> The reason that your canopy is bowing outward is that there is an acting
> pressure LOWER than ambient static on the outer surface due to the
airflow,
> not because of a pressure HIGHER than ambient static inside the fuselage.
> The pressure inside the fuselage starts out AT the total, or static,
> pressure prior to takeoff.  Once in motion, the pressure fuselage
gradually
> starts DROPPING due to the negative pressure (from the airflow) acting
> outside the fuselage.
>
> Try this example of the same effect:  go down the highway in your car.
Open
> the window halfway.  The pressure inside the car DROPS because the trapped
> static (total) pressure inside the car tries to escape to equalize the
> negative pressure flow going past the window.  So, the actual pressure
> inside the car (or fuselage) will actually be LOWER than the static
ambient
> pressure.

This depends on where the holes are in the fuselage are and what their
orientation is.  If you could open the windshield as a window, air would
rush in and inside pressure would be higher than outside.  A different
location and orientation can just as easily create a suction causing lower
than ambient cabin pressure.


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(978) 742-9014, http://www.embedinc.com

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