Does it have to WHITE!!!

The heat is in the IR region that you do not see with your eye. In the
IR spectrum things look very different. If you've ever looked at
things using an IR sensitive camera you'll see what I mean. I think
bees see in IR, and I noticed that flowers reflect a lot of IR even
though they may seem like very dark rich colors to the human eye.
Typically darker colors do absorb more IR however, but its more of a
coincidence than a requirement. Those handheld non-contact temperature
sensors are really cheap these days. You could make a sample sheet
with swatches of color, put it in the sun for 30 minutes, then shade
and measure immediately. See what kind of differences you get.

If anyone is wondering why I was looking at flowers with IR sensitive
cameras, it was part of testing a series of IR cut filters for a camera
we were designing. A group of flowers is a stereo typical test subject
for a color camera.

You could make an IR pass filter (daylight filter) from a piece of
exposed film negative. Put it in front of a black and white TV camera.
Then point it at your test subjects. The ones that are the brightest
are relecting the most IR and should be the coolest.

BTW, the touch test may not be a very good test because your finger is
really measuring the amount of heat rather than the absolute
temperature. Put another way, touching a 150 degree F piece of
plywood, or a 150 degre F piece of aluminum, you'll think the Al is way
hotter because the Al will transfer more heat to your finger.

firstflight wrote:
I have a composite kit aircraft, and it is time to paint! But I just hate
the idea of painting it WHITE (like most all the others). I understand that
HEAT is a big factor in this decision, and that white attracts the least
amount of heat which could disrupt the Epoxy over time. Since my plane is
held together with Epoxy, this seems like a valid concern.

What do you think people? Does it have to be white?? Could one choose a
light yellow, light gray, silver,etc....... and not be pushing the envelop
too much?

I happen to live in a very cool part of North America, so I am not too
worried about regular heat (like someone in Arizona might be).

Thoughts?

wrote:

You could make an IR pass filter (daylight filter) from a piece of
exposed film negative. Put it in front of a black and white TV camera.
Then point it at your test subjects. The ones that are the brightest
are relecting the most IR and should be the coolest.


Or better yet. Get one of the 'security cameras' from Harbor Freight.
Most CCDs are really sensitive to IR, so much so that they have to
include a filter for it to get any sort of decent picture. The 'night
vision' security cameras are really cheap cameras without the IR filter.

So I've been told.

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

Sure glad I have a wooden airplane.

Dan

On 27 Jun 2005 07:14:26 -0700, wrote:

Sure glad I have a wooden airplane.

....unless, of course, you're using epoxy to hold it together.....

Ron "Hot Sauce for Gander" Wanttaja

I was thinking the same thing, Ron, but most of the structural epoxy in
a wooden bird is not in direct sun (unlike composite wing skins), and
wood is a lousy heat conductor. Of course, you never have to worry
about ANY part of your airplane getting exposed to the sun, living as
you do in the PacNW! :-^

OT re honeybee vision: They can see UV, not IR.

"...their vision is not sensitive to the same range of colors as ours.
Theirs is insensitive to red but detects ultraviolet light which is
invisible to us."

http://koning.ecsu.ctstateu.edu/Plan...bees/bees.html