bearhawkproject.com Matt Kunkel's Bearhawk Build Log

26Jun/105 hrs

Elevator Trim Tube Spacers, Rudder Stops

Fabricated the elevator trim torque tube spacers from 6061T6 aluminum tube.  I used a tubing cutter to ensure square ends with minimal deburring needed after cutting.   Additionally, I worked on the rudder stops some more, trying to get an exactly 30 degree stop.  I had trouble trying to figure out how to measure the travel accurately.  I tried a cardboard cutout and did not like it since the vertical stab is offset and you can't set it on the horizontal stab either since there isn't a point of reference there.  I also didn't like using an angle finder ala Eric Newton Manual because I felt like the distances were just too short for an accurate measurement (also zero is about 1/4" above the bottom on my angle finder.

The solution was to find centerline of the plane and snap a line.  THen I dropped a plumbbob from the center of rotation (center of the front tube) and marked the floor.  From there I used the 30, 60, 90 (1, 2, sqrt(3)) rule to draw out 30 degree measurements.  I dropped a plumb bob from the rudder and now I can measure accurately.

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  1. Nice work with the plumb bob. I highly value your appreciation for accuracy and precision. Keep up the good work! Can’t wait for your next update!


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