Author Topic: SLS: Higher payload without second stage  (Read 12837 times)

Offline Lars-J

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Re: SLS: Higher payload without second stage
« Reply #40 on: 05/28/2017 06:28 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."

Yes, you are right, so much for my reading ability. :)

Offline sevenperforce

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Re: SLS: Higher payload without second stage
« Reply #41 on: 05/28/2017 06:34 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.
Being a big fan of parallel staging, I'd be interested to see the ICPS given an optional 2-engine (or even 4-engine) drop skirt a la Saturn S-1D to increase its payload to LEO. Fixes the underpower problem without increasing dry mass in the BLEO stage.

That's if it actually was ever going to be used for LEO. But of course it isn't.

Offline dror

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Re: SLS: Higher payload without second stage
« Reply #42 on: 05/28/2017 06:52 PM »

If I had the SLS budget to play with,

I have once suggested using SLS cores as space station habitats.
Much like the old Space Ilands group.

I was told that it won't work for several reasons such as heat management, wet launch complications and performance.

But now theres a group that seriously suggests doing that with centaur and got NASA funding to research into that as a possible gateway technology.
so maybe it is actually possible with SLS cores?!?

Also, there are those who suggest that it is smart to reuse the booster's engine compartment and have suggested applying HIAD and parachute combo to do that.there are those who plan to recover side boosters too (no link needed here)

I suggest that there could be a way in which SLS makes sense - that is if it was designed as follows-
Two RTLS advanced boosters
SMART style reuse for the core's engine compartment
On orbit recycle of modified O2 and H2 tanks as habitats for a space station.
Space station support systems and modules are launched as cargo

I don't know if that can eventually become cheaper than full reuse architecture like ITS, but it has a fair chance, if a big space station is one of the goals. That is because a bigger fraction of what is launched to orbit, stays on orbit.

"If we crave some cosmic purpose, then let us find ourselves a worthy goal. "
Carl Sagan, Pale Blue Dot

Offline Ictogan

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Re: SLS: Higher payload without second stage
« Reply #43 on: 05/28/2017 09:04 PM »

If I had the SLS budget to play with,

I have once suggested using SLS cores as space station habitats.
Much like the old Space Ilands group.

I was told that it won't work for several reasons such as heat management, wet launch complications and performance.

But now theres a group that seriously suggests doing that with centaur and got NASA funding to research into that as a possible gateway technology.
so maybe it is actually possible with SLS cores?!?

Also, there are those who suggest that it is smart to reuse the booster's engine compartment and have suggested applying HIAD and parachute combo to do that.there are those who plan to recover side boosters too (no link needed here)

I suggest that there could be a way in which SLS makes sense - that is if it was designed as follows-
Two RTLS advanced boosters
SMART style reuse for the core's engine compartment
On orbit recycle of modified O2 and H2 tanks as habitats for a space station.
Space station support systems and modules are launched as cargo

I don't know if that can eventually become cheaper than full reuse architecture like ITS, but it has a fair chance, if a big space station is one of the goals. That is because a bigger fraction of what is launched to orbit, stays on orbit.
Reuse only ever makes sense if high flight rates can be anticipated, which simply isn't the case for SLS. Reusing SLS would probably end up as cost effective as reusing the shuttle was.

Offline edkyle99

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Re: SLS: Higher payload without second stage
« Reply #44 on: 05/30/2017 12:20 AM »
Constellation was supposed to have us on the Moon today, too.
How's that coming?
It was canceled by President Obama.

 - Ed Kyle

Offline edkyle99

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Re: SLS: Higher payload without second stage
« Reply #45 on: 05/30/2017 12:23 AM »
Even if it doesn't wait, the commercial launchers will be flying before SLS..  Really, who's the one waiting here?
Which commercial launchers are you describing?  I can't think of any that will out-lift SLS that will be ready before SLS flies.

 - Ed Kyle

Offline Lars-J

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Re: SLS: Higher payload without second stage
« Reply #46 on: 05/30/2017 01:06 AM »
Constellation was supposed to have us on the Moon today, too.
How's that coming?
It was canceled by President Obama.

 - Ed Kyle

I think you missed his point. You write that we cannot rely on SpaceX, because of possible schedule and technical issues. But the same is valid for SLS. We are seeing schedule issues. And technical issues. AND... As you point out, also *political* issues. Trump could easily kill SLS if he point his mind to it. Any future president could so the same.

So we can count on neither. So planning any future human space exploration is fraught with these issues. But they are a fact of life, and are not a reason to dismiss SpaceX (or NASA) in an conversation.
« Last Edit: 05/30/2017 01:07 AM by Lars-J »

Online hkultala

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Re: SLS: Higher payload without second stage
« Reply #47 on: 05/30/2017 01:44 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)



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.
Being a big fan of parallel staging, I'd be interested to see the ICPS given an optional 2-engine (or even 4-engine) drop skirt a la Saturn S-1D to increase its payload to LEO. Fixes the underpower problem without increasing dry mass in the BLEO stage.

That's if it actually was ever going to be used for LEO. But of course it isn't.

2 RL-10' weight about 550 kg's together.

Absolutely no sense at all to add all that complexity and risks of the separation mechanism etc to save this, and have  the extra weigth of the separation mechanism for the first part of the flight.

Instead of adding that drop skirt, just add those two extra engines in fixed installation. But then it also makes sense to have bigger tanks etc.

So, absolutely no point of "trying to improve ICPS", instead switch to much better US totally. Like EUS
« Last Edit: 05/30/2017 01:45 AM by hkultala »

Online spacenut

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Re: SLS: Higher payload without second stage
« Reply #48 on: 05/30/2017 03:02 AM »
If ULA developed ACES, could this 5.5m upper stage be used on SLS to improve payloads?  If so, by how much?

Online hkultala

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Re: SLS: Higher payload without second stage
« Reply #49 on: 05/30/2017 03:23 AM »
If ULA developed ACES, could this 5.5m upper stage be used on SLS to improve payloads?  If so, by how much?

LEO capacity would increase considerably, and might be almost equals to SLS with EUS, as ACES has less fuel but it's lighter.

For BLEO, still considerable increase, but would leave more behind EUS as the amount of propellant would start to matter more.

Offline IRobot

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Re: SLS: Higher payload without second stage
« Reply #50 on: 05/30/2017 09:59 AM »
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
No, NASA should not wait, it should have done the same as with CRS.

Offline woods170

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Re: SLS: Higher payload without second stage
« Reply #51 on: 05/30/2017 11:31 AM »
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
No, NASA should not wait, it should have done the same as with CRS.
More specifically: COTS.
Issue the requirements for the required transportation services thru RPF's and let industry come up with solution-proposals.
As it was however, NASA was not allowed to do so by US Congress. NASA was ordered into using SSME's and SRB's by the folks from the Hill. SLS is not nick-named "Senate Launch System" for nothing.

Offline UltraViolet9

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Re: SLS: Higher payload without second stage
« Reply #52 on: 05/30/2017 08:50 PM »
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.

If SLS was driven by the Cold War or other national imperative, if SLS had a clear exploration goal, deadline, and funding, and if there were not multiple, proven vendors with HLVs coming online in the next half-decade, then yes, NASA should not wait to pursue SLS.

But that's not the case.  There is no strong exogenous driver for SLS.  There is no clear, agreed-to, funded exploration plan.  And there are three domestic HLVs from three different vendors close to first flight or under development today (and a fourth ginormous HLV in early design and technology testing).  It does not appear that SLS will be operational before or deliver more total tonnage to space over time than these domestic HLVs.  But even if that was not the case, the environment is such that a few years of delay or the large opportunity costs imposed by SLS are worth the difference.

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.


Online envy887

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Re: SLS: Higher payload without second stage
« Reply #53 on: 05/30/2017 09:23 PM »
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.

If SLS was driven by the Cold War or other national imperative, if SLS had a clear exploration goal, deadline, and funding, and if there were not multiple, proven vendors with HLVs coming online in the next half-decade, then yes, NASA should not wait to pursue SLS.

But that's not the case.  There is no strong exogenous driver for SLS.  There is no clear, agreed-to, funded exploration plan.  And there are three domestic HLVs from three different vendors close to first flight or under development today (and a fourth ginormous HLV in early design and technology testing).  It does not appear that SLS will be operational before or deliver more total tonnage to space over time than these domestic HLVs.  But even if that was not the case, the environment is such that a few years of delay or the large opportunity costs imposed by SLS are worth the difference.

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.

These are all good points. However, NASA is required by law to build SLS. They are required by law to NOT wait to pursue SLS - it has a specific deadline, which has already passed. And national policy is directed by the President and affirmed and funded by Congress - NASA can only advise both and cannot chose their own way.

Offline UltraViolet9

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Re: SLS: Higher payload without second stage
« Reply #54 on: 05/30/2017 10:31 PM »
These are all good points. However, NASA is required by law to build SLS. They are required by law to NOT wait to pursue SLS - it has a specific deadline, which has already passed. And national policy is directed by the President and affirmed and funded by Congress - NASA can only advise both and cannot chose their own way.

Agreed for the most part.  That's why I wrote:

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.

That said, the NASA Administrator has an important role to play in setting Administration policy and informing Congressional law.  At the end of the day, the NASA Administrator works for the White House within the limits set by the Congress.  But with the right leadership, NASA could begin moving the nation in this direction.


Offline okan170

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Re: SLS: Higher payload without second stage
« Reply #55 on: 06/03/2017 03:32 AM »
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...
« Last Edit: 06/03/2017 07:08 AM by okan170 »

Online envy887

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Re: SLS: Higher payload without second stage
« Reply #56 on: 06/03/2017 12:39 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...

I would already argue NASA should support a commercial vehicle to replace Orion.

Online spacenut

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Re: SLS: Higher payload without second stage
« Reply #57 on: 06/03/2017 02:00 PM »
Government helped build the railroads out west by giving land to the railroad companies along the routes.  Then the government backed off.  Same with space.  Government once built and developed every rocket (1950's 1960's).  Today building rockets is mostly in private hands.  Now they should develop deep space probes and habitats, fuel depots, etc, and bid the launches of the equipment.  Once an in space commerce has begun, then they can back off that. 

I think they should look at the assets they have, and form a committee of the various space vendors.  This committee should as a group design a Mars colony system, or even a moon colony system that can involve the most vendors, and then let NASA direct it, and begin building it.  If it uses SLS, good, if not, other launchers can participate. 

Offline TomH

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Re: SLS: Higher payload without second stage
« Reply #58 on: 06/03/2017 08:35 PM »
Government helped build the railroads out west by giving land to the railroad companies along the routes.

True, but they also gave cash subsidies.

Offline Lars-J

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Re: SLS: Higher payload without second stage
« Reply #59 on: 06/04/2017 06:24 AM »
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")

Tags: SLS ICPS Orion