Perry Mick wrote:
Aircraft spruce pn 03-40300, 3003-0 soft aluminum tubing, 3/16 od by .028
wall, good for 880 psi. So the ID would be .1315.
Length of one tube approx. 38" * pi = 120" or 10'
Internal volume is 1.63 cubic inch. Use about 30 tubes for 48.9 cubic
inches
of water in the rad not including tanks.
Water weighs 62.4 lbs/cubic foot, or .43 lb/cubic inch. So the weight of
the
water in the rad would be 21.2 lbs. I guess it's a little higher than I
thought.
So using squashed tubes would lower the weight of water and probably make
the heat transfer more effective.
Woops, made an error, corrected below:
Length of one tube approx. 38" * pi = 120" or 10'
Internal volume is 1.63 cubic inch. Use about 30 tubes for 48.9 cubic
inches
of water in the rad not including tanks.
Water weighs 62.4 lbs/cubic foot, or .036 lb/cubic inch. So the weight of
the water in the rad would be 1.77 lbs.
Perry
You would probably want to furnace braze all the tubes to a flat
sheet of aluminum and then roll the whole works up into the ID of
the duct.
Too much trouble and too expensive :)
Paul Lamar
I am thinking of forming the tubes around a large cylinder form, as it will
not be a cylinder, but a slightly expanding duct. Terminating them to the
tanks is still tbd. I would do the work myself so cost will not be a factor,
just cost of materials.
If it works I would prefer it to what I have now - IF it is more effective.
I think my rad size is marginal in hot weather and there is no room for a
larger rad. Will be a problem if I ever increase HP. I would love to just
get that thing out of the cowl completely. Would make the whole thing look
sleaker and have less drag. I would eliminate the belly NACA inlet
completely and reshape the bottom more like the original Long-EZ. And those
little cooling fins in the duct exit might look high-tech and cool too!
Perry
The surface area of a 16 by 19 inch conventional core two inches thick with 16 fins per
inch is enormous. Both sides of the fins work. Lets see 16 by 2 is 32 square
inches. Double that for 64 square inches per fin. 16 fins per inch is 1024 square
inches per inch of core length. Times 19 = 19,456 square inches roughly.
A flush skin rad 120 inches (in circumference) by 20 inches long is only 2400
square inches. Not likely to cool adequately. The first P38 had flush skin intercoolers
taking up the whole top and bottom of the leading edge of the wings. Later in the war
they did away with those and went with conventional intercoolers.
Late Schnieder cup racers had every square inch of the airplane including the floats
covered with skin radiators.
Paul Lamar
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