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Hairline fissures on tip up-7

F

FutureRV

Member
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My canopy has developed these short fissures/ cracks in the mid point of the canopy. It is occurring on both sides. Mid-point of canopy about 10 inches horizontal. Canopy is about 14 years old. Any idea why this would happen? What can be done to stop it or at least slow down the spread?
Thanks,
David
 
Mine did the same thing this summer. Had absolutely no cracks around any hole on the Plexiglas, then had these random cracks just show up. Can't tell if they're from a hole or just in a high stress area. I attributed it to the crazy heat we had in Texas this summer, as it was over 100 degrees F for the better part of two months. It was 120 degrees in the hangar with the door shut.

I'm curious if the VAF think tank has an explanation and a solution.
 
I think you'll find that the edges of the canopy were not finished properly after cutting.

A sharp (90°) edge in plexi will tend to crack over time - vibration, thermal expansion effects, will accelerate and amplify the effects.

Depending upon your level of OCD/AR, I think you have a couple of options --

1. Ignore it -- it won't get any better, and it might not get worse.
2. Loosen each nut 1/4 turn.
3. Stop drill each crack that is longer than 1/4" above the canopy side rail - use the smallest drill bit (#45?) you can comfortably control to drill at the end of the crack, debur, inject plexiglass welding solvent with #28ga needle/syringe.
4. Awwww nutz -- order a new canopy...
 
Thanks for the replies. Just seems weird after 13-14 years this would happen to the canopy. I am going to take the wait and watch approach. Stop drill when necessary and god forbid replace if it get too bad. 🤦🏻
 
FutureRV said:
Thanks for the replies. Just seems weird after 13-14 years this would happen to the canopy. I am going to take the wait and watch approach. Stop drill when necessary and god forbid replace if it get too bad. 🤦🏻
Click to expand...

But back off the nuts as suggested. This is what caused the cracks between the nuts.
 
While you're at it...

...remove a nut and screw and note how large the hole is through the transparency. Is it only large enough for the screw to go through? If so, then it may be too small. You want some edge distance between the metal screw and the transparency to allow for thermal expansion and contraction between the two different materials. If they're coming into contact with any pressure, you can develop a crack at that point in the hole.
 
14 years is a long time to remember what type of solvents the acrylic was exposed too.
I know my first canopy had similar crazing marks, I used lacquer thinner to clean glue & marker pen marks - till I found out it would cause this. I don’t do that any more.
 
I backed off a few nuts along base of canopy. Seems to have helped. Will just monitor over time. It went 13 years with no issues. 🤷*♂️
 
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