As I see it there are too possible choices.
You can use two evap cores like Tracy does or you
can use a one or two inch thick core of a wide selection of sizes.

In the first case the core total core volume is about 700 cubic inches
give or take a few.

In the second case it can be almost anything you want it to be.

Paul, I think that 700 cu.in. of radiator in an rv-4 cowl is a bit
optimistic. I just recieved the exact same rad that Chuck Dunlap
has(I beleive). Give me two weeks and I'll send pictures of the
installation. Can Chuck give any information on how his cooling
works? I know that you recommended just letting the air dump out of
the bottom of my cowl, but I think that that is lacking in elegance(a
serious engineering consideration). I've got what I think is a good
cowl flap mechanism setup that, like I say, I'll share in a couple of
weeks.

Brian Trubee
Making progress after all these years

Well Tracy does not think so :) If you use evap core it is probably
not optimistic :)
You have a point though. You can always improve the cooling by putting
more volume
in your heat exchangers. If two evap cores don't quite cut it put in
three :)

All joking aside I think Chuck's core will work fine with a little
aerodynamic tweaking.

Chuck, what is the latest on your cooling experience?

Paul Lamar

Brian,  what size core are  you using?   Mine is 465 cu in.    There is
plenty of evidence that done right a smaller radiator will work.  I
think the 600 to 700 cu in numbers are simply too much to fit in the
average aircraft.   People like Chuck and Ian have proven it can be
done without all that capacity.   Ian flew all over the Outback, where
it really gets HOT, with only 400 cu in   total volume in two heater
cores.

   There is only so much space.  In fact a big radiator can use so much
of the available space there is no room for proper ducting.     Also,
forces acting on a set of louvers at 200 mph will be considerable. The
wider they are, the stronger they will have to be.   There is a reason
we are prohibited from lowering the flaps at 200 mph. I worry about the
structure we need resist the loads imposed by the louvers.  If they are
attached to the radiator, then the radiator cannot just be hung by some
flimsy straps.  Perhaps the louvers should be built into the engine
mount and not attached to the radiator at all.

  Nearly two  years ago, I built a set of louvers out of aluminum but I
was never satisfied with them.  I am about to build another set but
will wait to see what  you have come up with.  I like that word
"elegant."  Jerry

 
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