Daniel, I think the top of the wing is actually flat. The dihedral will be from the bottom of the tip of the wing to the table top. So if you lay the wing upside down on the table, you will see that the bottom side (which is the top side with the wing upside down) will slant down to the tips. And that slant will equal 1 1/2 inches.

Check and see if there is a date on the plans, but I think the Skynight was a pattern ship dated in the mid to late 70's. It was at the beginning of when we started using epoxy glass in place of fibreglass (polyester resin ) in the kits.

I hope you enjoy building and flying it. It was a sweet pattern plane.

Frank