Hatz Biplane Association

The wing walk upper and lower plywood is basically missing from the Classic plans. It only exists on sheet 7 where it refers to sheet 10 for more info, sheet 10 has nothing to do with the wing walk. I am starting to make the wing walk and am wondering what other builders have used for the plywood width. The plans seem to show a free form curve overhang for the top walk and no extra for the bottom. I would like the wings to fit the fuselage with a minimal gap and I expect that I will need some additional material but I have no idea how much.
It also appears that the wing walk and any weight on the walk is supported but the glue joint between the angled end rib and the spars. Has anyone used anything additional like dowels through the rib into the spar to help support the shear load or is the epoxy good enough?

Hello Ed,
We made a cardboard template for the wing walk and allowed for about 1 inch of overhang of the root rib. Then we leveled the fuselage (with stringers on) and built a rack to lay the wing on with a couple pieces of tubing under the spars so we could roll it in and out from the fuselage. We stretched some plastic sheet over the stringers in the wing root area, positioned the wing 3 or 4 inches from the fuselage, and took measurements from the plastic to the wing walk and drew a line on the wing walk. From then on it was just a cut and fit operation with a saws-all and a hand held drum sander. I can see why there is no dimension in the plans
because every plane would be slightly different in that area.
John Hanson

Thanks John,
That is exactly what I was looking for. I like the idea of using temporary fabric around the fuselage.

I added several spanwise supports top and bottom between the root rib and a false rib glued to the first inboard rib. These supports were further supported by vertical braces between matching top and bottom members.

Don't remember how much overrun I allowed but use the plastic sheet approach described above with cardboard test pieces. Not only every plane is different, you will see slight differences between left and right wings.

Enjoy the process.

John

My build picture looks nearly the same as John's I even have that same pencil. Plywood top and bottom from the aft edge of the leading edge skin and bordering the inside of the trailing edge. I made kraft paper patterns for all four panels. Traced the patterns onto plywood then epoxy glued and nailed the plywood on. I clamped a piece of visqueen to the fuselage side an shaved the inboard edge of the wing walk until I got a tight fit. The bottom plywood needed very little trimming. The wing walk ply ended up being trimmed, in places, quite close to the end compression rib.