aerodynamic lift/drag ratio

Discussion in 'Powerboats' started by PetterM, Mar 28, 2008.

  1. PetterM
    Joined: Sep 2004
    Posts: 211
    Likes: 9, Points: 28, Legacy Rep: 201
    Location: Norway

    PetterM Senior Member

    What is a typical aerodynamic lift/drag ratio for high-speed power mono hulls? I am tying to evaluate some results that do not quite make sense.
  2. Mild Bill
    Joined: Nov 2007
    Posts: 33
    Likes: 1, Points: 8, Legacy Rep: 11
    Location: Northern Illinois

    Mild Bill Well, not entirely mild.

    Conventional aerodynamic theory plus test results on lifting bodies would suggest that the best aerodynamic L/D of a high-speed power mono hull could not be higher than 3 or 4, and is probably a lot lower.

    It depends in large part on CDo, the coefficient of profile drag (the drag due to air flow over the body at zero lift). I don't see how even the most refined high-speed power mono hull could have a CDo equal to or lower than the CDo of a lifting body. If the mono hull CDo is actually much higher (which I suspect is true), any benefit that might be gained from ground effect would be pretty much nullified.

    What are the results that do not quite make sense?
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