What colour?

On 03 Aug 2003 19:38:24 GMT, cal (BD5ER) wrote:

:As for the emissivity of paints perhaps a single layer sheet of the composite
:you intend to build your flying machine with can be used for tests. Paint
:small
:spots with the actual paint you's like to use. Place the sheet out in the sun
:and measure the temperature from the reverse side at each spot using your
:radiometer. Do this as soon as you place the sheet in the sun.
:
:Sounds like a reasonable test. If I only had the time. Mine will probably be
:white.
:
:I used to be a gunsmith, you can keep your Glock™
:
:I intend to. 8 years, about 11 cases of ammo, 2 misfires from bad factory
:ammo, and one from the gun due to stupid owner. It hits what it is pointed at,
:now if I could just point it better...........Other than that I'm happy with
:it.

What cal? I'm shooting .357 in mine, but thinking about going back to
..40.

Roger Halstead wrote:

It's been my experience which is admittedly limited, that metallic
colors/pigments tend to get hotter than the same colors with out the
metallic pigment. (hope I phrased that correctly)

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)



Would that be because the non-metallic paints have a much lower
coefficient of heat transfer? That is, the very outer layer heats up,
but then acts as insulation and doesn't transfer the heat energy any
deeper. The higher metal content would work as a heat wick.

Just guessing.

--
----Because I can----
http://www.ernest.isa-geek.org/
------------------------

Roger Halstead wrote in message . ..
On 4 Aug 2003 12:37:54 -0700, (Jay) wrote:

The reason your silver aircraft may have showed up so hot is because
your "heat gun" was actually peering at the image of the sun reflected
off the glossy surface. But its is true, the apparent color seems to

Shiny Aluminum gets really hot in direct sunlight.
At work we had a 1 inch thick 4' X 8' Aluminum plate laying on blocks
out in the sun. It was in a protected area where it had little
cooling. It actually got hot enough to burn a person trying to move
it. The temperature was only slightly below the boiling point for
water...bout 200 F.

I always figured shiny Aluminum wouldn't get all that hot until I saw
that.

Your perception of it being hot was based on the material conducting
heat into your fingers when you touched it. Plain aluminum is an
exceptionally good conductor of heat as opposed to a layer of paint
over the same material. Example: This guy I worked with told me that
growing up in Minnesota, they put a layer of styrofoam on the seat of
the outhouse so in the freezing winter they wouldn't get stuck. The
styrofoam was certainly below freezing when they sat down, but because
its ability to conduct heat was so small, it didn't freeze their
empennage off.

So a painted airplane could have a higher actual temperature but less
ability to make your finger feel hot when you touch it.

Your perception of it being hot was based on the material conducting
heat into your fingers when you touched it.

This is why I just always assumed that the wrenches I left out in the sun
"felt" so hot, but the other day I happened to leave some tools on the outside
window sill of my shop. When I went to retrieve them they were almost too hot
to hold. The strange thing is that the one black impact extension was far
cooler to the touch than the chrome ones.

I think there is a lot more to heat gain than just color and surface finish
than those of us unschooled in the ways of IR understand.

The .22 is quieter...

wrote:

On 03 Aug 2003 19:38:24 GMT, cal (BD5ER) wrote:

:As for the emissivity of paints perhaps a single layer sheet of the composite
:you intend to build your flying machine with can be used for tests. Paint
:small
:spots with the actual paint you's like to use. Place the sheet out in the sun
:and measure the temperature from the reverse side at each spot using your
:radiometer. Do this as soon as you place the sheet in the sun.
:
:Sounds like a reasonable test. If I only had the time. Mine will probably be
:white.
:
:I used to be a gunsmith, you can keep your Glock™
:
:I intend to. 8 years, about 11 cases of ammo, 2 misfires from bad factory
:ammo, and one from the gun due to stupid owner. It hits what it is pointed at,
:now if I could just point it better...........Other than that I'm happy with
:it.

What cal? I'm shooting .357 in mine, but thinking about going back to
.40.

"Dan Thomas" wrote in message
om...
Colour selection should be based on more than its emissivity. You want
something that will stand out if the Search and Rescue boys have to go
start looking for you. ELTs are fine, but they often don't work
properly

At 57A yesterday they had 50-some airplanes to search for a screaming ELT.
Whup-whup-whup-whup-wooop-wooop-wooooop-woooop-woooop.

They came by the hangar and harassed a few of us then went on, after I tore
into the rear sling to see if mine was on. They finally found it in an
airplane that had just landed, apparently about 10 feet above the asphalt.

I've seen large areas covered with bright orange trees in the fall. Never
seen any blue trees though.

What about "Blue" Spruce?

(Fastglasair) wrote in message ...
I've seen large areas covered with bright orange trees in the fall. Never
seen any blue trees though.

What about "Blue" Spruce?



Blue Spruce ain't very blue. A bright blue, like an intense sky-blue,
is an eye-catcher.
My favorite is a yellow with a hint of green (my Jodel proves it)
and I'll be locatable unless I go down in a canola field in June.
Notice that fire engines are using such colors these days. I
believe it was a result of research to find the most arresting shades.

Dan

On 9 Aug 2003 09:21:47 -0700, (Dan Thomas)
wrote:

(Fastglasair) wrote in message ...
I've seen large areas covered with bright orange trees in the fall. Never
seen any blue trees though.

What about "Blue" Spruce?



Blue Spruce ain't very blue. A bright blue, like an intense sky-blue,
is an eye-catcher.
My favorite is a yellow with a hint of green (my Jodel proves it)
and I'll be locatable unless I go down in a canola field in June.
Notice that fire engines are using such colors these days. I
believe it was a result of research to find the most arresting shades.

Dan
Cromium Yellow is used for fire trucks because it shows up best
through smoke, fog, and snow. Red dissapears in those conditions (goes
black)
Our plane will likely be "cub yellow" with blue or green highlights.