"Morgans" wrote in message
...

"Richard Riley" wrote
...
There's a chart listing ambient temperature, surface temperature and
color that composite builders take as gospel. I'm trying to get more
information about it

http://hallert.net/cozy/images/ColorCurveChart.gif

In the testing that I'm doing, these temperatures seem high. White
surfaces don't seem to be more than about 10 degrees F higher than
ambient, the chart shows a white surface on a 30 degree day at 85
degrees. Yesterday it was hot in So Ca, 90 degrees ambient - but
black surfaces were coming out at 185, not 210.

I would attribute the lower temperatures to the fact that the sun is much
lower in the sky, than at June 21, or around then.

I'll bet it was done as a worse case scenario, with the sun's rays the
most direct, and highest in the sky.
--
Jim in NC

Jim,

I have a metal sailplane which I keep tied down in the sun during the
soaring season. It is painted white and from my observations the white
numbers are correct.

For two weeks during the August several of us take our sailplanes to Mackay,
Idaho for a two week regatta.
(http://www.soaridaho.com/photogallery/Mackay_2006/) During that time all
the gliders are tied out in the sun. Several of the gliders have painted
wingtips. The chart appears to be correct. We all have tested it using the
"touch test" which consists of placing your hand on the white portion of a
composite wing follow by touching the painted wingtips. Blue is much hotter
then white and red is much hotter then blue.

I don't know if the low humidity and/or high mountain elevations are factors
or not. However, they do get hot tied down in the sun at 6,000 MSL with the
humidity less then 20%.

Wayne
HP-14 "6F"
http://www.soaridaho.com/Schreder/HP...Test_Brian.jpg