Bonding the windscreen is a critical milestone. It isn’t nearly as glamorous as mounting the engine or powering up the avionics, but it means a great deal to the overall aircraft structure and final outcome of the project. It’s a make or break moment.
Surface preparation of the bonding surfaces is very important. Various special primers promote adhesion. Accurately locating the about-to-be-bonded windscreen while things are battered with jet-black SikaFlex polyurethane marine adhesive, onto the frame and fuselage, is aided by reference holes and locating pins. Masking and protecting areas where adhesive does not belong, makes it just possible to get the assembly together without too much of a mess. Gentle, even clamping keeps the windscreen in place while the adhesive cures.
Minimum working temperature for the adhesive is 50ºF. At that temperature it will take up to 12 days to cure and it will be all I can do to keep my workshop warm enough though the winter days, here in Pacific Northwest Washington. Time will tell.
All in all, it seems like I’ve pulled it off! Looks like a good fit, no Plexiglass cracks and plenty of nice adhesive in the right places. Now I just hold my breath for a couple of weeks. Whew! Glad to have this step in my rearview mirror. What a relief.