Finished brake pedals began canopy frame
After finishing fabrication of the brake pedal assemblies, I fit them to the rudder pedals so that I could align and drill them for the brake master cylinders. The plans/instructions are very vague here with respect to alignment. After some head scratching (analysis of final installation geometry), I just went for it. I setup the rudder pedal weldaments on the bench both hanging straight down and aligned them with a plumb bob. Then I installed the four brake pedals. The big question is, what angle (if any) should the pedals be at relative to the plumb line? Part of the thought process here had to include that when they are mounted in the plane, are they hanging straight down or are they forward just a bit? This isn’t exactly clear in the plans, but if you were to pull the full size plans into AutoCAD (as I did) and did some real distance and angular analysis, just for the fun of it of course, you would find that the pedal assembly is all rotated at the same angle as the member it is mounted on. Ok, so what does all that over analysis mean? The plans suggest that if the assembly is built with everything lined up on a plumb line on the bench, installation will work out as illustrated in the plans. This means the rudder pedals (bottom tube) should line up and the brake pedals should be straight up and down on the plumb line as it sits at no angle on the bench. Ok, none of this really matters all that much, but I’m just amusing myself.
I configured the pilot’s side brake pedals plumb with the rudder pedals when drilling the bolt holes for the master cylinders. However, I chose to angle the passenger side brake pedals just a little further forward (about 1/4″ at the top of the pedal). The real test of all this is how it feels in the plane, but you would need for the seat cushions to be figured out in order to get the proper feel. With everything drilled and test fit, I put the rudder and brake pedals away for painting and installation much later.
Next, I moved on to the rear cabin frame (roll bar). The first task is fabricating a bunch of little parts from various angle and sheet stock. Luckily I figured out that the two F631-E joint plates are pre cut. Many thanks to Tanya’s great organization skills and keeping sub kits and their parts together. I went to retrieve the cabin frame parts and, hey, what are these two unmarked little squares of AS3-063 for…, what do you know, they are exactly the right size for F631-E. Otherwise I was thinking that I would need to fabricate these from a larger sheet, not that that would be any big deal either. Fabricating the attach angles (AA6-188) is another place where having a nice robust band saw is a life saver. If you don’t have one, I would highly recommend beg, borrowing, or stealing some time on one when you get to this point (Zach and David!), as it makes it quite painless. As I was cutting them out, I was trying to imagine the pain of those that would spend hours gnawing on these with a hack saw. You need the attachment angles fabricated so that you can take an accurate measurement of the true width that the canopy frame needs to be.
If you think about it, these cabin frame pieces are kind of interesting in that they are surely formed in a much different process than any other parts so far. I’m guessing that they must have been formed hot as opposed to cold (as most other parts are) because the amount of stretching and shrinking of the outer and inner flange radius would surely fracture and severely deform the part if worked cold, hence all the fluting that we do on other parts. I think you could make a real mess if you were to try to straighten them out more than they already are. The instructions say to just clamp them to a flat bench for match drilling.
I spent a couple of hours trimming and tuning the joint end of the aft pieces in order to get the overall width correct. There are a few dimensions that need to be considered all at once. I have included some pictures of the creative clamping that I had to do. In order to mark the rivet locations on the flanges, I made a little sharpie pen jig for the centerline, and used my calipers as small machinists dividers for the rivet spacing. I figured out the spacing by first roughly using a piece of string to get the length along the curve and dividing by the number of rivet spaces. I took that spacing measurement and laid it out on the flange using my “dividers”. Of course, the string isn’t very exact, so I then measured the error on the part and divided the error into the spacing measurement. I reset my dividers to the new (corrected) distance, and off I went.
Drilling the attach strips to the frame was kind of a no brainer. I did pre-bend the strips and used a bunch (as many as I had) of spring clamps. I have completed drilling both of the attach strips to the aft frame parts. Next is to drill the forward half which I have already trimmed for overall width.
