Kevin,

Its been a while, but  what I was doing was first, drawing an approximate
curve based on a truncated Streamline duct.  Then adjusting it mainly by eye
from inlet to core to fit my space constraints.  Then I used a CAD program
to plot lines of tangent and varied from one tangent line to the next by
approx 7 deg. (some figure from NACA wind tunnel testing data).  If the
tangent lines pretty well match my curve in a region I kept the curve, if it
varied too much then I adjusted my curve (by eyeball) to more closely follow
the tangent line.  That's the best I can recall of the process.

Ed


----- Original Message -----
From: "kevin lane" <n3773@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, April 05, 2005 12:57 AM
Subject: [FlyRotary] class in curves


> Ed - I am building intakes right now and noticed in your photo many
tangent
> lines you used to derive your shapes.  I'd love a quick lesson on what you
> are doing.  I've been simply mocking what I think sorta' looks the same.
> Since I am taking AutoCAD classes I could design stuff to any accuracy.
I'm
> guessing that your lines are some type of maximum curvature limits to
avoid
> separation?  I always wondered how one measured degrees of curvature on a
> curve.  I know, like you don't have enough to do ! :-)
> Kevin Lane  Portland, OR
> e-mail-> n3773@comcast.net
>
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>