<3C1FCB28.5B2B1FEE@ameritech.net>
In message <3C1FCB28.5B2B1FEE@ameritech.net>, Fred Fillinger
<fillinger@ameritech.net> writes
>It requires a wind tunnel to observe, and often shows up only at lift
>coefficients too low to sustain flight. Hoerner hints that with the
>location of max chord thickness on the Europa wing, sorry, won't
>happen. It has nothing to do with the "step," though, except in cases
>where one doesn't have the power to accelerate to the cruise speed
>where the phenomenon appears, but enough to stay there once in the
>bucket.
The low drag bucket in sailplanes occurs at lower speeds (referenced to
the stall speed) than are being considered for the Europa. It is not
necessary to use a wind tunnel. All that is necessary is a performance
curve carried out on the whole aeroplane. It is also possible to
temporarily install a drag measuring probe at the trailing edge of the
wing. The world expert is probably R.H. Johnson at the Texas Soaring
Center at Caddo Mills airfield near Dallas.
Ken Whiteley
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