Fri Sep 25 2020

Forward fuselage and canopy structure

Today, I adjusted the flanges of the canopy frame bow so that it matched the loft lines extending back from the firewall.

I was only able to adjust the flanges down to the point where the curved triangles side plates are welded to the canopy bow. The welds were made only on the inside surface, which caused some distortion resulting kind of a "ridge" on the outside along the welded butt joint.

So, I clamped the bow up in the vise and used a wood block and hammer to pound the "ridge" down to a point where the flange of the bow is parallel to the outer surface of the curved triangle side plates.

I also filed the bits of weld away which had penetrated through from the inside surface. As a result, the flange of the canopy bow sits lower than the outer surface of the the side plate. I'll need to make a shim to fill this space.

Here's a view of the gap which will need shimmed.

Okay, all the flanges now follow the loft lines extending aft from the firewall.

...but if I use the scale to see how the loft line extends beyond (aft) of the canopy bow, the curved, triangle side plates apparently don't follow the same loft lines.

This had me stumped for quite a while. After work, Chris was nice enough to come over and put another set of eyes on the problem. In the process of explaining my understanding of the geometry, Chris was checking the loft lines and it became apparent that the problem was likely that my loft lines weren't quite correct. For example, we found that if we use a straightedge to serve as a continuation (going forwar) of the top edge of one of the triangle side plates, that matches up quite well to the top edge of the firewall. So, it seems like there may not be a problem after all.