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Post by dmar836 on May 16, 2017 11:20:35 GMT -6
Ed put one on #77 and said it cured the cooling issues. I'm not quite there yet on my VWitt but mocking up reveals what a tight fit it is in there. I see #77 has a doghouse cooler sideways on top and separately ducted as well. #33(VWitt) has oil cooling lines coiled in the nose bowl. I likely have room for either so how about some chatter on cooling systems/ducting.
Dave
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Post by Supervee on May 16, 2017 18:53:14 GMT -6
When I first built Blueberry, I built racing boxes for baffles, but ,did not cool the head....John Monnett said the head didn't need to be cooled....Well, Wolfsburg Germany thought the heads on millions of Beetles needed to be cooled. I added / extended the baffle out to ram air down on and thru the head, and things cooled well. Jim Vliet built new, or re-built my baffles on #77 many years later.
Jeff Lange just spent an enormous effort to build baffle boxes for his #64 Sonerai, he has published some photos on line, they are worth a look, they are beautiful....
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Post by dmar836 on May 18, 2017 18:20:56 GMT -6
I'll look for Jeff's pics. Any idea how the copper-coiled cooler worked for S.J. and #33? It's kind of hanging out there near incoming air but not very efficient looking. Wondering if this coiled cooling plus a decent plenum would be adequate. Looking today, I am unable to run the doghouse cooler on top due to motor mount bracing. A cooler below causes issues with the delrin slider material in the Lecteon/Posa style carbs.
Dave
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Post by jvliet on May 18, 2017 19:08:30 GMT -6
Okay....the new baffles on #77 were completely my own design, downdraft setup. I used thin 2024 aluminum which was very stiff due to the facet design. I first made patterns using thin cardboard, then transferred the patterns to aluminum. #77 had a unique mechanical fuel pump which was needed for the Ellison injector. In the photo you see the top box (inlet side) but you can't see the tight wrapping on the bottom side of the cylinders - all the air must be directed through the cylinder fins. The heads also received high pressure air. Ed is right, it is important to direct some cooling air down through the head fins.
The oil cooler on #33 was the stock VW cooler, mounted sideways beneath the engine, with two hoses to the oil pump cover. This is a special oil pump cover that can be purchased from the VW car folks, used for an external oil filter setup. The air cooling inlet for #33 was beneath the nose (no openings in the cheek cowls) and this was an updraft cooling setup with the carb. mounted atop the engine just like Witt did. He used a Solex 32-PHN-1 sidedraft bowl carb on his V-Witt. I tried it and quickly found that it was dangerous - it was very prone to icing. Witt took his carb inlet air from the warm air that had passed over the oil cooler loops. I had to run constant carb heat on #33 until I changed to an Ellison injector.
#31 originally had an oil cooler of several loops of finned aluminum tubing.
The experts say that about 30% of the VW engine heat is dissipated via the oil, so it's important to have a decent oil cooler setup. It would be really neat to try a surface oil cooler - as used on some of the Schneider Trophy racers as well as the Caudron 460, Shoenfeldt Firecracker and Chester Goon in the 1930's.
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Post by dmar836 on May 19, 2017 20:48:26 GMT -6
Thanks guys! I'll certainly include the head fins in the plenum.
Jim, I like the idea of surface cooling but not sure how to pull it off on a small aircraft. Any ideas?
Dave
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Post by Supervee on May 20, 2017 4:53:06 GMT -6
Formula One Shoestring racer 'Judy', used a formed aluminum lower cowl that was actually an oil cooler...
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