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There are two things you can do to the
control surface shape that will both reduce drag and reduce flutter tendency. 1.
Increase the leading edge thickness by 15% of the leading-surface TE, on each
side, with a rounded shape. 2. Give the top and bottom surfaces a convex shape.
Doing (1) can lead to the creation of the (2) shape. The larger shape
ahead of the leading-surface TE does two things. It provides Coanda-effect to
turn air flow through the gap around toward the rear, and reattaches the flow
coming from the leading surface. This can result in a drag decrease of about 20%
locally, so that it is the same as with no control surface break. Ref: "The
Design of the Aeroplane", Darrol Stinton, p.444.
Scott: The nav antenna is given a
slight sweep-back in order to fill in the null along the array axis; remember
the donut shape with a null out to each side along the hole axis. And yes, Matt,
that could be destructive interference. But keep in mind that the destructive
signals could come from bad connections or leaky coax just as well as
re-radiation. If you didn't make the coax, I would definitely look at your whole
transmission line scheme as my experience is that builders show incredible
building talents but are often electrically-challenged when it comes to wiring.
The VSWR box is your friend there. I have written in the past about the
semi-rigid coax available from Andrew. It is an item well worth the cost when
thou$and$ are spent for avionics which then don't get good signals. Every link
in the chain is important.
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