Why Airplanes Fly - Voids Above A Planar Sheet

On Oct 4, 10:27 am, Le Chaud Lapin wrote:

The cigarettes would be lit so that stream of smoke floats
upward.

Can cigarettes be lit so that the smoke flows downward?

If flat pressure sensors were mounted below the wing, close to the
trailing edge, they would show a momentary increase in pressure.

We've been told for years by people who do wind-tunnel
experiments that the pressure on the bottom is not increased. Again,
it's not intuitive. We're feeling drag, not an increase in pressure.
If we hold a funnel (a version of a converging duct) with the big end
to the wind, we'll find accelerating airflow in it, decreasing
pressure, decreasing temperature, and drag that makes us think that
the pressure in it is increasing.
The air below is moving downward, something that could be
measured by an airspeed indicator, but that doesn't mean pressure is
increased. It means that the air has dynamic pressure now because it's
moving, and if it's moving its static pressure has decreased.
Better get building this thing. Get back to us as to the
pressure readings under the wing.

Dan

Dan