OSH ...aluminum needs polishing. HELP!!

"Bob Kuykendall" wrote in message
oups.com...
Earlier, Jim Weir wrote:

...Isn't a perfectly reflecting surface much better than
one that doesn't reflect the energy?...

In theory, yes.

In practice bare aluminum, even highly polished bare aluminum, absorbs
enough energy in direct sunlight to threaten some materials used in
bonded aluminum.

Thanks, Bob K.

Despite the obvious glare of visible light, polished aluminum absorbs far
mor solar energy than white.

Peter

"Peter Dohm" wrote in message
. ..

"Bob Kuykendall" wrote in message
oups.com...
Earlier, Jim Weir wrote:

...Isn't a perfectly reflecting surface much better than
one that doesn't reflect the energy?...

In theory, yes.

In practice bare aluminum, even highly polished bare aluminum, absorbs
enough energy in direct sunlight to threaten some materials used in
bonded aluminum.

Thanks, Bob K.

Despite the obvious glare of visible light, polished aluminum absorbs far
mor solar energy than white.


This was discussed a while back. For details see
http://www.soaridaho.com/Schreder/Co...olor_Temp.html

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

"Wayne Paul" wrote in message
...

"Peter Dohm" wrote in message
. ..

"Bob Kuykendall" wrote in message
oups.com...
Earlier, Jim Weir wrote:

...Isn't a perfectly reflecting surface much better than
one that doesn't reflect the energy?...

In theory, yes.

In practice bare aluminum, even highly polished bare aluminum, absorbs
enough energy in direct sunlight to threaten some materials used in
bonded aluminum.

Thanks, Bob K.

Despite the obvious glare of visible light, polished aluminum absorbs far
mor solar energy than white.


This was discussed a while back. For details see
http://www.soaridaho.com/Schreder/Co...olor_Temp.html

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

The following is from Bellcore. The first number is the solar energy
absorbed the second is the low temperature heat radiation. As you can see,
polished alumunum absorbs only slightly more than white paint but radiates
only 6% as much heat. In other words, although it absorbs little, it
radiates much less so it heats up more than any painted surface.

Polished Aluminum .15 .06

White .14 .97

Yellow .30 .95

Cream .25 .95

Light Grey, Green Blue .50 .87

Med. Grey, Green Blue .75 .95

Dark Grey, Green Blue .95 .95

Black .97 .96



Bill Daniels

Bill Daniels wrote:
The following is from Bellcore. The first number is the solar energy
absorbed the second is the low temperature heat radiation. As you can see,
polished alumunum absorbs only slightly more than white paint but radiates
only 6% as much heat. In other words, although it absorbs little, it
radiates much less so it heats up more than any painted surface.

Polished Aluminum .15 .06

White .14 .97

Yellow .30 .95

Cream .25 .95

Light Grey, Green Blue .50 .87

Med. Grey, Green Blue .75 .95

Dark Grey, Green Blue .95 .95

Black .97 .96

Hmm?
You think this may be why so many airplanes are mostly white?

"john smith" wrote in message
...
Bill Daniels wrote:
The following is from Bellcore. The first number is the solar energy
absorbed the second is the low temperature heat radiation. As you can
see, polished alumunum absorbs only slightly more than white paint but
radiates only 6% as much heat. In other words, although it absorbs
little, it radiates much less so it heats up more than any painted
surface.

Polished Aluminum .15 .06

White .14 .97

Yellow .30 .95

Cream .25 .95

Light Grey, Green Blue .50 .87

Med. Grey, Green Blue .75 .95

Dark Grey, Green Blue .95 .95

Black .97 .96

Hmm?
You think this may be why so many airplanes are mostly white?

It is absolutely why composite aircraft structures are white. My white
carbon/glass composite glider has a structure thermometer. The POH states
the maximun structure temperature at which a flight can begin.

The next time you have a chance to look at some old cars, compare the white
ones to, say, red ones. White paint seems to last forever. White paint
reduces air conditioning requirements and in turn increases gas milage.

Bill Daniels

"Bill Daniels" bildan@comcast-dot-net wrote in
:


"john smith" wrote in message
...
Bill Daniels wrote:
The following is from Bellcore. The first number is the solar
energy absorbed the second is the low temperature heat radiation.
As you can see, polished alumunum absorbs only slightly more than
white paint but radiates only 6% as much heat. In other words,
although it absorbs little, it radiates much less so it heats up
more than any painted surface.

Polished Aluminum .15 .06

White .14 .97

Yellow .30 .95

Cream .25 .95

Light Grey, Green Blue .50 .87

Med. Grey, Green Blue .75 .95

Dark Grey, Green Blue .95 .95

Black .97 .96

Hmm?
You think this may be why so many airplanes are mostly white?

It is absolutely why composite aircraft structures are white. My
white carbon/glass composite glider has a structure thermometer. The
POH states the maximun structure temperature at which a flight can
begin.

The next time you have a chance to look at some old cars, compare the
white ones to, say, red ones. White paint seems to last forever.
White paint reduces air conditioning requirements and in turn
increases gas milage.

Bill Daniels



But the red cars go faster. At least the police seem to think so.

"Jeff" wrote in message
.. .
"Bill Daniels" bildan@comcast-dot-net wrote in
:
You think this may be why so many airplanes are mostly white?

It is absolutely why composite aircraft structures are white. My
white carbon/glass composite glider has a structure thermometer. The
POH states the maximun structure temperature at which a flight can
begin.

The next time you have a chance to look at some old cars, compare the
white ones to, say, red ones. White paint seems to last forever.
White paint reduces air conditioning requirements and in turn
increases gas milage.

Bill Daniels



But the red cars go faster. At least the police seem to think so.


Oh darn... Does that mean I have to strip my plane and start all over?!?
;-) See: http://www.rtist.nl/Album/Pioniershal%202007/index.html

Rob

On Tue, 8 May 2007 18:53:17 -0600, "Bill Daniels"
bildan@comcast-dot-net wrote:


The following is from Bellcore. The first number is the solar energy
absorbed the second is the low temperature heat radiation.

Great post, thanks for the data !

-Nathan