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Ed - I can see the 7 degree tangent line concept. What I don't follow is the idea that the next tangent comes off the prior line a certain distance away. With these tangency origin points far apart the generated spline curve is gentle. As the points of tangency are pushed closer together the curve gets tighter. There must also be some ratio of delta X to delta Y along the curve to stay within the bounds of non-separation, right? I suppose that ration is based on air speed?
Freightliner is building a full-scale wind tunnel in Portland. I wish I could take my plane over and see what is really going on inside.
Kevin Lane Portland, OR
e-mail-> n3773@comcast.net
----- Original Message ----- From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, April 05, 2005 5:41 AM
Subject: [FlyRotary] Re: class in curves
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
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