REFLECTOR: NACA scoops

[Alex Balic]

Secondly, the problem with using the NACAs for radiator air is that they
do not build up a lot of pressure (vs a ram air scoop) I kept the top
ones to feed my turbo intercooler and dump air onto my turbo, fuel
pumps, and oil cooler, but the glycol radiator gets air from a belly
mounted ram air scoop - same setup that Dave Bertram has on his V8..
 
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Al Gietzen
Sent: Wednesday, October 19, 2005 10:43 AM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: NACA scoops
 
I don't want to rain on anybodies parade; but those considering liquid
cooled engines need to keep in mind that you are working with a limited
delta T for the air going through radiators.  About a 60F rise in the
air temp through the rad on a 90 F day is all you can expect, if
everything is right.  Considering that the specific heat of air is about
0.02 Btu/cu.ft F; you're going to need about 2200 cfm for every 100 hp
of engine output.  At a climb speed of about 120 kts, that's about 28
sq. in. of inlet area for a 100% effective scoop for every 100 hp.  If
you're lucky you'll get 75-80% effectiveness with a NACA scoop.
 
If I calculate correctly 2 X 11 X 2 X .8 = 35.2 effective sq. in. with
two of these NACA scoops.  This will work fine for 200 hp extended climb
on a 50 F day.  On a 90 F day expect this to cool about a steady 125 hp.
 
FWIW,
 
Al
 
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of NMFlyer1 at aol.com
Sent: Wednesday, October 19, 2005 5:07 AM
To: reflector at tvbf.org
Subject: Re: REFLECTOR: NACA scoops
 
Greg is right, 
 
 I talked to Scott S. about my desire to cool my 340HP V-6 in my 173 FGE
(standard size fuselage) with NACA scoops. He sent me the templates for
the XL due to the increased cooling needs. They are 11" x 2" at the aft
openning. I built them from the templates and found it quite easy. 
 
Although it might be more convienient to buy the premolded scoops, I
don't think it is necessary. I would call the Factory and ask about the
drop-down dimension you need (it is a ratio thing). By the time you
ordered the pre-molded ones and got them delivered, you could have
finished building yours "the old fashion way". 
 
Kurt. 
 
137 FGE 4.3L Alum. V-6 Chevy. 
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