Wow, three months since my last update. In that time, I have made some progress but in the process I had to learn A LOT! After finishing the channel under the front section, I decided to build the rudder bar. This proved to be a lot more challenging than I thought it would be. I built them according to the plans, but had to start over three times to get it right. I started by welding up the pedals that was ok. I am going to have toe brakes on both sides so I had to change the set up a little. Basically, the copilot side needed removable toe pieces like the pilot side. Also, I added a finger strap to the top of each pedal (not shown on the plans. Then came the trouble. I first welded the “V” that connects the two sides together. My plan was to weld that to the longer of the two rudder bar tubes and cut out the section for the right pilot pedal. The problem arose when final welding, it kept cracking! Finally after some advice from Supercub.org, I got the sequence down and no cracks. Getting everything to fit and turn was a pain; 4130 will not stay straight when welded. I finally got everything turning ok and it was time to make the attachment hardware. I made a set of the “U” shaped connectors but did not like the metal to metal contact. After a bunch of research, I settled on making pillow blocks out of UMHW Polyethylene. As my research made a full circle, I discovered that the RV aircraft have been using this method for a while now so I felt good about the change. One problem, how much friction in the pedals is too much?
Rudder pedal and cable connector tube welded.
Here is the rudder bar with most parts in place. Up to this point it was just a matter
of following the plans and reaming out the tubes for fit and ease of
movement. The difficulty came in
welding the “V”. After many
attempt I came upon the method of welding on the two side tubes of the “V” than
welding the gap.
The V. Gap must be maintained to keep weld from
cracking as weld expands and cools.
I used a hacksaw blade to keep “V” from collapsing in as weld expanded
to maintain the gap.
Hacksaw blade used to keep weld from closing in and cracking
and warping above tube. This took
a number of tries to get correct.
Final section to weld after saw blade removed. Inside of rudder bar tubes all needed
to be reamed to remove welding slag.
Here the final rudder bar is clamped in place with pillow
blocks as per my research. Very
time consuming task to build this assembly.