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Re: [Michalak] Leeboards

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  • Anders Bjorklund
    Make the leading edge a nice 30 deg ellipse about 50% of the plate thickness, bring that to full thickness at about 20% chord Trying to figure out how to go
    Message 1 of 81 , Jun 21, 2013
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      "Make the leading edge a nice 30 deg ellipse about 50% of the plate
      thickness, bring that to full thickness at about 20% chord"

      Trying to figure out how to go about that. I get the 20% chord, but not how
      to draw a "30 degree ellipse about 50% of plate thickness". Anybody know
      offhand? Otherwise, I'll keep Googling ...

      Anders


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    • Samantha Roberts
      Yes, you are using just the end of the ellipse to shape the leading edge. ________________________________ From: Anders Bjorklund
      Message 81 of 81 , Jun 21, 2013
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        Yes, you are using just the end of the ellipse to shape the leading edge.



        ________________________________
        From: Anders Bjorklund <andersbjorklund5@...>
        To: Michalak@yahoogroups.com
        Sent: Friday, June 21, 2013 8:08 PM
        Subject: Re: [Michalak] Leeboards



         
        I think I got it. Thanks. It looks like the tangent line back to the 20%
        chord would meet the ellipse VERY near its forward tip then. Interesting.

        Anders

        On Fri, Jun 21, 2013 at 2:10 PM, Samantha Roberts <
        samanthaeroberts@...> wrote:

        > A 30 deg ellipse is a circle viewed at 30 deg from the plane in which it
        > lies (if viewed at 90 deg, it appears as a full circle). This makes a 30
        > deg ellipse twice as long as it is wide. So if your plate thickness is 1",
        > the ellipse you need to draw is 1" long and 1/2" wide (50% of plate
        > thickness).
        >
        > Now draw a smooth curve that lies tangent to the ellipse and reaches full
        > thickness at 20% chord. Since John does not specify either this curve or
        > the one from 60% chord to the T.E., I assume he means that those shapes are
        > not critical. On the general principle of not trying to make water flow
        > around sharp corners, I would make those two curves come smoothly into the
        > flat section from 20% to 60% chord, but I am not sure how important that
        > might be.
        >

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