REFLECTOR: Need for Cabin Heat at Altitude

[Don Johnston]

That is correct. One of the gems I got from Malcolm regarding NACAs and
airflow is that "Air is like rope. You can pull it, but if you try to push
it, you'll just end up with a pile of rope all bunched on the floor.

NACA's are a mechanism to SUPPLY air. But something has to be able to pull
the air in. So you have to figure out a way to suck (or pull) the air out
of that NACA supply."

-Don

On Sat, Jun 29, 2013 at 5:52 PM, David Rene Dugas <renedugas at gmail.com>wrote:

> I don't know but have been told on the reflector that NACA's don't develop
> much pressure. They accept air with little drag but are a poor pressure
> device. YMMV.
> Not good for ram air as I understand it. Others may know the science.
>
> René Dugas
> Sent from an Apple REALLY smart phone.
>
> On Jun 28, 2013, at 9:27 AM, Brian Michalk <michalk at awpi.com> wrote:
>
> Okay, that does look just like the Jabsco blower that we found.
>
> How long did it take to bring your oil temps down to 195F, and did you
> stop taking data at that point, or did it stabilize there?
>
>
>
> On 6/28/2013 8:05 AM, Ruben Creus wrote:
>
>  I sent this message was it was not posted, so here goes again… see if
> this time works.****
>
> ** **
>
> Here I attach some pics. As you can see the flap opens and closes that
> naca scoop. As the fan is pointing at a 90 degree angle in relation to the
> oil cooler you need to create a perfect seal, so the naca scoop becomes a
> chamber where air gets pressurized and the only escape is the oil cooler.
> ****
>
> ** **
>
> In my tests I noticed that if the chamber is not a perfect seal, then and
> air escapes, if the air escapes then there is I no pressure built up, and
> therefore no air going to the cooler, but when the chamber is sealed then
> all the air builds up and can only go to the cooler. The other test I did
> was with a normal blower fan, and it losses a lot of CFMs vs. de squirrel
> cage fan that loses very little CFM. You can see that on the fan
> manufactures specs. Someone wrote a nice message explaining the difference
> and the reason for this. What I found out that the propeller design does
> not move much air when it has pressure in front of it, but with the
> squirrel cage each blade pushes air to the next and so forth… I am not fan
> engineer, but in practical terms it was a huge and extremely noticeable
> difference. I guess that is why they use squirrel cage fan for all ducting
> systems (like A/C) use squirrel fan, and open air systems use normal fan
> propellers.****
>
> ** **
>
> I did a test yesterday. OAT was 35C (95F).  I started the engine and the
> oil go up to 215F, then close the flap and turn the fan on and oil temp
> when down to 195F, allowing me to stay in the ground for as much time we
> want. (very convenient in large airports). ****
>
> ** **
>
> The other tests was in flight to close the flap and open the fan, and I
> had a very decent amount of air going to the cabin, pretty hot air!!  So
> very promising. Now I just need to wait until the winter to give a final
> verdict, but the amount of air is very decent and the temperature was very
> hot. So we will see what happens in the winter months.…. ****
>
> ** **
>
> I hope this is helpful and not too boring.****
>
> ** **
>
> Ruben****
>
> ** **
>
> ** **
>
>
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