Chris

Some of the Century Series Fighters had a RAT (Ram Air Turbine). It
was mounted on a hinged door and was deployed by a handle and cable
from the cockpit. It gave enough hydraulic pressure for minimal
control of the A/C with loss of engine hydraulic pressure.

If you connected a ventura on a hinged spring loaded door that
could be extended into the slip stream when needed your problem might
be solved simply and with not a lot of extra weight or drag in normal
flight?

You also could put a vacuum pump, that is propeller driven, on door
that could be extended if and when needed.

You of course need to mount door to open in a high pressure location
in the slip stream.

Big John

On Sun, 26 Oct 2003 08:20:49 -0600, Chris W wrote:

Here is why I was asking about the reverse NACA duct. I am thinking
that a simple venturi would be a great backup to an engine driven pump.
Naturally no one wants to add the drag that bolting a venturi tube on
the side of the plane would give. So I was trying to think of a way to
make it retractable. Then I started thinking about using a NACA duct
and keeping the venturi inside the plane, probably in the rear
fuselage. You would open a vent when you needed it and keep it closed
when you didn't. So the question I have now is how to make sure there
is no drag penalty when the venturi is not in use. Would it be
necessary to cover both entry and exit holes or would simply shutting a
valve to prevent air flow do the job?