Paul et al,

For what it's worth, a classic formula for cooling air inlet area in
low-to-moderate performance aircraft is .35 sq. in. per climb
horsepower. This is usually applied to air-cooled engines, but I suppose
the heat rejection per horsepower is not that different for a
liquid-cooled one. There is much dispute about outlet area; one
suggestion is 10% greater than inlet.

For air-cooled engines the cooling air requirement is a function of
delta-p, that is, the pressure drop across the engine. I have never
worked with a liquid-cooled installation, but I assume there is some
such factor for a radiator as well. Delta-p is in turn a function of
forward speed; if the dynamic pressure is below the required delta-p,
the expected cooling performance will not be obtained.

What strikes me about the photos is that if the central radiator is the
coolant radiator, there seem to be surprisingly large alternate routes
for the incoming air. The wind bloweth where it listeth, as the prophet
quite correctly pointed out. If the cowling provides an alternate route
with lower impedance than that of the main radiator, the air will follow
it and avoid the main radiator.

Peter Garrison

Yes I agree. Sealing around the rad is extremely important.

Thanks Peter.


Paul Lamar

Thanks Peter,

According to the formula I have more than enough inlet area, about 136 sq.
in.
The 3 air inlets are completely separate.    One side is for the oil
cooler -- about 38 sq. in.
Two inlets are for two separate water rads., one up front and one down
inside the pylon, this rad. has a Spal 10" fan pulling.

I suspect that the two side opening cause more restriction than the center
opening because the side openings feed the air to inside the pylon.  The air
ducts are complete and sealed to each rad.

It seems there is enough inlet and outlet area.   I should have enough rad.
volume.
I will do some air flow measurements!

Rino

Pito tubes Rino.

Paul Lamar