Step 7.9.2 reads fairly simply;
Dimple the stiffener angles and skin. After priming (if desired), rivet the stiffeners onto the skin, preferably using the
backriveting method described in Section 5. Following this, complete the trailing edge bend using the homemade
bending brake used on the empennage. The bent skins must be straight up to the radius and the radius must be
between 3/32” to 1/8”. Match the degree of bend to the full size end view drawings. The upper and lower skin
should just touch the spar when placed in position.
but would you believe this one paragraph is a whopping 15 hours work! Don’t believe it? Read my previous posts! So tonight felt great to finally get some riveting done. I grabbed the skins and carefully marked the numbering of the stiffeners so I know which one goes where. Next I put all the rivets in place on the skin and taped them there with 3M magic tape. I grabbed the stiffeners one at a time and applied JC5A jointing compound then set the stiffener in place on the skin. I had my rivet gun all set up and ready to go at around 40 PSI with the back riveting set inserted in the gun. I riveted the 7 rivets with about 3 hits.
Then it was a matter of repeating the process 32 times until each stiffener was riveted in place to finish both left and right skins. Next it was time to bend the skins to the correct angle. The instructions say that the drawings are full size so I grabbed an angle measure tool and measured the angle on the drawing: 15 degrees. I found the bending brake I made for the empennage a few years ago and set that up on the bench with the skin in place and butt up against the hinges.
I then used my body weight over the brake and skins to bend the skin as much as I dared. This was a scary process. Bend, bend, bend, please don’t crack or suddenly give and go flat! I grabbed the spar and offered up until the skins just touched the spar as per the instructions.
Once that was done I took the skins out of the brake and measured the angle. Would you believe it, 15 degrees bang on!
I also couldn’t believe that the plans are actual size, they look way smaller so I offered the skin up to the drawing. Guess what? It really is actual size!