In the last post I completed the attachment of the steps. Now I 'll be moving up to the front of the airplane and framing in the longerons and stiffeners on the forward fuselage. The forward fuselage is the section between the main spar and the firewall. Functionally, the forward fuse section is where your legs and feet go. Structurally, it supports the weight and thrust of the engine.
First the firewall which was completed in step 8.1 is clamped to the side skins to temporarily hold it in place. Then the bottom skin is set in place. Since the bottom skin is match drilled to the spar, the precise location of the firewall can be set relative to the bottom skin and side skins. The firewall flange is then match drilled to lock in its position.
Next holes are cut in the bottom skin to allow the landing gear struts through. Vans provides a template for the oval shape for which I am grateful. I hope the fit is good. I won't know for a while yet.
I wasn't entirely sure how to go about cutting the hole so I started with a roto-zip saw. The aluminum was too much for the lightweight drywall bits that I had, so I moved on to a sabre saw. The radius of the cut was too tight for the 5/16" wide metal cutting blade, but I was able to make do with that by frequently backing up and turning in to make a sharper turn. A little filing to finish and it's all good.
Carol has been cranking out a lot of the small parts like these flanges that help tie the big pieces together.
Here is an inside look at the framing. The horizontally oriented longerons carry the loads back from the firewall to the main spar. In the photo below, the firewall is just out of frame to the right. The fuselage is upside down so the gold colored structure at the upper left is the main spar carry through.
To complete the forward framing the lower longerons are fabricated and then match drilled to the lower forward weldments. First cut the angle stock to length:
The inside radius of the cutout is just a 1/4" hole.
The rest of the cut out is done on the band saw.
The finished longerons are filed smooth and then a twist is applied to allow the otherwise straight angle to conform to the tapering nose of the fuselage.
The next step is to match drill the longerons to the skins and to drill for AN3 bolts that go through the weldments.
Mark and drill.
Ream to final size: 3/16"
That completes the forward framing. Please remain seated until this posting ends.
No comments:
Post a Comment