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#31
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Question on the space elevator
to me to even consider the energy stored in the
pressurisation. My point was simply that the material that made the beanstalk feasible compared to conventional rocketry would help make rocketry more competitive against a beanstalk. certainly, very resistant and light material may lead to much simplified design , for tanks and engines (a hose that would not breaak whatever the way you plug it..etc..), and maybe (??) pressurized tanks would get rid of the pumps in this way , a rocket may be assembled within a few weeks and ready to launch with reduced infrastructure .. then the cost of the fuel may become a concern ... which is not today, compared to the overall costs of launches building an elevator would anyway requires some conventionnal launches .. we may never get this magic material for the elevator , though it seems now not completely impossible I read somewhere that the resistance achieved and tested for carbon nanotube/epoxy composite was half way to the required strentgh .. with hopes to do better the price of the material may now be over ¤/$ 1000 per gram ... IF someone finds a way to produce nanotubes by the ton , then many things may have to be reconsidered !! that may be tomorrow , that may be never ... I am very amused by the perspective of building bridges unwinding something that looks like scoth tape ;-) more than this, some people seems no to believe (or make others believe they believe) in the space elevator example: http://www.liftport.com/ (they even have a date for it : Countdown to Lift: April 12, 2018 ;-) or http://www.highliftsystems.com/ (or maybe this one ;-) : http://www.spaceelevator.ca/ when everything else fails ;-) -- Julie "please save Yuri" http://membres.lycos.fr/andromedanews |
#32
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Question on the space elevator
"David M. Palmer" wrote in message ...
... think of the energy wasted as you drop the ash from your fuel over the side and let it just fall back to Earth. (If you could use it as a counterweight to pull you up, then you'd be better off.) Are counterweights crazy? Obviously so if the "rope" has to run the whole length of the beanstalk, but what if it runs only 100 km or so? Attach a car at each end, one goes up while the other goes down. When the cars are at the extreme positions, they change over to a different pair of ropes. (Or the cargo moves to another car on a higher or lower rope.) This arrangement means there have to be two cars every 100 km or 500 on the beanstalk at all times, and they have to run on a schedule or all stop and wait for delays to be sorted out. That's a nuisance, but this scheme might reduce power requirements quite a lot. Are there any show stoppers? I've just guessed at a likely length of the rope; would a different guess have been better? |
#33
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Question on the space elevator
nafod40 writes:
Gordon D. Pusch wrote: The significant difference is that, when climbing a beanstalk, one only has to supply the change in _energy_, not the change in _momentum_, which is is instead provided by the lateral force exerted by the beanstalk, which very efficiently extracts momentum from the angular momentum of the Earth. Does the beanstalk have to be straight up and down? Pretty much so. (It is under an =ENORMOUS= amount of tension!) If canted so as to lag the Earth's rotation (at least during a climb maneuver) how would that make a difference? It wouldn't. Since gravitation is a conservative force, the amount of work required to climb to a given distance from the Earth against the force of gravity is independent of the path along which one climbs. Also, please be careful not to confuse "velocity" with "force" --- the two are entirely different concepts, with no direct relationship to each other. -- Gordon D. Pusch perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;' |
#34
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Question on the space elevator
Why not use the power naturally developed in the cable? ... see the NASA
teather experiment no details :-) "Makhno" wrote in message ... The current answer to the last question isn't magnets but .. lasers. Free Electron lasers beam power to the climber, which converts the energy into mechanical energy (wheels or treads). IIRC, a FEL has been designed that can do the job. There's a lot of traffic in this thread about powering the climber. Why can't it simply have a diesel/gasoline engine with its own oxygen supply? Or run electrical cables up the elevator to power an electric motor? Why make things more complicated than they need to be? |
#35
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Question on the space elevator
Simon Peacock wrote:
Why not use the power naturally developed in the cable? Because the cable isn't moving w.r.t. the magnetosphere. Paul |
#36
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Question on the space elevator
"Makhno" wrote
The current answer to the last question isn't magnets but .. lasers. Free Electron lasers beam power to the climber, which converts the energy into mechanical energy (wheels or treads). IIRC, a FEL has been designed that can do the job. If the elevator continues to stretch out way beyond the balance point, at a certain length if we cut the anchors on Earth, it would float out away from Earth, wouldn't it? If the center of mass is at escape velocity for it's orbit altitude, the whole thing will float away. So we can use that capability by just tossing off mass at a much greater altitude (thereby slowing the Earth's rotation) and using that to lift the elevator. via a long cable loop. We could toss off bags of water, or something else that would disperse and cause no harm. |
#37
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Question on the space elevator
but isn't the magnetosphere constantly moving.. and the cable stationary ?
"Paul F. Dietz" wrote in message ... Simon Peacock wrote: Why not use the power naturally developed in the cable? Because the cable isn't moving w.r.t. the magnetosphere. Paul |
#38
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Question on the space elevator
Simon Peacock a écrit :
but isn't the magnetosphere constantly moving.. and the cable stationary ? I dont think it s moving this fast as compared to much fasters orbit (LEO) Why not use the power naturally developed in the cable? the cable , ribbon, would have to be very thin to exist so it would not be able to carry much power without dammage (?) the (I think) only (now) conceivable way to build it is to produce a composite (epoxy ..)with short carbon nanotubes .. it's not expected to be conductive -- Julie "please save Yuri" http://membres.lycos.fr/andromedanews |
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