|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
RD-180 relplacement
On Thursday, May 11, 2017 at 8:42:25 AM UTC-4, Fred J. McCall wrote:
"Scott M. Kozel" wrote: Three separate heavy lift vehicles in development that would be capable of taking men to the Moon or Mars. Actually only one 'program'. And two commercial efforts. I don't really understand that. Last time one vehicle was developed and they built 16 of them and had programs in place to use them within a reasonable period of time, that provided economies of scale and focus to do the program. It was a national scale program and accomplished great things. Last time we had a single government program that spent money like water, made the trip, and then had no follow-on, which is why we can't get beyond LEO anymore. The current approach doesn't make sense; too many vehicle types in development and no real focus toward building enough of them to have an actual program. The 'government program' (how we did Apollo) is the high priced spread. It's true that it makes no sense because it has no real goal (it changes with every President) and is too expensive to fly. The other two efforts are commercial efforts, make more sense, spend a lot less money, and will be far cheaper to fly. If we did it the old way, we would ONLY have SLS, Musk and Bezos would keep their money, and we'd get another 'flags and footprints' mission to somewhere at best. What kind of commercial effort for such a vehicle and program could provide the tens of billions of dollars in private capital to fund it? What would be the business model? The federal government could provide 60-80% of the funding, but that would not be a private sector effort, that would be massive subsidization by the government. Sure Apollo was expensive, but I wonder how the private sector could profitably fund a program like that. |
#12
|
|||
|
|||
RD-180 relplacement
r"Scott M. Kozel" wrote:
On Thursday, May 11, 2017 at 8:42:25 AM UTC-4, Fred J. McCall wrote: "Scott M. Kozel" wrote: Three separate heavy lift vehicles in development that would be capable of taking men to the Moon or Mars. Actually only one 'program'. And two commercial efforts. I don't really understand that. Last time one vehicle was developed and they built 16 of them and had programs in place to use them within a reasonable period of time, that provided economies of scale and focus to do the program. It was a national scale program and accomplished great things. Last time we had a single government program that spent money like water, made the trip, and then had no follow-on, which is why we can't get beyond LEO anymore. The current approach doesn't make sense; too many vehicle types in development and no real focus toward building enough of them to have an actual program. The 'government program' (how we did Apollo) is the high priced spread. It's true that it makes no sense because it has no real goal (it changes with every President) and is too expensive to fly. The other two efforts are commercial efforts, make more sense, spend a lot less money, and will be far cheaper to fly. If we did it the old way, we would ONLY have SLS, Musk and Bezos would keep their money, and we'd get another 'flags and footprints' mission to somewhere at best. What kind of commercial effort for such a vehicle and program could provide the tens of billions of dollars in private capital to fund it? What would be the business model? A classic government engine development effort costs around $1.5 billion. Bezos is developing New Glenn, engines and all, for that amount of money. He's funding it (and most of the rest of Blue Origin) by selling a billion dollars of his Amazon stock every year. Bezos is worth around $81 billion. Meanwhile, Musk is only worth around $16 billion, so he's not funding it all with personal checks like Bezos is. He's funding a lot of it now by undercutting the rest of the world on launch costs. The federal government could provide 60-80% of the funding, but that would not be a private sector effort, that would be massive subsidization by the government. Bezos is funding BE-4 out of his own pocket. USAF is funding AR-1 development. BE-4 will be cheaper to buy (by a lot) and the government isn't paying to develop it. Meanwhile Musk is getting around $34 million from USAF to develop Raptor (while putting up $68 million of his own money). I wasn't kidding when I said that private commercial development costs an order of magnitude less than government funded development. Sure Apollo was expensive, but I wonder how the private sector could profitably fund a program like that. It wouldn't. It would get the same results for a lot less money and then sell missions to anyone who wanted them. Note that USAF has gone down this road now. They don't generally develop rockets. They just buy launch services. No reason NASA can't do the same. Or anyone else, for that matter. The entire budget for New Glenn is what it costs the government to develop an engine. I don't know what they'll charge for a launch. Look at SpaceX launch costs compared to Atlas or Delta. Estimates for SpaceX ITS is around $10 billion to develop with a launch cost of around $63 million. SLS development is about twice that to complete Phase I and costs almost a billion dollars per launch. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
#13
|
|||
|
|||
RD-180 relplacement
On Tuesday, May 9, 2017 at 4:28:12 PM UTC-4, Fred J. McCall wrote:
I'm confused. The program to replace the RD-180 is focused on engines with around 400,000 lb thrust at sea level. This focuses them on the AR-1 (kerosene/LOC) and BE-4 (methane/LOX). Why are they not looking at the RS-25 (LH2/LOX with similar thrust) or the Raptor engine (methane/LOX)? Seems like we're getting a lot of different engines when it might be more efficient to settle on just a couple. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw space x engines are built by robotics, the engine bells are made on 3d printers |
#14
|
|||
|
|||
RD-180 relplacement
JF Mezei wrote:
On 2017-05-11 08:56, Fred J. McCall wrote: True. And they still have a higher power to weight ratio than any other rocket engine, which means they still have to push those things. If you have an existing very precise design for the SSMEs, I am trying to understand why you can't automate with current manufactruring technology which is by far more precise than any human operator. I'm sure you are trying to understand that. But I don't think you will because you don't understand how this stuff works. I am in no way saying that producing an SSME would end up cheaper than a Merlin. But modern automated tooling should be able to produce parts that are well within tolerances of the SSMEs an thus make that engine less outrageously expensive than back in the 1970s when it was first produced. But not as much less as you seem to think. In terms of disposable vs re-usable, if you're keeping same design and materials, does it make a difference when you build it whether it will be flown a couple times (tests + 1 flight) versus re-used many many times? They're not keeping the same materials. That's how they're making it cheaper. Any reduction in build quality would severely increase risk of explosion on the one flight it does (or preceeding test firings), right? Wrong. I can understand how reusability comes into play when you design a new engine from scratch since you have to choose materials and designs that will last for dozens of hours of firing instead of maybe 30 minutes. 30 minutes is a preposterously long firing time for an expendable engine. But if taking an exsiting design that targetted reusability, wouldn't newly built SSMEs be inherently re-usable even if not intended? No, because part of the redesign changes materials. -- "Ignorance is preferable to error, and he is less remote from the truth who believes nothing than he who believes what is wrong." -- Thomas Jefferson |
#15
|
|||
|
|||
RD-180 relplacement
JF Mezei wrote:
On 2017-05-11 21:54, Fred J. McCall wrote: They're not keeping the same materials. That's how they're making it cheaper. For critical parts like the turbo pump, is that wise? It means essenstially building a new engine that will need to be tested and validated. They're going to have to do that anyway, since it will be a new production line with modifications to the engine. What materials can they substitute with which one when you consider the very very cold and "a little hot" temperatures the engine needs to handle? Would it be correct that for the 1970s, building the turbo pump was the most expensive portion? Does it make sense to change materials in this rather critical piece? Pay me $1.16 billion and I'll work it all up for you. By the time they get through all the modifications to manufacturing process and materials (which won't be done for the first six engines under the original contract) they think they can cut the price of the engine by about a third (so just under $40 million per engine in current dollars) 30 minutes is a preposterously long firing time for an expendable engine. 8 minute flight and probabnly a few test firings before. Wouldn't that bring it to 20-30 minute range? Why would you test fire an expendable engine before you fly it? You'll either test fire it and tear it down or you won't test fire it and you'll fly it. They're doing test firings now because of nozzle changes and a new engine controller and will later fly those engines, but those engines are RS-25D reusable engines. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
#16
|
|||
|
|||
RD-180 relplacement
|
#17
|
|||
|
|||
RD-180 relplacement
|
#18
|
|||
|
|||
RD-180 relplacement
|
#19
|
|||
|
|||
RD-180 relplacement
|
#20
|
|||
|
|||
RD-180 relplacement
|
Thread Tools | |
Display Modes | |
|
|