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#51
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Towards routine, reusable space launch.
In article ,
Sjouke Burry wrote: There was a design for interstellar traffic, using a big protection plate behind the spacepod, using a spring loaded tube to connect them,and provide a bit of distance between ship and plate. Explode nuclear bombs behind that shield. Current technology could implement it, but it would be kind of expensive. And that's just for the paper to print out the environmental impact statement! -- Mike Van Pelt | "I don't advise it unless you're nuts." mvp at calweb.com | -- Ray Wilkinson, after riding out Hurricane KE6BVH | Ike on Surfside Beach in Galveston |
#52
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Towards routine, reusable space launch.
On Jun/14/2018 at 12:53 AM, Fred J. McCall wrote :
Alain Fournier wrote on Wed, 13 Jun 2018 19:39:10 -0400: On Jun/13/2018 at 5:35 PM, Fred J. McCall wrote : Doc O'Leary wrote on Wed, 13 Jun 2018 12:57:19 -0000 (UTC): For your reference, records indicate that Jeff Findley wrote: In article , droleary@ 2017usenet1.subsume.com says... For your reference, records indicate that Jeff Findley wrote: Sure, sure, Star Trek style transporters with infinite range. I'll get right on that. No, you won?t. But you apparently *will* use it as a straw man to avoid actually addressing the likelihood that new technologies developed in the future will change the economies of space launches. Hell, that?s essentially what SpaceX is demonstrating today. Bull****. SpaceX is not demonstrating any new technologies. They've combined existing technologies in novel ways to solve the problems involved in building Merlin engines and Falcon launch vehicles. There is zero new tech in them. If you believe differently, name a new technology they're using in their engines, launch vehicles, Dragon, and etc. Sigh Of *course* there’s no “new technology” in *anything* that’s in the world today. Your engineering mindset has you in a motivated reasoning spiral. The fact remains that, over the course of time, new technologies have been developed that have made their way into space programs. SpaceX is taking advantage of some of those technologies today. It is a safe bet that such innovations will occur in the future, and somebody will take advantage of them. And it's an even safer bet that none of those 'new technologies' are going to replace "throwing stuff aft to move forward". A space elevator on Earth requires not 'new technology', but 'new physics'. It would be possible to build a space elevator using materials available today without any major new technology. But that wouldn't be economical. Not even remotely close to being economical. New materials would be needed to build a sane space elevator, but new physics isn't needed. See for instance http://space.nss.org/media/2000-Spac...A-CP210429.pdf I recall reading at least some analyses that said that the tensile strength required exceeded atomic forces (in other words, an impossibly strong material). Without having checked, I would guess that that applies for a non tapered cable. But if you taper the cable, it is physically possible to build a cable using several existing materials. Alain Fournier |
#53
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Towards routine, reusable space launch.
In article ,
says... On 2018-06-14 05:22, Jeff Findley wrote: Innovation in terms of engineering, but not new technology. OK, I understand your argument. But just because carbon fibre has existed for some time does not automatically "void" the "new technology" when it is used in new applications such as cryo tanks or aircraft fuselage. Carbon/fibreglass were originally just "fabric" that was cut to right shape, layed up and resin applied to it and let it cure. True, but that's essentially still the state of the art today. Composite layup machines have been around for decades. A guy I used to work with wrote the layup software for the Cincinnati Milacron machines back in the 1980s. What they sell today evolved from those machines: https://metal-cutting- composites.fivesgroup.com/products/composites/fiber-placement- systems/cincinnati-viper-fps.html Wouldn't you agree that it is new technology to take the raw strands in a large spool, and lay individual strands in a computer optimized position/direction just after the strand has been impregentated with resin? Nope, as I said, been done at least since the 1980s in an automated fashion. Sure the tech keeps getting better allowing for bigger structures, but it's an evolution of tech that's decades old. This new tech allows totally new applications that were not possible before with that same material. Airbus for instance developped new tech to combine 2 existing materials: glass fibre and aluminium (Glare which has layers of aluminium, layes of glass fibtre composited together). You can view this as either a new material, or just "engineering" of 2 existing materials. Materials tech is always evolving. This is a tad different than carbon fiber layup, so I'd count that as new, whenever it was first done. I'm not a materials engineer, so I don't know when that would be for glass fiber and aluminum. Coming back to SpaceX, I am not sure if their building an all composite cryo tank for BFR represents new tech or not. If they are using the same techniques/equipment as Boeing uses for the 787 for instance, it woudn't be "new technology". But it is also possible that they develop new way to lay the fibre to make the tank. There is also the issue of the resin and how it is cured which could potentially represent new tech (especially if they do away with an autoclave or curing oven). X-33 attempted to do just that. It failed due to the complex geometry. BFR/BFS is sticking with traditional cylindrical tanks, which is a proven geometry for carbon fiber composites. They're being pretty conservative as far as their use of carbon fiber goes, IMHO. From what I've read, they'll be sticking with traditional techniques to minimize development risks. I fully expect them to cure it in an autoclave. Orbital ATK, or whatever it's called now, is doing much the same with their OmegA SRB segments. Again, this is a proven technology used by Orbital ATK for many programs. NASA had a composite wound SRB program many decades ago. It was canceled due to cost overruns, but that technology is in use today and proposed for SRB upgrades for SLS, but that wouldn't fly for maybe 10+ years given the pace of SLS Block 1 development. http://www.spaceflightinsider.com/or...e-on-one-with- atks-charlie-precourt-about-composite-materials-and-nasas-space-launch- system/ 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. |
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Towards routine, reusable space launch.
The [JWST] telescope is folded, not only the solar arrays.
In particular the 6.5-m primary mirror is folded as well as many other pieces. It's frightening to watch the deployment videos. In article , Fred J. McCall writes: And THAT is because you cannot make a single mirror that large to adequate precision, At least three observatories with seven telescopes in active use will be surprised to learn that. Not to mention additional ones planned. Every JWST presentation I've seen that mentioned the subject said that using a deployable (folding) mirror is because the Ariane 5 shroud is too small to fit a 6.5-m mirror. I wouldn't be surprised if there are "black" programs with the same difficulty. That said, this particular use case doesn't necessarily justify a rockoon approach, which will be difficult at best for large boosters. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
#56
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Towards routine, reusable space launch.
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#57
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Towards routine, reusable space launch.
On Jun/15/2018 at 7:56 AM, Jeff Findley wrote :
In article , says... It would be possible to build a space elevator using materials available today without any major new technology. But that wouldn't be economical. Not even remotely close to being economical. New materials would be needed to build a sane space elevator, but new physics isn't needed. See for instance http://space.nss.org/media/2000-Spac...A-CP210429.pdf I recall reading at least some analyses that said that the tensile strength required exceeded atomic forces (in other words, an impossibly strong material). Without having checked, I would guess that that applies for a non tapered cable. But if you taper the cable, it is physically possible to build a cable using several existing materials. That's my understanding as well. Better materials would make a tapered cable practical. Today's materials result in a very huge tapered cable necessitating a huge counterweight making the whole thing impractical. So, we're arguing about impossible versus impractical here. Either way, it's not going to be built with today's materials. Yes. But I think I am a little less optimistic than you about it becoming practical in the future. If we have fantastic materials in the future, maybe an elevator will become more practical, but SpaceX is likely to figure how to build fantastic rockets if you give them fantastic materials. So if you can build an elevator that would seem practical today, that elevator might compete with a rocket that can be reused 1000 times between inspections AND have high orbital mass fraction. It is possible that we find a way to build a practical cable but not find any major improvement to rocket technology. But I wouldn't count too much on that. Of course maybe I just read too much into your sentence "Better materials would make a tapered cable practical." Alain Fournier |
#58
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Towards routine, reusable space launch.
On 6/15/2018 6:21 PM, Alain Fournier wrote:
On Jun/15/2018 at 7:56 AM, Jeff Findley wrote : In article , says... It would be possible to build a space elevator using materials available today without any major new technology. But that wouldn't be economical. Not even remotely close to being economical. New materials would be needed to build a sane space elevator, but new physics isn't needed. See for instance http://space.nss.org/media/2000-Spac...A-CP210429.pdf I recall reading at least some analyses that said that the tensile strength required exceeded atomic forces (in other words, an impossibly strong material). Without having checked, I would guess that that applies for a non tapered cable. But if you taper the cable, it is physically possible to build a cable using several existing materials. That's my understanding as well.* Better materials would make a tapered cable practical.* Today's materials result in a very huge tapered cable necessitating a huge counterweight making the whole thing impractical. So, we're arguing about impossible versus impractical here.* Either way, it's not going to be built with today's materials. Yes. But I think I am a little less optimistic than you about it becoming practical in the future. If we have fantastic materials in the future, maybe an elevator will become more practical, but SpaceX is likely to figure how to build fantastic rockets if you give them fantastic materials. So if you can build an elevator that would seem practical today, that elevator might compete with a rocket that can be reused 1000 times between inspections AND have high orbital mass fraction. It is possible that we find a way to build a practical cable but not find any major improvement to rocket technology. But I wouldn't count too much on that. Of course maybe I just read too much into your sentence "Better materials would make a tapered cable practical." Alain Fournier how about a Space Slingshot ? |
#59
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Towards routine, reusable space launch.
On Jun/15/2018 at 8:18 PM, Sergio wrote :
On 6/15/2018 6:21 PM, Alain Fournier wrote: On Jun/15/2018 at 7:56 AM, Jeff Findley wrote : In article , says... It would be possible to build a space elevator using materials available today without any major new technology. But that wouldn't be economical. Not even remotely close to being economical. New materials would be needed to build a sane space elevator, but new physics isn't needed. See for instance http://space.nss.org/media/2000-Spac...A-CP210429.pdf I recall reading at least some analyses that said that the tensile strength required exceeded atomic forces (in other words, an impossibly strong material). Without having checked, I would guess that that applies for a non tapered cable. But if you taper the cable, it is physically possible to build a cable using several existing materials. That's my understanding as well.* Better materials would make a tapered cable practical.* Today's materials result in a very huge tapered cable necessitating a huge counterweight making the whole thing impractical. So, we're arguing about impossible versus impractical here.* Either way, it's not going to be built with today's materials. Yes. But I think I am a little less optimistic than you about it becoming practical in the future. If we have fantastic materials in the future, maybe an elevator will become more practical, but SpaceX is likely to figure how to build fantastic rockets if you give them fantastic materials. So if you can build an elevator that would seem practical today, that elevator might compete with a rocket that can be reused 1000 times between inspections AND have high orbital mass fraction. It is possible that we find a way to build a practical cable but not find any major improvement to rocket technology. But I wouldn't count too much on that. Of course maybe I just read too much into your sentence "Better materials would make a tapered cable practical." Alain Fournier how about a Space Slingshot ? What do you mean by Space Slingshot? Alain Fournier |
#60
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Towards routine, reusable space launch.
JF Mezei wrote on Fri, 15 Jun 2018
22:13:01 -0400: On 2018-06-15 19:21, Alain Fournier wrote: Yes. But I think I am a little less optimistic than you about it becoming practical in the future. If we have fantastic materials in the future, maybe an elevator will become more practical, Apart from lifting geostationary satellites to just below orbit and then let them use their own thrusters to position to their assigned slot/longitude, what other use would a space elevator have ? You go above the GEO point on the cable and get flung on interplanetary trajectories. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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