Can I paint a composite plaine a silver / grey color?

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mcurcio1989

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I recently purchased a flying quickie Q200 from a local pilot/builder/owner. It needs a fresh coat of paint and originally I was thinking stick with the white but my paint guy (who is also a pilot) said that silver / grey would be comparable to white as far as reflecting light / heat. We all know that cirrus has gotten very comfortable with this but I am not going to compare there layup process to some guys in a garage building a quickie. So what are your thoughts? bad idea or no problem? I think it would look really nice in a silver color but I don't want to compromise the structure.
 

tspear

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Basically the limitation deals with the cure point of the resin. Cirrus bakes the parts in a giant auto-clave. This sets the cure point much higher then the local builder in his/her garage.
Therefore, I would be very suspect of trying to paint any structural component anything but white.

Tim
 

BBerson

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I tried silver paint on a patch next to white base. It gets very hot.
Polished aluminum reflects light, silver paint doesn't reflect, it absorbs.
 

Himat

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A guess, silver or grey paint may differ a lot on how hot they get in the sun.
A lot of the heat from the sun comes as invisible infrared radiation. The question will be then how reflective a certain silver or grey paint is to infrared light. Even a layer of clear lacquer can make a difference. Some absorb infrared light, others don’t.
 

pictsidhe

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Put a piece of polished aluminium out in the sun. It gets hot, despite being a reasonable light reflector, due to really low emissivity. White paint has high emissivity.
 

Marc Zeitlin

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I recently purchased a flying quickie Q200 from a local pilot/builder/owner. It needs a fresh coat of paint and originally I was thinking stick with the white but my paint guy (who is also a pilot) said that silver / grey would be comparable to white as far as reflecting light / heat. We all know that cirrus has gotten very comfortable with this but I am not going to compare there layup process to some guys in a garage building a quickie. So what are your thoughts? bad idea or no problem? I think it would look really nice in a silver color but I don't want to compromise the structure.
This:

http://hallert.net/cozy/images/ColorCurveChart.gif

is a color chart originally derived from Soaring magazine, back in the day. It's commonly used in the composite community to discuss what colors are acceptable. As you can see, even silver/AL is substantially hotter in still air in the sun than white. As you surmise, Cirrus uses different epoxies than us "guys in the garage", and can post-cure to higher temperatures. Personally, I counsel people to paint all STRUCTURAL areas of a composite plane white.

This:

http://imgproc.airliners.net/photos/airliners/7/2/6/2405627.jpg?v=v40

award winning COZY MKIV, in which I recently installed a new instrument panel and perform regular maintenance on, obviously has some dark colors on it. BUT, they're all in non-structural areas - the builder was careful to keep the dark colors only in places of very low stress. And let me tell you - you can easily feel the temperature difference when it's been out in the sun for a while.

So, use trim colors as desired, but keep anything other than white in low stress, non structural areas.

My $0.02.
 

mcurcio1989

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Great info gentleman, that is kind of what i suspected. Makes my decision easy!

Marc -Cool, chart and infromation - very infromative! I noticed you live in Tehachapi - that was where I picked up the engine (o-235) for my amphib this past winter. It was from a retired A&P who lived up in the mountains outside of Tehachapi actually.

Great looking Cozy, I imagine he has a hell of a time keeping that white prop clean!
 

pictsidhe

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The white seems a bit hot. Most non metallic paint has an emissivity around 0.9-0.95, while absorbtivity is highly dependent on colour, whites are down around 0.05, black is 0.9+. A bright white paint should be cooler than the chart indicates. Heat gain is determined by absorbtivity, heat loss by emissivity and convection. That colour curve gif looks like it only factors in convection. Experiment is the best way to decide as paint is highly variable.
 

wsimpso1

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There are two parts to the heat tolerance of a foam and fiberglass airplane. The glass transition temperature of the resin (called Tg) and the foam that immediately underlies the fiberglass reinforced plastics. Both the resin and the foam have to stay cool enough. Now a Q200 IS likely to have been built with resin that has limited thermal capability. It is also likely to have been built of foam with limited thermal capability. I would stay with white.

Oh, and airplanes painted white with a dash of blue thrown in approach the low vis blue camo scheme favored by the USAF for being hard to see...

Billski
 

BBerson

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There are some special made non-white colors that can be cool. Google "cool roofs". Or the work of Art Rosenfeld of the California energy commission for homeowners that don't like white roofs.
 

Hephaestus

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Anyone seen research done on these new IR reflective paints? Some make some interesting claims on reduced surface temperatures compared to white.
 

Marc Zeitlin

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Do an image search for "red lancair aircraft."
Different aircraft are fabricated from different materials. I believe that the Lancair aircraft (and someone correct me if I'm wrong) are fabricated from pre-preg cloth and matrix (I ASSUME epoxy, but don't know for sure) and are cured at elevated temperatures. This is substantially different from the hand layups and materials used in the moldless construction techniques of canard and Quickie type aircraft. So it MAY be perfectly acceptable for molded Lancairs to be painted with colors that lead to elevated temperatures - I do not have enough knowledge to say for sure.

But I CAN say for sure that a Long-EZ, COZY, Berkut, Q1, Q2, Q200, Dragonfly, or any other aircraft laid up with room temperature cured epoxies and using hot-wired styrofoam should be kept essentially white anywhere that it's exposed to the sun (top surfaces) and where structural integrity is critical.
 
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BJC

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Different aircraft are fabricated from different materials. I believe that the Lancair aircraft (and someone correct me if I'm wrong) are fabricated from pre-preg cloth and matrix (I ASSUME epoxy, but don't know for sure) and are cured at elevated temperatures. This is substantially different from the hand layups and materials used in the moldless construction techniques of canard and Quickie type aircraft. So it MAY be perfectly acceptable for molded Lancairs to be painted with colors that lead to elevated temperatures - I do not have enough knowledge to say for sure.

But I CAN say for sure that a Long-EZ, COZY, Berkut, Q1, Q2, Q200, Dragonfly, or any other aircraft laid up with room temperature cured epoxies and using hot-wired styrofoam should be kept essentially white anywhere that it's exposed to the sun (top surfaces) and where structural integrity is critical.
Agree. My post was purely in response to Tiger Tim's lament, which was not design specific. Thanks for ensuring that casual readers do not interpret it incorrectly.

My world record build time Glasair will be white.


BJC
 
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