Ahah! Now, you've finally gotten to the crux of the matter.

You say diameter is the important thing. You are right
because when you put a venturi into a hose you get
a suction effect at the ventur. The suction proves
lower pressure exists in the area of the venturi.

In the case of a single surface foil the lower pressure
IS caused by the increased length of the surface which
has the effect of making a smaller pipe for the air to
pass through.


"PIM" wrote in message ...

"Simple Simon" wrote
This longer path for the air lowers the pressure
because said air must move faster to cover the increased cord.

The air does not need to speed up to cover the extra length.

When you take a longer way to go home home,
you will just come home later!

same goes for water in a garden hose.
The length of the garden hose does not influence the speed through it.
Diameter and water flow is of importance.
(ok, a really long hose will have so much resistance that the flow will
drop)

Best Regards,
Pim


--
Posted by news://news.nb.nu