Hi,

I know this is not rotary related but I know that this is the only place
where I would get a professional answer to my questions.

I’m in the stage of fitting the panel as well as the turtle deck. Seeing
that it is a composite plane, it is quite airtight. I was thinking of
placing two small NACA ducts in the cowling to provide fresh air in the
cabin. However, I feel that this air must be expelled somewhere. Should
I place two same size ducts on both sides of the vertical stabilizer, in
the turtle deck? Another question. During flight, if I just close the
vent inside the cockpit, would it cause a lot of drag? Last question.
Does anybody have drawings for a NACA duct?

Regards,

Pierre Swanepoel

South Africa

Any outlet will work. Just a hole in the tail will work if the cockpuit
is indeed higher pressure than out side air.

However it is near impossible to seal a cockpit entirely.
Usually you will find the cockpit air at a lower pressure than
the outside air because of the bulge in the cross sectional area
of the fuse. so just about any cockpit air inlet works that faces
forward.

Here is the NACA duct proportions.

Paul Lamar