Blackbird
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Honeycomb Panel / Temperature Tolerance

Fri May 25, 2007 8:56 am

Can honeycomb panels take higher temperatures than regular metals? Because on a site about the Convair B-58 states that it's honeycomb panels allow it to fly at higher speeds and higher temperatures than traditional alloys.

Andrea Kent
 
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Starlionblue
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RE: Honeycomb Panel / Temperature Tolerance

Fri May 25, 2007 9:38 am

Quoting Blackbird (Thread starter):
Can honeycomb panels take higher temperatures than regular metals? Because on a site about the Convair B-58 states that it's honeycomb panels allow it to fly at higher speeds and higher temperatures than traditional alloys.

Well, I have quite a bit of experience with cooling of computer components. A good aircooling heatsink (for example a Thermalright Ultra 120 or a Scythe Ninja) is mostly empty space to allow maximum surface area. Some have fans and are "passively cooled". In the latter case, other fans in the case or just plain old convection will remove heat from the heatsink.

I'm going to guess that a honeycomb have greater ability to dissipate heat due to greater surface area. However that heat must go somewhere. Perhaps the gas trapped in the honeycomb (air?) also acts as a heatsink.
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rwessel
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RE: Honeycomb Panel / Temperature Tolerance

Fri May 25, 2007 12:20 pm

Quoting Blackbird (Thread starter):
Can honeycomb panels take higher temperatures than regular metals? Because on a site about the Convair B-58 states that it's honeycomb panels allow it to fly at higher speeds and higher temperatures than traditional alloys.

The honeycomb material allow you to build a much stiffer panel for a given weight, much like an I-beam is stiffer than a simple round beam with the same amount of material in cross section. The "filler" is there to provide the rigidity to prevent the honeycomb of metal from collapsing (since it's quite thin), although the filler adds some strength and stiffness of its own.

All metals weaken as they are heated, and long before they melt. As I understand it, the honeycomb simply allows you to build a panel that's still strong enough at the required temperature. You can take advantage of that in two ways. First, because the honeycomb design is inherently stiffer, a panel can be built that retains the required strength even though the component metal has weakened. The alternative being a much thicker ordinary aluminum panel which would have sufficient strength remaining at the desired temperature (with the obvious disadvantage of greatly increased weight). Second, the honeycomb design allows you to use a more heat resistant metal with an inferior tensile strength to weight ratio (like steel) while keeping weight reasonable.
 
Blackbird
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RE: Honeycomb Panel / Temperature Tolerance

Fri May 25, 2007 1:01 pm

Starlion,

So, a honeycomb panel with a cooling system and heat-sink could take higher operating temperature than regular sheets of aluminum and such?

Andrea Kent
(Should I get a heart-attack, blame Uncle Sam)
 
Blackbird
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RE: Honeycomb Panel / Temperature Tolerance

Sat May 26, 2007 4:33 am

You know, via heat-dispersion into the heat-sink (fuel)

Andrea K
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Starlionblue
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RE: Honeycomb Panel / Temperature Tolerance

Sat May 26, 2007 4:57 am

Quoting Blackbird (Reply 3):
So, a honeycomb panel with a cooling system and heat-sink could take higher operating temperature than regular sheets of aluminum and such?

I am assuming that the honeycomb itself is the primary heatsink. But sure. Heat dissipation is in large part about surface area (the other elements are shape and material). The more you have, the more area is presented to the cooling medium (gas or liquid).

A car radiator has many small cooling fins instead of a big one for the same reason.

You could use heatpipes to transfer heat to a radiator on colder part of the vehicle.

I have been playing with cooling a lot lately: http://quietpc.rosboch.net
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3DPlanes
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RE: Honeycomb Panel / Temperature Tolerance

Sat May 26, 2007 7:55 am

Quoting Blackbird (Reply 3):
So, a honeycomb panel with a cooling system and heat-sink could take higher operating temperature than regular sheets of aluminum and such?

In theory, sure. In practice however, the honeycomb is fully enclosed. Any added surface area in the honeycomb wouldn't "see" the heat (or any cooling material) directly - like you get in a radiator. It's a sandwhich - sheet metal, honeycomb, sheet metal - and it's too thin to have any fuel inside the honeycomb.

Actually I'd be quite surprised if it didn't actually make a better insulator than it does a heatsink. There's lots of air in the cells of the honeycomb, so the heat from the outside surface doesn't have much chance to transfer inwards.

That insulating ability, combined with the added strength mentioned above would be what I think your source is talking about.
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Starlionblue
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RE: Honeycomb Panel / Temperature Tolerance

Sat May 26, 2007 10:47 am

Quoting 3DPlanes (Reply 6):
In theory, sure. In practice however, the honeycomb is fully enclosed. Any added surface area in the honeycomb wouldn't "see" the heat (or any cooling material) directly - like you get in a radiator. It's a sandwhich - sheet metal, honeycomb, sheet metal - and it's too thin to have any fuel inside the honeycomb.

Agreed.

Quoting 3DPlanes (Reply 6):
Actually I'd be quite surprised if it didn't actually make a better insulator than it does a heatsink. There's lots of air in the cells of the honeycomb, so the heat from the outside surface doesn't have much chance to transfer inwards.

Agreed again.

Quoting 3DPlanes (Reply 6):
That insulating ability, combined with the added strength mentioned above would be what I think your source is talking about.

And again.


As 3DPlanes nicely points out, heatsinks work "both ways". You can use them to store heat, as is probably the case here. Or you can use them to dissipate heat. However this still involves storing the heat first. For the latter you need some sort of mechanism to get the heat out. Fluid (gas or liquid) circulation, heatpipes, even radiation are methods to d that.

In the book "2001", Discovery One had huge wing-like radiators. No air in space, so all you get is radiative heat transfer. But even Arthur C. Clarke said they couldn't put wings on a spaceship for the movie.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

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