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Propellers and Fans with divergent or convergent ducts - HOVERCRAFT

  1. Nov 5, 2007 #1
    Question -1:
    Is quote #1 below as given in the context of the provided link accurate? I mean I know its a pressure difference which allows propellers to move a craft, but doesn't the mass of the craft have something to do with the optimum ratio of air velocity to air pressure?

    Question - 2:
    Is quote #2 far below in the context given accurate?

    Quote-1:
    Hovercraft thrust
    http://hovercraft.org.uk/FUDforum2/...36&start=0&S=3df1be915756ee7d88ea526483100274
    ...........................................................................
    Quote-2:
    Hovercraft lift
    http://www.hoverclubofamerica.org/forum/index.php?showtopic=1402
    [quote name='kach22i' date='Nov 1 2007, 09:58 AM' post='13323']
    Remember resistance builds pressure, and you want that pressure to form under the craft, not in a chamber above it.

    Also remember that a narrowing duct increases velocity and lowers pressure, and a diffusing or getting larger duct lowers velocity and increases pressure as the air mass flow attempts to fill that greater volume.

    1. Look up the terms "pressure diffusion and constriction" in the context of air flow in ductwork.

    2. See my project, and my past mistakes and solutions.

    NOTE
    Example below is for "thrust", put on your thinking cap to imagine how it applies to "lift".
    http://www.globalsecurity.org/military/lib.../al0993/le2.htm
    [​IMG]
    ..............................................................

    http://www.globalsecurity.org/military/lib...m/1-506/Ch2.htm
    [​IMG]
    Aside:
    http://www.baihp.org/pubs/develop/index.htm
    [/quote]
     
  2. jcsd
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