10 November 2013

Wings: Pitot-static. AOA/pitot doubler plate riveted in.

The left wing's AOA/pitot tube doubler has been riveted in.  I'm using the PBK-12 Gretz Aero bracket.  A full description of my setup can be found here and another outlining my dual pitot approach.  

First I had to calculate the proper rivet sizes.  There are four separate thicknesses to consider.  Below are the calculations.  I opted to round up in all cases.  The additional length required after passing through the pieces to be riveted is 1.5x the rivet diameter.  So 1.5*3/32=-0.141.

3/32” Rivet
Skin 0.025 0.025 0.025 0.025
Plate 0.040 0.040 0.040 0.040
Spar 0.063 0.063

L Bracket 0.025

Additional 0.141 0.141 0.141 0.141
Total Length 0.294 0.269 0.206 0.231
Size (in 1/16”) 4.698 4.298 3.290 3.690
Rounded Up 5 4.5 3.5 4
Rounded Down 4.5 4 3 3.5

One interesting observation is that the #8 screw holes on the skin didn't quite line up with the corresponding holes on the backing plate, despite all my rivet holes lining up from when I originally fitted and match drilled the pieces.  It suggests the pilot bit slightly walked when I drilled the #8 holes.  It's not too big a deal as the screws will compress everything together, however it's a less than desirable occurrence.  It means the dimples in the skin and backing plate don't align.  Below shows the gap between the skin and plate.

Read the entries in my AOA series:

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