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Paul,
That thicker radiators seem to have disappointing performance appears to me to
have more to do with the plenum than radiator - like the P-51 had quite thick
radiators, but also a very good plenum. As Ed pointed out a couple of days ago,
the pressure drop across a thick radiator is not nearly as much higher than the
drop across a thin radiator as one would expect. On a pusher, you have a better
opportunity to create a really good plenum than would be the case (under cowl)
in a tractor configuration and one might find that for a given volume, thicker
radiators might be a better use of space than thinner units with more frontal
area. That being the case, a couple of 535 ci radiators should be more than
adequate for even a turbo'd 13B even on a hot day climb. It would appear that
you could even afford a somewhat compromised plenum. Given the much more modest
cooling requirements in cruise, the excess air can be dumped/bypassed ala' John
Slade's plenum flapper valve scheme. Bypassing radiators should be easier to do
with better recovery of cooling drag losses in a pusher than in a tractor.
When I get to that phase, my plan is to use the Cozy NACA duct (perhaps
supplemented with a lip that sags into the airstream) for radiators and oil
cooler with additional NACA ducts in the turtleback for the intercooler. I aim
to employ a bypass scheme like John's to greatly reduce the drag penalty of all
the "excess" cooling needed for takeoff and climb.
Bottom line: Plenum Rules!! ... Jim S.
Hi, Ed.....While looking at the various evaparator cores in the catalog at
AutoZone, I came upon two cores that are 7 inches thick. The one I am
interested in is 8 3/4 x 8 3/4 x 7 inches thick. If I were to use two of
these side-by side, I would have a cooling area of around 1071 sq.
inches.(minus end tanks, etc) Getting the air to flow through a 7" thick
core might just work in my canard at 200 mph, but of course I'm concerned
about take-off and climb. I can live with higher speed/lower vertical climb
operations, I am most interested in perfecting cruise operations, (which
should constitute about 95% of my flying) For ground operations I might be
able to find a small enough diameter fan. If I could make this work, it
would be a neat, compact installation that would fit rather nicely in my
SQ2000 without having to modify the cowling, etc. What are your thoughts on
an evaparator core that is 7" thick? Thanks in advance for your thoughts
and opinions. Paul Conner
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