Building the (Old) FLYLINE Great Lakes 2T-1A Kit (21)

We'll start with the bottom surface of the upper wing center section. Here I have cut a piece of polyspan big enough to cover the part and provide enough margin or overhang to grab hold of.

Whenever I am working with a wing panel I prefer to start sticking things down with a root, or panel end, rib. As before, the polyspan adheres to the previously applied BalsaRite RIGHT NOW when I apply the iron heated to 225 to 250 degrees F. This is where you get to exercise a lot of control...make sure the piece of covering you are working with is EXACTLY where you want it to be before you get the iron anywhere near it.

This is the opposite end of the center section (the root rib of the opposite main wing panel) with the polyspan being stuck in place. Notice that I have pulled just enough tautness into the piece of covering to induce those long tension folds. Those will go away when I add equivalent tension around the entire perimeter of the workpiece.

The trailing edge of the center section has a recess, or "cutout", that allows improved vision upward for the pilot who customarily flies from the rear seat. On this model the cutout is formed by using a wide section of balsa block which is trimmed and sanded to the cross section you see here. The covering should wrap smoothly around it and overlap top and bottom. The hard part of the job results from that entire cutout being one big compound curve. The only way to make covering material lay flat there is to STRETCH and shrink it. Here I am using the iron to seal the polyspan around the outer radius of the curve. To finish the job right, I am going to have to pull the covering even further around the curvature without wrinkling it.

The trick is more of that good old "pull and stretch" that we did on the wingtips.

Same as before, I bond the polyspan with a "down-and-around" pressure of the iron.

This is what the covering should look like from the bottom, before trimming. Because we need a generous overlap when the opposite side is covered, it's necessary to extend the first piece of polyspan well around and past the outside of the radius.

This is the bottom of the center section with the excess polyspan trimmed off the opposite surface. The polyspan extends as far as you can see around the trailing edge radius.

The bottom surface is covered. This is the top, with a new piece of polyspan attached at the root rib, as before.

It is necessary to add more covering adhesive (BalsaRite) where the top sheet of polyspan will extend beyond the edge of the bottom sheet.

This is the top/rear of the center section. I have begun to pull the top covering down and around the radius. You can see where I have sliced the covering overhang into narrow sections to permit easier wrapping around the radius without wrinkles.

This is the bottom of the center section showing where I have begun to trim the overhang after stretching and bonding it well around into an overlap.

Here the overlap is sealed down tight. There are a few slack spots, which will disappear when I do the final heat shrink of the entire wing.

This is a better look at the top center section with the covering sealed in place around the trailing edge radius and trimmed.

Covering the outer top wing panels is going to be just the same as it was with the lower wing, but without the ailerons to worry about. Because the polyspan I just attached has covered up the original appication of adhesive I need to add more over the rib where the new seam will be formed.

Here I have placed the polyspan sheet for the outer panel loosely in place, right over the line of fresh adhesive I just applied.

I am sealing the covering seam at the root rib just as I did on the lower wing. From here on the job of covering the upper wing is just the same as what we did on the lower wing. Next time I'll work on covering the fuselage.