Spars (page 3)

November 9, 2003

Once all of the capstrips are drilled, its time to start on the spacer bars that go between the top and bottom capstrips and under each rib attach angle.  These spacer bars serve two purposes.  One is obvious - to fill in the gap between the rib attach angles and the spar web between capstrips.  The other is to, in effect break the spar into several individual squares -  so to speak.  This spreads the stresses out more evenly and reinforces the spar web in between capstrips. Several people have asked on the internet group if there is a spacer bar on the aft side of the spar where only a nose rib with no center rib is riveted on.  The answer is YES.  There should be spacer bars on both sides of the spar web at each nose rib location.

After the spacer bars were all match drilled to the spar with #40 holes, the holes were all enlarged to #30 to accommodate the -4 rivets called out in the plans. Here is a picture of the first two spacer bars all drilled and clecoed to the spar web:

Once you get to the double stacked capstrips, closer to the splice area, the  1/2" wide X 1/4" thick spacer bars are used.  

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