Hysol between ribs and tank

[Esser]

Is there a reason other than aesthetics to fill the gap between the 1 and 3 ribs at the top of the fuel tank? I think I would rather leave it out if it's possible.

[jtpitkin06]

The number one rib gets blocking between it and the tank to prevent rib warping when you shrink the fabric. Bonding to the number three rib prevents the tank from pulling outboard during the shrinking process. Yes, the silicone adhesive is strong but it can creep.

The bonding is more than aesthetics, it is to prevent things from pulling out of alignment or breaking the bond between the tank and the spars during the fabric shrinking process.

[jiott]

I put blocking between the tank and #3 rib and did not put the Hysol there; this allowed rib stitching on #3 rib without drilling holes thru the Hysol. I did put Hysol on #1 rib in addition to the blocking because that's what the manual said to do. I guess it gives extra resistance to rib warping during the shrink.

[kmach]

If you do not fill between tank and #3 rib you can get paint cracking from fabric flexing . I wish he who built my wings had done it .

[jiott]

I used blocking between the tank and #3 rib, so there is no relative movement and I have had no paint cracking.