Author Topic: SLS: Higher payload without second stage  (Read 14226 times)

Offline redliox

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Re: SLS: Higher payload without second stage
« Reply #20 on: 05/27/2017 04:00 AM »
{snip}
Who cares about LEO for SLS?


Heavy cargo to LEO is probably the SLS's main market.

SLS's payload is too small to send people to Mars on a single launch. A ship yard to build Mars Transfer Vehicles is likely to be in LEO.

There aren't going to be any shipyards ala Star Trek.  The MTV is going to be a single-piece vehicle sent to the Gateway station is the current plan.  It also is going to be solar electric meaning even if the SLS can't deliver it the full distance by itself the MTV is going to spiral itself out.

However heavy cargo is indeed going to be SLS' market.  Missions to Europa or the Ice Giants benefit as do either space telescopes or the Gateway station, perhaps even commercial variants in LEO.  The market for heavy payloads won't have any other launcher for 5-10 years which makes it SLS' golden time regardless of opinion of it.
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Offline Patchouli

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Re: SLS: Higher payload without second stage
« Reply #21 on: 05/27/2017 04:20 AM »
The SLS flight avionics are not designed to send a payload into orbit. It is designed to get the upper stage to an optimum altitude, speed and trajectory to finish the job of orbital insertion. To attempt to use the core stage as a SSTO vehicle would require a complete re-write of the software.

Not that I'm advocating this should be done, but wouldn't re-writing the software just be on the order of $Millions, not $Billions?

And I understand that it's not just one system that would have to be rewritten, but multiple that have to be coordinated. It's just that you'd think the ability to adjust the trajectory would have anticipated the full range of possibilities.

Of course if the top-level design spec never called out for that possibility it makes sense to not build it in. Just one of those things that you'd think would not be hard in our modern age of computers...

Like I said in another post somewhere, it's not the individual software modules that are difficult - it's the system integration that's hard. individual modules may be beautiful and work exceptionally well but put them all together in a sandbox and they may not play well together. The rocket gods have very weird senses of humor. They like things that cause heartburn.

Shouldn't be a show stopper as the Saturn V was altered to fly in two stage configuration to launch Skylab when normally the S-IVB did finial orbital insertion.
In fact making a stage and a half SLS should be a lot easier.
« Last Edit: 05/27/2017 04:24 AM by Patchouli »

Offline TomH

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Re: SLS: Higher payload without second stage
« Reply #22 on: 05/27/2017 05:30 AM »
Shouldn't be a show stopper as the Saturn V was altered to fly in two stage configuration to launch Skylab when normally the S-IVB did finial orbital insertion.In fact making a stage and a half SLS should be a lot easier.

IIRC, the controller stayed in the same location, on top of the S-IVB, which in this case had been converted into the Skylab. In the case of flying SLS with no US, the controller has to be relocated.

Online AncientU

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Re: SLS: Higher payload without second stage
« Reply #23 on: 05/27/2017 06:43 PM »
{snip}
Who cares about LEO for SLS?


Heavy cargo to LEO is probably the SLS's main market.

SLS's payload is too small to send people to Mars on a single launch. A ship yard to build Mars Transfer Vehicles is likely to be in LEO.

There aren't going to be any shipyards ala Star Trek.  The MTV is going to be a single-piece vehicle sent to the Gateway station is the current plan.  It also is going to be solar electric meaning even if the SLS can't deliver it the full distance by itself the MTV is going to spiral itself out.

However heavy cargo is indeed going to be SLS' market.  Missions to Europa or the Ice Giants benefit as do either space telescopes or the Gateway station, perhaps even commercial variants in LEO.  The market for heavy payloads won't have any other launcher for 5-10 years which makes it SLS' golden time regardless of opinion of it.

Not sure that is correct.  By the time SLS Block 1 launches (EM-1, late 2019, or 2020), FH (Block 5+) will probably have more lift capacity and will be cheaper by 5x or so.  By the time Block 1B launches (EM-2, 2023?), there will likely be a reusable launcher with greater capability.  Block 2 is too far into the future (greater than 10 years) to even imagine SLS still being around.

SLS may never be Number One... and at its price point, no one will be able to fly on it except NASA flying US Senate dictated payloads.  There will be no Golden Age of SLS.
« Last Edit: 05/27/2017 06:46 PM by AncientU »
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Offline A_M_Swallow

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Re: SLS: Higher payload without second stage
« Reply #24 on: 05/27/2017 09:07 PM »
{snip}
Who cares about LEO for SLS?


Heavy cargo to LEO is probably the SLS's main market.

SLS's payload is too small to send people to Mars on a single launch. A ship yard to build Mars Transfer Vehicles is likely to be in LEO.

There aren't going to be any shipyards ala Star Trek.  The MTV is going to be a single-piece vehicle sent to the Gateway station is the current plan.  It also is going to be solar electric meaning even if the SLS can't deliver it the full distance by itself the MTV is going to spiral itself out.

However heavy cargo is indeed going to be SLS' market.  Missions to Europa or the Ice Giants benefit as do either space telescopes or the Gateway station, perhaps even commercial variants in LEO.  The market for heavy payloads won't have any other launcher for 5-10 years which makes it SLS' golden time regardless of opinion of it.

As well as the manned MTV there is the lander and surface equipment. Likely to be too heavy for even a SLS Block 2

Offline Lars-J

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Re: SLS: Higher payload without second stage
« Reply #25 on: 05/27/2017 09:27 PM »
As well as the manned MTV there is the lander and surface equipment. Likely to be too heavy for even a SLS Block 2

Right. So for any kind of human exploration architecture, SLS is *incapable* of doing it in one launch. There will always be assembly, either in LEO or in a higher orbit.

So while 'escape payload capability' is cool and all for robotic missions, it matters little in practice.

Offline sevenperforce

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Re: SLS: Higher payload without second stage
« Reply #26 on: 05/27/2017 09:42 PM »
As well as the manned MTV there is the lander and surface equipment. Likely to be too heavy for even a SLS Block 2

Right. So for any kind of human exploration architecture, SLS is *incapable* of doing it in one launch. There will always be assembly, either in LEO or in a higher orbit.

So while 'escape payload capability' is cool and all for robotic missions, it matters little in practice.
Why not just have SLS launch an autonomous, automatically cooled, rendezvous-and-docking capable hydrolox propulsion bus? Then let it rendezvous with whatever actual mission spacecraft is needed, which can be launched commercially.

Online spacenut

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Re: SLS: Higher payload without second stage
« Reply #27 on: 05/27/2017 09:49 PM »
If SLS had gone the route of Direct with plumbing for 5 engines, but use 3 engines on block 1, it would have gotten 70 tons to LEO.  Then add the two other engines, with a single engine J2X and get 130 tons.  Then add the new Black Knight boosters and get maybe 140-145 tons.  I do not understand why they went with 4 engines on the core.  I think it was a permanent compromise not using neither 3 or 5.   Direct with and evolving future upgrades would already be flying. 

Any Martian trip will either involve in space assembly, which could be done with cheaper rockets, or like SpaceX's approach, big ship and in orbit refueling.  Both involve rendeveau and docking.  Cheaper rockets win out. 

Online edkyle99

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Re: SLS: Higher payload without second stage
« Reply #28 on: 05/27/2017 10:12 PM »
Not sure that is correct.  By the time SLS Block 1 launches (EM-1, late 2019, or 2020), FH (Block 5+) will probably have more lift capacity and will be cheaper by 5x or so.  By the time Block 1B launches (EM-2, 2023?), there will likely be a reusable launcher with greater capability.  Block 2 is too far into the future (greater than 10 years) to even imagine SLS still being around.

SLS may never be Number One... and at its price point, no one will be able to fly on it except NASA flying US Senate dictated payloads.  There will be no Golden Age of SLS.
So, NASA is supposed to just wait for these proposed launch vehicles to finally appear?  Falcon Heavy was supposed to fly in 2013.  We still haven't seen this rocket and now it seems we won't see it until next year.   When we finally do see it, it still won't match SLS.  The company developing Falcon Heavy has suffered two big rocket explosions during the past two years.  Is NASA supposed to stop what it is doing and simply trust that SpaceX, Blue Origin (which recently suffered an engine test failure), and the like will actually succeed on their announced schedules, even though they are doing everything for the first time? 

NASA can't wait for promises when it has the propulsion in hand.  The others may eventually catch up - I hope they do - but there is no need to wait for them.

 - Ed Kyle
« Last Edit: 05/27/2017 10:21 PM by edkyle99 »

Online AncientU

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Re: SLS: Higher payload without second stage
« Reply #29 on: 05/27/2017 11:18 PM »
Constellation was supposed to have us on the Moon today, too.
How's that coming?
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Offline A_M_Swallow

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Re: SLS: Higher payload without second stage
« Reply #30 on: 05/28/2017 12:19 AM »
If SLS had gone the route of Direct with plumbing for 5 engines, but use 3 engines on block 1, it would have gotten 70 tons to LEO.  Then add the two other engines, with a single engine J2X and get 130 tons.  Then add the new Black Knight boosters and get maybe 140-145 tons.  I do not understand why they went with 4 engines on the core.  I think it was a permanent compromise not using neither 3 or 5.   Direct with and evolving future upgrades would already be flying. 

Any Martian trip will either involve in space assembly, which could be done with cheaper rockets, or like SpaceX's approach, big ship and in orbit refueling.  Both involve rendeveau and docking.  Cheaper rockets win out. 

As the ISS showed constructing spacecraft using say 10 tonne modules requires space walks to join wires and pipes together. I do not know I EVA still cost $1,000,000 an hour but they quickly get expensive. Showing small rockets actually reduces the total price requires a full cost cost trade.

Online envy887

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Re: SLS: Higher payload without second stage
« Reply #31 on: 05/28/2017 12:33 AM »
If SLS had gone the route of Direct with plumbing for 5 engines, but use 3 engines on block 1, it would have gotten 70 tons to LEO.  Then add the two other engines, with a single engine J2X and get 130 tons.  Then add the new Black Knight boosters and get maybe 140-145 tons.  I do not understand why they went with 4 engines on the core.  I think it was a permanent compromise not using neither 3 or 5.   Direct with and evolving future upgrades would already be flying. 

Any Martian trip will either involve in space assembly, which could be done with cheaper rockets, or like SpaceX's approach, big ship and in orbit refueling.  Both involve rendeveau and docking.  Cheaper rockets win out. 

As the ISS showed constructing spacecraft using say 10 tonne modules requires space walks to join wires and pipes together. I do not know I EVA still cost $1,000,000 an hour but they quickly get expensive. Showing small rockets actually reduces the total price requires a full cost cost trade.

The Russians have been building space stations without EVA for a long time.

ISS was built with EVAs because the Shuttle HAD to have crew and had the capability to support EVA.

It does not follow that using EELV class vehicles with automated assembly would not be cheaper than SLS.
« Last Edit: 05/28/2017 12:34 AM by envy887 »

Offline MATTBLAK

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Re: SLS: Higher payload without second stage
« Reply #32 on: 05/28/2017 12:50 AM »
Constellation was supposed to have us on the Moon today, too.
How's that coming?
No - by 2020 was supposed to be the first landing. But with the low funding it was allocated, it would have been a half-decade or more later than that :(
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Offline llanitedave

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Re: SLS: Higher payload without second stage
« Reply #33 on: 05/28/2017 03:25 AM »
Not sure that is correct.  By the time SLS Block 1 launches (EM-1, late 2019, or 2020), FH (Block 5+) will probably have more lift capacity and will be cheaper by 5x or so.  By the time Block 1B launches (EM-2, 2023?), there will likely be a reusable launcher with greater capability.  Block 2 is too far into the future (greater than 10 years) to even imagine SLS still being around.

SLS may never be Number One... and at its price point, no one will be able to fly on it except NASA flying US Senate dictated payloads.  There will be no Golden Age of SLS.
So, NASA is supposed to just wait for these proposed launch vehicles to finally appear?  Falcon Heavy was supposed to fly in 2013.  We still haven't seen this rocket and now it seems we won't see it until next year.   When we finally do see it, it still won't match SLS.  The company developing Falcon Heavy has suffered two big rocket explosions during the past two years.  Is NASA supposed to stop what it is doing and simply trust that SpaceX, Blue Origin (which recently suffered an engine test failure), and the like will actually succeed on their announced schedules, even though they are doing everything for the first time? 

NASA can't wait for promises when it has the propulsion in hand.  The others may eventually catch up - I hope they do - but there is no need to wait for them.

 - Ed Kyle

Even if it doesn't wait, the commercial launchers will be flying before SLS..  Really, who's the one waiting here?
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Offline TomH

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Re: SLS: Higher payload without second stage
« Reply #34 on: 05/28/2017 04:14 AM »
As well as the manned MTV there is the lander and surface equipment. Likely to be too heavy for even a SLS Block 2

Right. So for any kind of human exploration architecture, SLS is *incapable* of doing it in one launch. There will always be assembly, either in LEO or in a higher orbit.

So while 'escape payload capability' is cool and all for robotic missions, it matters little in practice.

B  I  N  G  O! This is part of what disturbs me when SLS is advertised as the most powerful launch vehicle ever. Sure the raw thrust of the boosters is high, but they are heavy with low initial T/W and higher gravity losses. The KeroLox ISP-Density was superior. Taking those factors into consideration, Saturn V was a more capable launcher than SLS. For those who wanted legacy hardware, there was an older legacy that was superior.
« Last Edit: 05/28/2017 04:19 AM by TomH »

Online hkultala

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Re: SLS: Higher payload without second stage
« Reply #35 on: 05/28/2017 06:43 AM »
{snip}
Who cares about LEO for SLS?


Heavy cargo to LEO is probably the SLS's main market.

SLS's payload is too small to send people to Mars on a single launch. A ship yard to build Mars Transfer Vehicles is likely to be in LEO.

There aren't going to be any shipyards ala Star Trek.  The MTV is going to be a single-piece vehicle sent to the Gateway station is the current plan.  It also is going to be solar electric meaning even if the SLS can't deliver it the full distance by itself the MTV is going to spiral itself out.

However heavy cargo is indeed going to be SLS' market.  Missions to Europa or the Ice Giants benefit as do either space telescopes or the Gateway station, perhaps even commercial variants in LEO.  The market for heavy payloads won't have any other launcher for 5-10 years which makes it SLS' golden time regardless of opinion of it.

Not sure that is correct.  By the time SLS Block 1 launches (EM-1, late 2019, or 2020), FH (Block 5+) will probably have more lift capacity and will be cheaper by 5x or so.


FH(block 5) has capacity of 63.8 tonnes to LEO, and it's quite LEO optimized-launcher.
Even with the very badly underpowered upper stage that makes it very bad for LEO maximum payload, SLS block 1 still has more capacity to LEO, payload to higher orbits where the (lack of) thrust in the US means less is much more than with FH.

FH would need quite a long tank stretch to even reach LEO payload of SLS, and for the interesting higher orbits, no tank stretch on FH is going to get it near SLS.

Quote
  By the time Block 1B launches (EM-2, 2023?), there will likely be a reusable launcher with greater capability.

New Glenn? ITS/BFR? New Armstrong

New Glenn won't outperform SLS (block1) to anything higher than LEO.

ITS/BFR and New Armstrong will have higher payload than SLS but the question is when they are ready.

Offline Lars-J

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Re: SLS: Higher payload without second stage
« Reply #36 on: 05/28/2017 07:38 AM »
FH(block 5) has capacity of 63.8 tonnes to LEO, and it's quite LEO optimized-launcher.
Even with the very badly underpowered upper stage that makes it very bad for LEO maximum payload, SLS block 1 still has more capacity to LEO, payload to higher orbits where the (lack of) thrust in the US means less is much more than with FH.

I get what you mean as far as upper stage efficiency... But very badly underpowered is a very poor choice of words.   ;D

The M1D-Vac (full thrust) is around 8.5 times more powerful than the most powerful RL-10 ever flown. So even with 4 RL-10 on the EUS, the F9 upper stage has more than twice the thrust.  8)

Online envy887

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Re: SLS: Higher payload without second stage
« Reply #37 on: 05/28/2017 01:56 PM »
  By the time Block 1B launches (EM-2, 2023?), there will likely be a reusable launcher with greater capability.

New Glenn? ITS/BFR? New Armstrong

New Glenn won't outperform SLS (block1) to anything higher than LEO.

ITS/BFR and New Armstrong will have higher payload than SLS but the question is when they are ready.
The first heavy lift vehicle with a refuelable upper stage will be able to send more mass to high orbits than SLS.
That could be Vulcan-ACES, or ITS which we know are under development. Or a Raptor upper stage on FH or ITS derived vehicle which could still fly before 2022.
« Last Edit: 05/28/2017 02:29 PM by envy887 »

Offline sevenperforce

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Re: SLS: Higher payload without second stage
« Reply #38 on: 05/28/2017 02:08 PM »
FH(block 5) has capacity of 63.8 tonnes to LEO, and it's quite LEO optimized-launcher.
Even with the very badly underpowered upper stage that makes it very bad for LEO maximum payload, SLS block 1 still has more capacity to LEO, payload to higher orbits where the (lack of) thrust in the US means less is much more than with FH.

I get what you mean as far as upper stage efficiency... But very badly underpowered is a very poor choice of words.   ;D

The M1D-Vac (full thrust) is around 8.5 times more powerful than the most powerful RL-10 ever flown. So even with 4 RL-10 on the EUS, the F9 upper stage has more than twice the thrust.  8)
No, I think that's what he WAS saying. The SLS was the referent of that pronoun. "Even with (the SLS's) very badly underpowered upper stage, SLS block 1 still has more capacity to LEO."

Online hkultala

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Re: SLS: Higher payload without second stage
« Reply #39 on: 05/28/2017 04:05 PM »
FH(block 5) has capacity of 63.8 tonnes to LEO, and it's quite LEO optimized-launcher.
Even with the very badly underpowered upper stage that makes it very bad for LEO maximum payload, SLS block 1 still has more capacity to LEO, payload to higher orbits where the (lack of) thrust in the US means less is much more than with FH.

I get what you mean as far as upper stage efficiency... But very badly underpowered is a very poor choice of words.   ;D

The M1D-Vac (full thrust) is around 8.5 times more powerful than the most powerful RL-10 ever flown. So even with 4 RL-10 on the EUS, the F9 upper stage has more than twice the thrust.  8)



SLS block 1 uses ICPS, not falcon upper stage. ICPS (with that single 110kN RL-10) is the very badly underpowered upper stage I was talking about.





« Last Edit: 05/28/2017 04:07 PM by hkultala »

Tags: SLS ICPS Orion