On Jun 3, 5:41 pm, wrote:

The prop does not throw air outward. We've been over that
one before. The air column actually narrows behind the prop, due to
the lowered pressure caused by the air's acceleration. We can see it
on cool mornings when the dew point is just below ambient temperature,
and the vapor trails off the prop tips outline the periphery of the
air column, showing it to be squeezing inward.


More on the narrowing of fluid flows behind propellers:

Marine propeller: http://www.aip.org/pt/feb00/maris.htm

Helicopter rotor: http://www.camrad.com/CAMRADIIresults.html

Behind transport props: http://home.att.net/~polar/130contrail.jpg

Behind an F4U's prop: http://people.bath.ac.uk/ensmjc/Research/corsair.gif

In no case do we see air (or any other fluid) being thrown out
centrifugally.

Dan