wrote in news:380a3b72-e9e1-4b9f-86a5-
:

On May 23, 7:52 am, Bertie the Bunyip wrote:
wrote i
So it's a process to cause the air to exert a force in a
direction perpendicular to the airflow. It fools the air, if you like,
which is why we call it an "air foil." A foil is a device to deceive.


Actually it's a synonym for blade.


Not quite. From the Merriam-Webster Dictionary:

Foil:
1 obsolete : trample
2 a: to prevent from attaining an end : defeat always able to foil
her enemies b: to bring to naught : thwart (foiled the plot)
synonyms: see frustrate.

So my "deceive" is much less accurate than "frustrate."

Your definiton matches one of the the Cambridge Dictionary's


That definition isn't relevant to this application, though.

definitions:

foil (SWORD) gatiful
noun [C]
a thin light sword used in the sport of fencing


More relevant, I suppose, but that definition is dervied from leaf or blade
as well. Foil as in thwart and foil as in blade have two completely
different origins, from waht I've been able to find...


http://www.thefreedictionary.com/foil

So I'd say arfoil was not used becasue of it's ability to frustrate air (
engineers just don't think like that, they seek harmony) but more because
of their resemblance to a leaf or blade.
Actually, the one in that link that stands out is the architectural one.


Bertie