Top Spar Cap








These photos depict the dry areas of the spar cap. They are located mid-spar towards the outboard end. I used MGS 285 epoxy with slow hardener with working temp in the low 70's. The epoxy samples passed the scratch test. Shall I continue with the top skin layup? Please click on photos to enlarge.

I've decided, with the help of other experienced builders/flyers, to scrap the spar cap. There was simply too many dry spots on the surface layers and even throughout the thickness of the cap. Using a laser and incandescent light, it was apparent that the structure is unsound. A few solutions to repair the cap were offered, but I felt it best if I just start fresh with the wing cores. At least I'll feel better while penetrating turbulent air.

An experienced builder/flyer asked: "I'm also wondering how the builder got this far along and not knowing that a good/wet layup should look like."

A great question!! This was the layup done 2 days before Oshkosh. An out of town friend was driving in to help me with the subsequent wing skin layup after my return from Oshkosh. I felt it important to have the spar cap done and was under production pressure to complete the task. Although I did notice the problem early in the layup and despite some attempt at wetting out the dry strands, I deluded my self into thinking that subsequent plies will wet out the underlying layers... this was a very bad and costly assumption. Lesson learned!