Author Topic: NASA defends decision to restart RS-25 production, rejects alternatives  (Read 87605 times)

Offline TomH

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....this engine's operational envelope occupied sea-level all the way through to orbital....the SLS has been designed around a complex, very expensive sustainer engine....now these engines are part of a 2 stage expendable configuration...

I think this is pretty much still a sustainer from launch to disposal orbit. The Block II with LUS would have used both stages to reach LEO with a massive payload. The Block IB and Block IIB are designed for the core to reach disposal orbit and the EUS to serve as an EDS. So that operational envelope you mention is still a requisite factor.

Offline rayleighscatter

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The first four RS-25's ordered started production in October 1976 and NASA completed their acceptance testing of all four in early 1979 so we know delivery took less than 2.5 years.

NASA wants engines in five years, they'll get them in five years. Contractors will take as much time as they're provided with.

Offline deltaV

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Theres that, but also it seems like bad business acumen to invest 0.7-1 Billion to save maybe 20 million per engine on six engines. They have to build 35-50 engines for it to make sense (break even).

I would guess that even if they didn't modernize the design and didn't produce any new engines they'd still have to spend hundreds of millions of dollars to keep the SSME program alive. Engineers and technicians don't take kindly to being laid off and told to come back in a decade, and even if they cooperated their memories would have faded. The alternative plan you're comparing NASA's plan to has higher costs than the zero you implied.
« Last Edit: 01/06/2016 11:17 pm by deltaV »

Online A_M_Swallow

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How good is the RS-25E as a vacuum engine?
Could we use it to power a large LEO to lunar orbit reusable transfer vehicle?
Also LEO to Mars orbit return?

Offline robertross

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Original Aerojet Rocketdyne release:

http://ir.aerojetrocketdyne.com/releasedetail.cfm?ReleaseID=944137

 "The RS-25 engines designed under this new contract will be expendable with significant affordability improvements over previous versions," added Jim Paulsen, vice president, Program Execution, Advanced Space & Launch Programs at Aerojet Rocketdyne. "This is due to the incorporation of new technologies, such as the introduction of simplified designs; 3-D printing technology called additive manufacturing; and streamlined manufacturing in a modern, state-of-the-art fabrication facility."

'The new engines will incorporate simplified, yet highly reliable, designs to reduce manufacturing time and cost. For example, the overall engine is expected to simplify key components with dramatically reduced part count and number of welds. At the same time, the engine is being certified to a higher operational thrust level.'
Remembering those who made the ultimate sacrifice for our rights & freedoms, and for those injured, visible or otherwise, in that fight.

Offline oldAtlas_Eguy

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Original Aerojet Rocketdyne release:

http://ir.aerojetrocketdyne.com/releasedetail.cfm?ReleaseID=944137

 "The RS-25 engines designed under this new contract will be expendable with significant affordability improvements over previous versions," added Jim Paulsen, vice president, Program Execution, Advanced Space & Launch Programs at Aerojet Rocketdyne. "This is due to the incorporation of new technologies, such as the introduction of simplified designs; 3-D printing technology called additive manufacturing; and streamlined manufacturing in a modern, state-of-the-art fabrication facility."

'The new engines will incorporate simplified, yet highly reliable, designs to reduce manufacturing time and cost. For example, the overall engine is expected to simplify key components with dramatically reduced part count and number of welds. At the same time, the engine is being certified to a higher operational thrust level.'
That answers my 3D printing question. But it only covers up the: some of our old suppliers won't talk to us or are out of business so we will find new ones or build the parts in-house using 3D printing since we don't have the tooling or any idea how to or where to get the tooling originally used to manufacture the part.

Offline Zed_Noir

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So AR is basically developing a new engine that is also call RS-25.

Think it is like the J-2X to J-2 relationship. So the new engine should be call the RS-25X.  :P

Offline robertross

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Original Aerojet Rocketdyne release:

http://ir.aerojetrocketdyne.com/releasedetail.cfm?ReleaseID=944137

 "The RS-25 engines designed under this new contract will be expendable with significant affordability improvements over previous versions," added Jim Paulsen, vice president, Program Execution, Advanced Space & Launch Programs at Aerojet Rocketdyne. "This is due to the incorporation of new technologies, such as the introduction of simplified designs; 3-D printing technology called additive manufacturing; and streamlined manufacturing in a modern, state-of-the-art fabrication facility."

'The new engines will incorporate simplified, yet highly reliable, designs to reduce manufacturing time and cost. For example, the overall engine is expected to simplify key components with dramatically reduced part count and number of welds. At the same time, the engine is being certified to a higher operational thrust level.'
That answers my 3D printing question. But it only covers up the: some of our old suppliers won't talk to us or are out of business so we will find new ones or build the parts in-house using 3D printing since we don't have the tooling or any idea how to or where to get the tooling originally used to manufacture the part.

I know one thing for sure: the SLS rocket is becoming grossly expensive. I'm know many questioned its costs from day one, but being justified by its large lift capability & volume. However with decreasing budgets for NASA & a questionable economic position for the USA & the world as a whole, it might soon be facing some critical questions as to sustainability. That perhaps is why the ideas are still being debated as to where this rocket should take people (or science missions): the moon, Mars, asteroid, or other destinations.

I love this engine & what it has done & could one day offer, but there comes a point where you have to scratch your head and wonder if this is all going too far for the (economic) realities of today. I guess we'll have to wait and see, but I'm getting nervous.
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Offline QuantumG

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However with decreasing budgets for NASA

It isn't.
Human spaceflight is basically just LARPing now.

Offline Endeavour_01

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Lets not forget everyone that this is the initial engine contract. The main purpose of this contract is to restart production and get the production level to a sustainable point. Note that sustainable is not the amount of engines the SLS program will need AJR to produce to fly indefinitely. It is what is required to sustain the knowledge base and equipment needed to make RS-25s. Once we get into the 2020s more contracts will be issued to fulfill future engine needs. Production can be increased if needed.

In terms of cost the first 4 engine sets for SLS are already bought and paid for. For the next SLS flight that will use the engines discussed here it will add a total of $300 Million to flight costs (I am putting the $1.15 Billion to restart production under DDT&E). Presumably the cost will drop to somewhere around $200 Million for the next flight set. That is about 1/10th of the current budget for SLS.
I cheer for both NASA and commercial space. For SLS, Orion, Falcon 9, Falcon Heavy, Dragon, Starliner, Cygnus and all the rest!
I was blessed to see the launch of Space Shuttle Endeavour on STS-99. The launch was beyond amazing. My 8-year old mind was blown. I remember the noise and seeing the exhaust pour out of the shuttle as it lifted off. I remember staring and watching it soar while it was visible in the clear blue sky. It was one of the greatest moments of my life and I will never forget it.

Offline sdsds

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So AR is basically developing a new engine that is also call RS-25.

Think it is like the J-2X to J-2 relationship. So the new engine should be call the RS-25X.  :P

No, it isn't.

How good is the RS-25E as a vacuum engine?

Hmm. I wonder what the size of a "fully" expanded RS-25-Vac nozzle would be? Fun to think about, but CxP discovered there would be trouble trying to restart an RS-25 in space.
« Last Edit: 01/07/2016 04:38 am by sdsds »
-- sdsds --

Offline Khadgars

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Lets not forget everyone that this is the initial engine contract. The main purpose of this contract is to restart production and get the production level to a sustainable point. Note that sustainable is not the amount of engines the SLS program will need AJR to produce to fly indefinitely. It is what is required to sustain the knowledge base and equipment needed to make RS-25s. Once we get into the 2020s more contracts will be issued to fulfill future engine needs. Production can be increased if needed.

In terms of cost the first 4 engine sets for SLS are already bought and paid for. For the next SLS flight that will use the engines discussed here it will add a total of $300 Million to flight costs (I am putting the $1.15 Billion to restart production under DDT&E). Presumably the cost will drop to somewhere around $200 Million for the next flight set. That is about 1/10th of the current budget for SLS.

Completely agree.  I think a lot of people did not read the article correctly and jumped to misinformed conclusions.


Offline oldAtlas_Eguy

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The other item is that there are not just 6 engines but actually 8. 6 flight and 2 test articles for qualification testing. The 2 test articles are part of the $1.15B restart costs.

The fact that there will be new parts manufacturing (different sources and newer manufacturing methods) is a good thing even if the actual design does not change in any appreciable difference. The key is to maintain the design such that the old and new engines are interchangeable without even a software change required on the rocket side. Otherwise there would be a lot of redone engineering for the "new" engine also making it very difficult to mix on same rocket.

Offline Oli

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What I find disturbing is that the fifth set of engines are only required in 2027, so there will only be four SLS flying in the next 11 years?  :o
I was under the impression that they'd be aiming at a somewhat higher launch cadence.  :-\

Yeah, they seem to be pretty confident they don't need the engines before 2027.

Looks like not much will be happening in the 2020s... :(

Offline Lars-J

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Lets not forget everyone that this is the initial engine contract. The main purpose of this contract is to restart production and get the production level to a sustainable point. Note that sustainable is not the amount of engines the SLS program will need AJR to produce to fly indefinitely. It is what is required to sustain the knowledge base and equipment needed to make RS-25s. Once we get into the 2020s more contracts will be issued to fulfill future engine needs. Production can be increased if needed.

And this is a prime example where 'sustaining the knowledge base' is overrated, and we are anchored down to old technology and old manufacturing methods. Don't treat AR and its engine know-how as a resource that once lost can not be recovered. It can. And it can be done better.
« Last Edit: 01/07/2016 07:24 am by Lars-J »

Offline Chalmer

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Theres that, but also it seems like bad business acumen to invest 0.7-1 Billion to save maybe 20 million per engine on six engines. They have to build 35-50 engines for it to make sense (break even).

I would guess that even if they didn't modernize the design and didn't produce any new engines they'd still have to spend hundreds of millions of dollars to keep the SSME program alive. Engineers and technicians don't take kindly to being laid off and told to come back in a decade, and even if they cooperated their memories would have faded. The alternative plan you're comparing NASA's plan to has higher costs than the zero you implied.

Why would you keep the program alive if you didnt want to produce more engines?

The alternative plan im comparing to, is AJR just producing replicas of the current engines and not doing any further development and updating.

As per stated earlier in this thread that would mean a production price of around 20 million more per engine.

Now the contract is for 1.5 Billion. So a large amount of that is for updating. Earlier in the thread 750 Million was mentioned as the cost of delevopment .. Since it is unknown i used an interval.

I did not imply zero cost for the alternative.


As the Shuttle program was winding down and alternatives like DIRECT were being discussed there was an estimate that about $750m was needed to modernize RS25 production. At the time the idea was that additional RS-25D engines would cost ~$72m each, but that could be cut to ~$39m each once modernization of production was complete. So without modernization a purchase in 2015 to take delivery of six engines in 2017 would have been $432; after modernization it would have been $234m. That was without production restart costs as the contract would have been let before the line was truly shuttered.

Apparently what AJR now proposes is ~$410m for restart; $750m in modernization; price drop to $57m per unit for small batches. The $39m per engine estimate mentioned above was for approximately 8 to 12 engines per year... which might have been affordable with DIRECT or AJAX. Apparently the need for those quantities isn't (yet) in the picture for SLS....
« Last Edit: 01/07/2016 11:51 am by Chalmer »

Offline Chalmer

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Lets not forget everyone that this is the initial engine contract. The main purpose of this contract is to restart production and get the production level to a sustainable point. Note that sustainable is not the amount of engines the SLS program will need AJR to produce to fly indefinitely. It is what is required to sustain the knowledge base and equipment needed to make RS-25s. Once we get into the 2020s more contracts will be issued to fulfill future engine needs. Production can be increased if needed.

In terms of cost the first 4 engine sets for SLS are already bought and paid for. For the next SLS flight that will use the engines discussed here it will add a total of $300 Million to flight costs (I am putting the $1.15 Billion to restart production under DDT&E). Presumably the cost will drop to somewhere around $200 Million for the next flight set. That is about 1/10th of the current budget for SLS.

You cant just wave away what you think is DDT&E of 1.15 Billion. That cost is still there and very much part of the cost of the SLS. Only it is not part of the marginal cost.

These six engines, from which the 2 first "MTBF" engines will be used for components for the fourth SLS flight (Using the last of the 16 engines avaliable now) have an average cost of 250M. Even if marginal cost of the last engine in this batch and the first in a possible follow on is about 60 mill. 

Offline Chalmer

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The other item is that there are not just 6 engines but actually 8. 6 flight and 2 test articles for qualification testing. The 2 test articles are part of the $1.15B restart costs.

The fact that there will be new parts manufacturing (different sources and newer manufacturing methods) is a good thing even if the actual design does not change in any appreciable difference. The key is to maintain the design such that the old and new engines are interchangeable without even a software change required on the rocket side. Otherwise there would be a lot of redone engineering for the "new" engine also making it very difficult to mix on same rocket.

This is wrong. At least from what ive read in the document.

Quote from: Page 3 justification document
The number of new flight engines to be included as part of the contract is six (6). This amount of flight hardware is necessay to fulfill the needs of one SLS launch (four engines are used per launch) and two complete sets of engine hardware (i.e., the equivalent of two engines) necessary for risk mitigation in the form of spare hardware for both newly certified engines and residual RS-25 engines.

Offline Chalmer

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What I find disturbing is that the fifth set of engines are only required in 2027, so there will only be four SLS flying in the next 11 years?  :o
I was under the impression that they'd be aiming at a somewhat higher launch cadence.  :-\

Yeah, they seem to be pretty confident they don't need the engines before 2027.

Looks like not much will be happening in the 2020s... :(

Something like one every 2 years, after initial gap. 2018,2021,2023,2025 and then the new engines in 2027.

Looks right to me.

Also at a launch rate of 1 SLS per 2 years, that match what is Baseline steady state production of 2 engines per year.

I know this contradicts what has been said to be minimum safe launch rate.

Offline Endeavour_01

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After going through the document I noticed that it is more than a year old (dates back to 2014). I am wondering if the 2027 number for SLS-5 is the result of the earlier once every 2 year flight rate (like Chalmer said). That anticipated flight rate seems to have changed in the last year.


You cant just wave away what you think is DDT&E of 1.15 Billion. That cost is still there and very much part of the cost of the SLS. Only it is not part of the marginal cost.

I wasn't "waving the cost away." My point was that the cost of new RS-25 engines will not break the bank for flight costs like a number of people have said.
I cheer for both NASA and commercial space. For SLS, Orion, Falcon 9, Falcon Heavy, Dragon, Starliner, Cygnus and all the rest!
I was blessed to see the launch of Space Shuttle Endeavour on STS-99. The launch was beyond amazing. My 8-year old mind was blown. I remember the noise and seeing the exhaust pour out of the shuttle as it lifted off. I remember staring and watching it soar while it was visible in the clear blue sky. It was one of the greatest moments of my life and I will never forget it.

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