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Re: Bernoulli's relationship



At 02:04 PM 11/9/00 -0500, Hugh Haskell wrote, regarding the "static port"
used for altimeters and such:
The opening is usually
angled a little toward the rear of the plane and set flush to the
skin of the plane, so it is essentially measuring the pressure in the
boundary layer, where the air is not moving, relative to the plane.

Whaaaaat?????

1) I've seen dozens of different types of static ports, and I've never seen
one angled toward the rear. And I can't imagine why you would want that.

2) Not all of them are flush with the skin of the plane. For instance on
Piper Cherokees etc., it's at the end of a blade, more than 2 inches from
the nearest skin.

3) Whether or not it's in the boundary layer has nothing to do with how
accurately it measures the static pressure. There are places in the
boundary layer that are a full 1.0 Q above ambient. There are other places
that can get to be several Q below ambient.