Building, testing and operating an experimental aircraft

Showplanes Fastback: Canopy Glassing

15 Aug 2014

Once the plexiglass bubble had cured to the canopy frame, Dad and I got busy filling in the gaps and preparing to add a fiberglass layup around the seam. When finished, the canopy should look like one organic unit, rather than two dissimilar parts joined together.

Epoxy Filler Mixture Epoxy Filler Mixture

We broke out the West System epoxy, and mixed up several batches of flox filler until we got the consistency we wanted for spreading.

Filling the Gaps Filling the Gaps

I went around the seam with the flox, filling in the gap between the plexi and the canopy frame.

Flox Fillet Flox Fillet

Once the flox fillet had cured, we sanded over the area in preparation for the fiberglass layup.

Fiberglass Strips Fiberglass Strips

Dad cut several 2.5-inch-wide strips of glass while I prepared the epoxy station to wet out the strips.

DIY Prepreg Station DIY Prepreg Station

For the layups, we used the “Homemade Prepreg” method outlined by Mark Forss in his Hints for Homebuilders video segment. This process results in nice, neat strips of wetted glass that peel off the plastic backing like a sticker, ready to lay onto the workpiece. It also helps cut down on frayed edges that have to be trimmed or sanded away later.

Glass Strip Layup Glass Strip Layup

We then applied two layers of the fiberglass strips around the edges of the bubble, being careful not to overlap our masking tape line and have edges we’d need to trim away.

Fiberglass Layup in Place Fiberglass Layup in Place

The final result was a nice layer of fiberglass seam tape that effectively hides the joint between the plexi bubble and the canopy frame.

Filling and Sanding Filling and Sanding

What followed next was, of course, days of filling and sanding, filling and sanding.

Yep, More Sanding. Yep, More Sanding.

After the filling and sanding came – you guessed it – more filling and sanding. I have no idea how the Lancair guys do it, but the results sure can be pretty.

On to the priming!

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