Chapter 14 - Section 5

Outside Hard Points

This step is pretty straight forward. I marked out the locations of all six hard points on CS1 per plan. I used a router to put a 3/16" radius the entire length of the spar before embedding the outside hard points. Remember the radius of the 1/4" hard points you made in page 7? It was .2" which is close to the 3/16" router bit. A slight touch afterwards made the hard points nice and flush.

Installing the Outside Hard Points

Locations of the 6 external hard points are identified in Fig. 9. I wanted to make sure they will match up with my interior hard points (installed in Step 3). So I transferred the locations of my interior hard points onto the outside foam surfaces (at that time) for future reference. Therefore I was pretty certain that the interior & outside hard points will match up before I start digging into the foam. None-the-less, its a relief to see the back side of the interior hard points when the foam is removed for the outside hard points. After I floxed the hard points, I clamped or weighted them down for cure.

Applying the Shear Web

I cut up the UNI using the same method as I did in Chapter 9 Section 2. This time, with a 20" step along the edges of the UNI, I'll end up with 14" width strips - perfect for the shear web (layup #5). 

According to Fig 10, the plan has you cover the exposed foam (CS2 & CS3) with duct tape and newspaper. I chose to cover the inside step with the duct tape as well. I am glad I did it because epoxy drips all over the place especially onto the inside steps. I can imagine what it will be like if those 'dripped' epoxy cures on the foam. Note my duct tape and scotch tape protecting the exposed foam.

I pre-wetted the UNI on Saran wrap, then I pressed them down onto the appropriate CS1 surface. I continued to smooth them out down both sides with the excess UNI (~.5" on each side) hanging over the trough. Then I trimmed the excess UNI with my electric scissors. Once trimmed, I completed the smoothing and layup. Then I removed the Saran wrap. The whole task took Susann and me 8 hours to complete.