JAXAshby wrote in message
...
I haven't heard of this design ("S" shaped airfoils) in
aerodymamics before

Naughty Jax.

You've mis-quoted me by adding the bit in brackets. In full:

"Now I think the device you're proposing is designed to add a
downward speed to the air, then subtract that speed, leaving no
net change in downward speed. Is that correct? If so, you're
proposing that a net force can be generated by displacing air
through a distance, rather than adding momentum to it.
Interesting.

*I haven't heard of this design in aerodymamics before* except in
the context of windmills. I can see how such a device would
generate a magnificent torque (lift at the front, cancelled by
'anti-lift' at the rear)."

The design I was referring to was the technique of creating lift
without adding downward momentum to the passing air, and I have
asked if my understanding of your device (the S foil) and its
working is correct.

Because, I always thought that if there was a force, you had a
linked change in momentum.

So (unless I mis-understand you) you're proposing a revision of
the basic laws of physics.

Explain please. Without mis-quoting.

JimB