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I was a bit disappointed in the article, myself. For
instance his insistence about adhering to no more than a 7-14 deg slope for the
diffuser is the number NACA found to be best for wind tunnels. He makes no
mention of many other types of diffusers (such as the streamline duct with a
measured (laboratory) pressure recovery of 84% and can have slopes of divergence
approaching 65 deg near the cooler core). Almost appears as if he had
never heard of K&W. On the other hand, perhaps for air cooled
engines, he may not be that far off. The fins on the jugs of air cooled
engines may not offer as much back pressure as say a radiator which may make the
NACA duct work better.
However, there is a NACA publication on NACA ducts and
here is a brief extract on their conclusions about its use
Does not say they can not be used for radiators, etc, but
apparently they felt not the best choice for those applications. Note
it qualifies this conclusion a bit by referring to all
flight conditions. Does this imply that if you
selected A flight regime (say cruise) to optimize for, that it could be make to
work fine there? Don't know, so many questions, so little time.
{:>) I personally tried a NACA duct early on trying to solve my oil
cooling problem, didn't work for me - but, it was probably not a fair test as I
had other problems than just pressure recovery {:>)
Anyhow, my $0.02 on the topic.
Ed
----- Original Message -----
Sent: Thursday, March 09, 2006 8:58 PM
Subject: [FlyRotary] Re: NACA's, Cooling and Sport
Aviation Mag..
>I read that article
as well. I had the same skepticism about the NACA
> intake for cooling.
My understanding is that with an NACA inlet, you
> don't get the ram
pressure you need to force air through a high
> fin-count radiator. Am I
wrong about this?
>
> Bill Dube'
>
> David Staten
wrote:
>
>> At the risk of invoking PL's name, anyone else read
this months Sport
>> Aviation mag from EAA, and notice an article on
cooling that seems to
>> indicate that NACA's are acceptable and
adequate for aircraft cooling
>> needs? I have no idea regarding the
authors credentials, and I no
>> longer monitor PL's "newsletter".. I
was curious more than anything
>> else... Pauls reaction, others
reactions, etc.
>>
>> Translation.. yes.. I'm stirring the
pot/Trolling... I figure if we
>> are using NACA's on the Velocity,
that makes us somewhat of a NACA
>>
supporter..
>>
>> Dave
>>
>> --
>>
Homepage: http://www.flyrotary.com/
>>
Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/
>>
>
> --
> Homepage: http://www.flyrotary.com/
> Archive
and UnSub: http://mail.lancaironline.net/lists/flyrotary/
>
NACA-Ducts for Radiators not a good idea.gif
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