Refinishing gelcoat

In article ,
says...
It struck me the other day that the materials used to cover R/C models these
days could be used to 'refinish' ships on which the gelcoat had
deteriorated. We are already 'happy' to stick .5m wide pieces of orange tape
to the surfaces of gliders and do so with impunity.

Solarfilm ( a trade name ) can be obtained in 10m long rolls up to .7m
wide. I'm fairly certain that a roll would do the upper surface of a 15m
ships wing. If the wing was lightly sanded first to remove any raised edges
of the cracked gelcoat and to restore the profile, the material could be
laminated to the wing leaving an incredibly slick finish. These materials
are surprisingly srong and an entire roll weighs very little.

I've had some Monokote (Solarfilm equivalent) and a wing tip sitting
on my bench for several months now, planning to experiment with
covering up small dents in wings, bridging the depression caused by a
shrinking spar, and just adding some decoration. Ian's posting
motivated me to actually try sticking a few pieces on to the wing tip
(left over from fitting winglets).

It's going to take some practice to get it on smoothly, I can see.
Part of the problem is the temperature required to activate the
adhesive (instructions say to set the iron at 275 F), which is well
above the epoxy limit. Another problem is avoiding air bubbles when
covering large areas. I'm sure these can be dealt with.

The biggest problem I can see is ensuring that the covering doesn't
peel up in flight, perhaps rendering an aileron or elevator unusable.
Determining the effects of long term exposure (longer than a year,
say) will be important, as gliders typically spend far more time
outdoors than model airplanes, so their experience might not be a good
guide. What will sunlight, desert temperatures and wave flight chills
do to the material when applied over fiberglass or carbon structures?

Even if you convince yourself it's safe and sane, regulatory and
insurance issues need to be dealt with. In the US, a covering on the
flying surfaces might need an FAA approval, and I'd like to be there
when the first pilot goes to the insurance company and explains how he
is going to cover his glider with a plastic sheet, wants to know how
that might affect his coverage.

So, maybe someone with some wrecked wing parts lying around can try
the idea, and set the panels outside for exposure testing. Flight
testing with a full chord, 10 inch wide strip of white material near
the wing root probably wouldn't be hazardous, even if the strip
peeled. Ditto for pieces on the turtle deck. Or maybe on a spoiler cap
- if it peels up and acts like a small spoiler, it's in the right
place!

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Eric Greenwell
Richland, WA (USA)