REFLECTOR: Need for Cabin Heat at Altitude

[Ruben Creus]

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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