Scott Chastain
Active Member
Be ever hearing, but never understanding,
Be ever seeing, but never perceiving.
---Isa 6:9
Be ever seeing, but never perceiving.
---Isa 6:9
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It's surely interesting that so many canopies bonded on with Sikaflex have developed serious cracks.
Compae the coefficient of expansion of the plexi with the aluminum (IIRC it's a factor greater than 3) It gets significant as the edge of the canopy grows in length.
That would be great until you are upside down and trying to get out. It is a pain to change the canopy, but not that bad once you just dive in and do it.Too bad someone couldn't come up with a canopy material that was crack proof!
It's interesting that so many screwed on canopies have developed them as well.
Yes, but surely the migration to Sikaflex was prompted almost exclusively by the initial belief that bonded canopies would not crack.
I thought the benefit was that canopies wouldn't have stress concentration points (like screw holes). So the chance of cracking would be *reduced*. I don't think anyone could guarantee no cracks ever, when moving between temperature extremes.Yes, but surely the migration to Sikaflex was prompted almost exclusively by the initial belief that bonded canopies would not crack.
To ensure good performance in environments where temperature varies widely, Plexiglas® sheet should be installed in a channel frame that permits the sheet to expand and contract freely. The channel frame should be deep enough for the sheet to contract fully and still stay within the frame.
Avoid inflexible fasteners such as bolts that do not permit expansion and contraction. Tapes and sealants that adhere to both the acrylic sheet and the frame should be sufficiently extensible to accommodate thermal expansion of both.
Understood! I was suggesting that the article go on the Wiki, but not on the Sikaflexing page... that was just an example. A different page could be added for Repairing Canopy Cracks.However, I wanted to address the repair option when posting this thread, not the original build process with either rivets, screws, or SikaFlex. For those whose canopies suffer cracks---even severe ones like mine---it might be good to know that repair is not only possible but also acceptable. I'll leave the debate over why the cracks occur to another thread.
Be ever hearing, but never understanding,
Be ever seeing, but never perceiving.
---Isa 6:9
I don't understand. The first post I see in this thread is this one but members are commenting on the repair. Did some posts or pages get deleted?
It would appear that Scott has edited all of his posts, removed the aviation content, and replaced it with scripture.
Since the original thread was so valuable, I saved it as a PDF way back when. Unfortunately it's more than 70 megs, too busy to post here. If someone has a place where I can upload it without establishing a new account anywhere, I'll do that. Ideally, then you'll post that link here for everyone to access.