Bob Kuykendall wrote:
Earlier, wrote:
Take a look at some of the papers on the site...
I did. I also chatted about them with one of the aero engineers whose
work is cited in them. We agree that it's a bunch of hokum. It looks
almost like it was designed to spawn a bunch of conspiracy theories
like the ones about GM suppressing the 200 mpg carburator.
As regards the topic of winglets raised by another poster, they're
great for span-limited and bending-moment-limited situations, which is
why they're popular on sailplanes and airliners. L/D-wise it's more
effective to just make the wing longer - that is, a 2-foot span
extension usually increases the performance more than a 2-foot tall
winglet. But of course, extra span drives the wing bending moment up
more, so there are many cases where you can have a winglet but not the
equivalent span extension.
That feathered tip is about the exact opposite of Steve Wittman's tiny tip
trapezoid approach.
(for the newbies)
Some early NACA reports indicated that the outer one-chord-length of wing
span was disturbed by the tip vortex. (That vained thing might show some
promise in this respect, but the drag of it - just due to increased surface
area alone - and all ALL speeds???)
Anyway,
If the tip chord were reduced, what would happen to the total wing tip vortex?
The story goes Steve decided to test this eye-dia by modifying one wing tip.
He took off and tip-toed around the pattern holding near full aileron to hold
near level. Landed, rolled it back into the hanger and fixed the OTHER tip.
Steve's tip modification did indeed reduce the sink rate for any given speed.
Ergo...
Richard
May you always have a Tailwind...