Author Topic: NASA is trying to make the Space Launch System rocket more affordable (Ars)  (Read 11829 times)

Offline Markstark

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Offline Stan-1967

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following the links to the RFI documents, it looks like this is only for EUS.

https://www.fbo.gov/index?s=opportunity&mode=form&tab=core&id=4599556849e76bc3d5f4bc8b43b2276e&_cview=0
« Last Edit: 12/15/2017 10:41 PM by Stan-1967 »

Offline Stan-1967

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The RFi is still heavily biased in favor of staying with the RL-10.  From the report:

"The current vehicle is designed to the following engine parameters.

Isp ~ 460
MR ~ 5.5 - 5.9 (range)
Weight ~ 2100 lbs (total of 4 engines)
Length ~ 10.5 ft (gimbal to nozzle exit)

These engine design parameters may be traded with each other to maintain the vehicle design constraints noted above."


Vinci & BE-3 will have a very hard time to meet the ISP number if they can only be 10.5 ft. long, as the expansion ratio will have to be much less, hence lower ISP.   Both BE-3 & Vinci would have to push chamber pressure beyond current design.  Can they do this by 2023?  Maybe.  Who else has a candidate?  Mitsubishi maybe?

The fact they issued an new RFI suggests somebody out there thinks they can meet the spec, or maybe they are just hedging to preclude any challenges to AR winning the contract.

Offline GWH

Doesn't both the Vinci and BE-3 allow for extendable engine nozzles?
For Vinci this is stated on the wiki page for that engine: https://en.wikipedia.org/wiki/Vinci_(rocket_engine) - 465s ISP is listed.
And I believe the proposal for BE-3 for Orbital ATKa division of Northrop Grumman's Next Generation Launcher was to use an extendable nozzle on the BE-3U.

But I have never seen any numbers on BE-3's ISP...
« Last Edit: 12/15/2017 11:50 PM by GWH »

Offline Stan-1967

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Closer examination makes it pretty clear this is targeted to allow Vinci to compete.   The Wiki article also confirms this in the reference section, as their is a history of NASA considering Vinci going back to 2014.

The Vinci rocket is 4.2 meters tall, vs an RL-10B is 4.14 meters tall with the extendable nozzle.  The RFI says the engine can be 10.5 ft from gimbal to nozzle exit.  I can't find the specifications for the RL-10B regarding it's height when the nozzle is not extended, but it seem reasonable that it fits within the 3.2 meters ( 10.5 ft) specified in the RFI.  Vinci has a much higher chamber pressure, so it can get to ISP of 460 with a lesser expansion ration than RL-10B

The questions then are can Vinci be made with an extendable nozzle that fits within the allotted form factor, & do the Europeans want to try and do this when they have Ariane 6 to get ready for?

BE-3 is simply not a candidate for this RFI. It will never get to 460 s ISP with an open cycle.  BE-3 would also be under expanded within the allotted length.  It it has 4X more thrust, so throat area is likely 4X larger than RL-10 assuming same chamber pressure. ( which is not known).  To make BE-3 work, the specs would have to change, & the interstage & GSE would have to be re designed.

Offline woods170

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Closer examination makes it pretty clear this is targeted to allow Vinci to compete.   The Wiki article also confirms this in the reference section, as their is a history of NASA considering Vinci going back to 2014.

The Vinci rocket is 4.2 meters tall, vs an RL-10B is 4.14 meters tall with the extendable nozzle.  The RFI says the engine can be 10.5 ft from gimbal to nozzle exit.  I can't find the specifications for the RL-10B regarding it's height when the nozzle is not extended, but it seem reasonable that it fits within the 3.2 meters ( 10.5 ft) specified in the RFI.  Vinci has a much higher chamber pressure, so it can get to ISP of 460 with a lesser expansion ration than RL-10B

The questions then are can Vinci be made with an extendable nozzle that fits within the allotted form factor, & do the Europeans want to try and do this when they have Ariane 6 to get ready for?

The "Europeans" as you refer to them is actually ESA. And ESA is in the process of finishing a simplified design of Vinci, for Ariane 6, that actually does away with the extendable nozzle.
This RFI comes at an exceptionally bad time given that the new baseline for Vinci is now fixed nozzle.

If and when the contractors for Vinci want to offer Vinci with an extendable nozzle they will have to pay to complete development of such a nozzle out of their own pocket. But that won't pay off given the extremely low flight frequency of SLS IMO.

Online IanThePineapple

I know New Glenn's optional third stage will have a "vacuum-optimized" BE-3U.

Here's what I could find about it. Nothing very specific though.
From Blue's site:
Quote
BE-3U variant
The BE-3 will be upgraded with a larger nozzle to operate in the vacuum of orbital space, becoming our BE-3U. One BE-3U will power the third stage of our New Glenn launch vehicle. With extensive testing and use on New Shepard and the BE-3, the BE-3U will be one of the best understood rocket engines before it ever launches into space.
« Last Edit: 12/16/2017 02:46 PM by IanThePineapple »
Proud creator of Ian's Paper Model Rocket Collection:
https://forum.nasaspaceflight.com/index.php?topic=42383.0

Offline Markstark

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Thanks for the replies. Seems like there are not many potential alternatives to the RL-10 based on the specifications provided.

Offline jak Kennedy

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They really don't want the SLS to fly do they with the never ending spec changes. The BO engines may be cheaper but how many billions will it cost to implement? Every day it doesn't go anywhere it still eats through NASA money. Cynical? Me! ::)

Offline Markstark

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They really don't want the SLS to fly do they with the never ending spec changes. The BO engines may be cheaper but how many billions will it cost to implement? Every day it doesn't go anywhere it still eats through NASA money. Cynical? Me! ::)
As I understand it, this potential engine change would affect Block IB missions with the Exploration Upper Stage (EM-2+). It would not affect EM-1 (Block I). In any case, I'm happy to hear that NASA is at least considering cost reduction efforts.

I know many people here would prefer to kill it all together but NASA doesn't have the power to do that. Therefore cost reduction efforts are welcomed.
« Last Edit: 12/16/2017 05:49 PM by Markstark »

Online brickmack

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They really don't want the SLS to fly do they with the never ending spec changes. The BO engines may be cheaper but how many billions will it cost to implement? Every day it doesn't go anywhere it still eats through NASA money. Cynical? Me! ::)

Agreed. RL10 isn't THAT expensive, ~20 million a piece at the absolute most pessimistic (and thats before the modernization Aerojet is working on now). Even a 90% cost reduction would save only about 72 million dollars a flight, realistically probably much less. Unless SLS flies a lot more often than looks likely, its probably never going to justify this expense.

Meanwhile RS-25 is optimistically about 70 million a piece, and presents a hard limit to flightrate as well, but theres no real effort to fix that problem. The focus on the upper stage is just weird.

Offline calapine

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From a political perspective Vinci engines for EUS could be a barter item for an ESA seat on crewed Orion missions. Something that was mooted as idea several times, once even by Wörner, if I remember correctly.

« Last Edit: 12/16/2017 06:17 PM by calapine »

Offline Rocket Science

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This is all window dressing as the high cost is "baked into" the design plus all the Cape infrastructure required...
"The laws of physics are unforgiving"
~Rob, Physics instructor, aviator, vintage auto racer

Offline ncb1397

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They really don't want the SLS to fly do they with the never ending spec changes. The BO engines may be cheaper but how many billions will it cost to implement? Every day it doesn't go anywhere it still eats through NASA money. Cynical? Me! ::)

Meanwhile RS-25 is optimistically about 70 million a piece, and presents a hard limit to flightrate as well, but theres no real effort to fix that problem.

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/

Online Coastal Ron

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Lowering cost overall for any product that is already in production is difficult, since everything is set up for the current design and cost structures. Sure you can spend more money to try and save money in the short-term, like for the engine swap they are hoping to do, but even that has to pay for itself within a reasonable amount of time in order to realize the cost savings.

Of course if they really want to save money on the SLS NASA should just release the production cost information - that will generate a lot of suggestions for how to save money...  ;)
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline Markstark

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EUS is not in production yet.

Offline oldAtlas_Eguy

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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.

Online brickmack

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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

Online Coastal Ron

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EUS is not in production yet.

The 1st stage is, and that's where most of the costs are for the SLS.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline Zed_Noir

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According to Eric's Ars Techncia article. Each of the re-furbished RL-10C's cost about $17M each.  :o

So just the engines for the EUS costs more than a Falcon 9 flight! And that's with re-furbished RL-10C's. Scary to guess the cost of newly build RL-10's will be.

Some of the comments in the article suggest humorously that just put a Falcon 9 on top of the SLS as the upper stage. ;D

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