Re: How Important Is Cross-section Shape Of Wing?

Date:         31 Mar 2001 16:43:05 
From:         "Ken Ishiguro" <kenish@earthlink.net>
Organization: EarthLink Inc. -- http://www.EarthLink.net
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> Either way you look at it, the shape of the wing is not the main element.
> Otherwise, how could a plane fly upside-down?

Planes designed for sustained inverted flight have symmetrical or nearly
symmetrical airfoil cross sections.  You will note a plane flying inverted
is nose-up...this is to give the wing a positive angle of attack.  Also, the
vertical component of thrust is a big contributor, too.

If airflow over the top of the wing were unimportant, then subsonic
transport aircraft could fly faster than the usual mach 0.85 .  The limiting
factor is when the airflow over the top of the wing accelerates and becomes
supersonic, lift goes away.  This wouldn't be true if the top of the wing
was not a factor.  (BTW, a "supercritical airfoil" is one designed to allow
supersonic flow over the top of the airfoil).

A thin layer of frost on the top of the wing can drastically reduce lift.
This too, would not happen if airflow over the top of the wing didn't
matter.

>As an old barnstormer was
> reported to have said, "Give me enough power, and I'll fly a barn door."
>
You're confusing two modes of flight...flight due to wing lift (sailplanes
as the ultimate example), and flight due to brute thrust (the Space
Shuttle).

Ken Ishiguro