pictsidhe
Well-Known Member
Even Texans, huh?
It would be easy to make a bit of fun of the inferiority complex often displayed by our neighbors to the north, but the truth is that he is absolutely right. When you see a white Long EZ from Texas you know there is a builder out there who supresssed his inner desire to put a giant Lone Star flag on there, or a A&M/UT color scheme in the interest of saftey.Even Texans, huh?
I think he has it the wrong way round!I was told by a wood kit company owner, it’s not 140 inside the wing. The surface might be 140 but by the time the temperature gets to the first glue joint it’s only 100. Wood is good at insulating. If it was steel, I would be worried. Big heat sink then.
(Sorry, sometimes I have to figure things out for myself. I get there, eventually.)Unless I am not seeing something, the only reasonable options are 1.) even at reduced strength due to heat, the epoxy is still sufficient
Seems like it really doesn’t matter, as full strength was not necessary to begin with, only sufficient strength.Not to put a bullseye on my back,buuuut....I'm going to ask a dumb question anyways.
I understand that epoxy will lose strength as the temperature rises.
I also understand the FOS aspect.
And last but not least...I understand the temperature variations that you can get with different colors.
With that being said.....
Will the epoxy return to full strength once the temperature has decreased ?
And.........if it does....
How many heat cycles can it go through before it no longer returns to full strength with the temperature decrease ?
Asking for a friend......lol
Kevin
I had the same dumb question. From what I read, at the range of temps we're talking about here, it will return to full strength. Apparently, if you don't get it hot enough to actually break down the polymer matrix, it will retain its resiliency.Will the epoxy return to full strength once the temperature has decreased ?
And.........if it does....
How many heat cycles can it go through before it no longer returns to full strength with the temperature decrease ?
Interesting academic discussion.
My planes are built with T88. No worries...
Yes!The kit I am building (Pulsar I) is a FRP and I really want to paint it silver. My thinking is that silver would have a fair amount of reflective properties to it and help with solar heating of the epoxy.
I really don't like the idea of being limited to a white only color.
Anyone think I could get away with Silver?
/snip/
Be sure to use a primer that reflects uv, to protect the epoxy.The kit I am building (Pulsar I) is a FRP and I really want to paint it silver.
I actually asked they guys at System Three if T-88 benefited from a post cure and they said it did not. Many laminating epoxies do, just not T-88.To my knowledge Post Cure of Epoxy will complete the cross-matching of the molecules (resin and hardener) to give the highest strength and resistance to heat soak to a certain temperature. You need to check what that temperature is.
Without Post Cure the Epoxy remains under cured and under strength, I've heard of wings distorting when left out to heat soak in the open.
I would suggest different Epoxies have different values for Post Cure, so too does the foam in a foam sandwich, where some foams out-gas earlier than others, which can lead to delamination.
Although Epoxy falls victim to UV degradation it doesn't happen overnight, however Epoxy is the strongest and has the highest adhesion, compared to Polyester and Vinyl-ester.
Hope that helps.
George
Yes!
Pigments incorporating the oxides of magnesium (white) or aluminum (silver) have similar reflective properties.