REFLECTOR: Need for Cabin Heat at Altitude

Tue Jun 25 20:17:28 CDT 2013

I have an axial fan.  It doesn't work very well.

The biggest problem is that the fan is larger than the face of the oil 
cooler, so I built a rigid plenum that adapts the large round fan to the 
smaller square cooler.  I would rather the fan blow into the cooler so 
that the hot air is dumped overboard, but what happens is that the air 
gets "slung" out away from the center, as well as towards the cooler.  
You can feel a large portion of the air escaping around the ducted fan.

Now, reverse the polarity, and it draws air out fairly well, and dumps 
that hot air into the cabin.  Even so, it's still not up to the 105CFM 
specs mentioned.  I think it's more like 30CFM.

On 06/25/2013 07:54 PM, Don Johnston wrote:
> 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 
> <mailto: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
>     <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
>     <mailto: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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