....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...
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).
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.'
Quote from: robertross on 01/07/2016 12:10 amOriginal 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.
However with decreasing budgets for NASA
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.
How good is the RS-25E as a vacuum engine?
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.
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? I was under the impression that they'd be aiming at a somewhat higher launch cadence.
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.
Quote from: Chalmer on 01/06/2016 02:04 pmTheres 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.
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....
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.
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.
Quote from: zodiacchris on 01/06/2016 02:31 amWhat 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? 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...
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.