Kenneth
Member
I just finished up my first tank and was excited to get it fit on the wing. Unfortunately, it was pretty obvious from the start that the tank and leading edge skins were no longer in alignment on the top side of the joint. However, the bottom is perfect and there is no problem on that side.
Here is a picture of the joint with the screws backed out to show you the offset between the leading edge and tank skins.
I figured this could be fixed after finding this thread: Tank Pillowing Thread
After my first round of shimming using 5/8" x 5/8" shims between the joint plate and inboard leading edge rib, I had everything lined up perfectly when cleco'd together, but after riveting the gap got worse!
I've since reshimmed (nearly .080" in some places) and the fit is once again perfect prior to riveting.
Just to verify what I was doing was OK, I talked to Tom at Van's and he said he hadn't heard of this ever happening before and suggested that I remove the shims and try machine countersinking the dimples in the joint plate. I just don't think I got him to understand that the issue was not only when the screws were tightened, but that the misalignment causes the joint to deform (tank skin is bent down to match the leading edge skin.)
I don't want to discount his expertise and recommendation, but isn't my shimming technique acceptable also?
Thoughts? Do I have bigger issues I'm not seeing? It appears that the leading edge rib is just slightly offset down which would account for some of the mis-fit, but certainly not .080".
Thanks for any advice,
--Ken
Here is a picture of the joint with the screws backed out to show you the offset between the leading edge and tank skins.
I figured this could be fixed after finding this thread: Tank Pillowing Thread
After my first round of shimming using 5/8" x 5/8" shims between the joint plate and inboard leading edge rib, I had everything lined up perfectly when cleco'd together, but after riveting the gap got worse!
I've since reshimmed (nearly .080" in some places) and the fit is once again perfect prior to riveting.
Just to verify what I was doing was OK, I talked to Tom at Van's and he said he hadn't heard of this ever happening before and suggested that I remove the shims and try machine countersinking the dimples in the joint plate. I just don't think I got him to understand that the issue was not only when the screws were tightened, but that the misalignment causes the joint to deform (tank skin is bent down to match the leading edge skin.)
I don't want to discount his expertise and recommendation, but isn't my shimming technique acceptable also?
Thoughts? Do I have bigger issues I'm not seeing? It appears that the leading edge rib is just slightly offset down which would account for some of the mis-fit, but certainly not .080".
Thanks for any advice,
--Ken