Brodhead Pietenpol Association

When I clamp the 1/16" plywood on top of the ribs near the leading edge I cannot get the span between the ribs to be flat. It's not a particularly tight radius, probably about 18" but I'm wondering if this normally requires steaming the plywood. If so what does the jig for that look like? Would 90 degree or 45 degree layup plywood be preferred for this? Is Mahogany not suitable for this?

Plywood was soaked in hot water for about 15 minutes. Pipe was heated with a heat gun. Used water and a sponge to keep plywood from drying and getting singed. Left the clamps on until dry, overnight, I think.