Canopy fasteners

[mike.smith]

Any thoughts about what order to install the fasteners into the canopy frame? Since there is so much bending and squishing that goes on as the canopy is pushed onto the frame, I'm assuming that if I mark the hole locations all at once, when I start fastening the canopy material the canopy edges aren't necessarily going to end up where I thought they would.

I can just see me starting to fasten, and finding the canopy material bowing up between fasteners.

I'm going to use screws and nuts, rather than tapping the bows, to secure the canopy.

Mike Smith

[kmacht]

Mike,

Not sure what you mean by canopy fasteners but for the bows I just used some stainless steel countersunk washers and screws. You will need some rubber faucet washers to put between the canopy and the bows if there are any gaps that need to be filled. Just adjust the number and size of washers to get a good consistent fit to the fuselage. For the sides of the canopy I used some round head stainless phillips screws. You have to tap the canopy frame at least on the opening side because nuts owill get in the way of the canopy lock bar. Yes, the material will deform a bit as you tighten them down. I had to tighten it all down and then mark where it needed to be trimmed at the side / fuselage intersection and then pull it all back off. You will get very good at taking the canopy on and off by then anyways. One other suggestion is to make sure you use oversize holes in the canopy material. I went about an 1/8" bigger on the hole size than was needed for the screws.

Keith
#554

[fastj22]

I screwed up my first canopy by tightening the bow screws too much. It looked scalloped and I had several cracks from the stress. My second canopy came out great.
First off, don't tap the holes in the bows, just drill through them. Then use machine screws (I think #6) with self locking nuts to secure them. Buy an assortment of lengths. And the counter sunk washers they specify. And a bunch of regular thin washers.
Now here's the trick, when you start attaching the canopy, there will be gaps between the glass and the bow that vary from nonexistent to maybe 1/8 inch. Shim the gap with washers and find the right length screw to go through the countersink on top, the glass, the washers/shims and leave enough for the nut on the bow side . Then just tighten the nut until it self locks. You should be able to turn the screw by hand. Don't tighten it any more. Any more and you are in danger of cracking and distorting the shape. As long as the nylon in the nut has engaged, it won't come loose.
My new canopy and windshield has been one year through extreme temp changes and is not cracked or distorted.

[mike.smith]

I screwed up my first canopy by tightening the bow screws too much. It looked scalloped and I had several cracks from the stress. My second canopy came out great.
First off, don't tap the holes in the bows, just drill through them. Then use machine screws (I think #6) with self locking nuts to secure them. Buy an assortment of lengths. And the counter sunk washers they specify. And a bunch of regular thin washers.

That's essentially what I plan to do. I guess my question was more about the process of transferring the holes from the canopy material to the frames. I assume I locate and drill all the holes in the canopy material first, but then do I locate a couple of hole locations on the bows, drill them and set the screws, mark another couple of holes, remove all the fasteners, drill and clean the second set of holes, install the second set of screws, mark the third set of holes, etc, etc.

I guess my point/question is: I'm afraid if I transfer all the canopy hole locations at once to the frames, that when I go to fasten the canopy I'm going to find that with each fastener I install, the adjacent canopy/frame holes are going to be more and more misaligned due to the canopy moving (squishing out sideways for lack of a better description), to the point that working from one part of the frame to the other, I'll find the final holes are something like a quarter inch out of aliment.

Am I making sense?

Mike

[fastj22]

I think I see your point. I would measure and drill the bows first. Then place the canopy on the frame and drill the top hole in the glass. Then work down each side. You can sight the bow hole easily through the glass. Also, oversize the glass holes a bit to give it some movement.

Oh and be very careful when adjusting your latch. if its too tight, don't force it. My first hole crack came when I jambed the latch forward, pulling the canopy down on the windshield frame too tight.