We are trying to create carbon wing (see photos) from textrem with infusion, almost whole wing is ok, but last part, after few minutes on sun it goes wrong.

Can you please give us some hint, what we are doing wrong?

If this is happening on first exposure to the sun then simply you need to be curing the part for longer with a postcure. 

At room temperatures, many resins simply dont cure 100% straight away.  You may well be able to demould and trim but some uncured resin remains.  In the sun a black part can easily and quickly get to 40C and then at high as 60C even in moderate climates.  That will certainly make many a resin go soft causing the deformation you are seeing.

The solution is a postcure to ensure all the resin is fully cured upto any reasonable operating temperature, based on the Tg of the resin system.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant