Rob Housman wrote:
>
> Very interesting, and not just on topic. Your measurements are certainly
> consistent with the published chart. The Europa chart looks to me to
> indicate about 5F/3C offset at low temperature and less than 10F/6C at
> high temperature, of the yellow above the white curve.
Rob, it looks rather linear, so that the temp rise is a flat as a % of
the ambient temp.
> Perhaps I am a bit more sensitive on this subject because any eastward
> departure from the LA basin involves crossing the Mojave Desert where the
> temperature on the ground will often exceed 115F/46C. I guess the folks
> in UK don't comprehend how hot it gets here because the chart doesn't go
> above 110F ambient.
That's a problem. Course, I don't know why you'd want to land in the
Mojave, and you'd be OK at altitude. But gotta to stop somewhere soon,
and could be almost as hot. You can test silver metallic, but I
recall my silver Dodge was cool, but can't retest. She's incarcerated
in my garage until a new driveway cures.
> Not even suggested in the Europa manual is the variation with latitude of
> the amount of the sun's energy reaching the ground (or an aircraft in
> flight). Closer to the equator there will be a greater heating effect on
> the aircraft structure at any given ambient air temperature, and this is
> also true at altitude. Using ambient air temperature as an indicator of
> how hot the structure will get ignores the affect of latitude.
Hadn't thought of that. Surface temps are substantially not the
direct heating effect of the sun, but rather reflectance from the
earth's surface. Hence cooler at altitude, and there will be cooling
effect in the slipstream. But also, if I understand the above article
correctly, reflectance of the substrate back through the paint.
> Have you made any measurements at higher ambient temperatures (and I do
> understand that you won't experience anything close to desert heat so near
> to Lake Erie)? Will you elaborate, off list if appropriate, about your
> measurement scheme?
When you live near Lake Erie, the winters and the Lake breezes here
make 85F unbearable! I used a digital, infrared sensor (about $80 US,
e.g., jcwhitney.com has). Just point the laser spot and read the
temp. Didn't test anything at temps above 80F ambient, but one can
extrapolate to 115F.
Regards,
Fred F., A063
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