Bullseye
Well Known Member
Well, I keep chugging along on this right wing skeleton.
Except by ?chugging along,? I really mean ?don?t seem to be making any progress.?
Yesterday, I spent some time leveling the inboard and outboard main spar webs to 0.0?. After that, I dropped some plumb bob?s from the spar and carefully measured from the plumb bob string to the top of the rear spar. The outboard side showed 2 1/4″, and the inboard side showed 2 3/4″. A half inch of twist doesn?t sound like a lot, but of course I wanted this to be perfect.
I chose to split the difference. I pulled the outboard edge of the rear spar down (aircraft axes) and clamped, then pushed the inboard side up and clamped.
Here?s my problem. It seemed like I really had to push the rear spar ends to get it exactly where I wanted it, and there was plenty of (what I?ll call) springback force.
Of course, after clamping the rear spar in place, I remeasured the spar, and it was now no longer square. (Moving the rear spar moves the ribs, which twists the main spar.)
I releveled the main spar and really tightened up the clamps all around. I?m now level with the main spar and within 1/32″ on the rear spar.
I?m sure I can get it even closer, but I?m worried about how much force I?m holding with the clamps. I know the skins are supposed to keep the wing straight once riveted, but this seems like a lot of force to hold.
Thoughts?
Except by ?chugging along,? I really mean ?don?t seem to be making any progress.?
Yesterday, I spent some time leveling the inboard and outboard main spar webs to 0.0?. After that, I dropped some plumb bob?s from the spar and carefully measured from the plumb bob string to the top of the rear spar. The outboard side showed 2 1/4″, and the inboard side showed 2 3/4″. A half inch of twist doesn?t sound like a lot, but of course I wanted this to be perfect.
I chose to split the difference. I pulled the outboard edge of the rear spar down (aircraft axes) and clamped, then pushed the inboard side up and clamped.
Here?s my problem. It seemed like I really had to push the rear spar ends to get it exactly where I wanted it, and there was plenty of (what I?ll call) springback force.
Of course, after clamping the rear spar in place, I remeasured the spar, and it was now no longer square. (Moving the rear spar moves the ribs, which twists the main spar.)
I releveled the main spar and really tightened up the clamps all around. I?m now level with the main spar and within 1/32″ on the rear spar.
I?m sure I can get it even closer, but I?m worried about how much force I?m holding with the clamps. I know the skins are supposed to keep the wing straight once riveted, but this seems like a lot of force to hold.
Thoughts?