Paul, I have read your article on cooling the rotary. (ACRE site)
I agree with almost all of it. I do believe however an oil to water
cooler would work fine if the radiator was sized correctly. As with
any other system you have to be careful and overkill all the
connections. I am planning to used the wiggins coupling or
straight AN fittings on my water connections and wouldn't be too
concerned there. I understand your reluctance to "put your eggs in
one basket." I am sure however if the radiator fails in a w/c aircraft
engine you are going to have an engine failure. The oil cooler won't
do it alone. Even though the rotary uses the oil for 30 percent of its'
cooling. The rotary isn't the only case where this is true. A failure of
the water radiator wouldn't necessarily fail the oil system either.
No cooling of course. Perhaps the best compromise is the layout
you did for a long ez was it? Where the builder had the Water
radiator and the Oil radiator paired in the lower inlet scoop. This
location allows a louver system to work on both rads as well.
Bill Jepson
I think the second independent cooling system buys you a little more
time to get it on the ground. If the oil severely overheats you risk bearing
failure. The same argument applies to mounting the water pump down low.
It buys you time. Before you were on here Power Sport spent a lot
of time and money on oil/water heat exchangers and finally gave up.
Mazda too had a water/oil heat exchanger on the early RX7's and also gave up.
Works great in a car where you want the oil to heat up fast on start up.
Paul Lamar
There is another fundamental problem I forgot to mention which is the real
show stopper. The delta T between water and oil is not that much. Lets
say the oil is 230 F and the water 220 F. Delta T = 10 F. The rate of heat transfer
will be way down compared to an air/oil heat exchanger. Air 100 F
oil 230 F. Delta T = 130 F. It is true that the coef. of heat tx between water and
metal is better than between air and metal but not enough
to make up that huge handicap.
Paul Lamar
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