Author Topic: SLS General Discussion Thread 2  (Read 224341 times)

Online AncientU

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Re: SLS General Discussion Thread 2
« Reply #340 on: 03/15/2016 02:37 PM »
What was so wrong with using the F-1B?

Congress has determined that the AR-1 shall exist, ye, verily.

That's not to rule out a future such decree on behalf of the F-1B, which I think would have given me more joy, as arbitrary declarations go. Perhaps when SpaceX and/or Blue get around to fielding a really great big rocket, Congress will hold hearings on why the USA doesn't have one yet.

USA will have two (or three, if VulcanHeavy is built, too) -- Congress will have to decide whether to follow their own law, or change it to keep their pet project(s) relevant.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0
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« Last Edit: 03/15/2016 04:05 PM by AncientU »
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Online Carl G

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Re: SLS General Discussion Thread 2
« Reply #341 on: 03/15/2016 04:02 PM »
Let's try and keep the politics out of this thread. In fact, let's do more than try, let's not.

Offline daveklingler

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Re: SLS General Discussion Thread 2
« Reply #342 on: 03/15/2016 04:44 PM »
For Block IB, its just under 1g at SRB separation. Actual acceleration is 9.5 m/sē.

Steven, are you set up to easily simulate an AR-1-based SLS?  I'm assuming you've long since set up a spreadsheet, since you've done several simulations at this point.

Offline daveklingler

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Re: SLS General Discussion Thread 2
« Reply #343 on: 03/15/2016 04:46 PM »
What was so wrong with using the F-1B?

Congress has determined that the AR-1 shall exist, ye, verily.

That's not to rule out a future such decree on behalf of the F-1B, which I think would have given me more joy, as arbitrary declarations go. Perhaps when SpaceX and/or Blue get around to fielding a really great big rocket, Congress will hold hearings on why the USA doesn't have one yet.

USA will have two (or three, if VulcanHeavy is built, too) -- Congress will have to decide whether to follow their own law, or change it to keep their pet project(s) relevant.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0
-- Robotbeat's signature line

NOTE: The USG is not the USA.

I was attempting to be sardonic.

Offline The Amazing Catstronaut

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Re: SLS General Discussion Thread 2
« Reply #344 on: 03/15/2016 07:07 PM »
Do not forget SLS is a political beast. Congress can change their minds as to what they want. As in a 200+mt launcher for Mars not just a 100mt maybe a 130mt launcher. Such as liquid boosters, 5 engine RS-68A core, J-2X second stage and a RL-10 EDS. Plus use something else (commercial LV) to get Orion into LEO where it docks with the rest of the Mars stack. Constellation resurrected.

They sure can, but it won't stay that way if it takes forever.  Sending SLS skyward is taking the best side of forever anyway, due to all the little nuances which need to be worked out before the twenty twenties (or 2018 for all of us in ESA funding nations/s). A changed congress may not be sympathetic to SLS either. Sure, they want a jobs program, but they also want to look competent and that they're at least attempting to use government funds efficiently.

Constellation architectures are not a paragon of efficiency, cost saving or even mission capability. There's better alternatives that can be done with either a leaner, skimpier architecture, or by going more massive and less. Either option contains higher prospective dollar value than Constellation.

« Last Edit: 03/15/2016 07:09 PM by The Amazing Catstronaut »
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Offline Steven Pietrobon

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Re: SLS General Discussion Thread 2
« Reply #345 on: 03/16/2016 03:07 AM »
Steven, are you set up to easily simulate an AR-1-based SLS?  I'm assuming you've long since set up a spreadsheet, since you've done several simulations at this point.

Its relatively easy, but each simulation takes me half a day to perform. I use my own custom coded Pascal software. Its not a spreadsheet. I have already simulated liquid boosters with three AJ1E6 dual nozzle engines. I could use that to simulate six AR-1 engines.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline TomH

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Re: SLS General Discussion Thread 2
« Reply #346 on: 03/16/2016 04:03 PM »
Steven, are you set up to easily simulate an AR-1-based SLS?  I'm assuming you've long since set up a spreadsheet, since you've done several simulations at this point.

Its relatively easy, but each simulation takes me half a day to perform. I use my own custom coded Pascal software. Its not a spreadsheet. I have already simulated liquid boosters with three AJ1E6 dual nozzle engines. I could use that to simulate six AR-1 engines.

I could be mistaken, but I think he means AR-1 on the core, not AR-1 boosters.

Offline daveklingler

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Re: SLS General Discussion Thread 2
« Reply #347 on: 03/18/2016 01:22 AM »
Steven, are you set up to easily simulate an AR-1-based SLS?  I'm assuming you've long since set up a spreadsheet, since you've done several simulations at this point.

Its relatively easy, but each simulation takes me half a day to perform. I use my own custom coded Pascal software. Its not a spreadsheet. I have already simulated liquid boosters with three AJ1E6 dual nozzle engines. I could use that to simulate six AR-1 engines.

I could be mistaken, but I think he means AR-1 on the core, not AR-1 boosters.

I did mean the core, but I recognize that the boosters have a slightly better chance of seeing AR-1s than the core does.  It sounds like you're saying that the code you already wrote is applicable to either one?

I just found your 2013 SLS/F1B/AJ1E6 paper and reread it.  It seems like you might be able to take AJR at their word and basically plug in RD-180s, since they have said emphatically that they are doing their best to duplicate the RD-180 in every significant way.  I don't think they can come in much less or much above the RD-180's thrust level, nor can the Isp vary much, which means identical chamber size and pressure, bell dimensions, etc. Somewhere I did see something to the effect that every significant physical aspect of the RD-180 has been copied.

So in other words, you might be able to use an RD-180 in simulations.  Not sure whether that helps.  :)

Offline Steven Pietrobon

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Re: SLS General Discussion Thread 2
« Reply #348 on: 03/18/2016 05:41 AM »
I did mean the core, but I recognize that the boosters have a slightly better chance of seeing AR-1s than the core does.  It sounds like you're saying that the code you already wrote is applicable to either one?

OK, I misunderstood and thought you were thinking of the boosters. I could also use AR-1's on the core, although this might require a bit more changing of the code.

Quote
I just found your 2013 SLS/F1B/AJ1E6 paper and reread it.  It seems like you might be able to take AJR at their word and basically plug in RD-180s, since they have said emphatically that they are doing their best to duplicate the RD-180 in every significant way.  I don't think they can come in much less or much above the RD-180's thrust level, nor can the Isp vary much, which means identical chamber size and pressure, bell dimensions, etc. Somewhere I did see something to the effect that every significant physical aspect of the RD-180 has been copied.

So in other words, you might be able to use an RD-180 in simulations.  Not sure whether that helps.  :)

I already have estimates of the performance of the AJ1E6, which I would use for the AR-1. I think that would be better than using the RD-180 as a reference.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline TomH

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Re: SLS General Discussion Thread 2
« Reply #349 on: 03/18/2016 02:47 PM »
Changing the core to Kerolox would mean it is an entirely new rocket. The tanks have to be resized for the vastly different fuel/oxidizer volumetric ratio.

Though I first suggested it as fantasy, I think something much easier than this would be to replace RS-25 with J-2X, strengthen the core with strong-backs, and place it on top of BFR (S1 of MCT). What was the SLS core becomes the most powerful ever US atop the most powerful ever S1.

You get a stupendous initial boost from a reusable S1. Your SLS based US is air startable with an engine that has been fully developed and paid for. No longer needed are RS-25E, advanced boosters, or EUS. The SLS core could likely handle the remainder of ΔV to Earth orbit, TLI, LOI, and finish as a crasher stage for a robust Lunar lander.

I know it won't fit in the VAB, but it would mean NASA could simply lease S1 service from SpaceX, eliminate development of the three components listed above, begin developing other needed systems, and perhaps focus primarily on Luna while SpaceX focuses primarily on Mars.

Some have stated it would be better to build a Metholox US whose diameter matches the S1. The thing is, SpaceX is not planning that, but the BFS instead. This would be a way to leverage what is already in design by both entities. NASA is building the SLS core, but can't afford to do much else at the present time. SpaceX is in the middle of designing Raptor and MCT. Under this scheme, NASA would simple lease S1 launch service on BFR that is headed toward development. NASA could do relatively modest changes to SLS, forget advanced boosters, RS-25E, and EUS, and turn its attention to a lander. Mars is explored by SpaceX with some help from NASA and Luna is explored by NASA with some help from SpaceX.

Steven, if you have any interest in running calculations on this monster, I would be greatly interested in the results.

« Last Edit: 03/18/2016 02:59 PM by TomH »

Offline Zed_Noir

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Re: SLS General Discussion Thread 2
« Reply #350 on: 03/18/2016 03:29 PM »
...
Though I first suggested it as fantasy, I think something much easier than this would be to replace RS-25 with J-2X, strengthen the core with strong-backs, and place it on top of BFR (S1 of MCT). What was the SLS core becomes the most powerful ever US atop the most powerful ever S1.

You get a stupendous initial boost from a reusable S1. Your SLS based US is air startable with an engine that has been fully developed and paid for. No longer needed are RS-25E, advanced boosters, or EUS. The SLS core could likely handle the remainder of ΔV to Earth orbit, TLI, LOI, and finish as a crasher stage for a robust Lunar lander.

I know it won't fit in the VAB, but it would mean NASA could simply lease S1 service from SpaceX, eliminate development of the three components listed above, begin developing other needed systems, and perhaps focus primarily on Luna while SpaceX focuses primarily on Mars.

Some have stated it would be better to build a Metholox US whose diameter matches the S1. The thing is, SpaceX is not planning that, but the BFS instead. This would be a way to leverage what is already in design by both entities. NASA is building the SLS core, but can't afford to do much else at the present time. SpaceX is in the middle of designing Raptor and MCT. Under this scheme, NASA would simple lease S1 launch service on BFR that is headed toward development. NASA could do relatively modest changes to SLS, forget advanced boosters, RS-25E, and EUS, and turn its attention to a lander. Mars is explored by SpaceX with some help from NASA and Luna is explored by NASA with some help from SpaceX.
....

No need. Adopt the the rumored SX Raptor powered reusable upper stage as a lander. Just stick a HAB or cargo module on top of the upper stage.

Offline TomH

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Re: SLS General Discussion Thread 2
« Reply #351 on: 03/18/2016 03:35 PM »
No need. Adopt the the rumored SX Raptor powered reusable upper stage as a lander. Just stick a HAB or cargo module on top of the upper stage.

That would require extra refueling launches. This approach also acknowledges the realpolitik of keeping pork flowing to particular states/districts and satisfying high ranking congresspersons.

Offline Zed_Noir

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Re: SLS General Discussion Thread 2
« Reply #352 on: 03/18/2016 03:50 PM »
No need. Adopt the the rumored SX Raptor powered reusable upper stage as a lander. Just stick a HAB or cargo module on top of the upper stage.

That would require extra refueling launches. This approach also acknowledges the realpolitik of keeping pork flowing to particular states/districts and satisfying high ranking congresspersons.

Might be a bit of misunderstanding. The SX upper stage devised lander will go on top of your fantasy stack. So the lander's prop tanks should be fully filled for Lunar descend from LLO.

Offline Lobo

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Re: SLS General Discussion Thread 2
« Reply #353 on: 03/18/2016 04:46 PM »
No need. Adopt the the rumored SX Raptor powered reusable upper stage as a lander. Just stick a HAB or cargo module on top of the upper stage.

That would require extra refueling launches. This approach also acknowledges the realpolitik of keeping pork flowing to particular states/districts and satisfying high ranking congresspersons.

Might be a bit of misunderstanding. The SX upper stage devised lander will go on top of your fantasy stack. So the lander's prop tanks should be fully filled for Lunar descend from LLO.

Tom,
I know this configuration has piqued your interest.  But I think cross pollinating these two would be much more difficult and expensive than either just sticking with SLS as is, or just switching to use MCT outright and buying launch services from SpaceX and cancelling SLS and Orion. 

(I think the latter will likely be what happens eventually anyway, but if it happened sooner, it could mean MCT is ready to fly sooner too.)

I just think that modifying the core to accommodate having a booster under pushing rather than above it pulling probably would be about as extensive as switching it to kerolox or whatever, by the time it's all said and done.  Especially with government and government contractors.


Offline TomH

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Re: SLS General Discussion Thread 2
« Reply #354 on: 03/18/2016 06:04 PM »
I just think that modifying the core to accommodate having a booster under pushing rather than above it pulling probably would be about as extensive as switching it to kerolox or whatever, by the time it's all said and done.

My friend Lobo!

I remember the time when you proposed ganging three F9s with strongbacks and sticking a cluster on each side of SLS to act as the boosters. That's actually where I got the idea that I stated above of just strengthening the sides of the core with strongbacks only, no actual modifications of the walls. If clustering a trio of F9s on each side with strongbacks is possible, then it seems a strongback alone for structural reinforcement should also be possible.

I'm trying to think of the cheapest way to preserve certain congressmen's pork interests and yet still make it possible for NASA to do something with what otherwise is a boondoggle.

...just switching to use MCT outright and buying launch services from SpaceX and cancelling SLS and Orion....will likely be what happens eventually anyway, but if it happened sooner, it could mean MCT is ready to fly sooner too.)

This is what I expect will indeed happen. OTOH, those particular congresspersons have proven remarkably able to keep this pork line flowing. Though far from ideal, this preserves the pork currently in place, but perhaps could allow NASA to actually cook that pig and serve some food.
« Last Edit: 03/18/2016 06:15 PM by TomH »

Offline TomH

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Re: SLS General Discussion Thread 2
« Reply #355 on: 03/18/2016 06:04 PM »
Might be a bit of misunderstanding. The SX upper stage devised lander will go on top of your fantasy stack. So the lander's prop tanks should be fully filled for Lunar descend from LLO.


Ahhh, thanks!

Offline Lobo

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Re: SLS General Discussion Thread 2
« Reply #356 on: 03/18/2016 06:57 PM »
I just think that modifying the core to accommodate having a booster under pushing rather than above it pulling probably would be about as extensive as switching it to kerolox or whatever, by the time it's all said and done.

My friend Lobo!

I remember the time when you proposed ganging three F9s with strongbacks and sticking a cluster on each side of SLS to act as the boosters. That's actually where I got the idea that I stated above of just strengthening the sides of the core with strongbacks only, no actual modifications of the walls. If clustering a trio of F9s on each side with strongbacks is possible, then it seems a strongback alone for structural reinforcement should also be possible.

I'm trying to think of the cheapest way to preserve certain congressmen's pork interests and yet still make it possible for NASA to do something with what otherwise is a boondoggle.

Ahhh...my youthful idealism back then.  ;-)

I probably could work to design strongbacks that way.  I guess when I proposed it for three F9 cores, it was before there really was much known about MCT, that that could be a rival HLV alternative.  And it was a reach for way to try to make an off the shelf liquid booster work with the type of SLS core they were developing.

Adapting it to fit on top a serial booster just seems like it's another reach beyond my reach.  :-)
But I am certainly flattered my reach could be inspiration.  Heh.

In addition to the load carrying strongbacks themselves...which probably wouldn't be too hard, there'd be adapting different air-lit engines to the MPS instead of RS-25's, then all the interfaces to stack the two.  (We've seen the issues with adapting the ICPS to SLS and then moving to the EUS.  So I think we'd see something like that play out getting an SLS core on there, but then later getting the PoR upper stage on there in the BFS.)

And then there's the height of this monster, and that LH2 will need to be brought to wherever it launches from (not to mention getting the SLS cores itself to wherever that is, if someplace other than LC-39.)

Not that it's not an interesting idea.  I just think by the time you are done you could be into it for more money than just sticking with SLS as is (to satisfy the pork considerations).
Like choosing to remodel a house.  If you aren't careful, you can be into it for most...or all...of the price of just going and buying a different house with the layout you preferred.
It could be easier to cancel SLS and have NASA pay SpaceX for an expendable Raptor powered upper stage first, while they are developing the actual BFS.  That upper stage can have all the same interfaces and sizes and such that BFS will, so that nothing new is needed for when BFS will sit on the booster.  It probably wouldn't have great BLEO capability for it's size, but since the stage would be expendable, it'd be a lot lighter than the BFS, so it might be adequate for NASA's purposes?  And more "conservative" than SpaceX's fully reusable plans with LEO refueling.  It becomes a really big F9R then.

It wouldn't be as politically popular as stocking with SLS because the contracts would run out with Boeing and ATK, but I think it may be more feasible than trying to put SLS on BFR. 

...just switching to use MCT outright and buying launch services from SpaceX and cancelling SLS and Orion....will likely be what happens eventually anyway, but if it happened sooner, it could mean MCT is ready to fly sooner too.)

This is what I expect will indeed happen. OTOH, those particular congresspersons have proven remarkably able to keep this pork line flowing. Though far from ideal, this preserves the pork currently in place, but perhaps could allow NASA to actually cook that pig and serve some food.

Yup....we never know...I think once a rival is flying, and with Elon promoting the heck out of it and offering attractive pricing...I think it'll be hard to deny any more like it is when it's just a paper rocket.
« Last Edit: 03/21/2016 06:01 PM by Lobo »

Offline Steven Pietrobon

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Re: SLS General Discussion Thread 2
« Reply #357 on: 03/19/2016 04:29 AM »
Steven, if you have any interest in running calculations on this monster, I would be greatly interested in the results.

No interest at the moment. If it ever gets near to happening, I would do a simulation.
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Offline turbopumpfeedback2

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Re: SLS General Discussion Thread 2
« Reply #358 on: 03/28/2016 01:56 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?

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



« Last Edit: 03/28/2016 02:00 PM by turbopumpfeedback2 »

Offline Jim

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Re: SLS General Discussion Thread 2
« Reply #359 on: 03/28/2016 02:25 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.

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