Yesterday I measured the air temprise through my oil cooler.  Paul Lamar had
told me that typical figures should be around 10 degrees for an efficient
system.   This sounded wrong to me (I know, he hates that) because in my
"mental model" of an efficient aircraft cooling system, it is best to use
the fewest cubic feet of cooling air possible.  Every CF of cooling air used
represents drag.  This means that we must remove more BTU per CF of air,
i.e.  we need to heat it up as much as possible.

The ambient air temp at time of test flight was 66 deg. F.   Air exiting the
oil cooler was between 106 and 111 deg F., depending on power setting.  This
is a 40 - 45 deg temp increase.  I was surprised at the small range of temps
at first but when you factor in the increased flow at higher power settings,
it makes sense.

Today I'm going to measure the outlet air from the right side evaporator
core.  Ed Andersen is going to be doing similar measurements on his plane
and it will be interesting to compare the results.

Tracy Crook