.......... If the APU(Aux. power unit)caught on fire during a start, the
NACA duct

immediately closes. This door was the only acceptable means to do this.

It was

not a function of getting more air to the APU. ...........>
Doug

I guess this could be done just as well with a regular scoop (like a belly
cowl flap just facing forward, .....sorry but my Rhino-prowess still
sucks!), and the ram effect would probably be a lot better. Or a straight in
scoop on the vertical stab leading edge with a internal shutter or ball
valve. I guess there are plenty more solutions.
Any Boing engineer on the list? Like to comment?

So what's the verdict?
Is there any valid use for the NACA duct, where there is NO better (less
drag....) alternative?

Thomas J.

If there ever was a good place for a NACA scoop on the front of the
cowling 
is it. As Tom Parkes found out it did not work well here either. Once 
you raise the lip it is just another bad scoop taking in the boundary
layer.
Ed Anderson had a similar experiences five years ago.

Paul Lamar
 
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