John wrote:

Morning Paul,
You made a comment that you knew the oil cooler NACA ducts on Nemesis NXT

wouldn't work. I've been trying to improve the NACA ducts on my BD-5 and
wonder if you could send me data on why the Nemesis ducts are not working?
My BD-5 has three NACA ducts (see photo), two on either side of the fuselage
"keel" to feed the rad and one further back for the oil cooler. They work
fairly well but on hot days (above 90ºF) climb rates are down around 300 fpm
to keep things in the green. There was an article in Sport Aviation in Nov
03 describing the installation of vortex generators ahead of NACA ducts.
They were supposed to DOUBLE the airflow. I've tried that and they do seem
to help but not that much. Any information would be appreciated. If the
price of a rotary engine I'm looking at doesn't go "through the roof" I may
be joining the Rotary community by converting my BD-5 to rotary power.

Regards,
John Lewis
N501BD

The NACA scoops have been around so long people fail to read the original
tech
papers and that includes Boeing engineers and Jon Sharp, Nemesis Nxt
designer, who works
for the Lockheed Skunk works no less. They use them because they look kool
but
they don't cool :)

Paul Lamar

Alex Madsen wrote:

This is an interesting webpage on adding baffles to NACA ducts to increase
cooling. http://4dw.net/marcborom/LongEZ/NACA_AirFlow.htm It looks like the
duct is not designed with the "ideal" profile so I do not know how much it
applies to ducts with the recommended profile. If I can get a lab group
together for ME Lab I would like to study this in schools wind tunnel this
fall.

Alex Madsen

No flush intake will ever work as well as a ram air intake for heat exchangers IMHO. 
It is too easy for the air to decide to just bypass the opening.

Paul Lamar
 
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