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Thread: Mass driver to launch payload into orbit

  1. #1 Mass driver to launch payload into orbit 
    Forum Cosmic Wizard icewendigo's Avatar
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    How about building a maglev accelerator with a tube several kilometers long that arrives at a mountain and curves upwards to launch car sized rocket mostly constisting of payload(instead of mostly fuel)? If it were meant for resilient supplies(not for humans) you could even intitiate the acceleration with a cannon-like explosion.

    If it was not possible/useful decades ago when it was probably first imagined, maybe the technologies available today can make it an intersting option?

    Any thoughts?


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  3. #2  
    Time Lord
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    Use a mountain near Vancouver Canada, you could have a 45° run from sea level to 1.2km peak altitude. I guess most of the Rockies are suitable.



    We just built a 15km underground subway, costing $2 billion. So maybe ballpark cost of your project: $1 billion US.

    A good source of power since you're going up a mountain, is hydroelectric. You can supplement the neighbouring city grid by day, and launch stuff by night when demand is low.


    A pong by any other name is still a pong. -williampinn
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  4. #3  
    Universal Mind John Galt's Avatar
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    Vancouver is too far north. you want something more equatorial to benefit from the higher velocity.
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  5. #4  
    Forum Cosmic Wizard icewendigo's Avatar
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    So an international mass driver project could be located in Equador or Venezuella or New Zeland...

    As there been recent studies to eveluate if its feasable?
    (I'll go check out space.com? or nasa)

    Without any facts, my feeling it that the initial cost of the infrastructure would be relatively high but that once done lauches could be nighly/weekly occurences and might be much less expensive.
    Maybe a canon like charge could kick start the ride trough the tunnel so that the payload/minirocket already goes fast from the start as it accellerates along the maglev tunnel?
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  6. #5  
    Forum Professor Wild Cobra's Avatar
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    Quote Originally Posted by icewendigo
    So an international mass driver project could be located in Equador or Venezuella or New Zeland...

    As there been recent studies to eveluate if its feasable?
    (I'll go check out space.com? or nasa)

    Without any facts, my feeling it that the initial cost of the infrastructure would be relatively high but that once done lauches could be nighly/weekly occurences and might be much less expensive.
    Maybe a canon like charge could kick start the ride trough the tunnel so that the payload/minirocket already goes fast from the start as it accellerates along the maglev tunnel?
    I have a hard time thinking it would be plausible to do. The speed required for escape velocity would cause too much heat from atmospheric friction. I think the heat shield alone would be an engineering nightmare.
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  7. #6  
    Forum Radioactive Isotope skeptic's Avatar
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    I think cobra is right. However, a driver might be useful to start another type of vessel on its way. Escape velocity is 7 miles per second. To get that on a short run up a mountain side would not be possible, I suspect. And as cobra said, the atmospheric friction would burnt it up.

    Let us instead imagine an object about the size of a jumbo jet accelerated up that mountain side. When it leaves at the top, it ignites scramjet motors which continue to accelerate it substantially further. When the air gets too thin to support scramjets, rocket motors ignite to continue the acceleration.

    One of the problems with the scramjet idea is the need to get to high velocity before they can be used. The mass driver might accomplish that nicely.

    However, I do not think $US 1 billion would do it. Add a couple of zeros. Also, I do not think that magnetic levitation technology is yet up to the task. Maybe in a few more decades??
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  8. #7  
    Time Lord
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    As skeptic said, the driver needn't (and shouldn't) accelerate a package to escape velocity. It would help immensely by eliminating the initial rocket stage.
    A pong by any other name is still a pong. -williampinn
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  9. #8  
    Forum Cosmic Wizard icewendigo's Avatar
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    I found this in wiki on Space Gun

    On the practical side, the most prominent recent attempt to make a space gun was artillery engineer Gerald Bull's Project Babylon, which was also known as the 'Iraqi supergun' by the media. During Project Babylon, Bull used his experience from Project HARP to build a massive cannon for Saddam Hussein of Iraq. This gun, had it been completed, would have been the first true space gun capable of launching objects into space. However, Bull was assassinated before the project was completed.

    Its not been done but though technically challenging it appears that its possible to reach escape velocity from the ground (its sad that this visionary scientist Gerald Bull was assasinated by Israeli murderers[likely suspect])

    I assume the objects that this space gun were to be of modest size, but over decades of further research and dev we might have been able to send supplies to the International Space Station
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  10. #9  
    Forum Radioactive Isotope skeptic's Avatar
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    icewendigo was talking about http://en.wikipedia.org/wiki/Space_gun

    This article makes it clear that a space gun could not carry humans or delicate instruments due to the enormous accelerations required, and also states that orbit could not be achieved without corrections on route to its trajectory - meaning rocket motors attached to the projectile capable of making a substantial change to its direction of movement.

    The last attempt at a space gun was from Saddam Hussein. More rational and expert nations know damn well that it is not a practical alternative.

    The suggested mass driver, using electromagnetic levitation, though, might form part of a total package that might work, when combined with on board jet and rocket motors. An electromagnetic mass driver can be designed with an acceleration compatible with human welfare.
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  11. #10  
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    Quote Originally Posted by skeptic
    The last attempt at a space gun was from Saddam Hussein. More rational and expert nations know damn well that it is not a practical alternative.
    The Iraqi supergun was unashamedly meant for long-range bombardment in lieu of an air force. More rational and expert nations put a stop to that!



    The OP suggested resilient payloads (not human). This would be a nice compliment to space stations: rolls of sheet metal & insulation, cannisters of air and water, frozen dinners. Let the fragile stuff go up separately with fragile humans.

    I'm thinking we could buffer delicate parts in ice. For example 2nd stage rocket engine & nozzle packed solid in ice that melts off before it needs to fire.

    Is all that pricey superconductor levitation hardware necessary? Cannons don't need it.
    A pong by any other name is still a pong. -williampinn
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  12. #11  
    Forum Professor Wild Cobra's Avatar
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    On the bright side, I remember reading articles in the 70's about doing such things for materials that may be mined from the moon in the future. A linear accelerator could be used to launch materials to a Lagrangian orbit, earth orbit, or to earth. One thought was to have a processing center at the L1 orbit, then mone the processed metals to earth. Such an orbit has benifits for making alloys because of zero G.
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  13. #12  
    Time Lord
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    Quote Originally Posted by Wild Cobra
    Such an orbit has benifits for making alloys because of zero G.
    Other benefits, not obvious: you don't need a container - a big ball of heated ore may simply float in the vacuum insulation of space. Then give it a little spin, and you've "made" a centrifuge.
    A pong by any other name is still a pong. -williampinn
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  14. #13  
    Time Lord
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    Quote Originally Posted by Wild Cobra
    I have a hard time thinking it would be plausible to do. The speed required for escape velocity would cause too much heat from atmospheric friction. I think the heat shield alone would be an engineering nightmare.
    Yeah, and no matter how fast you were going, the atmosphere would slow you down to a lower speed before you ever got up to orbit. Air friction slows fast moving objects more than slow moving objects, even after both travel the same distance. If you started at Mach 20, you'd probably be down to mach 10 or lower before you even got a mile away from the cannon.

    Here's a link that doesn't directly relate, because it's about bullets in water, but it should give you the same general idea. Air is considered a "fluid" for purposes of drag, just not as dense a fluid as water.

    http://kwc.org/mythbusters/2005/07/m...oof_water.html

    Quote Originally Posted by skeptic
    I think cobra is right. However, a driver might be useful to start another type of vessel on its way. Escape velocity is 7 miles per second. To get that on a short run up a mountain side would not be possible, I suspect. And as cobra said, the atmospheric friction would burnt it up.

    Let us instead imagine an object about the size of a jumbo jet accelerated up that mountain side. When it leaves at the top, it ignites scramjet motors which continue to accelerate it substantially further. When the air gets too thin to support scramjets, rocket motors ignite to continue the acceleration.

    One of the problems with the scramjet idea is the need to get to high velocity before they can be used. The mass driver might accomplish that nicely.

    However, I do not think $US 1 billion would do it. Add a couple of zeros. Also, I do not think that magnetic levitation technology is yet up to the task. Maybe in a few more decades??
    The trouble for scramjets is that they are usually only optimized to a specific pressure and velocity. If that problem could be solved, like perhaps by making an engine that's able to change its own geometry, then this would be awesome.

    In theory, a scramjet with the right geometry should be able to reach escape velocity in the upper atmosphere and cruise on out into space without needing any additional rockets. Maybe it could use an ion drive after that point?
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  15. #14 Two stage Three stage 
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    Firstly we need to work in a paradigm shift. It is not only wrong but really really wrong, to build all the complicated stuff here on earth and launch it into space.

    We need to launch the machine-shop and electronics shop and optics shops into space. Send the engineers and techs up there and build whatever we want UP THERE. The one time cost of putting the construction of those complicated things up there is paid back by the savings of being able to ship only raw materials (and those only until we reach other sources of raw materials).

    ________________________

    First stage puts the payload at altitude - ONLY at altitude to be intercepted by second stage. Second stage is an orbiting "coil-gun" which gradually accelerates the payload to orbital velocity.

    The coils of the orbiting "gun" are laser aligned, not connected physically. A series of rings separated by vacuum. All orbiting together. Several advantages come from this.

    1. You don't have to be anywhere near so rigorous with the ground based system. It only has to go to altitude. Needn't be brutal at all.

    2. You can do something like Rutan's designs to launch passenger pods from earth if you like.

    3. No individual ring of the orbital gun is particularly huge and impossible.

    4. The orbital gun is already in vacuum.

    5. It can be long enough so that the acceleration is gradual enough for delicate things. No problem with length.

    6. The initial orbit of the payload is the orbit of the orbital "gun" and gently arrived at. It does not intersect the earth.

    7. Things accumulated at the end of the gun could be aggregated and moved to their destinations with robotic tugs.


    ----

    Downsides:
    1. You have to build the orbital "gun" by moving/building coils into precise orbits.

    2. Building it needs the Ground based driver and solid resources (material for conductors etc) launched to orbit... or a fair bit of conventional rocketry.

    3. The orbital gun decelerates as the payload is accelerated, and needs to:

    a. Work in both directions (catching things at orbital velocity and decelerating
    them to rest relative to the surface so that they can simply fall).

    b. Have recovery thrusters and fuel replenishment to maintain its orbit. (Ion
    propulsion?)

    c. Both.

    ....

    I am sure someone else has thought of this already. Kingsbury had something like it in one of his books.

    A third stage could fire things to escape velocity

    respectfully
    BJ
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  16. #15  
    Forum Cosmic Wizard icewendigo's Avatar
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    ~ Air = Fluid which decelerates the space cannon / mass driver projectile ~

    Would it be possible to use a laser cannon to clear out air or create a vacuum line in the path of the projectile, or create a projectile that emits a magnetic field strong enough to repel a significant percentage of air from its path (ex: 90% of the air is repelled and doesnt touch the surface while 10% causes friction)
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  17. #16  
    Forum Professor Wild Cobra's Avatar
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    Quote Originally Posted by icewendigo
    ~ Air = Fluid which decelerates the space cannon / mass driver projectile ~

    Would it be possible to use a laser cannon to clear out air or create a vacuum line in the path of the projectile, or create a projectile that emits a magnetic field strong enough to repel a significant percentage of air from its path (ex: 90% of the air is repelled and doesnt touch the surface while 10% causes friction)
    Like cavitation in water?

    Who knows. I personally think it wouldn't work right. The laser would be too much faster than the projectile, and the air would close back in on it with even more density I think.
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  18. #17  
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    Quote Originally Posted by kojax
    Yeah, and no matter how fast you were going, the atmosphere would slow you down to a lower speed before you ever got up to orbit. Air friction slows fast moving objects more than slow moving objects, even after both travel the same distance. If you started at Mach 20, you'd probably be down to mach 10 or lower before you even got a mile away from the cannon.
    A partial workaround is build the device on a mountain were you're above half the atmosphere and near the equator...like the Andes.
    Meteorologist/Naturalist & Retired Soldier
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  19. #18  
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    Quote Originally Posted by Lynx_Fox
    Quote Originally Posted by kojax
    Yeah, and no matter how fast you were going, the atmosphere would slow you down to a lower speed before you ever got up to orbit. Air friction slows fast moving objects more than slow moving objects, even after both travel the same distance. If you started at Mach 20, you'd probably be down to mach 10 or lower before you even got a mile away from the cannon.
    A partial workaround is build the device on a mountain were you're above half the atmosphere and near the equator...like the Andes.
    You still have to come to terms with the peak acceleration, which is likely to be quite high. Most payloads are limited.

    This idea has been considered and rejected.
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