>I take it from the replies so far that there is no danger of
>softening and warping the tailplane, rudder, flaps and ailerons
>at a temperature of 55C
John - it's probably NOT a good idea to take your parts straight up
to the final post-cure temperature. As I understand the post-cure
process, the cured layup starts with a fairly low Glass Transistion
Temperature (Tg) - that is the temperature at which it starts to go
wobbly. The ideal is to take it up to just below the initial Tg and
hold it there for a while. This heat-soak will raise the Tg, so you
can then increase the temperature again to just below the new Tg and
hold it again. You may have to repeat this more than once to get to
the final post-cure temp. The professional glider builders &
repairers, such as my inspector, have post-curing ovens with
controlled temparature ramping, and I plan to use his facilities for
all my foam-cored bits at once.
Another important consideration is that the foam core will melt
before you reach the highest possible post-cure temperature for the
(Ampreg 20) epoxy resin. So, don't just go by the resin
manufacturer's numbers (he doesn't know what other materials you
might be using), stick to what the foam can stand.
>Therefore no special support is needed.
I'd prefer not to risk the bits unsupported. My plan is to lightly
but firmly clamp each trailing edge between a couple of ali angle
pieces. They can then be suspended on the protruding ends of the ali
and hang vertically downwards, minimising the likelihood of unwanted
stresses.
regards
Rowland
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