> A recent issue of Scientific American carries a mind virus! :)
>
> In the "Working Knowledge" column, the author presents an incorrect and
> long-debunked explanation of how wings work:
>
> "because the wing top is curved, air streaming over it must travel
> farther and thus faster than the air passing underneath the flat bottom.
> According to Bernoulli's principle, the slower air below exerts more
force
> on the wing than the faster air above, thereby lifting the plane."
>
http://www.scientificamerican.com/article.cfm?chanID=sa006&colID=9&articleID=00009993-1F9A-1417-9F9A83414B7F012B
>
>
> The above explanation is wrong, and is known as the "Equal Transit-Time
> Fallacy." This incorrect explanation is widespread among children's
> books, but I'm suprised to see it in a reputable magazine like SciAm.
>
> It's debunked here:
> NASA GRC: Incorrect lifting-force theory #1
> http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html
> http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html
>
>
> Also see other debunkings:
> Anderson/Eberhardt: a physical description of flight
> http://www.aa.wa****ngton.edu/faculty/eberhardt/lift.htm
>
> Denker: How Airplanes Fly
> http://www.av8n.com//how/htm/airfoils.html#sec-inverted-camber
>
> Irrotational inviscid flow: Streamline animations
> http://www.idra.unige.it/~irro/profilo1a_e.html
>
> Or just ask yourself this: if airfoils *must* be more curved on
> top, doesn't this prove that symmetrical airfoils cannot work,
> and that upside-down flight is impossible?
Yes, but the NASA page *does* say the air flow over the top of the an
airfoil that is producing lift *is* faster, and furthermore that this
*does* create lift from the Bernoulli principle!
The only fact that is incorrect is that the streams over the top and
bottom have to meet at the trailing edge. In fact the flow over the top
is faster even than this. The question is *why* does it have to be
faster than the flow over the bottom?
Also, notice in the animation with a symmetrical airfoil there is *no*
lift at zero angle of attack. Then this might suggest in the
symmetrical case it is just Newton's force laws at work.
Bob Clark
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