This entry represents 3 afternoons of work.

I won't rivet on the fwd skin until the engine is hung and I can determine control cable routing and firewall penetrations for the IO390. However, I want to be able to cut holes in it for defrost fans, VFR GPS antennas and wiring for the LED strips that go under the glare shield. Therefore it makes sense to locate the windshield so I can see where to cut the holes and route stuff. Also, I want to get he windshield trimmed to its final shape while I can still get the shop warm and not run the risk of cracking it.

Therefore, even though I'm not installing it yet, the last few afternoons were devoted to warming the shop up in the afternoon sun and working on the windscreen before winter hits here in Kansas.

Lots of people have had difficulty with not having enough material left over on the aft lower corners if they follow Vans instructions and cut the lower edges of the canopy before they make the big cut. I got this heads up last year when I was researching the canopy on VAF, so I had made the big cut first, the set the windshield blank aside still full length way back then.

The print doesn't give any dimensions whatsoever for the windscreen but the side view shows that the lower edge sort of butts up to the upper aft edge of the skin where it swoops back to the roll bar. So, I went to VAF and asked what people have had success with in regard to how much the windshield should overlap the skin in that corner.

I got answers back that ranged from "none" to "as much as you can get" Larry Larson pointed out that the skin tapers in as it goes up so you should strive to cut high enough that you can suck the Plexiglas in and the fiberglass fairing with have a smooth transition over it.

So, I did an initial trim that wasn't much more than cutting off the mold lines, set it in place, looked at it, and discovered a problem; With the aft corners clamped in place, the sides were pooched out enough that I could stick my fingers in the gap on both sides. I don't know if this is just the normal shape of the canopy blank, or if it spread out while sitting in my hot shop all summer long. I had a couple of strips of duct tape holding it together to prevent it from sprawling out, but I can see how it could bow in between them and cause the gap. If I ever do another one of these, I'll take better care to make sure the lower edges don't have an opportunity to develop a bow while in storage. At any rate, This needs to be addressed.

This started two additional afternoons of trimming, measuring, clamping, and then doing it all over. This has turned out to be one of the more complicated fitment processes of the whole plane. Absolutely nothing on this is at a constant angle to anything else, and the fit of the lower edge is challenging because it curves in two directions at once. The windshield curves back and down, and the skin obviously curves down laterally at the same time.

I laid down a tape grid pattern on the skin to help with symmetry, but ultimately it was just a bunch of trial fit, then trim some more.

I try to include as much info as possible in these entries in case it might help somebody else in the future, but in this case, I don't have much detail; In order to minimize the gap on the lower edges, I ended up with about 1/8" overlap at the aft corner, transitioning to about 3/8" overlap fwd where the skin starts to swoop up. I also found that the best fit was to slide the entire thing aft about an inch from where it seems like it should lie and trim that much off the original Big Cut line. The tape grid was helpful for initial trimming for symmetry, but eventually I ended up stripping it off and just referencing rivet holes fir final adjustments. I ended up using 10 clips to hold it down tight-ish to the skin. The two closest to the center lines pick up existing rivet holes through the skin and underlying bulkhead. The rest are through new holes in the skin, including 3 on the aft sides to suck in the remaining gap.

Overall, I'm happy with how it turned out. I checked with a radius gauge and straight edge and don't think the clips will sit too proud to get a good fairing radius, although I may chamfer the edge of the Plexiglas where the clips sit so they will ride a little lower just to make sure. The biggest gap to the skin is about 1/8" which is easily bridged with Sika.

I will say definitively, that the canopy and windshield is without a doubt the least fun part of the whole project. You have to dress the edges after every trim to eliminate stress risers and potential catastrophic cracking while maneuvering the Plexiglas. All that trimming and sanding takes forever, even with cutoff discs, flapper wheels, vibrating sanders, and other arcane instruments of mass construction.

Dust gets everywhere. In your hair, in your ears and eyes, all over the shop. I hate it. I also had the heater running full blast even when the afternoon temp hit 70* and while the Plexiglas loves it when it's over 80* in the shop, me not so much.

I'm glad this is done.