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RD-180 relplacement
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 |
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#3
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RD-180 relplacement
Jeff Findley wrote:
In article , says... 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)? RS-25 is hella expensive and ULA already knows that LH2/LOX produces a large, expensive, vehicle (e.g. Delta IV). So that's right out since Delta IV is already flying (no development costs there). But do note that ULA really wants to ax Delta IV in favor of Atlas V due to its high cost. So why aren't they using something other than RS-25 on SLS? Raptor (methane/LOX) isn't "fully baked" yet (BE-4 is ahead of it). That sounds wrong to me. SpaceX test fired a full up Raptor engine (albeit a lower thrust developmental engine) at their Texas facility last year. The BE-4 has never been test fired and they didn't even have a full engine put together until this year. Seems like we're getting a lot of different engines when it might be more efficient to settle on just a couple. AR-1 is a "backup" engine at this point since it's so far behind BE-4 in both schedule and (estimated) per unit price. But, AR-1 is about the right size for two of them to be a "drop-in" replacement for RD-180 on Atlas V. So, if ULA stumbles on Vulcan, an AR-1 engined Atlas V might be a good stop-gap measure. Aerojet Rocketdyne says they can start delivering AR1 engines in 2019, so the finish line isn't all that far behind BE-4. Blue Origin says the BE-4 will cost 60% of what an AR1 costs (at $12.5 million each); so BE-4 engines are only around $7.5 million each? The government is paying a lot of money to develop AR1, so I'd bet on it being pushed for use somewhere. And AR1 does have the advantage of not needing a bunch of new infrastructure to handle fueling and such. At any rate, Aerojet Rocketdyne is being paid good money to develop AR- 1. Even if it meets the same fate as J-2X, they're getting money now which helps keep the company alive. How many billion dollars of taxpayer money are we going to spend developing engines that never get used? Around $1.5 billion for AR1. Around $1.2 billion for RS-25 (which only gets used if SLS keeps flying). Another $1.2 billion for J-2X. Meanwhile Merlin engines used on Falcon 9 cost around $1.2 million each with engines in the Raptor/BE-4 class going for $7.5 million each? Meanwhile the entire development budget for New Glenn is around $2.5 billion and what little public data there is puts development costs for Raptor engines in the hundreds of millions of dollars (vice billions) and I expect BE-4 development is similar. What that says is that private companies developing engines mostly on their own nickel is looking to be an order of magnitude cheaper than traditional contracted engine development programs... -- "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 |
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RD-180 relplacement
On Wednesday, May 10, 2017 at 5:30:17 AM UTC-4, Fred J. McCall wrote:
Jeff Findley wrote: In article , says... 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)? RS-25 is hella expensive and ULA already knows that LH2/LOX produces a large, expensive, vehicle (e.g. Delta IV). So that's right out since Delta IV is already flying (no development costs there). But do note that ULA really wants to ax Delta IV in favor of Atlas V due to its high cost. So why aren't they using something other than RS-25 on SLS? Raptor (methane/LOX) isn't "fully baked" yet (BE-4 is ahead of it). That sounds wrong to me. SpaceX test fired a full up Raptor engine (albeit a lower thrust developmental engine) at their Texas facility last year. The BE-4 has never been test fired and they didn't even have a full engine put together until this year. Seems like we're getting a lot of different engines when it might be more efficient to settle on just a couple. AR-1 is a "backup" engine at this point since it's so far behind BE-4 in both schedule and (estimated) per unit price. But, AR-1 is about the right size for two of them to be a "drop-in" replacement for RD-180 on Atlas V. So, if ULA stumbles on Vulcan, an AR-1 engined Atlas V might be a good stop-gap measure. Aerojet Rocketdyne says they can start delivering AR1 engines in 2019, so the finish line isn't all that far behind BE-4. Blue Origin says the BE-4 will cost 60% of what an AR1 costs (at $12.5 million each); so BE-4 engines are only around $7.5 million each? The government is paying a lot of money to develop AR1, so I'd bet on it being pushed for use somewhere. And AR1 does have the advantage of not needing a bunch of new infrastructure to handle fueling and such. Three separate heavy lift vehicles in development that would be capable of taking men to the Moon or Mars. 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. 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. |
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RD-180 relplacement
"Scott M. Kozel" wrote:
On Wednesday, May 10, 2017 at 5:30:17 AM UTC-4, Fred J. McCall wrote: Jeff Findley wrote: In article , says... 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)? RS-25 is hella expensive and ULA already knows that LH2/LOX produces a large, expensive, vehicle (e.g. Delta IV). So that's right out since Delta IV is already flying (no development costs there). But do note that ULA really wants to ax Delta IV in favor of Atlas V due to its high cost. So why aren't they using something other than RS-25 on SLS? Raptor (methane/LOX) isn't "fully baked" yet (BE-4 is ahead of it). That sounds wrong to me. SpaceX test fired a full up Raptor engine (albeit a lower thrust developmental engine) at their Texas facility last year. The BE-4 has never been test fired and they didn't even have a full engine put together until this year. Seems like we're getting a lot of different engines when it might be more efficient to settle on just a couple. AR-1 is a "backup" engine at this point since it's so far behind BE-4 in both schedule and (estimated) per unit price. But, AR-1 is about the right size for two of them to be a "drop-in" replacement for RD-180 on Atlas V. So, if ULA stumbles on Vulcan, an AR-1 engined Atlas V might be a good stop-gap measure. Aerojet Rocketdyne says they can start delivering AR1 engines in 2019, so the finish line isn't all that far behind BE-4. Blue Origin says the BE-4 will cost 60% of what an AR1 costs (at $12.5 million each); so BE-4 engines are only around $7.5 million each? The government is paying a lot of money to develop AR1, so I'd bet on it being pushed for use somewhere. And AR1 does have the advantage of not needing a bunch of new infrastructure to handle fueling and such. 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. -- "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 |
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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. |
#7
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#8
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RD-180 relplacement
Jeff Findley wrote:
In article , says... Jeff Findley wrote: In article , says... 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)? RS-25 is hella expensive and ULA already knows that LH2/LOX produces a large, expensive, vehicle (e.g. Delta IV). So that's right out since Delta IV is already flying (no development costs there). But do note that ULA really wants to ax Delta IV in favor of Atlas V due to its high cost. So why aren't they using something other than RS-25 on SLS? Because the cheaper RS-68, used on Delta IV, isn't regeneratively cooled and can't handle the heating environment at the base of the core stage caused by both the main engines and the SRBs. This was discovered early on in Ares V development, which planned on using the much cheaper RS-68. In general, Ares V/SLS is a giant cluster *&^# of a program. If it ever does fly it will be the biggest, most expensive, lowest flight rate launch vehicle in history. I'm inclined to say that RS-25 'won' the studies because it got extra points for being 'Shuttle-derived', which was a stupid requirement in the first place. Raptor (methane/LOX) isn't "fully baked" yet (BE-4 is ahead of it). That sounds wrong to me. SpaceX test fired a full up Raptor engine (albeit a lower thrust developmental engine) at their Texas facility last year. The BE-4 has never been test fired and they didn't even have a full engine put together until this year. I should say it's my opinion that Raptor is behind BE-4. Since both companies are private and somewhat secretive, good information is hard to come by. But from what's been reported in the press, Blue Origin has a full size complete BE-4 development engine built and is getting ready to test fire it. SpaceX could be at that point too but all I've heard so far is that they've fired a lower thrust development engine, which indicates they're not quite ready for full scale testing. Blue Origin, on the other hand, thinks BE-4 is ready for "full scale" testing. But the proof will be on the test stand, will it not? Blue Origin says BE-4 will be ready for delivery this year (or they did; not sure if that's still their story now). Blue Origin has more schedule pressure for this class engine than SpaceX does, since they want it picked up by ULA for the engine for Vulcan (2020-2021 launch dates) and the big thing they're touting is that it will be available sooner than AR-1, which is the alternative engine. That being said, BE-4 has apparently moved right at least some number of months, since originally the full up engine tests were supposed to start last year but they've only just got complete engines built. Meanwhile, SpaceX has no real schedule driver for Raptor other than internal (ITS 2024 or so, which could easily move right) and their real priority development right now is Falcon Heavy. Seems like we're getting a lot of different engines when it might be more efficient to settle on just a couple. AR-1 is a "backup" engine at this point since it's so far behind BE-4 in both schedule and (estimated) per unit price. But, AR-1 is about the right size for two of them to be a "drop-in" replacement for RD-180 on Atlas V. So, if ULA stumbles on Vulcan, an AR-1 engined Atlas V might be a good stop-gap measure. Aerojet Rocketdyne says they can start delivering AR1 engines in 2019, so the finish line isn't all that far behind BE-4. Blue Origin says the BE-4 will cost 60% of what an AR1 costs (at $12.5 million each); so BE-4 engines are only around $7.5 million each? The government is paying a lot of money to develop AR1, so I'd bet on it being pushed for use somewhere. And AR1 does have the advantage of not needing a bunch of new infrastructure to handle fueling and such. ULA is more worried about the per flight cost down the road. If they have to install liquid methane tanks and plumbing, they'll do it to lower costs. SpaceX is already undercutting *everyone* on launch costs and that's without taking reuse into account. ULA is desperate to stay alive at this point with SpaceX eating into its DOD launches that it used to have a monopoly on. ULA is saying that base Raptor (with no solids) will cost around $100 million per launch. That gets you around 10 tonnes to LEO. Current Falcon 9 has double the payload and is only 2/3 the cost, which makes it about 1/3 the cost per pound. So ULA's new best effort at economy still costs 3x what the competition costs. At any rate, Aerojet Rocketdyne is being paid good money to develop AR- 1. Even if it meets the same fate as J-2X, they're getting money now which helps keep the company alive. How many billion dollars of taxpayer money are we going to spend developing engines that never get used? Around $1.5 billion for AR1. Around $1.2 billion for RS-25 (which only gets used if SLS keeps flying). Another $1.2 billion for J-2X. Meanwhile Merlin engines used on Falcon 9 cost around $1.2 million each with engines in the Raptor/BE-4 class going for $7.5 million each? Meanwhile the entire development budget for New Glenn is around $2.5 billion and what little public data there is puts development costs for Raptor engines in the hundreds of millions of dollars (vice billions) and I expect BE-4 development is similar. What that says is that private companies developing engines mostly on their own nickel is looking to be an order of magnitude cheaper than traditional contracted engine development programs... Maybe the US Government should get out of the game of funding development of engines and launch vehicles. SpaceX and Blue Origin have both proven that private industry can do this themselves, with sufficient funding. USAF has (mostly) gone this direction. NASA hasn't. What NASA needs to do is put together performance requirements specs for what they want and then be flexible about trading away requirements for schedule and dollars to commercial vendors. Along the lines of "You want X, Y, and Z. We can give you X and Y in A years for B money, but Z will double the cost and schedule. How badly do you need Z?" AJR sat on its ass for how long after RD-180 was picked for Atlas? They've known for *decades* that the US needed a high thrust LOX/kerosene engine to remain competitive in the global launch market and they literally sat on their hands waiting for a government handout to start development. AJR deserves to go under at this point. It's management is wholly dependent on old style cost-plus contracts. They don't know how to innovate. They don't know how to compete on cost. Yep. But they've been burned before on developing engines and not being able to sell them after, so I can kind of understand why they would risk a billion of their own money. Since they don't make vehicles, engine development is riskier for them. NASA and DOD need to switch their space support back to the same style of support that NACA used to give to aircraft and (jet) engine manufacturers in the US. NACA didn't design and build commercial engines or aircraft. And NACA certainly didn't operate its own airlines. It's well past time for the US Government to get the hell out of the launch business and let good old fashioned capitalism and market based competition sort out the cheapest way to orbit. Yep, it's past time for this change. For what they're spending on SLS/Orion development NASA could have pretty much funded the total development of both ITS from SpaceX and New Glenn from Blue Origin and had change left. This is the kind of **** that the "crazy" people on the old sci.space argued for back in the early 1990s when they were pushing CATS (cheap access to space). It's now been over 30 years since then, and SpaceX has proven them right. The government needs to get the *&%# out of the way and support the commercial providers rather than building yet another Government Luanch System which will be a drain on NASA's budget for decades to come. Yep, I remember that. Even back then people were saying 'performance uber alles' was the wrong approach and proposing things like 'big dumb boosters' and accepting the addition weight of using swaged steel rather than aluminum because of the cost advantage. But it kind of took Elon Musk to find the right path to cheaper launches. -- "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 |
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#10
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RD-180 relplacement
To know the kind of engine you need, you need to know the vehicle it will be used for. To know the kind of vehicle you need, you need to know where it is going and what the vehicle is used for. To know where you are going and what you are doing, you have to have a long-term plan. Is anyone doing this? NASA is not - not officially. China is - officially. * * * Chinese Engines YF-77 (165,000 lbf) http://aviationweek.com/awin/chinese...xceed-saturn-v Chinese Vehicles Long-March 11 (140,000 lb LEO) http://www.americaspace.com/2012/07/...g-new-rockets/ Chinese Missions Mars http://en.people.cn/200705/22/eng20070522_376754.html Solar Power Satellite http://news.xinhuanet.com/english/20..._134109115.htm * * * A 140,000 lb payload to orbit, built with a common core and two outboard stages - all to the same design. Five Y-77 engines on each. So, three modules each the same size and weight is about 1/2 the size of a Space Shuttle External Tank, with FIVE Y-77 engines at the base of each. Each module; 316 tonnes module weight 36 tonnes structure weight Structure 43 tonnes LH2 237 tonnes LOX 77 Y-77 Engine Thrust 5 Number of Engines 1.218 Gees at lift off. So, theres a core, and two outboard tanks, equipped with cross feeding, drain the two outboard tanks first and blast off with 15 Y-77 engines. When the two outboard tanks are drained they are dropped and fly back to the launch centre after boosting the system to 2.2 km/sec. The central core adds another 5.8 km/sec to attain orbit with 63.6 tonnes payload. The central core re-enters, and returns to the launch centre. * * * Reaching for 400,000 lbs. Expanding to 7 common core boosters with five Y-77 engines - raises the weight higher. A seven element launcher puts up 182.0 tonnes payload (400,000 lbs) with four elements dropping off and flying back to the launch centre after adding 1.5 km/sec. The three element system continues as the second stage. The two elements dropping off after taking the vehicle up to 4.3 km/sec. Then finally the core element takes 182 metric tons to LEO. All fly back to be reused. * * * What to do when you get to orbit - Interplanetary Stages - Nuclear thermal stage - One interesting detail is the development of ceramic coated pellets of uranium that contain liquid uranium under supreme heating achieving 1600 sec Isp (15.68 km/sec Ve) using liquid hydrogen. This is an old idea, going back to the 1960s; https://books.google.co.nz/books?id=...XGA9cQ6AEIJTAA A 4000 MW thermal nuclear rocket the size of NERVA, operating at this level, produces 52.0 metric tons of thrust. The advantage of this system 182 metric ton payload can deliver a lot more across the solar system than chemical rockets! https://www.lanl.gov/science/NSS/iss...ory4full.shtml Nuclear Electric Stage The nuclear thermal source is also used as a power supply using a closed Brayton cycle process. This produces 2000 MW electrical, from a 4000 MW thermal source which when used in an advanced ion engine that produces 54 km/sec exhaust speed (5500 sec Isp) produces 7.5 tonnes of thrust providing even greater payload fractions to Mars and beyond, and mass only 1.5 tonnes. On board Nuclear Electric & Nuclear Electric on Mars A nuclear thermal source will be used as a power supply to power the ship, the same way the nuclear power plant on a nuclear sub is used. The nuclear thermal source will be used as a power supply after landing. To power a lunar or mars or other planetary city. Including industrial processes that produce chemical fuels on Mars for boosters. http://emits.sso.esa.int/emits-doc/E...33-SoW-RD1.pdf For all these reasons, anyone serous about deep space manned travel will develop nuclear rocketry. The PR angle The technology is different enough from existing power plant designs, that they can be incorporated in advanced high temperature reactors on Earth, and the high profile nature of the successful missions they enable, are sufficient to promote their high technology, high reliability and high safety. A definite coup. Something the Chinese would exploit mid 21st century to sell compact high efficiency flexible power plants to cities and nations around the world struggling in a post oil future. https://www.gen-4.org/gif/jcms/c_9362/vhtr The radiation angle What about radiation? Well, Cosmic Background Radiation and Solar radiation outside vanAllen belts of Earth, are definite safety hazards as well. The shielding required of a nuclear source could also shield astronauts aboard ship. A shadow shield has long been promoted as a 'safe haven' or 'storm shelter' or even a 'sun shield' for manned interplanetary missions. Another is to use powerful electro magnet and surplus electrical power to make a mini-magnetic shield around the ship. https://home.cern/about/updates/2015...eld-astronauts * * * It takes 3.6 km/sec to exit LEO and head for Mars along a Hohmann Transfer Orbit. So, propellant fractions are; Chemical u = 1 - 1/exp(3.6/4.3) = 0.557 -- 39,930 lbs useful of 140,000 lbs, 114,100 lbs useful of 400,000 lbs Nuclear Thermal u = 1 - 1/exp(3.6/15.68) = 0.200 -- 98,970 lbs useful of 140,000 lbs, 282,770 lbs useful of 400,000 lbs Nuclear Electric u = 1 - 1/exp(3.6/54) = 0.063 -- 118.190 lbs useful of 140,000 lbs, 337,700 lbs useful of 400,000 lbs A nuclear thermal rocket powered stage delivers 2.48x what a chemical stage delivers. A nuclear electric rocket powered stage delivers 2.96x what a chemical stage delivers. Now, a nuclear electric power source has a lot of other uses as well! So, a nuclear electric source, built around a nuclear thermal rocket, is a reasonable add-on to a nuclear thermal rocket programme. If you're going to send large numbers of payloads across the solar system, you can do it more cheaply with the right engines, and nuclear rockets are the right engines. * * * Now this uses 1950s era technologies, updated slightly for today. Something the Chinese would feel comfortable doing as part of an integrated programme. https://www.google.co.nz/url?sa=t&rc...e4ZL10FXWssogw So, despite the small size of the Chinese Space Budget about 1/10th the size of NASA, in combination with support from the Chinese nuclear weapons and power programmes, a credible effort is being sustained along the lines described here. |
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