hydroplane handling issues ??

Discussion in 'Powerboats' started by afrhydro, Jul 23, 2008.

  1. afrhydro
    Joined: Mar 2008
    Posts: 243
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    Location: port charlotte fl

    afrhydro Senior Member

    hydroplane handling issues ?? suggestions

    ok i hope i can explain this so you understand what I'm talking about
    not every time but some times i dont know why
    after you get up to speed
    see video below

    the boat drifts left then right back and forth i always just get off the gas
    i posted a video of another boat doing the same thing and he just drives threw it
    is there away the fix this


    http://dragboatracing.com/Media/Vid...ctive-From-The-Seat-Of-Problem-Child-TFH.aspx
     
  2. eponodyne
    Joined: Aug 2007
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    Location: Upper Midwest

    eponodyne Senior Member

    Do you have air traps installed?
     
  3. afrhydro
    Joined: Mar 2008
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    Location: port charlotte fl

    afrhydro Senior Member

    i just installed a set but have not tried it yet
    plus i re aranged all my weight more forward now as well
    maybe it wont do it now
    ill have to find out
    but i was just asking what would or could cause it
     
  4. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

    You have to remember that a hydroplane, whether a three point, or pickle fork (from the video it's hard to tell but it looks like a pickle fork) is not really a boat, it's a low flying aircraft that touches the water at a few places on the hull. So the laws of aerodynamics are more important at speed than hydrodynamics. You have a wing forward. That wing is supposed to keep the bow down. But since the bow goes way up at startup you are making a big change in the angle of attack and creating lift instead of downthrust. I don't know what the rest of the boat looks like, but you haven't said anything about steering and rudder size, and how much of the stern is in the water. All these things effect your steering. Hydroplanes should never have more than a degree or two angle of attack when at speed. Otherwise they kite, that is take off and fly. Which is what appears to be happening in the video. It seems to be on the verge of taking off. Unfortunately they don't fly well. So you need to look at how high the bow is flying and how much rudder surface is actually in the water, plus how much slack is in the steering. There should be none.

    Back to the canard (the wing at the front), some of the unlimited hydroplanes use an adjustable wing that changes angle as the bow rises to get the bow back down. But it's not manual it's down by a computer.

    Just some thoughts.
     
  5. afrhydro
    Joined: Mar 2008
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    Location: port charlotte fl

    afrhydro Senior Member

    i been wanting to put two canards on this since i built it
    front and rear and try to fly it
    here is a mix of pictures
    some old some new
    i have moved the cockpit forward added air traps and transome wedges like trim tabs kinda
    it has always run as a tail dragger so far
    i have blown the tail a few times and that when the steering issues really show up
    its a prototype that i designed and built and still a work in progress
     

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  6. afrhydro
    Joined: Mar 2008
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    Location: port charlotte fl

    afrhydro Senior Member

    i think i see it
    the pad on the sponson needs to be fatter
     

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  7. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

    Also, you might want to think about adding a small fin on the inboard side if each sponson. It doesn't have to be real big, just maybe six inches long by six deep, triangular. Just something to keep it going in straight line. Since it's a drag boat, you don't have to worry about going around the buoys so this won't affect turning ability.
     

  8. afrhydro
    Joined: Mar 2008
    Posts: 243
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    Location: port charlotte fl

    afrhydro Senior Member

    i like your thinking
    Don't tell me that I can't. Tell me how I can!"

    yea i have a set of fins made up but i never put them on yet
    cause we just cruising around most of the time
    just hit it for short burst from time to time
     
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