The online builders manual for the Marske Pioneer Canopy

CANOPY

Photos and text by Mike Hostage

01 Canopy Seal– Canopy assembly in plan was left fairly well up to the builder's imagination. The plans showed an aluminum frame, bent out of tubing, but I was unsuccessful at bending anything close to acceptable so I came up with another solution. Basically, I built a fiberglass frame, glued the acrylic canopy bubble to it, glassed the bubble inside and out, then popped it free of the fuselage. This photo shows 1/8" spacer, made out of felt, used to mold in a gap in my mounting frame. The gap was to house a rubber air seal, to keep canopy sealed, but the canopy fits so snugly that I never installed the seal.

02 Glue Barrier – Masking tape placed around perimeter of canopy frame, where the fiberglass layups would go (to form the canopy frame). I used wax to help keep the fiberglass from sticking to the tape. Photo shows double layer of fiberglass laid up around perimeter of fuselage.

03 Rails – After fiberglass cured, edges were trimmed inside and out. I also popped the glass frame clear of the fuselage, then set it back in place. Good thing I did so, because later, when the bubble is in place and glass layers were glued on to hold it there, I had a hard time popping the whole assembly off the fuselage. If I hadn't done this first part early, I might have had a real problem! I cut some canopy rails out of left over ash. The holes were for lightness and good looks. The top piece of wood rests on top of the fuselage rail and the ash piece extends down the inside surface (as can be seen in the view of the far rail). Looking at the closer rail, you can see the wood piece resting on top of the fiberglass frame, layed up in the previous step. Next, the canopy gets glued to this outer face (the wood piece and the part of the fiberglass frame that extends down the outside of the canopy).

04 DISASTER! – Got too cavalier in trimming the acrylic bubble. Caused a crack to propagate across the front of the windscreen. Ruined this canopy. Jim blew another bubble for me and I found the right tools and process to successfully trim it. I first rough cut the bubble from the excess flange material. I used duct tape across the cut line, at 6" intervals, to support the cut. As I would pass a duct tape piece (cutting right through it) I would put a new piece of tape across the cut, to hold the two pieces in proper relation to each other. This prevented putting excess stress on the cut point, which was what caused my ruined canopy on the first attempt. I also used an air-powered cutoff tool, with a 3" wheel, to cut the acrylic. It cut like a hot knife through butter!

05 New Glass – New bubble as it comes from Jim. Note initial cut line marked on glass.

06 Rear Pins – Aluminum pins which secure the canopy to the rear part of the fuselage. Matching tubes mounted in fuselage frame.

07 Glass On – Bubble being glued to frame. Used straps, rope and duct tape to hold glass tight against framework. Used polyester resin to attach glass where it touched wood rail and outer surface of fiberglass frame. Once set, used polyester resin and fiberglass cloth to sandwich glass to fiberglass frame, around full perimeter of frame.

08 Inside layer – This is a view of the canopy and frame as seen looking from the underside of the assembly, which is leaning up against my workbench. Once outer fiberglass work had cured, popped canopy and frame free of fuselage. Next step was to complete sandwich with inside layers of glass. First applied masking tape to keep epoxy from migrating onto canopy that was supposed to stay clean, then applied glass. Trimmed fiberglass when it was in the "green" stage, so it would have a neat edge. One note, you have to use the polyester resin anywhere you want the fiberglass to stick to the acrylic. The regular epoxy doesn't stick.

09 Flange – Next step is to build up a fairing to meet the edge of the canopy frame assembly. Here, the canopy frame is masked off to prevent the epoxy filler material from sticking to the canopy.

10 Flange – Fairing material after the tape and canopy have been removed.

11 Sanding – Fairing has been sanded and initial filler material has been applied to fuselage. Much work needed to seal pinholes and defects in fuselage surface. Do careful, painstaking work now as it will pay off in a beautiful painted surface.