Wayne.B wrote in message
...
On Thu, 1 Apr 2004 10:33:19 +0100, "JimB"
wrote:

I'm not proposing that the air 'has to catch up'. I'm just
saying
that if it loses pressure, it's got to gain speed (or disperse
energy in some other way).

==================================

Let's try for an intuitive approach using a flat plate (your
hand, for
example). Imagine sticking your hand out the window of a
moving car
and "flying" it through the air as most of us have probably
done as a
kid until our parents yelled at us.

If you hand is more or less parallel to the ground, you have
wind
resistance (drag), but no lift. Tilt you hand slightly upwards
and
now the wind strikes the bottom of your palm and forces it
upwards
(lift). The reason lift is created is that your hand is
deflecting
molecules of air downwards (change in momentum), and the
resultant
force is upwards. It's simple Newtonian mechanics.

It's OK Wayne. I understand the dynamics of lift reasonably well.
I'm trolling to check that Jax also understands it.

JimB