One
of the first tasks is to set the roll bar into position. To do this, you
also need to have the forward support attached to the ribs that extend from the
firewall. This is looking down into the cabin just rear of the firewall.
The
support angle aluminum didn't quite come up flush with the forward angle so we
had to install a number of spacers. There is a good 1/4" of spacers
here with a very long rivet installed.
After
getting that aligned, we had to set the incident angle of the roll bar. To
ensure the slider matches up correctly with the roll bar, it needs to be 90
degrees offset from the longerons.
Initial
fit-up of the slider showed it to be substantially out of alignment with the
plane. We needed to do some serious bending.
To
ensure we only bent what we wanted to, we built a small jig to hold it in
position while we yanked on one side or the other. Lots of blocking wood
attached to the table to keep it from bending in the center.
As
we were bending the front bow, we heard a terrible sound - ping! and the rear
bow cracked (right above the weld).
Initially
frustrated, we soon realized that we would probably have cut it there to shorten
it anyway.
One
of the final things to fit is the front bow to the roll bar. We were too
high on the pilot side.
Raising
the roller attach point on the co-pilot side solved most of the problem.
It isn't a perfect fit, but the offset between plexiglass pieces will be
fiber-glassed in so we stand a good chance of being able to hide the misalignment.
After
getting the frame fully squared, we trim the rear skin to match. At this
point it is only an approximate trim. We do the final trim after the rear
skirts are added on the plexi.
One
of the things we did to make it smoother was to add a bushing inside the black plastic
roller. With this installed, there is no binding at the swivel point.
