Author Topic: NASA is trying to make the Space Launch System rocket more affordable (Ars)  (Read 6302 times)

Offline MATTBLAK

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...Or task SpaceX with making a wide LOX/CH4 fueled stage, powered by a pair of (subscale) Raptor engines... ;)
« Last Edit: 12/17/2017 09:47 PM by MATTBLAK »
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Offline A_M_Swallow

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...Or task SpaceX with making a wide LOX/CH4 fueled stage, powered by a pair of (subscale) Raptor engines... ;)

The Masten Broadsword engine has about the right amount of thrust.

Offline oldAtlas_Eguy

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Really?

Quote
According to information the redesign reduced the number of parts needed to assemble the accumulator from twenty-eight to six, eliminated 123 welds and one bolted joint.  The extensive changes would have been impractical or impossible using conventional manufacturing means, and have also reduced the unit cost by a third.
https://www.nasaspaceflight.com/2017/12/rs-25-next-phase-testing-stennis-hot-fire/

Not good enough. The price target is to eventually reach 50 or 60 million dollars per engine https://spaceflightnow.com/2015/11/27/aerojet-rocketdyne-wins-propulsion-contracts-worth-nearly-1-4-billion/ . Not on the initial production run either, but eventually. 200-240 million dollars per flight is still a lot of money. These upgrades can probably get them to that ballpark, but they still need another factor of 5 or so cost reduction on top of that to make SLS sorta competitive (or, at least, not have its engines for a single stage cost more than most entire launch systems). Probably the only fix viable at this point would be to implement a scaled up version of SMART engine recovery (which most Shuttle derived superheavy launchers before SLS assumed anyway, for exactly this reason)

If a RFI about engines to use on EUS just came out then the pick for which engine would no t occur until contract  award sometime after about 9 months from now. Putting the CDR for EUS at about 6 months later or around Apr 2019. Then 3-4 years to build/qualify and that is NET Apr 2022 to as late as Apr 2023 for delivery of first EUS flight hardware. EUS could become the critical path for SLS 1B flights.

I thought they had decided on engines for EUS. This RFI says that the design work on EUS is still very preliminary and the detailed design is on hold until a decision on engines.

The RFI specifies that the first 2 missions will use RL10C as previously planned, and they don't need it ready until mid-2023. So that gives some scheduling margin for the change
Huh?

So over the first 4 flights 3 US developments. Where are they getting all this money to throw away. Oh right taxpayers.

Online brickmack

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I'm thinking SLS may *never* have a stable configuration at this rate. Especially if you count Orion:

EM-1: totally new obviously

Europa Clipper: first SLS 1B

EM-2: first fully integrated SLS 1B/Orion

EM-3: Orion gets a new main engine, new EUS engine

Flight 5: RS-25E

Flight 10 (maybe sooner): Castor 1200

Thats 6 major redesigns/unique configurations in the first 10 flights. Not counting the minor component level upgrades needed early on by every launcher. And that still doesn't get SLS to its performance targets, so there may be even more upgrades in between/after those that NASA hasn't decided on yet!

Offline corneliussulla

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I am sure it would be much cheaper to ask SX to quote them on 2x falcon heavy to get exploration mission components into LEO and doc them. Maybe one falcon heavy and a falcon 9 would do the job. That's about $200 mill. You could do that close to 10 times for the price of SLS. Might require a bit of rengineering on the exploration craft but got to be worth it. SLS is a bad joke from budget point of view.

Offline Rocket Science

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Leaving the core stage as is for the most part as is, the other possible change could be to make the side boosters either flyback or boost back. It has been demonstrated in "serial staging" by SpaceX's Falcon 9 and soon to be demonstrated by Falcon Heavy's "parallel staging". Technically feasibility is not the issue; but politically feasibility is the main question. The issue of the low flight rate may also begs the question why bother at this point?
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Online envy887

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Leaving the core stage as is for the most part as is, the other possible change could be to make the side boosters either flyback or boost back. It has been demonstrated in "serial staging" by SpaceX's Falcon 9 and soon to be demonstrated by Falcon Heavy's "parallel staging". Technically feasibility is not the issue; but politically feasibility is the main question. The issue of the low flight rate may also begs the question why bother at this point?

The technical feasibility is certainly an issue (for launch, not landing), but the main problem is that the Congress contingent from Utah would have a fit over ditching the solids.

Offline Rocket Science

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Leaving the core stage as is for the most part as is, the other possible change could be to make the side boosters either flyback or boost back. It has been demonstrated in "serial staging" by SpaceX's Falcon 9 and soon to be demonstrated by Falcon Heavy's "parallel staging". Technically feasibility is not the issue; but politically feasibility is the main question. The issue of the low flight rate may also begs the question why bother at this point?

The technical feasibility is certainly an issue (for launch, not landing), but the main problem is that the Congress contingent from Utah would have a fit over ditching the solids.
Hence my phrase "political feasibility"... ;)
"ditching the solids"; they are planning to do that with every flight into the Atlantic... You made a funny! ;D

Edit to add:
« Last Edit: 12/19/2017 01:58 PM by Rocket Science »
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Offline oldAtlas_Eguy

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I'm thinking SLS may *never* have a stable configuration at this rate. Especially if you count Orion:

EM-1: totally new obviously

Europa Clipper: first SLS 1B

EM-2: first fully integrated SLS 1B/Orion

EM-3: Orion gets a new main engine, new EUS engine

Flight 5: RS-25E

Flight 10 (maybe sooner): Castor 1200

Thats 6 major redesigns/unique configurations in the first 10 flights. Not counting the minor component level upgrades needed early on by every launcher. And that still doesn't get SLS to its performance targets, so there may be even more upgrades in between/after those that NASA hasn't decided on yet!
But those major changes are not happening fast. That is because there is 1 to 3 years between flights.
EM-1 to EC -> 3 years (2023)
EC to EM-3 -> 2 years (2025)
EM-3 to Flight 5 -> 2 years (2027)
Flight 5 to Flight 10 -> 5 years (2032)

Upgrades every couple of years is not uncommon. It is just that flights occur also only every couple of years.
« Last Edit: 12/19/2017 02:32 PM by oldAtlas_Eguy »

Offline Khadgars

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I am sure it would be much cheaper to ask SX to quote them on 2x falcon heavy to get exploration mission components into LEO and doc them. Maybe one falcon heavy and a falcon 9 would do the job. That's about $200 mill. You could do that close to 10 times for the price of SLS. Might require a bit of rengineering on the exploration craft but got to be worth it. SLS is a bad joke from budget point of view.

This thread is not about SpaceX nor its ability to replace SLS.  You can discuss that on 10,000 other threads.

Offline Lar

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I am sure it would be much cheaper to ask SX to quote them on 2x falcon heavy to get exploration mission components into LEO and doc them. Maybe one falcon heavy and a falcon 9 would do the job. That's about $200 mill. You could do that close to 10 times for the price of SLS. Might require a bit of rengineering on the exploration craft but got to be worth it. SLS is a bad joke from budget point of view.

This thread is not about SpaceX nor its ability to replace SLS.  You can discuss that on 10,000 other threads.

He's exaggerating. But it (probably) is over 9000.

So yeah, let's stay focused on SLS.
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Offline Patchouli

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Leaving the core stage as is for the most part as is, the other possible change could be to make the side boosters either flyback or boost back. It has been demonstrated in "serial staging" by SpaceX's Falcon 9 and soon to be demonstrated by Falcon Heavy's "parallel staging". Technically feasibility is not the issue; but politically feasibility is the main question. The issue of the low flight rate may also begs the question why bother at this point?

A flyback stage with seven BE-4s or AR-1s or nine Raptors would allow SLS to meet it performance targets.
I wonder could a modified New Glenn core be used as a booster?
« Last Edit: 12/19/2017 09:28 PM by Patchouli »

Online envy887

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Leaving the core stage as is for the most part as is, the other possible change could be to make the side boosters either flyback or boost back. It has been demonstrated in "serial staging" by SpaceX's Falcon 9 and soon to be demonstrated by Falcon Heavy's "parallel staging". Technically feasibility is not the issue; but politically feasibility is the main question. The issue of the low flight rate may also begs the question why bother at this point?

A flyback stage with seven BE-4s or AR-1s or nine Raptors would allow SLS to meet it performance targets.
I wonder could a modified New Glenn core be used as a booster?

I always thought that 5.5 meter diameter boosters were the largest that NASA seriously considered due to VAB or MLP constraints. But SpaceGhost1962 mentioned studying triple core 8.4 meter vehicles in the VAB, though I'm not sure how many changes that would entail.

New Glenn boosters would have considerably higher thrust and ISP than the current solids. How high and fast would they stage? Does downrange landing the boosters help payload (Blue isn't planning on RTLS as far as I can tell)?

Offline Patchouli

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I always thought that 5.5 meter diameter boosters were the largest that NASA seriously considered due to VAB or MLP constraints. But SpaceGhost1962 mentioned studying triple core 8.4 meter vehicles in the VAB, though I'm not sure how many changes that would entail.

New Glenn boosters would have considerably higher thrust and ISP than the current solids. How high and fast would they stage? Does downrange landing the boosters help payload (Blue isn't planning on RTLS as far as I can tell)?

New Glenn has a max thrust  3,850,000lbs  which is very close to that of the five segment RSRM which is around 3,600,000lbs.
They would stage higher and faster but probably not as much as the Dynetics Pyrios booster would have since they would normally be saving some of the propellant for landing.

You probably could deal with it by just throttling back the RS-25s for part of the flight .
« Last Edit: 12/20/2017 02:01 AM by Patchouli »

Online envy887

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I always thought that 5.5 meter diameter boosters were the largest that NASA seriously considered due to VAB or MLP constraints. But SpaceGhost1962 mentioned studying triple core 8.4 meter vehicles in the VAB, though I'm not sure how many changes that would entail.

New Glenn boosters would have considerably higher thrust and ISP than the current solids. How high and fast would they stage? Does downrange landing the boosters help payload (Blue isn't planning on RTLS as far as I can tell)?

New Glenn has a max thrust  3,850,000lbs  which is very close to that of the five segment RSRM which is around 3,600,000lbs.
They would stage higher and faster but probably not as much as the Dynetics Pyrios booster would have since they would normally be saving some of the propellant for landing.

You probably could deal with it by just throttling back the RS-25s for part of the flight .

The 5 seg RSRM thrust averages about 2.9 mlbf, per this profile from Ares 1, and it burns for 130 seconds. The thrust profile for SLS might be different, but total impulse will be the same.

New Glenn will carry a lot more fuel (~1000 tonnes), and burn it for a longer time (~200 sec) at continuous max thrust profile for much higher total impulse. I'll take a look at what the performance should be on SLS with 2 of those boosters, but it should be good with downrange recovery.

Edit: plugging some numbers into the Silverbird calculator, it looks like this would be an absolute beast. With EUS it would put 146 tonnes to LEO and 58 tonnes to TLI even with downrange booster recovery. Makes sense since the GTOW would be nearly 3500 tonnes, 1000 tonnes more than RSRM-boosted SLS. Plus it has much more powerful and efficient boosters.
« Last Edit: 12/20/2017 02:52 AM by envy887 »

Online brickmack

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New Glenn has a max thrust  3,850,000lbs  which is very close to that of the five segment RSRM which is around 3,600,000lbs.
They would stage higher and faster but probably not as much as the Dynetics Pyrios booster would have since they would normally be saving some of the propellant for landing.

You probably could deal with it by just throttling back the RS-25s for part of the flight .

At shutdown it'll be producing a lot of thrust still (while solids "throttle" almost to zero), unless they shut down all but the center engine or something. This was a problem for all previously-studied liquid boosters, the loads from the boosters pushing on the core stage just before BECO are too high. Even with RSRMV they've already had to alter the core stage throttle profile to mitigate this, but with any liquid option they'll probably have to add a 5th RS-25 to minimize the relative acceleration (and, unless thats coupled with some sort of engine reuse, this only exacerbates the most critical cost and schedule problem of the program)
« Last Edit: 12/20/2017 04:02 AM by brickmack »

Online envy887

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New Glenn has a max thrust  3,850,000lbs  which is very close to that of the five segment RSRM which is around 3,600,000lbs.
They would stage higher and faster but probably not as much as the Dynetics Pyrios booster would have since they would normally be saving some of the propellant for landing.

You probably could deal with it by just throttling back the RS-25s for part of the flight .

At shutdown it'll be producing a lot of thrust still (while solids "throttle" almost to zero), unless they shut down all but the center engine or something. This was a problem for all previously-studied liquid boosters, the loads from the boosters pushing on the core stage just before BECO are too high. Even with RSRMV they've already had to alter the core stage throttle profile to mitigate this, but with any liquid option they'll probably have to add a 5th RS-25 to minimize the relative acceleration (and, unless thats coupled with some sort of engine reuse, this only exacerbates the most critical cost and schedule problem of the program)

The F-1B only had two throttle settings, and the lowest was 72% of max. And with two off-center engines on Pyrios they could not shut some of them down to "throttle".

BE-4 will throttle much lower, somewhere around 30%, and is much more controllable since it's a requirement for landing. If they need to, they can shut down 2, 4 or 6 engines leading up to separation. The extra 80+ seconds of burn time will allow the RS-25s to burn an extra 140 tonnes of fuel, increasing the core stage TWR at booster sep and further reducing the difference in acceleration of the boosters and core.

With the relatively slow liftoff (~1.23 TWR at liftoff) and the large mass of the core stage (at staging it will mass 50% more than two NG upper stages), the boosters should be going fairly slow at staging compared to New Glenn, although much faster than RSRMs will be. I figure about 2.3 km/s at booster sep for NG booster SLS, vs 2.5 km/s for NG, vs 1.4 km/s for RSRM boosted SLS.

The extra velocity at staging with NG boosters is sufficient to put the entire EUS and Orion in orbit with only a small circularization burn from the EUS (even with downrange recovery of the boosters).
« Last Edit: 12/20/2017 01:00 PM by envy887 »

Offline Rocket Science

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New Glenn has a max thrust  3,850,000lbs  which is very close to that of the five segment RSRM which is around 3,600,000lbs.
They would stage higher and faster but probably not as much as the Dynetics Pyrios booster would have since they would normally be saving some of the propellant for landing.

You probably could deal with it by just throttling back the RS-25s for part of the flight .

At shutdown it'll be producing a lot of thrust still (while solids "throttle" almost to zero), unless they shut down all but the center engine or something. This was a problem for all previously-studied liquid boosters, the loads from the boosters pushing on the core stage just before BECO are too high. Even with RSRMV they've already had to alter the core stage throttle profile to mitigate this, but with any liquid option they'll probably have to add a 5th RS-25 to minimize the relative acceleration (and, unless thats coupled with some sort of engine reuse, this only exacerbates the most critical cost and schedule problem of the program)

The F-1B only had two throttle settings, and the lowest was 72% of max. And with two off-center engines on Pyrios they could not shut some of them down to "throttle".

BE-4 will throttle much lower, somewhere around 30%, and is much more controllable since it's a requirement for landing. If they need to, they can shut down 2, 4 or 6 engines leading up to separation. The extra 80+ seconds of burn time will allow the RS-25s to burn an extra 140 tonnes of fuel, increasing the core stage TWR at booster sep and further reducing the difference in acceleration of the boosters and core.

With the relatively slow liftoff (~1.23 TWR at liftoff) and the large mass of the core stage (at staging it will mass 50% more than two NG upper stages), the boosters should be going fairly slow at staging compared to New Glenn, although much faster than RSRMs will be. I figure about 2.3 km/s at booster sep for NG booster SLS, vs 2.5 km/s for NG, vs 1.4 km/s for RSRM boosted SLS.

The extra velocity at staging with NG boosters is sufficient to put the entire EUS and Orion in orbit with only a small circularization burn from the EUS (even with downrange recovery of the boosters).
Now if we can recover the core main engines in a "pod" as has been studied over the years we will begin to see potentially real cost savings in the out years with a flyback/boostback architecture...
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Online envy887

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New Glenn has a max thrust  3,850,000lbs  which is very close to that of the five segment RSRM which is around 3,600,000lbs.
They would stage higher and faster but probably not as much as the Dynetics Pyrios booster would have since they would normally be saving some of the propellant for landing.

You probably could deal with it by just throttling back the RS-25s for part of the flight .

At shutdown it'll be producing a lot of thrust still (while solids "throttle" almost to zero), unless they shut down all but the center engine or something. This was a problem for all previously-studied liquid boosters, the loads from the boosters pushing on the core stage just before BECO are too high. Even with RSRMV they've already had to alter the core stage throttle profile to mitigate this, but with any liquid option they'll probably have to add a 5th RS-25 to minimize the relative acceleration (and, unless thats coupled with some sort of engine reuse, this only exacerbates the most critical cost and schedule problem of the program)

The F-1B only had two throttle settings, and the lowest was 72% of max. And with two off-center engines on Pyrios they could not shut some of them down to "throttle".

BE-4 will throttle much lower, somewhere around 30%, and is much more controllable since it's a requirement for landing. If they need to, they can shut down 2, 4 or 6 engines leading up to separation. The extra 80+ seconds of burn time will allow the RS-25s to burn an extra 140 tonnes of fuel, increasing the core stage TWR at booster sep and further reducing the difference in acceleration of the boosters and core.

With the relatively slow liftoff (~1.23 TWR at liftoff) and the large mass of the core stage (at staging it will mass 50% more than two NG upper stages), the boosters should be going fairly slow at staging compared to New Glenn, although much faster than RSRMs will be. I figure about 2.3 km/s at booster sep for NG booster SLS, vs 2.5 km/s for NG, vs 1.4 km/s for RSRM boosted SLS.

The extra velocity at staging with NG boosters is sufficient to put the entire EUS and Orion in orbit with only a small circularization burn from the EUS (even with downrange recovery of the boosters).
Now if we can recover the core main engines in a "pod" as has been studied over the years we will begin to see potentially real cost savings in the out years with a flyback/boostback architecture...

This "pod" would be coming back from orbit. Might be a lot cheaper to shorten the core and land it downrange, and use the difference in height to build a large 2nd stage.

Offline FinalFrontier

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Honestly, it's like a bandaid for gangrene at this point. SLS will not be made significantly cheaper no matter what you do, the reason it's so expensive is due purely to the politics that drive the funding for it. You would have to totally change the contracting process and centralize many more contracts to one area and one or two companies to really make a dent, and if you did that there'd be no political will to fund it at all.

If they want to actually make the exploration plan as a whole cheaper, the easiest way would be to cancel SLS and use the money to bid launch services from commercial. Like every other payload. Then all NASA has to do is fund mission payloads. Which, is what they should be doing anyway.

We know how to launch large things into space what we are going to have challenges with is launching complex life sustaining infrastructure to the surfaces of other planetary bodies, and to do so routinely and in a sustainable way so as to sustain permanent settlement. NASA should be focusing on building the equipment needed for this, things like the DSG for example should be the focus. Bid the LV out like you would do for any other payload.

At this rate SLS will hardly be flying at all anyway by the time things like BFR/New Glenn/Vulcan LV family are supposed to be starting. Further design changes or engine changes will impact later exploration missions and make this slip even worse.

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