Yes, it now appears that composite gliders will outlast metal ones. The
gelcoat will degrade but the underlying structure seems to last forever.


be careful, guys; you have to distinguish:

one thing is the gelcoat. it protects the fiberglass (or carbon) structure
underneath from UV light which harms the epoxy resin. regular gelcoat is
not resistant to UV light forever; cracks in the gelcoat work their way
into the laminate. a while ago, i had to repair the outer layer of glass of
a fiberglass wing just because of that. the problem appears especially when
the gelcoat (or filler, when using automotive paint) is very thick, making
the surface or paint layer too stiff to follow the fiberglass' strains,
which results in cracks.

another thing is the structure itself. as mentioned above, it's strength can
be affected e.g. by UV light and it has to be protected against. if this
protection is maintained, and the structure had been designed and
calculated in a correct way, fatigue is not really an issue, and the
material's strength remains. aluminum is much worse...


uli