Canopy causes cockpit fire

Yesterday afternoon Mark Mocho (MM Fabrication) opened
the canopy of his Pegasus to get his cell phone. By
the time he made a call to me, his soaring hat, which
was lying atop the glare shield, was smoking. The
canopy was acting like a big magnifying glass and focusing
the sun's rays onto a quarter-size spot just above
the instrument panel. Scary to think what would have
happened if he'd walked away for a few minutes.

Photos are at http://www.silentwingsairshows.com/canopy.html
Notice the burn marks on the instrument panel from
previous solar encounters. One shot is of Mark (no
that's NOT Jack Nicholson) duplicating the sun angle
with a flashlight.

I'd heard of this phenomenon before, but couldn't figure
out exactly how it happened. Seems it's not the light
coming through the canopy, but the light reflected
from the inner surface (which is roughly parabolic
in shape), that causes the problem. At a shallow grazing
angle, enough light is reflected to get smokin' hot.
Nice trick to know if you ever get ants in your cockpit
;o)

Bob