Reuben wrote:
What would the group here say this flier flies
in a calendar year? 50 hours, more? If I chose 50 hours added 25
percent (for time not spent flying, rigging, staged on the line and so
forth) to represent the time of total exposure to the UV for the year.
That is 62.5 half hours for that year, right? At the end of ten years
we would have 625 hours. Not quite a month's worth of continuous UV
exposure. What about 20 years for this owner. 1250 hours. Just shy of
two months of continuous exposure. If your topcoat of choice can't
handle that, Oh boy. What about in your region's winter months when UV
intensity is generally at its lowest level. Hmmm.

A pilot that flies his glider only 50 hours a year probably should think
about selling it or getting some partners! Maybe he doesn't have to
worry about UV. Let's a take my situation:

-200 hours a year of flying (about 40 hours above 10,000 feet)
-tied out all day for about 1 week in summer at low altitudes
-tied out all day for about 2 weeks in summer at high altitudes (5000+ feet)

Breaking it down:

140 hours flying but kept in trailer
60 hours being rigged/derigged (4.5 hour flights, 30 flights)
60 hours flying but kept outside
140 hours exposure while tied down
---------
400 hours a year UV exposure - 6.4 times Reuben's example

And, many of these hours are at high altitudes in clean air, where the
UV will be much more intense.

So, should I be worried about UV exposure? When I polish my glider, I
notice the top of the wings makes my polishing rag turn white sooner
than the bottom of the wing. I believe this because the gel coat on the
top is suffering more than the gel coat on the bottom, and my guess is
it's UV.

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Eric Greenwell
Washington State
USA