Chapter 14 - Step 6

This step involves the addition of the top and bottom spar caps.

Front View of Top Spar Cap Dam May 21, 2002. In preparation for the spar cap layup, you need to build the "dam" on the aft face. The approach is to attach some boards to the aft face so the top is even with the spar foam so you can put in the proper layers of spar cap tape. I used some 1/4" x 2" strips of fiber board. I clamped each piece in place then adjusted the height until it was level with the other side of the trough. Remember the outboard ends of the troughs slope a bit so don't simply use a level to get the correct height.

Being anal, I actually cut the dam boards at B.L. 37 since this is where the taper starts. If you use one long piece the height won't be correct in many places. To attach the boards, I hot glued along the bottom edge every 4 or 5 inches. When done adding all the pieces for the dam I realized there was no way they would stay in place, tight against the spar, only being attached along their bottom edges. I then proceeded to hot glue a whole set of boards to the dam. After doing this the dam seems more stable and secure but I am going to be careful not to put too much force on them during the layup.

Back View of Top Spar Cap Dam May 21, 2002. Here is the dam from behind.

I used the spar jig as a brace to help hold the spar steady during the layup. In front of the spar I clamped a board to the workbench and the spar sits against it. The jig is then pushed against the back of the spar. I added some boards under the spar along the bottom spar cap trough. All this is keeping the spar from moving. Now all I need to do is rig up the spar cap tape and I'm ready to go.

Spar Tape Threads May 27, 2002. Following another builder's suggestion, I layed out the threads from each layer of spar cap tape so I could easily tell how many layers I had applied.

May 27, 2002. Here is the completed bottom spar cap. This isn't a difficult layup but it is long and tedious. The only thing to watch is that the strands don't bunch up where the spar bends.

Spar Cap Detail May 27, 2002. A closer look of the spar cap with the peel ply in place.