Why are airplanes white?

Judah wrote:
Dudley Henriques wrote in
:

Judah wrote:
Dudley Henriques wrote in
:

You DO realize of course that by bringing this up you have opened a
whole new source of potential revenue for Al Sharpton and Jesse
Jackson?????????
:-))

So long as there are no Black aircraft that have been specifically
attacked by White aircraft this should not be an issue.

Well....could be......and I know Twanna Brawley isn't an airplane, and
she most certainly wasn't attacked, but lo and behold......who shows up
to "save the day and "make it all right again" but Sharpton!!!! :-))
DH

Tawana Brawley claimed to have been raped, which certainly made Sharpton
see Green. The allegations were later proved untrue and everyone involved
(especially Sharpton) walked away quite Red-faced.

I'm Green enough that before the incident, I saw the world through Rose-
colored glasses.

Quite frankly, this whole talk about Sharpton and Jackson is just a Red
herring anyway, because they are both too Yellow to ever fly an airplane.

I just hope this conversation doesn't give them the Green light to start
profiteering from the aviation industry.

Blue skies...

I do believe this thread is getting to be quite colorful.

--
Dudley Henriques

"B A R R Y" wrote in message
...
On Sat, 3 Nov 2007 09:31:29 -0400, "Morgans"
wrote:


Fiberglass airplanes almost demand it. If they get too hot, the epoxy
gets
hot, and gets weak. Very weak.



Some of the new Cirrus versions are not white.

Are they cured in autoclaves?

Epoxy can be designed to stay stronger at higher temperatures, but
generally, they are then required to cure in autoclaves, with the high
temperature and pressure making the higher yield temperatures possible.
--
Jim in NC

It gives the manufacturer more options in selecting trim colors, just as
all
Boeing jets come out of the factory green.

I thought Boeing jets come out of the factory covered in Zinc Chromate
rather than paint?

I thought Zinc Chromate is green. At least the Zinc Chromate I have is
green.

Right; and the problem (or reason) for that statement is...?
--
Jim in NC

On 3 Nov, 21:26, Tony wrote:
No Jay, black is more absorbant and more emissive than a shiny
surface. If it's sun light heating you're trying to reduce, you'd want
to reflect away the energy with a reflective surface. If, though, the
thing you're worried about is hotter than its surroundings and you are
interested in radiating the heat away, you'd want increased
emissivity, and make it black. A black body radiater is considered
perfect, and it is very black indeed.

On Nov 3, 5:22 pm, Jay Honeck wrote:



I did read recently that the SR-71 was black to
reduce the surface temperature by increasing
radiation away from the aircraft.
silverf sur
???

I thought black increased surface temperature?

Mixed top and bottom posts -oh dear.

I thought black increased surface temperature?

It depends - is the most complete answer. I don't
have a canned response but I will try to make
something up.

I think that it is true to say that a black surface
both accepts incoming radiation more effectively
and also radiates more effectively than a white
surface. If you had an aeroplane with a heater inside
it would be warmer inside (in any particular
experimental setup) if it was white than if it was black.

The SR-71 has an internal heater (even though
the source is external air the heat we care about
ends up inside the structure) that is heating it up
and it is cooled more effectively if it is black.
This is of course counterbalanced by a greater
absorbtion of solar radiation but this effect is
insignificant compared to the heating power
(I incorrectly refered to enengy earlier but
it is power - the rate of energy transfer - that
matters here) delivered by the
aerodynamic heating at mach whatever.

In the case of a light aircraft where aerodynamic
heating is negligable the incoming solar radiation
effect dominates and white is cooler.

By the way I don't know for a fact that
the surface finish makes any difference
to the outgoing radiation.
I have heard that it does but I don't know
from first hand measurements or through any
reliable schooling (which would presumably have
involved first hand measurements).

I do know that it affects the absorbed radiation,
well that's obvious to anybody.

Finally, parked on the tarmac a SR-71 would
be cooler if painted white.

If you plan to take your machine to mach 3,
better start planning that new paint job now.

"Dudley Henriques" wrote

I do believe this thread is getting to be quite colorful.

I must say that I like it a lot more than the other recent thread that took
a definite "brown" tone to it!
--
Jim in NC

"Richard Riley" wrote
If you're talking about this one

http://www.maddyhome.com/cozy/chapter?c=25&s=5

It's the same data, just recharted.

No, I'm almost certain it was a study made by the fiberglass boat people.

This version of the data is a bit easier to see, so that is a good thing.
g

The thing that really stuck out from the study that I remember is that there
was a larger jump from white to yellow, even. It really pointed out why
white is so important if you don't want solar gain. I don't know why it
would be any different than the study you listed, and from how the data was
gathered, I would imagine that this data is more accurate.

Of course, it would also make a big difference in "how yellow" the yellow
is, too. A very intense yellow could well be more heat absorbing than a
"mellower yellow." g
--
Jim in NC

If you plan to take your machine to mach 3,
better start planning that new paint job now.

Dang. And here I just shot my budget on that Pulsar installation.
Guess Atlas' new Mach 3.3 ablative paint will have to wait...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Morgans wrote:
"Dudley Henriques" wrote

I do believe this thread is getting to be quite colorful.

I must say that I like it a lot more than the other recent thread that took
a definite "brown" tone to it!

Yes, that one DID seem to enhance a certain spirit of "comoderie" around
here
:-))

--
Dudley Henriques

"Dudley Henriques" wrote

Yes, that one DID seem to enhance a certain spirit of "comoderie" around
here
:-))

Well, that's one way to put it.

I think the thread stunk! g
--
Jim in NC

Morgans wrote:
"Dudley Henriques" wrote
Yes, that one DID seem to enhance a certain spirit of "comoderie" around
here
:-))

Well, that's one way to put it.

I think the thread stunk! g

You win. I'm eating a Baby Ruth!!!

--
Dudley Henriques