Roll bar placement question

[Airhead]

I would like to find out if anyone else, when mounting the roll bar, noticed that the dimension shown on Dwg 42, View C-C, for placement of the roll bar on the F-721 aft canopy deck is 2 5/8? from a pre punched rivet hole, however, in my preliminary bar placement (not yet drilled) I was taking the measurement to be to the rear of the roll bar itself. When I looked closely I saw that the dimension is actually to the rear of the mounting plate welded on the bottom of the bar. In the iso view (bottom left corner) and Detail A (just above that) the plate is shown with a square rear corner which is not how they actually make the weldment. Mine is rounded off with a weld fillet around the base of the bar. The question ; Is the measurement actually to be the rear of the bar, or the no longer present rear of the plate? The difference is about 1/16? by scaling from the drawing. Maybe this would not make any difference as long as both sides are the same, but I won?t know until later in the canopy mounting procedure.

Thanks for help,
Bob B

 

[KayS]

Hi Bob,

a difference of 1/16 doesn't make a difference. you're right... it just should be equal on both sides. you're fine, doesn't matter from which point you measure.

Kay

btw: if i would have to do it again i would place the roll bar about 3/16 more aft. because the roll bar touches the curved edge of forward top skin at the triangle of the roll bar so the skin will be flexed outwards. i don't like that. if you place the roll bar more aft that flexing would be decreased. to compensate the more aft roll bar i would make the slider tracks 3/16 shorter.

 

[Airhead]

Thanks for the tip Kay. I think I'll clamp everything in place, cleco on the skin and check the fit.