Fred R. Klein wrote:
>
> And I'm not an aerodynamicist, and probably know just enough to get myself
> in real trouble. I seem to recall that interference drag between fuselage
> and wing primarily builds up aft of the center of lift when there is no
> gentle transition, but I may be completely off-base. Perhaps fairing the
> leading edge is just as important...I do not know.
The first part is apparently valid, and common is from no to small
fillet radius from leading edge to max chord thickness, then increasing
in radius to between 4-8% times chord at the trailing edge. Extending
the fairing aft of trailing edge is very important, but how it should
all look on a given fuselage is something only a wind tunnel can
disclose. Hoerner's work looks at various aspects in isolation, meaning
he doesn't tell you exactly how to design the fairing. Strojnik
("Laminar Aircraft Design") says there are "no fixed rules," and points
out that if too large, other types of drag increase especially in
cruise. Raymer ("aircraft Design: A conceptual Approach") implies that
various fairing arrangements can be roughly equivalent in efficiency,
and at minimum "eyeball" it so that it "looks good."
Guess this doesn't help much, but might save folks some $$ in not buying
too many books!
Fred F.
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