check this report out.  it may make you wonder if Tracy is actually on to
something when he recommends the thicker radiators.  there is no date on the
report, but it appears to have been written quite some time ago. I only wish
the drawings were better.  it points out how auto radiators are lousy for
aircraft because of the higher air speeds. kevin
"Properties of Special Types of Radiators"
http://naca.larc.nasa.gov/reports/1921/naca-report-86/index.cgi?page09.gif