Growing up in Winnipeg, it was normal each fall to fit 'frost shields' to
the car. "Frost shields' were a sheet of stiff plastic with a perimeter
band of rubber, with an adhesive to stick to the car's glass windows, and
sufficient additional rubber buttons to maintain an air gap everywhere.
Canadian Tire stocked them in a variety of shapes and sizes. When visiting
friends down south, we told them it was bullet proof glass.

It was standard practice to fit frost shields to gliders used to fly high
in the southern Alberta wave at Cowley at least up to my first experiences
there, and my diamond climbs, in the early 1980s. Then, Canadian Tire
stopped stocking them. But, they did work.

Indeed. There might BE a reason the frosty bits of North America have mostly
moved on from single-pane house windows.

In the soaring world, the participants with whom I spoke from the Sierra Wave
Projects could no longer (if ever) identify a
single-source/individual/"inventor" of "double-paned" canopies...but all
agreed they worked superbly for them. Triple panes were experimented with, but
their conclusion(s) were the additional benefit wasn't worth the
effort/nuisance, and, double-paning was good enough. They spent a LOT of time
above (say) 30k', often hours per flight...

The 'art' of double-paning glider canopies seems to be sufficiently arcane
that each (prolly statistically tiny) group of 'wave junkies' every generation
has to re-learn both: a) of the theoretical benefits, and b) how to
double-pane. Current SSA members can find several "How To" articles in back
issues of soaring post-1972 (and earlier?).

Somewhat-bendy plastic (e.g. lexan, these days), suitable cutting technology
(eg. box cutter, diamond scribe) and viscous/lowish-sticky goop are your
friends...

Bob W.

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