Miata Mailing List: February 1996, Message #122
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   From: aeromer@ix.netcom.com ((WBPL) )
Subject: Re: NACA "Duck"
   Date: Fri, 2 Feb 1996 21:24:48 -0500

Miata List,

The NACA (National Agency for Civil Aviation) duct was developed as the 
most effecient (ie. lowest drag) opening in the skin of an aircraft.  
You will see these on fighters and other high performance airplanes.
There is quite a difference in the performance of a "NACA Duct" 
depending on where it is located in the airflow.  The "Miata Duck" is 
perhaps totally ineffective located where it is on the headlight door.  
It is certainly useless when the headlamps are up!  There may even be 
air expelled via the duct ie. de-pressureizing the engine compartment.
Don't sweat the rain, the "duct" is there for looks only.  If you 
really want the look, cut the shape out of black vinyl and stick it on.

If you really want to test this put a few drops of dirty engine oil on 
the headlight door around the duct.  Drive fast (in Montana this could 
be fun) and when you stop look at how the drops of oil have streaked 
your highly polished h/l door and hood!

This subject has been explored on the list several times in the past.  
One good suggestion which was posted here a few months ago was to 
connect a real "duct" from the high pressure area at the base of the 
windshield (easy and invisable access requiring some cutting however) 
to the airintake on the Left front wheel well.  Makes sense to me.

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William B. Peter Lee, Ph.D.               _________   ___
AeroMer@ix.netcom.com                  | __/o|oo\____/__| 
UNC/USC/UCLA/USN                      <=[___ | __/------/
LAMM@netcom.com                        |  /    \
xLotus/xRover/xCessna/94MX-5M            <=KITFOX-IV=<
N 34 16.134  W 118 35.453

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