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Towards routine, reusable space launch.
Doc O'Leary wrote on Fri, 8 Jun
2018 13:10:48 -0000 (UTC): For your reference, records indicate that "Robert Clark" wrote: Several companies are proposing satellite megaconstellations that would require hundreds to thousands of communications satellites. This may finally provide the impetus to produce reusable launchers. What are the actual numbers when it comes to savings from a reusable rocket? That depends on a lot of things. It’d also be interesting to know how new technologies might impact the economics of launching items into space (including just making disposable launch vehicles much cheaper). Real reuse will always be cheaper. If you can make disposable launch vehicles much cheaper, the same technologies allow making reusable launch vehicles much cheaper. Once you start to contemplate the need for multiple daily launches, even recovering boosters to reuse them seems like a slow and labor-intensive process. But orders of magnitude faster than throwing them away and building a new one. On the path to a space elevator, it seems like there should be many more ways to reach escape velocity that do a better job than what Musk is doing today. You've discovered a good supply of unobtainium, have you? Otherwise, rockets are your man for getting stuff to orbit for the foreseeable future. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
#2
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Towards routine, reusable space launch.
For your reference, records indicate that
Fred J. McCall wrote: Doc O'Leary wrote on Fri, 8 Jun 2018 13:10:48 -0000 (UTC): What are the actual numbers when it comes to savings from a reusable rocket? That depends on a lot of things. Well, sure, but it always helps to have some data to work with before beginning an optimization process. Best/worst cases or averages or whatever. What the savings is related to the total cost of the launch is going to be guiding factor on how much effort it makes sense to expend to re-use different parts of the system. It’d also be interesting to know how new technologies might impact the economics of launching items into space (including just making disposable launch vehicles much cheaper). Real reuse will always be cheaper. If you can make disposable launch vehicles much cheaper, the same technologies allow making reusable launch vehicles much cheaper. That is non-obvious. Ideally, I would think a “zero waste” system would be cheapest; every kg of mass that gets sent up either stays up (doing something useful) or was the fuel. All this booster landing (and subsequent refurbishing for relaunch) we’re seeing, while cool, is definitely *not* the most efficient use of resources. Once you start to contemplate the need for multiple daily launches, even recovering boosters to reuse them seems like a slow and labor-intensive process. But orders of magnitude faster than throwing them away and building a new one. But that’s still assuming old technologies rather than new ones. You don’t “throw away” a space elevator. Nor a mag-lev cannon. I’m not sure how viable a high-altitude balloon launch would be, but it may also be cheaper than traditional first-stage rockets. On the path to a space elevator, it seems like there should be many more ways to reach escape velocity that do a better job than what Musk is doing today. You've discovered a good supply of unobtainium, have you? Otherwise, rockets are your man for getting stuff to orbit for the foreseeable future. It’s always a good idea to noodle around with other technologies, no matter how impossible they appear to be today. Because, yes, rockets are the way to get to orbit, but I’m most interested in the *unforeseeable* future that has humans on other planets around other stars. Just being satisfied with rockets is not going to make that happen. -- "Also . . . I can kill you with my brain." River Tam, Trash, Firefly |
#3
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Towards routine, reusable space launch.
In article , droleary@
2017usenet1.subsume.com says... For your reference, records indicate that Fred J. McCall wrote: Doc O'Leary wrote on Fri, 8 Jun 2018 13:10:48 -0000 (UTC): What are the actual numbers when it comes to savings from a reusable rocket? That depends on a lot of things. Well, sure, but it always helps to have some data to work with before beginning an optimization process. Best/worst cases or averages or whatever. What the savings is related to the total cost of the launch is going to be guiding factor on how much effort it makes sense to expend to re-use different parts of the system. It?d also be interesting to know how new technologies might impact the economics of launching items into space (including just making disposable launch vehicles much cheaper). Real reuse will always be cheaper. If you can make disposable launch vehicles much cheaper, the same technologies allow making reusable launch vehicles much cheaper. That is non-obvious. Ideally, I would think a ?zero waste? system would be cheapest; every kg of mass that gets sent up either stays up (doing something useful) or was the fuel. All this booster landing (and subsequent refurbishing for relaunch) we?re seeing, while cool, is definitely *not* the most efficient use of resources. Falcon 9 is the "first generation" reuse for SpaceX. For "zero waste", you'll have to wait for their "second generation" which will be BFR/BFS. Once you start to contemplate the need for multiple daily launches, even recovering boosters to reuse them seems like a slow and labor-intensive process. But orders of magnitude faster than throwing them away and building a new one. But that?s still assuming old technologies rather than new ones. You don?t ?throw away? a space elevator. Nor a mag-lev cannon. I?m not sure how viable a high-altitude balloon launch would be, but it may also be cheaper than traditional first-stage rockets. High altitude balloon launch is a tad risky and only gains you a bit of altitude and zero velocity. Not worth the complexity and cost, IMHO. On the path to a space elevator, it seems like there should be many more ways to reach escape velocity that do a better job than what Musk is doing today. You've discovered a good supply of unobtainium, have you? Otherwise, rockets are your man for getting stuff to orbit for the foreseeable future. It?s always a good idea to noodle around with other technologies, no matter how impossible they appear to be today. Because, yes, rockets are the way to get to orbit, but I?m most interested in the *unforeseeable* future that has humans on other planets around other stars. Just being satisfied with rockets is not going to make that happen. Sure, but SpaceX has proven that you can reduce costs dramatically by using existing technology and introducing reuse of as many components as possible. They're getting close to catching fairings and they have some ideas for second stage reuse too. That would be very close to "zero waste" with Falcon, if they can get to that point. BFR/BFS is planned to be "zero waste" from the very beginning. Fully reusable TSTO with "gas and go" like operations. Also don't count out Blue Origin. They're off to a slow start, but have a very reliable funding source in Jeff Bezos ($1 billion a year). Besides, how you going to get those space elevator bits into orbit? That's right, conventional (hopefully reusable) launch vehicles. Jeff -- All opinions posted by me on Usenet News are mine, and mine alone. These posts do not reflect the opinions of my family, friends, employer, or any organization that I am a member of. |
#4
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Towards routine, reusable space launch.
For your reference, records indicate that
Jeff Findley wrote: High altitude balloon launch is a tad risky and only gains you a bit of altitude and zero velocity. Not worth the complexity and cost, IMHO. Like I said, it might not *currently* be viable, but as an alternative technology it brings new sets of trade-offs to the table such that a few tweaks here and there might make it viable for certain kinds of launches (e.g., “bulky” items that are hard to make aerodynamically efficient benefit from starting at the highest possible altitude). BFR/BFS is planned to be "zero waste" from the very beginning. Fully reusable TSTO with "gas and go" like operations. But that’s not the true “zero waste” I was talking about. Any resources that you’re sending up *and* down, along with any fuels you burn to do it safely, is a waste. It may be a necessary waste for the current launch technologies, so it’s good to minimize it, but I still say it’s a good idea to think about ways to shoot stuff into space that doesn’t involve a lot of heavy stuff coming back to Earth. Also don't count out Blue Origin. They're off to a slow start, but have a very reliable funding source in Jeff Bezos ($1 billion a year). I’m not counting them out, but when the topic is cost/efficiency, the basic question is still how much energy is being expended to get each kg into orbit. So long as the idea is still to send a lot of supporting (non-fuel) heavy stuff up only to have most of it come back down, there are wastes that a new technology can come in and improve upon. Besides, how you going to get those space elevator bits into orbit? That's right, conventional (hopefully reusable) launch vehicles. Hope for bigger things. I fully believe that, for a society to be advanced enough to make a space elevator project realistic, it’s value would be more incremental than revolutionary. Rockets are the best we have right now, but we’re stuffed if that’s the best we can do. -- "Also . . . I can kill you with my brain." River Tam, Trash, Firefly |
#5
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Towards routine, reusable space launch.
On 6/10/2018 10:16 PM, Doc O'Leary wrote:
For your reference, records indicate that Jeff Findley wrote: Hope for bigger things. I fully believe that, for a society to be advanced enough to make a space elevator project realistic, it’s value would be more incremental than revolutionary. A space elevator is not possible in reality. It is a running joke in engineering land. calculate the mechanical loads. calculate the weight of copper cables, and the mechanical cables calculate the weight of the tower, and estimate the sizes of tower sections to support the weight at different levels estimate the weight of the electric motor 150 HP going to use a counterweight ? just ballpark it, assume 0.1 m/sec and 2000 # weight of cargo, and 100,000 foot high. |
#6
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Towards routine, reusable space launch.
Doc O'Leary schrieb:
I’m not counting them out, but when the topic is cost/efficiency, the basic question is still how much energy is being expended to get each kg into orbit. At the moment, not at all. Ballpark calculation: An older version of a Falcon 9 reportedly had 488 tons of total fuel, 147 of it RP-1 (a modified kerosene). Liquid oxygen is quite cheap, and if we give RP-1 a cost of 1 dollar per kg, we probably are in the right ballpark. So, around 150 000 Dollar per launch. This is _very_ low compared to all the other costs. A launch cost around 50 to 60 million dollars now, if I remember the figures right. |
#7
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Towards routine, reusable space launch.
On Monday, June 11, 2018 at 12:19:47 AM UTC-4, Sergio wrote:
On 6/10/2018 10:16 PM, Doc O'Leary wrote: Hope for bigger things. I fully believe that, for a society to be advanced enough to make a space elevator project realistic, it’s value would be more incremental than revolutionary. A space elevator is not possible in reality. It is a running joke in engineering land. calculate the mechanical loads. calculate the weight of copper cables, and the mechanical cables It wouldn't use copper cables, it would use carbon nanotube technology, something that currently doesn't exist. Whether it ever will is debated. That is for Earth. For the Moon, the tether could be constructed from currently available materials. |
#8
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Towards routine, reusable space launch.
Doc O'Leary wrote on Mon, 11 Jun
2018 03:16:38 -0000 (UTC): For your reference, records indicate that Jeff Findley wrote: High altitude balloon launch is a tad risky and only gains you a bit of altitude and zero velocity. Not worth the complexity and cost, IMHO. Like I said, it might not *currently* be viable, but as an alternative technology it brings new sets of trade-offs to the table such that a few tweaks here and there might make it viable for certain kinds of launches (e.g., “bulky” items that are hard to make aerodynamically efficient benefit from starting at the highest possible altitude). And just what such items do we send to space? BFR/BFS is planned to be "zero waste" from the very beginning. Fully reusable TSTO with "gas and go" like operations. But that’s not the true “zero waste” I was talking about. Any resources that you’re sending up *and* down, along with any fuels you burn to do it safely, is a waste. It may be a necessary waste for the current launch technologies, so it’s good to minimize it, but I still say it’s a good idea to think about ways to shoot stuff into space that doesn’t involve a lot of heavy stuff coming back to Earth. Well, let us know if you think of one that doesn't require unobtainium or payloads to take tens of thousands of gravities on launch. Also don't count out Blue Origin. They're off to a slow start, but have a very reliable funding source in Jeff Bezos ($1 billion a year). I’m not counting them out, but when the topic is cost/efficiency, the basic question is still how much energy is being expended to get each kg into orbit. So long as the idea is still to send a lot of supporting (non-fuel) heavy stuff up only to have most of it come back down, there are wastes that a new technology can come in and improve upon. We're constrained by the real world. Magic materials are right out. Besides, how you going to get those space elevator bits into orbit? That's right, conventional (hopefully reusable) launch vehicles. Hope for bigger things. I fully believe that, for a society to be advanced enough to make a space elevator project realistic, it’s value would be more incremental than revolutionary. Rockets are the best we have right now, but we’re stuffed if that’s the best we can do. Just why are we 'stuffed'? Be specific. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
#9
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Towards routine, reusable space launch.
In article , droleary@
2017usenet1.subsume.com says... For your reference, records indicate that Jeff Findley wrote: High altitude balloon launch is a tad risky and only gains you a bit of altitude and zero velocity. Not worth the complexity and cost, IMHO. Like I said, it might not *currently* be viable, but as an alternative technology it brings new sets of trade-offs to the table such that a few tweaks here and there might make it viable for certain kinds of launches (e.g., ?bulky? items that are hard to make aerodynamically efficient benefit from starting at the highest possible altitude). Balloon launch isn't worth the trades which have to be made, IMHO. BFR/BFS is planned to be "zero waste" from the very beginning. Fully reusable TSTO with "gas and go" like operations. But that?s not the true ?zero waste? I was talking about. Any resources that you?re sending up *and* down, along with any fuels you burn to do it safely, is a waste. It may be a necessary waste for the current launch technologies, so it?s good to minimize it, but I still say it?s a good idea to think about ways to shoot stuff into space that doesn?t involve a lot of heavy stuff coming back to Earth. By your definition, a passenger carrying aircraft is "waste" because it flies from one destination to another while carrying passengers. But that sort of "waste" is absolutely not a metric to optimize. Passengers are buying the cheapest ticket for the flight that gets them to their destination. They don't give a rat's ass about the "waste" of the actual aircraft having to fly there and back. Back to space launch. We're nowhere near the minimum cost per kg payload to orbit with chemical launch vehicles. Propellant costs are currently less than 1% of launch costs, even for SpaceX. Any "waste" of propellant that allows full reuse of hardware is currently worth the investment. When your hardware costs more than two orders of magnitude more than your propellant does, it makes a hell of a lot of sense to "expend" a bit of propellant to get your expensive hardware back intact. When faced with an optimization problem, you look for the biggest "bang for the buck" bits to optimize. Propellant "waste" is *not* that, not by a couple orders of magnitude. Also, your launch hardware is a precious commodity, so it makes all the sense in the world to recover it and use it multiple times, just like a passenger carrying jet aircraft. Jeff -- All opinions posted by me on Usenet News are mine, and mine alone. These posts do not reflect the opinions of my family, friends, employer, or any organization that I am a member of. |
#10
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Towards routine, reusable space launch.
Jeff Findley schrieb:
By your definition, a passenger carrying aircraft is "waste" because it flies from one destination to another while carrying passengers. Of course. Firing passengers from large-caliber guns generates much less waste, obviously, and should be the preferred solution :-) |
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