Thermal Conductivity , Ice & Me (or You, too)

The composite materials are used as insulation in certain cases. Think
of fiberglass.

Next, look at the paint used for the a/c in question. The composites
are painted below the surface while the metal a/c have painted
surfaces.

Now, given the insulative qualities of the composites, and the surface
area with which to "absorb" energy (heat), the aluminum a/c will shed
ice much faster when placed in a heated hanger than will a composite.
Now if you place a fan in that heated hanger, the composite will de-ice
at a faster rate.

OTOH - at altitude and with air speed, I do not know if the composite
will ice faster than the aluminum, because the aluminum is not (well, I
wouldn't think it) as smooth as the composite. So water has something
to adhere to which will start the process (talking about rime). Because
of the smoothness of the wing, I don't know, and have no experience
with clear ice and its ability to stick to the wing. But because my
step-son is close to test flying his Vari-eze (I think that is the one
he is building), we may be able to find out by this time next year.

So you other composite drivers, how about practical experience?

Later,
Steve.T
PP ASEL/Instrument

"Steve.T" wrote:

The composite materials are used as insulation in certain cases. Think
of fiberglass.

Fiberglass, in and of itself, is not a particularly good insulator. When it's
spun into a sort of glass wool and traps a lot of small air bubbles, that
changes. The air *is* a good insulator.

George Patterson
He who would distinguish what is true from what is false must have an
adequate understanding of truth and falsehood.

"George Patterson" wrote in message
...


"Steve.T" wrote:

The composite materials are used as insulation in certain cases. Think
of fiberglass.

Fiberglass, in and of itself, is not a particularly good insulator. When
it's
spun into a sort of glass wool and traps a lot of small air bubbles, that
changes. The air *is* a good insulator.

Depends on how you look at it. In the long-wavelength infrared
spectra the atmosphere is virtually transparent. In that regard, air is an
excellent conductor since it poses no resistance to thermal radiation. And
it is the radiation that accounts for the type of heat loss involved in
these discussions, not conduction. So it is the thermal emissivity of the
wing surface that really matters -- not the molecular conductivity.

On Sat, 12 Feb 2005 05:18:37 GMT, "Casey Wilson" N2310D @ gmail.com
wrote in NkgPd.2805$uc.202@trnddc01::

So it is the thermal emissivity of the
wing surface that really matters -- not the molecular conductivity.

If the molecular conductivity is unimportant, once the surface changes
temperature, how does the rest of the material change temperature
without conduction?

"Larry Dighera" wrote in message
...
On Sat, 12 Feb 2005 05:18:37 GMT, "Casey Wilson" N2310D @ gmail.com
wrote in NkgPd.2805$uc.202@trnddc01::

So it is the thermal emissivity of the
wing surface that really matters -- not the molecular conductivity.

If the molecular conductivity is unimportant, once the surface changes
temperature, how does the rest of the material change temperature
without conduction?

Go back and read it in context. I didn't say there was no conduction.
What I said was (in different words) that conduction is not the process of
the wing surface losing thermal energy. Here, I'll put it in another term so
you can do some more nit picking: Because the atomosphere is transparent in
certain important wavelengths, the heat of the wing is being sucked into
outer space.

On Sun, 13 Feb 2005 04:34:40 GMT, "Casey Wilson" N2310D @ gmail.com
wrote in ANAPd.26325$uc.19139@trnddc04::


"Larry Dighera" wrote in message
.. .
On Sat, 12 Feb 2005 05:18:37 GMT, "Casey Wilson" N2310D @ gmail.com
wrote in NkgPd.2805$uc.202@trnddc01::

So it is the thermal emissivity of the
wing surface that really matters -- not the molecular conductivity.

If the molecular conductivity is unimportant, once the surface changes
temperature, how does the rest of the material change temperature
without conduction?

Go back and read it in context. I didn't say there was no conduction.
What I said was (in different words) that conduction is not the process of
the wing surface losing thermal energy. Here, I'll put it in another term so
you can do some more nit picking: Because the atomosphere is transparent in
certain important wavelengths, the heat of the wing is being sucked into
outer space.


Yes. I understood what you said. And I thank you for the insight
into the arcana of IR radiation.

However, I believe the question that I posed provides further insight
into the RATE of temperature change that we were discussing.
Obviously conduction is required to move the heat to the surface.

"Larry Dighera" wrote in message
...
On Sun, 13 Feb 2005 04:34:40 GMT, "Casey Wilson" N2310D @ gmail.com
wrote in ANAPd.26325$uc.19139@trnddc04::


"Larry Dighera" wrote in message
. ..
On Sat, 12 Feb 2005 05:18:37 GMT, "Casey Wilson" N2310D @ gmail.com
wrote in NkgPd.2805$uc.202@trnddc01::

So it is the thermal emissivity of the
wing surface that really matters -- not the molecular conductivity.

If the molecular conductivity is unimportant, once the surface changes
temperature, how does the rest of the material change temperature
without conduction?

Go back and read it in context. I didn't say there was no conduction.
What I said was (in different words) that conduction is not the process
of
the wing surface losing thermal energy. Here, I'll put it in another term
so
you can do some more nit picking: Because the atomosphere is transparent
in
certain important wavelengths, the heat of the wing is being sucked into
outer space.


Yes. I understood what you said. And I thank you for the insight
into the arcana of IR radiation.

However, I believe the question that I posed provides further insight
into the RATE of temperature change that we were discussing.
Obviously conduction is required to move the heat to the surface.

Ahh, now I see your point. You are obviously correct that it is
a systemic process.

In article ANAPd.26325$uc.19139@trnddc04,
"Casey Wilson" N2310D @ gmail.com wrote:

Go back and read it in context. I didn't say there was no conduction.
What I said was (in different words) that conduction is not the process of
the wing surface losing thermal energy. Here, I'll put it in another term so
you can do some more nit picking: Because the atomosphere is transparent in
certain important wavelengths, the heat of the wing is being sucked into
outer space.

Well, I'll pick a tiny, purely semantic nit:

The heat of the wing isn't being "sucked" into space; it's being
actively _radiated_ into space -- but space, being cold (3 degrees K in
the limiting case), isn't radiating back.

But this is only to quarrel with your phrasing, not at all with your
basic argument.

The heat of the wing isn't being "sucked" into space; it's being
actively _radiated_ into space -- but space, being cold (3 degrees K in
the limiting case), isn't radiating back.

But this is only to quarrel with your phrasing, not at all with your
basic argument.

Actually, I like the imagery of the heat being sucked into space.

Jose