This entry starts a new section for the RV-12 airplane project. Building and installing the Roll Bar assembly. No longer will neighbors think I an building an aluminum boat, but a genuine airplane!
Step 1: Study Figure 1 in the RV-12 plans on page 24-02 to determine the forward edge, top and bottom of the Roll Bar Straps. Run the roll bar strap back and forth over the edge of a table to add a curvature to the parts. Be careful not to let the parts kinks across the rivet holes. The curve does not have to be the final installed shape but enough to allow easy assembly of the roll bar. Deburr the edges of all parts used to create the Roll Bar Assembly. Cleco all of the parts of the Roll Bar Assembly together.
Builder's note: I deburred the roll bar parts first and tried the table edge idea mentioned in the plans. This didn't work so well so I went to bending them a little at a time by hand. This required several passes over the entire lengths of the straps but worked very well.Just don't kink them.
Step 2: Final-Drill #30 all #40 holes in the flanges of the Roll Bar Frames and Roll Bar Straps.
Step 3: Disassemble the roll bar parts, then machine countersink the outer flanges of the Roll Bar Frames for the head of the rivets that will eventually lay underneath the canopy except holes common to the Roll Bar Bases. Machine countersink the two holes on the inside lower center face of the roll bar taht will get flush blind rivets.
Builder's note: The RV-12 plans don't call out a countersink to use, however since the rivets are all CS4-4 blind rivets I used a #30 120 degree countersink.
The rest of the time for this work session was spent preping and priming the roll bar part. Next time I'll assembly the roll bar for the RV-12 aircraft.
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