AviationBanter - View Single Post - The Impossibility of Flying Heavy Aircraft Without Training

David CL Francis

On Mon, 27 Feb 2006 at 09:29:48 in message
.com,
wrote:

Conservation of angular momemtum causes the air to continue swirling
after the aircraft has passed. Once the pressure changes caused by
the passage of the aircraft have died out and the pressure restored to

ambient the net downward flow from the entire aircraft is equal to net
upward flow from the entire aircraft, provided the aircraft is in level
flight.
The point missed her is that the pressure changes and velocity changes
to the air after the wing has passed only die away because energy is
lost far away from the wing's immediate influence. Making a big deal
about the fact that the disturbance disappears and thus the atmosphere
stays much as it was before (only a bit hotter) seems to suggest that
there is no momentum change as the wing does its work. Perhaps this is
what is meant but it cannot be used as proving in any sense that the
wing has no net effect.

The same argument would not be very convincing in demonstrating that the
air going into a fan dissipating 1000s of HP is the same going out as it
was coming in!
--
David CL Francis