>I have been doing a bit of research on wing tip shape, and it would appear
that a smoothly rounded tip produces the most induced drag, because of the
ease with which higher pressure air can on the bottom of the wing can
*escape* around to the top of the wing.
>
>I am considering a Hoerner wing tip which appears to reduce the tip
vortices. I shaped one out of scrap foam over the weekend which matches
nicely with the rest of the wing.
>
>Has anyone else considered this option or taken it up with the factory? Is
there any reason why Europa went for rounded teardrop wing tips other than
for ease of manufacture or to provide a convenient surface for mounting
wing tip lights ?
>
>Mark Clark
>#285 Centurion
>South Africa
Don Dykins' book on the design of the super efficient wing explains many
factors involved in the definition of the final wing geometry.
We asked Don to comment on the idea of Hoerner wingtips for the Europa and
the following is a summary of his reply:-
One essential element is matching high and low speed requirements.
Yes, tip devices can be designed to reduce induced drag, but they will at
the same time increase the tendency to tip stall and may therefore
adversely affect stall handling.
Reduced induced drag will enhance climb performance but will have little
effect on cruise performance where the induced drag is small.
For a new design the added complication and risk of extra development
flying and time it was not worthwhile.
As a development exercise on an existing design it could be interesting,
but be careful.
Poor basic design gives the prospect of good improvements - by definition
there is little be gained on the Europa!
Roger Bull
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