Graham:
You wrote:
>Post curing. This is a good thing to do because it increases the strength of
>the
>resin. Epoxy resin cures initially quite quickly but doesn't reach full
>strength for some time. Weeks even. Even then if a part is heated to say 50
>grad
>it will soften slightly and if not properly supported may change shape. So,
>store your finished parts carefully. Ideally post curing should be done within
a
>few days of initial cure. A container on a hot day would be a good way. Just
>make sure the parts are supported so that they are not able to change shape.
QUESTION: Why, ideally, should post curing be done whithin a few
days of initial cure? If it isn't, (and the parts are kept in
stable conditions) does this mean that there is no need for post
curing after a certain time? If so how long? I have some parts
which were laid up 18 months ago....
(I recall there was someone who managed to fold their tail feathers
over their supports when their post curing oven went wrong a year or
so ago).
You also wrote:
>
>Flatter, gleibe Ich is Deutsch for flutter, nicht war? The Europa
>doesn't flutter, even at the speeds Pete Clarke sometimes achieves.
>The movement of the tail on the video is probably flexing of the
>airframe due to turbulence, quite
>possibly the aircraft flying through it's own wake. Another possible cause
>would
>be high speed stall, which will cause buffet and therefore flexing. Flutter is
a
>high speed high frequency resonance and usually destroys the aircraft. I will
>ask Pete Clarke if he can comment next time I meet him.
>Personally I feel quite confident in the strength of the aircraft, after all I
>will never subject it to the same loads the Pete regularly does.
I am not saying the Europa flutters or not although I hope it
doesn't as I am building one... However I know through experience
most of your hypothesis above is flawed but I will leave it to
others to explain more scientifically than I can.
regards
-------------------------------------------------------
Richard Meredith-Hardy TEL + 44 (0)1462 834776
rmh@flymicro.win-uk.net FAX + 44 (0)1462 732668
CIS: 100071,2422
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