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Posted for "Mark & Lisa" <marknlisa@hometel.com>:
Paul,
Can you tell me more about the outer lip of the NACA duct? Are you
referring to the aft lip, or the sides? My understanding is the sides edges
must be sharp to induce the vortexes that create the airflow into the the
duct. Do I have this wrong?
Regards,
Mark Sletten
Legacy FG N828LM
http://www.legacyfgbuilder.com
-----Original Message-----
From: Paul Lipps [mailto:elippse@sbcglobal.net]
Sent: Friday, April 21, 2006 20:57
Subject: Why a Lancair
...snip...
Don't steal cylinder cooling air from the
upper plenum to feed the oil cooler. Feed it with a separate inlet with a
diverging duct, then give it a converging duct and outlet pointing to the
rear; don't just dump it into the area ahead of the firewall. Don't use the
so-called "NACA" duct unless you understand its pressure recovery vs duct
flow ratio. It's just one of three of the family of "submerged" ducts. Its
proper name is divergent curved-wall submerged duct. There is also
straight-wall divergent submerged duct and a parallel-wall submerged duct.
Is the outer lip of your NACA duct sharp or is it rounded and shaped like an
inverted leading edge? If it's sharp, it's wrong!
...snip...
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