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B Efficient Fast Orbital Transportation/Construction?

  1. Jan 15, 2017 #1
    Is it plausible that you could launch a flywheel into a geostationary orbit, have it spinning very fast, and from both sides release two parcels at the same time so the flywheel doesn't go off course and so the 2 parcels travel in orbit to the other side of the Earth and re-attach to another awaiting flywheel? If this is correct this would allow for minimal energy loss and fast travel/construction.
     
  2. jcsd
  3. Jan 15, 2017 #2

    berkeman

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    How do you keep the flywheels spinning?
     
  4. Jan 15, 2017 #3
    Because they're in space?...Won't they basically indefinitely keep spinning?
     
  5. Jan 15, 2017 #4

    sophiecentaur

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    If they are to be used for projecting a payload into a higher orbit then they will, in principle, need just as much energy put in as if you use a burst of rocket fuel.
     
  6. Jan 15, 2017 #5
    I'm confused, is the whole idea plausible?
     
  7. Jan 15, 2017 #6

    berkeman

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    No. The energy put into the projectiles subtracts from the rotational energy of the flywheel. There is no "free energy".
    Not as you stated it, it's not practical. The projectiles still need maneuvering fuel to accurately reach their target, so you don't save much by having to keep using fuel to spin the flywheels back up.
     
  8. Jan 15, 2017 #7

    sophiecentaur

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    I'm confused too because you haven't actually described what it would do. In principle, you could use two long arms to give two loads a lot of kinetic energy by gradually building up the speed with a low power unit and then releasing them at just the right time in the rotation cycle. What would be done on the other side - remember that the two loads would have a higher orbit from the original launch system.
    What is your system supposed to achieve? Is it a kind of postal system?
     
  9. Jan 15, 2017 #8

    berkeman

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    Good point, I missed that subtlety. :smile:
     
  10. Jan 15, 2017 #9
    It's supposed to achieve a whole bunch of flywheels (and technological-structure) staying in space - in a geo-stationary orbit, with the flywheels holding the stored energy for a long time, and so, when the constructors want to transport matter, they can *quickly and *efficiently transport matter to even the other side of Earth say, and capture back the energy in the awaiting flywheel so minimal energy is lost.

    Could it work?
     
  11. Jan 15, 2017 #10

    berkeman

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    In a word, No.
     
  12. Jan 15, 2017 #11

    berkeman

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    Did you understand Centaur's point about what happens to your orbital height as a function of the added energy? Do you have any idea how much fuel it would take to try to maneuver to have both projectiles hit the far flywheel at exactly the same time? If you were off by so much as a second trying to dock, it could destroy both projectiles and the far flywheel.
     
  13. Jan 15, 2017 #12
    So you're saying the far flywheel on the other side of Earth, when hit by the precisely timed parcels, will go into higher orbit??

    I don't get it, you have two flywheels on opposite sides of Earth, with the same orbital height all perfectly, and one flywheel is spinning fast with two loads, then releases them and they re-attach to the other flywheel. I'm really anticipating what could be wrong :) !!
     
  14. Jan 15, 2017 #13

    berkeman

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    When the projectiles leave the first flywheel with a higher velocity than they had when attached to the first flywheel, they will rise to the higher orbit that corresponds to that higher velocity. They miss the far flywheel as they fly right over it, unless you burn maneuvering fuel to lower their velocity and aim for the far flywheel. But if they have the lower velocity to match the far flywheel's orbital height...

    And you still are not understanding how hard it is to super-precisely match two projectiles over many thousands of kilometers of flight.

    Maybe it's time to put down the comic books and pick up the physics textbooks? :smile:
     
    Last edited: Jan 15, 2017
  15. Jan 15, 2017 #14
    I understand the precision. I'm putting the precision on the shoulders of a future super-artificial-intelligence.

    So as you said at the end, if their velocities when let go were not so big then they would not go diagonal and rather be on the same height level and would work?
     
  16. Jan 15, 2017 #15

    berkeman

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    It would be more efficient to just use fuel to give the extra transfer velocity to any inter-satellite transfers.

    Thread closed temporarily for Moderation (and out of scientific frustration...)
     
  17. Jan 15, 2017 #16

    berkeman

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    After a Mentor discussion, @IsItSo -- if you can PM me your quantitative analysis of this proposal, we can re-open your thread. Until that time, it will remain closed.
     
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