|
|
I'll add a comment that may or may not have any relevance. I have
NACA ducts on the side of my plane that are used for cabin cooling, so
no real back pressure to speak of. The original builder told me they
worked marginally for that. They would sometimes flow OK, and at other
times not at all. I suspect that if the plane were flown slightly
uncoordinated, one side or the other might be blanked in the position
they are in. This might be less of a problem on "rounder" surfaces
but does seem to indicate some sensitivity to getting the installation
right.
Bob W.
On Thu, 9 Mar 2006 21:25:33 -0500
"Ed Anderson" <eanderson@carolina.rr.com> wrote:
> 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 -----
> From: "Bill Dube" <william.p.dube@noaa.gov>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> 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/
> >
--
http://www.bob-white.com
N93BD - Rotary Powered BD-4 (first engine start 1/7/06)
Custom Cables for your rotary installation -
http://www.roblinphoto.com/shop/
|
|