Originally Posted by savneo
Regarding the spar I'm going to glue a .5x10x80mm carbon strip on the bottom of the wing. I do not want to cut into the wing to add a spar. The strip will add lots of tensile steinght.
That would be of limited benefit on its own as the top surface is still under compression and will still crease and fold. What you need is a more sold web, to keep the top and bottom surfaces separated but attached.
My understanding is that these pressed wings do not have any spar. I have an eDago which again uses the same wing format. I never broke the wing but I'm pretty certain there is nothing but polystyrene inside which is still compressable.
If you want to strengthen the wing then you are better off cutting a verticle slit and use 1/16" ply as the full depth spar and sub spar (no need for full span either). This is a fairly standard technique for foam and obeechi veneered wings.
Of course the other way would be to stiffen the wing surfaces using glass or carbon fibre cloth and laminating resins. Again, probably not necessary to do the whole wing.
Even stronger - do both.