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Air Levitation Skis

  1. Apr 8, 2017 #1
    Are there any good research papers or established theories on using skis with either porous air bearings or an air skirt with holes to send pressurized air out? One of my concerns right now is the stability of a ski (ie any particular shape each ski/section should be and whether we should divide each ski up into sections) and most optimal way of funneling air out from a compressed source to the atmosphere. Essentially these skis will support a hovercraft-like contraption that is supposed to run over a fairly smooth surface.
     
  2. jcsd
  3. Apr 8, 2017 #2

    anorlunda

    Staff: Mentor

    It sounds like a variation on the air puck. Since air pucks are manufactured by several sources, a search for air puck design may help.

    I think that there are industrial versions of the air puck used to assist moving heavy things. They should come with data sheets.
     
  4. Apr 8, 2017 #3
    Our design is supposed to support between 1/2 - 1 ton of weight moving at high speeds. Would an air puck design suffice for such parameters?
     
  5. Apr 8, 2017 #4

    anorlunda

    Staff: Mentor

    Yes, if the surfaces are sufficiently flat, hard and smooth. Snow would be a poor surfaces.
     
  6. Apr 8, 2017 #5
    When I said high speeds, I was talking about speeds between 100-200mph. Right now we're working with a smooth, metal track surface that has plus or minus 1 mm height differences at the gaps. Would these air bearings survive impacts at those speeds with such height variations?
     
  7. Apr 8, 2017 #6

    anorlunda

    Staff: Mentor

    WOW that's really fast.

    I'm not really an expert on those things. But as a general guess, I would think no, they would scrape. The high speed also raises questions of dynamic loading changes, and the air cushion being stripped away by friction.

    The industrial things I mentioned, would have little in common with 100-200 mph applications.

    If you are making something that impacts human safety, I'm very sure that you'll need to comply with applicable codes and need a sign-off from a registered professional engineer, instead of asking for advice from strangers on the Internet.
     
  8. Apr 8, 2017 #7
    This is for a design class, not practice but it still has to be realistic. You're saying that at high speeds, the air cushion of a traditional air bearing will almost disappear because of friction?
     
  9. Apr 8, 2017 #8

    anorlunda

    Staff: Mentor

    I said that I'm no expert.

    But I do know that at low speeds, the air flows out in all directions including the direction if motion. Friction at high speed must diminish the forward air flow. Quantitatively, I can't say.
     
  10. Apr 8, 2017 #9

    Baluncore

    User Avatar
    Science Advisor

    See; https://en.wikipedia.org/wiki/Air_bearing

    As the ski moves forward, half the supporting air will be left behind.

    At high speeds it would be possible to use ram air pressure ; to support a load of ;
    100 mph -- 0.178 psi -- 25.56 lbs/sqft
    150 mph -- 0.399 psi -- 57.52 lbs/sqft
    200 mph -- 0.710 psi -- 102.26 lbs/sqft
    250 mph -- 1.110 psi -- 159.78 lbs/sqft
    300 mph -- 1.598 psi -- 230.08 lbs/sqft

    To understand the support process you should study the concept of “oil wedge” bearings.
    https://en.wikipedia.org/wiki/Fluid_bearing#Michell.2FKingsbury_tilting-pad_fluid_bearings
     
  11. Apr 9, 2017 #10
    Thank you. This makes sense.
     
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