There is no fine fitting here...

Yeah, I've seen lots of gliders like that.

I have fitted a couple of canopies, and I can say that the more effort and attention you put into it, the better it turns out. The fit of the canopy transparency to the frame, and the assembly to the fuselage, is the first and last thing you see when you get in and out of a glider, so it's nice when it it all looks good.

Pretty much anyone can learn to do it, but when you learn by doing the lessons are too often too late for the learning.

Some points from our experience:

* If you fit the canopy so that the edge is proud of the contour, you can always add a bit of filler to the fuselage and make it look just fine. But if you fit the canopy so that the edge is below flush of contour, it is much harder to deal with.

* Canopy frames often have built-in stresses and preloads that spring them out of shape when the transparency is removed. So it is usually best to fit the canopy while the frame is mounted to the fuselage and maybe has a few spring clamps to hold it into place on the fuselage.

* Canopy transparencies are often not very consistent in thickness around the perimeter; this is a side effect of the stretch forming operation. So don't expect to create an inset the exact canopy thickness and have it come out perfect. The thickness varies, and you also need room for the bonding paste.

* It might be an old wives tale, but I've been told that the BGE diluents in laminating epoxies can attack and craze acrylics. In my shop we use an undiluted bonding resin for canopy transparencies, just in case.

* Squeezeout happens. Use lots of masking tape, and wax the fuselage and everything else you don't want stuck together. The DG guys actually use a narrow strip of weatherstripping along the upper edge of the canopy frame to keep the squeezeout from coming up and into the cockpit. I've not tried that, but it sounds like a good idea.

* Do not attempt to cut, drill, sand, or file the transparency unless it is above about 70 degrees F. Fresh acrylic plastic is actually quite easy stuff to work with when it's warm. But like glider pilots, the colder and older canopies get, the more disagreeable they become.

--Bob K.