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Cant go Far Wont Go Far

  1. Oct 24, 2003 #1
    This is my first post to the physics forum and I see my input is well needed. First off Fossil fuels are like fossils they are history. We cant even get into orbit with out tons of the stuff. O2 as a fuel Is just a band-aid on a larger problem. Sure it is lightweight such as hydrogen but since space is a void any depleatable resource would be inefficient and therefore useless. Nuclear Propulsion as we know it may be perfect for an underwater stay in a military submarine but that technology is to crude and still in it raw form. Maybe in the future larger spaceships or commercial space programs my investigate Nuclear Propulsion but a reactor in a spacecraft is just not a bright idea. My favorite theory would be magnetic repulsion. You see examples of that in levitation experments and high speed trains. See
    my theory is based on the same principle we use today in space travel. You use the majority of your fuel during takeoff, but once in orbit you only need minimum thrust to propell an object and without any external forces acting upon the vehicle the only forces acting on the craft would be magnetic repulsion. But there is more to it than that. Or is it?
    Last edited: Oct 24, 2003
  2. jcsd
  3. Oct 24, 2003 #2


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    Science Advisor

    Greetings !

    Welcome to PF Smart Guy ! :smile:

    Hmm... what exactly do you want us to push against ?

    Live long and prosper.
  4. Oct 24, 2003 #3
    you could tie a magnet to the trailer hitch.
  5. Oct 24, 2003 #4
    The problem is that the tension in the trailer cable will pull back any magnetic repulsion you get.

    A fossil fuel propulsion system may be 'heavy' in terms of the fuel, but the engine itself is relatively straightforward and light. Compare that with a magnetic/ion/nuclear propulsion system where the reactor, shielding, coils, magnets, etc. will weigh a lot.

    Oxygen is an oxidiser. Not a fuel.
    Space may be a near vacuum but who said you can't mine stuff along the way? :wink:

    Commerce (and maybe a good marketing team) can turn 'not bright ideas' into good ones. Hey, a good insurance salesman can con you bankrupt and keep you smiling along the way

    The levitation so far accomplished has only been miniscule. Don't forget magnets are big, heavy blocks of ferritic material. If you're talking about ceramic-based superconductors, then you will still need a power plant and a cryogenic cooling system (at least until room temp. superconductors are developed).
  6. Oct 27, 2003 #5
    There are various designs for magnetic sled type launching pads to minimize friction while gaining momentum and then the sled stays on the tracks while the rocket takes off.
  7. Feb 15, 2004 #6
    Just don't bring your NIB magnet collection with you (to space)
    -or run out of track
    -or power (were launching, launching, screACH shatter BOOM BANG!)
  8. Feb 15, 2004 #7


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    Staff: Mentor

    We don't generally use hydocarbons for rocket fuel (except in small amounts for thrusters). They space shuttle uses hydrogen and oxygen for the main engines and aluminum and ammonium percholrate for the boosters.
  9. Feb 15, 2004 #8
    Re: Re: Cant go Far Wont Go Far

    Well well I see this is a topic to be discussed. Oxygen is an oxidiser huh? Whats that high school physical science class. Bush has proposed a mission to mars by 2020, but has no earthly idea on how to get there. I have submitted a few other topics to this forum but I feel the best about this one. I feel the people who participate in this forum is the cream of the crop, but so far this thread has not produced any good theories. First of all space travel has no rules, no guidelines and most important no size limitations. To rule out nuclear power would foolish, because if nuclear belongs anywhere it would be in space, and away from us. To say advances in levitation are miniscule is totally false. We can lift a passenger train off the ground while traveling over 150 mph. That is more than enough repultion to launch an object from a space craft. I started this topic with a bogus theory to provoke conversation. Since we are on the same page I figured there would be more critisism about about magnetic repulsion. Propulsion bases would be far to complicated and expensive not to mention. Any type of fuel that is diplinishable is useless in space. Its far to vast. I'll check back later.
    Last edited: Feb 15, 2004
  10. Feb 15, 2004 #9
    Now that is a good idea more speed at takeoff less friction less fuel less polution that may work.
  11. Feb 16, 2004 #10


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    Greetings !
    This idea has been considered many times.
    It's greatest problem is purely economical.
    The velocities such a track needs to produce
    are at least about half the total velocity the
    rocket will require or more (all of it, for example,
    considering that some will be lost to friction and
    a bit during ascent to LEO). The lenght of the maglev
    track required for this is huge - tens of kilometers
    for unmanned rockets and hundreds of kilometers for
    manned rockets (due to acceleration limmitations).
    The track could be circuilar - but it'll still be
    very big in order to sustain the centripatal acceleration
    and that'll also require more magnets and power.
    In addition, the whole acceleration process will have
    to take place in a vacuum tube containing the track which
    further adds a lot to the costs. In short, we're talking
    many billions of dollars just for small and medium sized

    Maybe, if that magnetic supertrain underwater suspended
    maglev track that's supposed to ceonnect the US and the UK
    is ever built it could also be used for this sort of stuff.
    You still didn't say what kind of magnetic propulsion
    you're talking about. What do you want to push AGAINST ?
    The solar wind, the Earth's magnetic field or what ?

    The first idea works best today, in theory, using the
    M2P2 prop. system - dispersing a cloud of magneticly
    contained gas many kilomneters in diameter around the
    spacecraft to capture solar wind particles and transfer
    their momentum to it.

    The second idea doesn't seem practical because it requires
    too much power. You can't use a closed electric circuit
    because then no force will be produced, so you need
    to get your current from the surrounding plasma and
    then get rid of it at the other end, and you need huge
    amounts of current and/or lenght of the conductor/plasma
    containment tube to get any considrable net thrust - considering
    how weak the Earth's magnetic field is. Increasing the
    field using ferromagnets won't work cause they're just
    too massive for it to be effective.

    Peace and long life.
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