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Gimbaled flywheel

  1. Nov 9, 2007 #1
    Ok so I just had a bit of a eureka moment. Conventional battery flywheels are not made to be portable (gyroscopic forces make this quite difficult). This can be offset with gimbaled systems, negating the gyroscopic effects that occur in a fast-moving flywheel. However, these types of systems are often bulky and require a lot of space. My solution: build the flywheel into the gimbals! Picture this: a tube, bent to form a ring. This ring has a series of electromagnet arrays spaced out along its length. Within this ring, we put another ring, this one solid. This new "inner-ring" is our flywheel. Any comments/suggestions?
     
  2. jcsd
  3. Nov 9, 2007 #2

    brewnog

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    How is the middle ring suspended? Just by a normal gimbal arrangement?
     
  4. Nov 9, 2007 #3
    Thats what I'm picturing yes.
     
  5. Nov 10, 2007 #4

    Danger

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    Some sketches would be nice. I'm having a bit of trouble picturing it.
     
  6. Nov 10, 2007 #5

    mgb_phys

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    Be careful playing with flywheels http://www.xkcd.org/332/
     
  7. Nov 10, 2007 #6
    Hehe I like that. I'll do up a quick sketch and have it up by tomorrow. How do I post pictures?
     
  8. Nov 11, 2007 #7
    Oops, ok, I just read up on the forum rules and discovered that I'm not allowed to post pictures. I can email it to whoever is interested in seeing it though, through attachment. The best way I can describe it is as a ring within a ring, attached in the normal gimbaled-arrangement to another ring within a ring, and so on. The outer rings would have electromagnets along their lengths, able to spin up the inner rings to sufficient speeds.
     
  9. Nov 12, 2007 #8
    posting pics is not allowed??? from when??? it aint so dude, either attach it or there is a button to paste pics

    lolz!!! greetings HUMANS, i m gyro man
     
    Last edited: Nov 12, 2007
  10. Nov 13, 2007 #9
    Ok here is a quick diagram I did up not too long ago. Its rough, I'm working on a mac and I had to download a paint program which I'm not too family with (quite buggy :S).
     

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  11. Nov 13, 2007 #10

    mgb_phys

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    It works - the problem with using flywheels to store energy.
    They have to be massive, the more mass the more energy.
    They have to be large, energy increases with diameter^2.
    They have to spin fast, so need to run in vacuum, supporting pumps etc.

    Flywheel storage is sometimees used instead of batteries in backup power.
    Some buses have a flywheel as an alternative to batteries for stop-start travel in cities. The flywheel is mounted horizontally so the gyroscope effect only acts to stop the bus tipping over.
     
  12. Nov 13, 2007 #11
    Right, but picture these rings in a gyroscope formation. Would this not save space, allowing us to use more flywheels at a slower, safer speed?
     
    Last edited: Nov 13, 2007
  13. Nov 13, 2007 #12

    mgb_phys

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    If you mean putting several gyros at 90deg to each other as in a gimbal then no - you are using a lot more space then simple spinning a single heavy cylinder.
     
  14. Nov 13, 2007 #13
    But my idea is to incorporate the flywheel into the gimbal system itself, negating the need for a seperate gimbal system needed to stabalize the gyroscopic forces.
     
  15. Nov 13, 2007 #14

    Danger

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    Nice picture, but I'm still a bit lost here. How is it attached to whatever it's attached to? I don't see any axles or studs or anything there.
    More importantly, what makes it spin? If you're thinking of it working like a linear induction motor bent into a circle, your 'flywheel' can't be solid. You'd have to have alternating N & S magnetic domains for the electromagnets to work against. Maybe I'm missing something? :confused:
     
  16. Nov 13, 2007 #15
    Sorry, I just thought to include the single flywheel in my diagram. If completely assembled it should look something like a gyroscope in a box, the box being the support structure for the gyrsocope. The rings would move about freely (like in a gyroscopic) whichever way the forces are acting on them. On the matter of actually getting the flywheel to spin, I am not familiar with electromagnets and their workings. I just assumed that maybe the core of the flywheel itself could be composed of alternating north and south magnetic domains, and that this would be the most efficient way to speed the flywheel up. I'll try and post another picture.
     
  17. Nov 15, 2007 #16
    Does anybody have an idea as to what types of equations I need to use in order to figure out the energy capacity of a ring-like flywheel? Are they more or less the same as a traditional disk based flywheel?
     
  18. Nov 15, 2007 #17

    mgb_phys

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    The kinetic energy of a rotating flywheel = 1/2 I w^2
    w = (omega really) rotation rate in rad/s
    I ( moment of inertia) depends on the shape, generally it is of the form =constant * mass * radius^2, so the more mass and the bigger the radius the more energy. For a loop I = 1/2 m r^2
    It's fairly easy to derive but there is a list for common shapes http://en.wikipedia.org/wiki/List_of_moments_of_inertia.
     
  19. Nov 15, 2007 #18
    How about a good, preferably free 3d design tool that I can use to do up a couple diagrams :) any suggestions?
     
  20. Nov 18, 2007 #19
    Still at it I see. Great.

    I'm thinking the money guys are gonna' go to the metal oxide capacitors for energy storage on mobile equipment.

    I wanted some excitement one day 'bout 35 years ago and my brothers and I had the rear wheel off a 305 honda dream. All I remember now is that when we tried to hang on to it when we got it spinnin' with a grinder we got a lot more excitement than we wanted. The old man was less than pleased with what happened in the garage when it got away from us. We decided we spun it too fast. It seemingly had a mind of its own. We had, at first, a chair that would swivel in a complete circle. We revved it a little and found that if we could hold it and sit in the chair it could turn the chair in a circle one way or the other depending on which way we tried to turn the wheel. Cool. But if a little speed is neat a lot should be really neat. What a mess. Shelves bent. Parts scattered everywhere. Ah youth.
     
    Last edited: Nov 18, 2007
  21. Nov 19, 2007 #20
    I like to think outside the box :) I am not a physics major, nor am I particularly good at math, and that is one of the main reasons why I come on these forums. I have learned more here then anywhere else, and am very grateful for all feedback that I have received. On another note, I have been reading about EEstor's claims and while I think it would be a tremendous paradigm shift to the mobile electronics economy, I have my doubts as to whether or not they've actually come up with something tangible. Flywheels are a proven technology, and although they has been tremendous research and development put into them, it just hasn't been enough to yield desired results.
     
    Last edited: Nov 19, 2007
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