REFLECTOR: Need for Cabin Heat at Altitude

Mon Jul 1 12:22:13 CDT 2013

We really need to start a different thread or change the name of this one.

While similar, getting better engine oil cooling and getting better cabin
heat are two different topics.

-Don

On Mon, Jul 1, 2013 at 12:10 PM, Rene Dugas <renedugas at gmail.com> wrote:

> Brian,
> Just a small reverse scoop forward of the aft firewall should suck cool
> air from the nose compartment down the duct and out.  No forward scoop at
> all.
>
>
> Sent from Rene's iPad. A pleasure.  Go Apple.
>
>
> On Jun 30, 2013, at 10:45 PM, Brian Michalk <michalk at awpi.com> wrote:
>
> Thanks for the information.
>
> By the way, I am currently separating my oil lines, as suggested by Scott,
> I believe.
> I flew on Saturday in 104F heat.  CHT's were manageable, but the oil temp
> was not.  This was the first test after capping off my second parallel oil
> cooler.  Results were better than previous.
> If the split oil lines do not get me the cooling I need, then I'll
> probably install the fan and reconnect the second oil cooler.  If that
> still fails, then I will try ventilating my ducts to turn them into coolers
> too.
>
> If I can get this to work in 105F weather, I will be able to fly
> anywhere.  Density altitude at my 600' airport was 3500'.  Incredible.
>
> On 06/30/2013 05:07 PM, Ruben Creus wrote:
>
> **
>
> It took approximately 10min..  Note that the oil temp is read at the
> engine block, so assume that cooling the cooler only cools a small amount
> if oil at a time and then heats when running back into the engine… so the
> cooling effect needs a bit of time to really cool down the oil as a whole.
> ****
>
> ** **
>
> When reached 195F I left it there for another 10 min and it did not
> change, but you could see the temp going back and forth to 194 – 195. ****
>
> ** **
>
> When I did this same test in the winter with a temporary set up, the OAT
> was 15C instead of 35C, and I was able to get the oil go down to 185F. So
> ground cooling PASS!!  I will report this next winter about the heat in the
> air, but as I said, I just tried it in the air this week and it was blowing
> a very decent amount if air in the cabin, and definitely very hot… I had to
> turn it off as I was cooking myself there. So I have high hopes, but until
> the real test happens all is a hypothesis, a very good one though….****
>
> ** **
>
> About the fan, yes it was the Jabsco 105CFM.   They have more powerful
> models but I could not find a place to fit it. Also from reading about heat
> comments last year,  it looks like the speed of the air going through the
> radiator is a factor, the slower the hotter it gets. So, more CFM might
> give you more air but less hot….So I figure it our that if the 105CFM give
> enough air then the slower the better. I guess in a perfect world. There
> will be different point of speed/temp with different models… but we do not
> live in a perfect world!****
>
> ** **
>
> Ruben****
>
> ** **
>  ------------------------------
>
> *From:* Brian Michalk [mailto:michalk at awpi.com <michalk at awpi.com>]
> *Sent:* Friday, June 28, 2013 10:27 AM
> *To:* ****Velocity** Aircraft Owners and Builders list**
> *Subject:* Re: REFLECTOR: Need for Cabin Heat at Altitude****
>
> ** **
>
> 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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