This tip was submitted by Barry Bieber, Glasair II-S RG
The flap and aileron panels are rather flexible and it’s easy to get unwanted low areas along the trailing edge when you bond them together. This method allows you to clamp the panels together with minimum distortion.
Just prior to closing the flap or aileron, cut a piece 5-lb. foam 1/2″ wide x 3/4″ high x the length of the surface. As shown in Figure 2, bond this foam into place with Q-cell approximately 1/2″ forward of the trailing edge of the lower panel, leaving enough area for the mill fiber mix, which will bond the upper and lower panels.
Fit the upper panel into place and sand the 1/2″ wide foam until the panels meet at the trailing edge and onto your ribs. Sand only enough to get the panels to fit back to rib contact and trailing edge contact. Too much sanding? You will have to start over
After the fitting is complete, try clamping the panels and locate where your flat boards need to be placed to apply proper pressure against the trailing edge and the foam piece you installed. Before final closing; Q-cell the sides only of the piece of 5 lb. foam to seal it from moisture. When closing the flap or aileron, Q-cell the top of the foam, again to seal it from moisture.