Sun Oct 19 2008

Auxiliary longeron and gussets

The first three photos on this page are actually from the night before.

I decided to make the holes in the forward bottom fuselage skin for the landing gear mount weldments. First thing was to remove the forward bottom skin so I could fit the gear mount to F-704 main spar bulkhead. Unfortunately my spacer bolts were in the way. I removed the nuts and washers to allow the weldment to fit on.

Unfortunately I found that the nutplates at the top flange of the spar were preventing me from pushing the weldment into place.

After some fiddling around I realized I could slide the weldment over the lower bolt (actually at the top of the spar...remember this is all still upside down) and sort of tilt and rotate the weldment to clear the nutplates. But then the top bolt wouldn't quite fit into the hole in the weldment. I broke out the die grinder and ground some off the threads to allow the weldment to pivot into place. That led to the revelation this bolt stud is about 1/2 inch too long. The weldment can't slide all the way back. I'm gonna have to hack off the end of this stud. I'll do that's too late to start messing with all that tonight.

After picking up Kody, we did some work on the plane. First was to drill this #10 hole for the heater box control cable to pass through.

Then it was time to align one of the F-713 auxiliary longerons. One hole isn't quite in line with the others as you can see.

I trimmed both ends of the F-715 to 79.5 degrees which exactly matches the angle needed to butt up to both the firewall and the F-704 bulkhead.

The aft end needed some extra chopped off before drilling.

Next I decided to do the modifications to the F-684 Gussets.

Here I've got everything laid out per the plans, but that lower bend line should be tangent to the lower circle...something isn't quite right here.

I decided to just make the slot slightly smaller...after all I could always enlarge it if necessary.

The first one's done!

And the second one!

The instructions say that the F-715 auxiliary longeron needs a "slight twist". WTF does that mean? What happened to the nice precise callouts I'm used to? Anyway I decided to determine the correct angle. First I held the angle finder up to the side skin at the F-704 Bulkhead. The reading was 1 degree.

Out at the lower firewall weldment, I again checked the angle. This time it's 6 degrees. That difference of 5 degrees is how much I needed to twist this puppy.

Got 'er clamped in the vise and took an initial reading.

After clamping on the end with some wood blocks and Vise-Grip pliers, I gave it the required 5 degrees of twist.

This worked perfectly and I was able to clamp the auxiliary longeron in place.