Fuel Tanks - Proseal bottle #5

Started off this morning with our fifth bottle of proseal! We installed the T-1005 tank attach brackets and T-1003B aft-inboard ribs on both tanks. This used more sealant than I thought it would, and we actually got pretty close to using the whole bottle on just those four pieces. I used the leftover to install the fuel feed and return fittings, vent fittings, and then drilled out and redid a small handful of rivets we had marked with a sharpie that didn't come out to our liking-- maybe 5 or 6 or so.

L and R tanks, respectively after the last of the ribs had been installed

Close-up of R fuel tank inboard rib. From left to right, you can see the vent fitting, return fitting, and feed flange; as well as custom access panel cutout (bottom) and fuel sender cutout (top)

Close-up of L tank, mirror image of R tank above

Inside of R tank inboard rib

Inside of L tank inboard rib

Once that was done, I got out the coil of vent tubing and realized... doh! We were supposed to install the vent line before riveting the inboard rib into place to facilitate feeding the line through all the ribs. Actually, it wasn't very difficult to feed it through anyway, it just went slower and took a little more care. Next thing to do was get started on a fuel tab. Although it's not in the plans, I figure it would be really useful to have tab sticking down into the fuel tank from the filler neck to mark the 2/3 full point, like you see on some production aircraft. The trick is, how far down from the filler neck is really 2/3 full? Given the angles due to dihedral and angle of incidence the plane sits at on level ground, plus the airfoil shape of the tank itself, this isn't an easy question to answer. I had posted a question on VAF a couple days ago but haven't heard any responses... I suppose it's sort of an odd question and it would take someone to have to go out to their plane and measure. So, I'll have to take a stab in the dark on this. Ready for some Kentucky Windage? Here goes:

Given that the tank is about 9" tall at the baffle, if we were dealing with a square and level tank we'd want our mark to be 3" down from the top. Dihedral causes more fuel to settle near the root than at the filler location, but incidence angle/airfoil shape will affect it also. Best guess, 3.5" down from the filler neck should give us 2/3 full, within say 1/8 tank plus or minus. We'll see how good this guess was in another year or so, I suppose!

The fuel tab, 3/4" wide with lengths of 1/2", 3-1/2", 3/4"

Tomorrow, time permitting, we'll make the second tab and install them to our custom fuel cap flanges, along with the vent line holder!