Chapter 14 - Section 5

Exterior 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 exterior 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 Exterior Hard Points

Locations of the 6 external hard points are identified in Fig 9. Wanting to make sure they will match up with my interior hard points (installed in Step 3), 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 & exterior hard points would match up before I started digging into the foam. None-the-less, its was a relief to see the back side of the interior hard points when the foam was removed for the exterior 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 would be like if the 'dripped' epoxy cures on the foam. Note my duct tape and scotch tape protecting the exposed foam.


I pre-wet the UNI on Saran wrap, then I pressed it down onto the appropriate CS1 surface. I continued to smooth it 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. Once completed, I added peel ply per plan.