without second stage
« Reply #60 on: 06/04/2017 02:47 PM »
Yes, NASA builds means NASA designs and oversees contractors.  However, highways, ports, canals, airports, etc are built by the government (overseeing contractors).  They do not build the trucks, cars, ships (except navy vessels, then with contractors), nor railroad locomotives, cargo cars, or planes. 

Notice, it is the transportation infrastructure they build and maintain.  Ok, so NASA should concentrate on communication satellites between Earth and Mars, Earth and the moon.  They should build in space fuel depots, maybe even Mars cyclers like a bus route between Earth and Mars.  Private companies and/or other earth nations can take advantage of this and build moon mining bases, Mars colonies, in space manufacturing.  NASA should also construct an artificial gravity space station (maybe in conjunction with a fuel depot) in order to experiment with long term effects of moon or Mars gravity. 

If SLS can help build these, good, but it will be expensive.  Hopefully they can do something to get SLS costs down.  Otherwise, they should pay or partly pay for others to build, like COTS.  They do however need to standardize all connections, fuel, docking, etc.  All railroads are standard guage.  All home building materials are standard sizes like doors, windows, studs, joists, plumbing, etc. 
« Last Edit: 06/04/2017 02:48 PM by spacenut »

Offline Paul451

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Re: SLS: Higher payload without second stage
« Reply #61 on: 06/04/2017 06:55 PM »
So, NASA is supposed to just wait for these proposed launch vehicles to finally appear?  Falcon Heavy was supposed to fly in 2013. [...]   
NASA can't wait for promises when it has the propulsion in hand.

{sigh} These threads wouldn't keep getting swamped with SpaceX arguments if people wouldn't keep repeating the same nonsense.

What "propulsion" does NASA have "in hand"? They haven't even figured out how to weld the tanks.

Meanwhile, for FH, the actual flight-hardware is in test-firing before final vehicle assembly. It's likely that they'll have at least three FH flights under their belt before SLS flies. And a dozen FH flights before SLS flies a second time. So in what way would NASA be "waiting" for FH, but have SLS "in hand"?
« Last Edit: 06/04/2017 06:56 PM by Paul451 »

Offline spacenut

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Re: SLS: Higher payload without second stage
« Reply #62 on: 06/04/2017 07:04 PM »
This is why I think with FH coming on line and BO with New Glenn in a couple of years.  Both doing 40 tons reusable.  IF NASA concentrated on building a fuel depot.  Both their 2nd or 3rd stages could do a lot of tonnage to deep space.

Online envy887

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Re: SLS: Higher payload without second stage
« Reply #63 on: 06/04/2017 07:21 PM »
Propulsion = SSME of which NASA has 15 in hand.

Of course, this is not a significant advantage, since propulsion for at least Falcon Heavy is also in hand. RD-180 and RS-68 are also available, though they and SSME have all outlived their usefulness.

Offline ncb1397

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Re: SLS: Higher payload without second stage
« Reply #64 on: 06/04/2017 07:45 PM »
Good Government 101 tells us that there is a public sector and a private sector and that the government should not try to duplicate in the public sector what industry can deliver from the private sector.  National policy should move NASA out of the ETO segment, focus NASA resources on the in-space (transit, EDL, surface) technologies and systems that industry is not pursuing, and leverage and build on the ongoing ETO developments in the private sector.

How long until the same argument is used to say that NASA shouldn't be building any in-space vehicles at all?  After all commercial interests might do that on their own as well...

Does the US government build cars? Boats? Trains? Aircraft? If not, what makes spacecraft so unique that NASA should build them?

(And yes I know that much of the Stuff NASA builds is done through contractors, but for the purposes of this discussion I assume that "NASA builds" means "NASA designs and oversees contractors building it")

https://en.wikipedia.org/wiki/List_of_currently_active_United_States_military_land_vehicles
https://en.wikipedia.org/wiki/List_of_active_United_States_military_aircraft
https://en.wikipedia.org/wiki/List_of_current_ships_of_the_United_States_Navy

Quote
The Grumman Long Life Vehicle (LLV) is an American light transport truck. The Grumman LLV was designed as a mail truck for the United States Postal Service, which is its primary user.
https://en.wikipedia.org/wiki/Grumman_LLV

NASA owns some RQ-4 globalhawks, full list here:

https://en.wikipedia.org/wiki/List_of_NASA_aircraft

Really, the argument is that the U.S. government can't design, build, own or operate space vehicles since SLS is not exactly built by NASA..they just had input into design and have ownership and control of the completed vehicles. They could only pay United Airlines for tickets to transport people for example and not own a 747 or other transport plane because that is competing with commercial services. If space actually opens up, this structure would represent a pretty extreme inversion of the power structure between corporate and government entities that exist today where corporations are ultimately under control and subservient to governments.

The same argument could be used to ask why NASA owns any fixed wing aircraft or employs any pilots when they could just charter flights from private companies.
« Last Edit: 06/04/2017 08:17 PM by ncb1397 »

Offline Hog

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Re: SLS: Higher payload without second stage
« Reply #65 on: 06/05/2017 01:29 PM »
Propulsion = SSME of which NASA has 15 in hand.

Of course, this is not a significant advantage, since propulsion for at least Falcon Heavy is also in hand. RD-180 and RS-68 are also available, though they and SSME have all outlived their usefulness.
Typo maybe?
16 RS25s are available, 14 with flight experience, and 2 new build green engines that haven't even been fired at all, ME2062(built in 2010) ME2063(built in 2015).  Both engines are EM-1 contingency engines and are scheduled for primary flight usage on EM-2.
Paul

Online envy887

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Re: SLS: Higher payload without second stage
« Reply #66 on: 06/05/2017 02:58 PM »
Propulsion = SSME of which NASA has 15 in hand.

Of course, this is not a significant advantage, since propulsion for at least Falcon Heavy is also in hand. RD-180 and RS-68 are also available, though they and SSME have all outlived their usefulness.
Typo maybe?
16 RS25s are available, 14 with flight experience, and 2 new build green engines that haven't even been fired at all, ME2062(built in 2010) ME2063(built in 2015).  Both engines are EM-1 contingency engines and are scheduled for primary flight usage on EM-2.

I thought it was 15, without going to check. Regardless, NASA has sufficient available, but I disagree with NASA's assessment that they are the most expedient propulsion for a new SHLV.

Offline okan170

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Re: SLS: Higher payload without second stage
« Reply #67 on: 06/05/2017 03:19 PM »
(And yes I know that much of the Stuff NASA builds is done through contractors, but for the purposes of this discussion I assume that "NASA builds" means "NASA designs and oversees contractors building it")

If people keep expanding out into space, eventually I imagine NASA moving to buying and operating designs from others for certain tasks- but not simply buying seats and space forever.  At least unless we start having US armed forces aircraft and ships owned and operated by their manufacturers, and not government personnel as well.

Offline RonM

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Re: SLS: Higher payload without second stage
« Reply #68 on: 06/05/2017 03:22 PM »
Propulsion = SSME of which NASA has 15 in hand.

Of course, this is not a significant advantage, since propulsion for at least Falcon Heavy is also in hand. RD-180 and RS-68 are also available, though they and SSME have all outlived their usefulness.
Typo maybe?
16 RS25s are available, 14 with flight experience, and 2 new build green engines that haven't even been fired at all, ME2062(built in 2010) ME2063(built in 2015).  Both engines are EM-1 contingency engines and are scheduled for primary flight usage on EM-2.

I thought it was 15, without going to check. Regardless, NASA has sufficient available, but I disagree with NASA's assessment that they are the most expedient propulsion for a new SHLV.

Congress is funding a Shuttle-derived SHLV, so RS25 is what NASA will use.

Online AncientU

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Re: SLS: Higher payload without second stage
« Reply #69 on: 06/06/2017 12:28 AM »
Propulsion = SSME of which NASA has 15 in hand.

Of course, this is not a significant advantage, since propulsion for at least Falcon Heavy is also in hand. RD-180 and RS-68 are also available, though they and SSME have all outlived their usefulness.

Actually, it is costing them $1.15B for the next 6 engines... not hardly 'in hand' when you have to pay $200M for the next one.
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Offline ncb1397

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Re: SLS: Higher payload without second stage
« Reply #70 on: 06/06/2017 12:31 AM »
Propulsion = SSME of which NASA has 15 in hand.

Of course, this is not a significant advantage, since propulsion for at least Falcon Heavy is also in hand. RD-180 and RS-68 are also available, though they and SSME have all outlived their usefulness.

Actually, it is costing them $1.15B for the next 6 engines... not hardly 'in hand' when you have to pay $200M for the next one.

It is $1.15B for RS-25E. $350 million for 6 engines.

Offline edkyle99

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Re: SLS: Higher payload without second stage
« Reply #71 on: 06/06/2017 03:27 AM »
So, NASA is supposed to just wait for these proposed launch vehicles to finally appear?  Falcon Heavy was supposed to fly in 2013. [...]   
NASA can't wait for promises when it has the propulsion in hand.

What "propulsion" does NASA have "in hand"? They haven't even figured out how to weld the tanks.

Meanwhile, for FH, the actual flight-hardware is in test-firing before final vehicle assembly. It's likely that they'll have at least three FH flights under their belt before SLS flies. And a dozen FH flights before SLS flies a second time. So in what way would NASA be "waiting" for FH, but have SLS "in hand"?
NASA has RS-25 and five-segment booster and RL10 and, for Orion, AJ-10.  In-hand.

As for Falcon Heavy, there is no waiting.  It is not an SLS replacement.  The way SpaceX wants to fly it (recovering boosters and first stage) it will barely boost 5.5 tonnes toward the Moon, compared to SLS Block 1's 24.5 tonnes.  Even if the entire rocket was thrown away it would not match even SLS Block 1, and would only lift a bit more than half as much as Block 1B's 39 tonnes. 

The engines for rockets that might one day be SLS class are still in development.

 - Ed Kyle
« Last Edit: 06/06/2017 03:36 AM by edkyle99 »

Offline woods170

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Re: SLS: Higher payload without second stage
« Reply #72 on: 06/06/2017 06:05 AM »
So, NASA is supposed to just wait for these proposed launch vehicles to finally appear?  Falcon Heavy was supposed to fly in 2013. [...]   
NASA can't wait for promises when it has the propulsion in hand.

What "propulsion" does NASA have "in hand"? They haven't even figured out how to weld the tanks.

Meanwhile, for FH, the actual flight-hardware is in test-firing before final vehicle assembly. It's likely that they'll have at least three FH flights under their belt before SLS flies. And a dozen FH flights before SLS flies a second time. So in what way would NASA be "waiting" for FH, but have SLS "in hand"?
NASA has RS-25 and five-segment booster and RL10 and, for Orion, AJ-10.  In-hand.

As for Falcon Heavy, there is no waiting.  It is not an SLS replacement.  The way SpaceX wants to fly it (recovering boosters and first stage) it will barely boost 5.5 tonnes toward the Moon, compared to SLS Block 1's 24.5 tonnes.  Even if the entire rocket was thrown away it would not match even SLS Block 1, and would only lift a bit more than half as much as Block 1B's 39 tonnes. 

The engines for rockets that might one day be SLS class are still in development.

 - Ed Kyle
This entire discussion about FH being able to replace SLS (or not) is entirely moot. SLS is a political pork barrel and will not be going away any time soon. So there is no need whatsoever to have it's capabilities replaced by whatever other rocket.
FH will serve it's own market, regardless of SLS being there or not.
« Last Edit: 06/06/2017 06:05 AM by woods170 »

Online envy887

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Re: SLS: Higher payload without second stage
« Reply #73 on: 06/06/2017 02:41 PM »
The way SpaceX wants to fly it (recovering boosters and first stage) it will barely boost 5.5 tonnes toward the Moon...


Edit: reply moved here: https://forum.nasaspaceflight.com/index.php?topic=43073.0
« Last Edit: 06/06/2017 02:43 PM by envy887 »

Offline UltraViolet9

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Re: SLS: Higher payload without second stage
« Reply #74 on: 06/06/2017 07:21 PM »
Good Government 101 tells us that there is a public sector and a private sector and that the government should not try to duplicate in the public sector what industry can deliver from the private sector.  National policy should move NASA out of the ETO segment, focus NASA resources on the in-space (transit, EDL, surface) technologies and systems that industry is not pursuing, and leverage and build on the ongoing ETO developments in the private sector.

How long until the same argument is used to say that NASA shouldn't be building any in-space vehicles at all?  After all commercial interests might do that on their own as well...

There are always technology and capability frontiers appropriate for government risk-taking that are beyond private investment. 

We can take all the current commercial plans at face value, and there are still many, large, unfilled, and unfunded gaps to enable human space exploration and activities beyond LEO:  nuclear power sources (space and surface), long-term cryogenic storage, reusable propulsion and subsystems for transit stages and landers, non-chemical propulsion for fast crew transit, high-power electric propulsion for efficient cargo transit, non-propulsive EDL techniques for large landers, surface habitation, surface mobility, ISRU, etc.

And even if we hypothetically reject a NASA role in developing new in-space systems, there are many, promising, advanced, but largely unfunded ETO techniques that promise efficiencies beyond current private heavy lift and reusability efforts:  more efficient/powerful upper stage engines, air-breathing engines, microwave thermal, laser thermal, etc. 

The point is that the bulk of NASA's talents and resources should be focused on the tip of the spear in space exploration and technology, however you define that (ETO versus in-space, existing versus advanced technologies, etc.).  We have three private entities covering the HLV haft.

Offline UltraViolet9

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Re: SLS: Higher payload without second stage
« Reply #75 on: 06/06/2017 08:15 PM »
As for Falcon Heavy, there is no waiting.  It is not an SLS replacement.  The way SpaceX wants to fly it (recovering boosters and first stage) it will barely boost 5.5 tonnes toward the Moon, compared to SLS Block 1's 24.5 tonnes.  Even if the entire rocket was thrown away it would not match even SLS Block 1, and would only lift a bit more than half as much as Block 1B's 39 tonnes. 

Unfortunately, TLI (or mass to any destination) is not the only, or most important, metric, especially when considering a human space exploration campaign or research base.

Payload mass per launch may be the right metric for packing the most transponders on a GEO comsat or for a one-off mission.  But total payload delivered over time (per year or over years) matters more when establishing a base or supporting a campaign. 

Reliability when launching crew or critical assets is also crucial, as the in-space, EDL, and surface segments will be riskier than the launch.  If just leaving the Earth's atmosphere is too risky, it can drive unacceptable LOM/LOC figures for the entire mission or campaign.

Resiliency of the launch effort can be important -- the ability to recover quickly from a launch failure and/or field an alternate launch when crew or critical assets are waiting in space.

And development cost, development schedule, and operational costs are obviously big.  They have to leave enough in the kitty for developing and operating all the other elements in the mission or campaign on a reasonable timeframe.


Offline TomH

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Re: SLS: Higher payload without second stage
« Reply #76 on: 06/07/2017 01:31 AM »
Propulsion = SSME of which NASA has 15 in hand.

Of course, this is not a significant advantage, since propulsion for at least Falcon Heavy is also in hand. RD-180 and RS-68 are also available, though they and SSME have all outlived their usefulness.
Typo maybe?
16 RS25s are available, 14 with flight experience, and 2 new build green engines that haven't even been fired at all, ME2062(built in 2010) ME2063(built in 2015).  Both engines are EM-1 contingency engines and are scheduled for primary flight usage on EM-2.

I thought it was 15, without going to check. Regardless, NASA has sufficient available, but I disagree with NASA's assessment that they are the most expedient propulsion for a new SHLV.

I thought there were 15 left over from STS , but they had enough spare parts to assemble a 16th. With engines changing from reusable to expendable, it was no longer necessary to keep a collection of spare parts on hand.

Offline AS-503

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Re: SLS: Higher payload without second stage
« Reply #77 on: 06/07/2017 02:02 AM »
So, NASA is supposed to just wait for these proposed launch vehicles to finally appear?  Falcon Heavy was supposed to fly in 2013. [...]   
NASA can't wait for promises when it has the propulsion in hand.

What "propulsion" does NASA have "in hand"? They haven't even figured out how to weld the tanks.

Meanwhile, for FH, the actual flight-hardware is in test-firing before final vehicle assembly. It's likely that they'll have at least three FH flights under their belt before SLS flies. And a dozen FH flights before SLS flies a second time. So in what way would NASA be "waiting" for FH, but have SLS "in hand"?
NASA has RS-25 and five-segment booster and RL10 and, for Orion, AJ-10.  In-hand.

As for Falcon Heavy, there is no waiting.  It is not an SLS replacement.  The way SpaceX wants to fly it (recovering boosters and first stage) it will barely boost 5.5 tonnes toward the Moon, compared to SLS Block 1's 24.5 tonnes.  Even if the entire rocket was thrown away it would not match even SLS Block 1, and would only lift a bit more than half as much as Block 1B's 39 tonnes. 

The engines for rockets that might one day be SLS class are still in development.

 - Ed Kyle

If SLS is ever tasked with boosting mass to the moon it would be a precursor to (or even including) a manned flight, right?
Are there any plans to fly any lunar-centric missions on SLS?
Hasn't it been proven (even on this very forum) that the Orion LAS can not "outrun" a failed SRB on any mission?
ICPS or Block X second stage, or no second stage, how can the tonnage matter when SLS can't fly humans without black zones on ascent with the shuttle derived 150+ foot SRB?

If you recall back to the 2005 ESAS (Remember Mike Griffin's thumb-on-the-scale architecture study), there was an overwhelming emphasis on astronaut safety for next-gen space craft and LV while at the same time a "mandate" that any new system be developed with shuttle derived hardware. While there were/are developmental short term cost savings with shuttle-derived LV, in other ways it was/is the literal definition of insanity in terms of operational cost savings and crew safety.

You're a fan of aerospace history Ed, do you remember Burt Rutan's assessment of ESAS from 2005?
BTW this is not a provoking question, I love your website and most of your observations.

Offline tea monster

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Re: SLS: Higher payload without second stage
« Reply #78 on: 06/07/2017 06:58 AM »
There has been talk of a 'Lunar Gateway' Lagrange station: https://www.nasaspaceflight.com/2016/05/orbital-atk-cislunar-habitat-missions-sls-orion/
Nasa are looking at this, but nothing has been funded or mandated by The Hill yet. http://www.space.com/14518-nasa-moon-deep-space-station-astronauts.html

Debating the pros and cons of the SLS is kind of pointless as it seems that political considerations drove most of the design decisions. If you accept the brief of "Fly something derived from Shuttle components to save time and development cost" then we would have been several years into a Shuttle C flight program by now and probably had enough money left over to develop a Mars transfer vehicle and a lander.

Even I'm getting fed up with bashing the SLS at this point - only because thinking of where we would be if other choices had been made is way too depressing.

Back on topic: With this 'no second stage' SLS, would the first stage then arrive in a stable orbit? If it does, would it be possible to use it in the same fashion as proposed for Shuttle external tanks -collect them up in orbit and use them as building bricks for a large space station?

Taking a huge assumption that the technical problems of cryogenic on-orbit refueling could be conquered, would there be any advantage to using these things to send hefty payloads around the solar system?

Offline Paul451

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Re: SLS: Higher payload without second stage
« Reply #79 on: 06/07/2017 01:21 PM »
Back on topic: With this 'no second stage' SLS, would the first stage then arrive in a stable orbit?

It wouldn't arrive in orbit at all. The RS-25's can't restart, so you can't do a circularisation burn. You'd need to add OMS engines to the core to perform the circularisation.

The OP's question presumes the circularisation is performed by the payload. (So, I guess it would be better to say 70 tonnes to LEI, rather than 70 tonnes to LEO.)

If it does, would it be possible to use it in the same fashion as proposed for Shuttle external tanks -collect them up in orbit and use them as building bricks for a large space station?

If you built a module whose shell mimicked the size (and aerodynamic performance) of the largest possible SLS payload fairing (10x30m?), you'd have a monster space station placed in orbit in a single launch. Skylab II Trump Station Gold.

[However, this suffers from the usual problem with SLS: there's no way to afford SLS development/operations and the development of such a station. Nor is there any real point, except giggles.]

Taking a huge assumption that the technical problems of cryogenic on-orbit refueling could be conquered, would there be any advantage to using these things to send hefty payloads around the solar system?

A) The core will hold over 800 tonnes of propellant. Seemed a bit overkill. What payload could you launch that would require such a transfer stage? You could assemble a giant ship from several launches, but then you could have also assembled a modular propulsion system, making reusing the core redundant.

2) The RS-25's restart problem.

iii) Being LH fuelled, the time it would take to refuel the core (ie, the number of launches required) would make leakage-rate a significant loss. You'd need a major redesign to make the tanks near enough to ZBO to make the idea useful.

Tags: SLS ICPS Orion