In message <Pine.SOL.3.91.960124075111.2277A-
100000@world.evansville.net>, Steven A Eberhart <newtech@evansville.net>
writes
>
>I too plan on building an Europa and build radio controlled models. I am
>designing a 40% scale Europa with Rutan wet layup fuselage and Europa
>style hot wired foam flying surfaces.
>
Whilst there is obvious pleasure in making the model as close a
representation to the real thing it may be better to stick with a
section profile known to provide good scale model handling particularly
near the stall.
A Europa wing foil scaled to 40% will have a tip chord of something like
405mm which at approach speeds of say 14 m/sec (40mph) resulting in a
Reynold number of around 375,000 at the tip and about 470,000 at the
root, well critical for that kind of section. Boundary layer flow and
separation bubbles get very complicated below Re 500,000 especially on
foils with favourable pressure gradients extending so far aft as on the
Europa foil.
You may consider using a well documented turbulent section, eg.
NACA2415, which may provide broadly similar lift coefficient and
pitching moments though at the expense of some additional cruise drag.
I would hate to think that all your hardwork might get dashed to bits on
the first outing.
--
Graham E Laucht
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