REFLECTOR: Need for Cabin Heat at Altitude

Tue Jun 25 20:03:22 CDT 2013

http://www.yaskawa.com/site/dmdrive.nsf/link2/MNEN-5JFQNY/$file/AR.HVAC.02.pdf

Steve 

Date: Tue, 25 Jun 2013 19:54:16 -0500
From: numa at comcast.net
To: reflector at tvbf.org
Subject: Re: REFLECTOR: Need for Cabin Heat at Altitude

I'm not sure I understand the requirement for a centrifugal fan. With the outside entrance and exit closed, it's effectively a closed loop. There doesn't appear to be significant resistance from the oil cooler. So as long as the size of the input and output are similar, I don't understand why an axial fan wouldn't accomplish adequate airflow to be effective. 

-Don

On Tue, Jun 25, 2013 at 12:33 PM, Ruben Creus <ruben at vainneg.com> wrote:

We just did a similar thing than what is
in the email below. We install an squirrel cage fan, and a flap on the oil
scoop. Different tests show that for this magic trick to happen, there one very
important requirement. And that is, “a
perfect seal” around the flap. First, you need to build up
air pressure in front of the oil cooler to force the air into the radiator.
Second, a bilge fan cannot work under pressure, but a squirrel fan does. A squirrel fan is designed to work under
air pressure losing just few CFM. A bilge fan will lose most of its CFM under
pressure.

I did a test in winter and summer, and
finally installed it last week in with the help of the Sebastian folks. Scott
did a super detail job there!  We achieved a perfect seal, and we are
using a squirrel cage fan with 105CFM. The results were impressive. It blows a
good amount of air, maybe 1/3 of what you would get with the flap open in
flight, but it looks to be good enough to blow a good amount of air. But again,
to build pressure in front of the radiator you need a perfect seal. Otherwise,
air will escape, no pressure will built and all the effort will be a waste.
Remember,  this can only work with a squirrel cage fan. A regular bilge
fan cannot work under pressure. 

We hade in fact this Sunday a real test
scenario, waiting on an airport for the clearance and the clear to take off,
the oil temp started to go up, and there we go!!, we closed the flap and turn
the fan on and the oil temp started to go down. So we had in group oil
cooling!!! Now the question remains, will in the winter generate enough
recirculation heat to heat the cabin in on the ground and in flight?
  Our unorthodox tests of last winter say yes, but it is not until
now we permanently mounted the solution, so when the cold weather comes back in
few months I will report to the group the results, but it looks very promising.

Ruben

From: Don Johnston
[mailto:numa at comcast.net] 

Sent: Sunday, June 23, 2013 8:24
PM

To: Velocity Aircraft Owners and Builders list

Subject: Re: REFLECTOR: Need for
Cabin Heat at Altitude

I don't know if it's going
to work (since I'm not flying yet), but I've created a controllable door that
will block off the outside air from the nose oil cooler which will allow inside
cabin air to be passed through the oil cooler via a blower. Effectively heating
cabin air instead of outside air. 

http://www.velocity-xl.com/blog/2008/06/14/12-3-6-nose-oil-cooler/

http://www.velocity-xl.com/blog/2013/05/03/12-3-6-nose-oil-cooler-control/

-Don

On Sun, Jun 23, 2013 at 7:15 PM, victor delta <vdelta at pacbell.net>
wrote:

Looking for experiences, solutions, implementations,  ideas and
otherwise  for requirement to assure reasonable cabin temperature/heat for
passengers when flying in lower to mid flight levels ongoing.

Especially welcome comments from those that fly their aircraft high most of the
time, at night and/or during winter months.

Thanks in advance for all contributions.

VD

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