On Tuesday, November 28, 2017 at 10:31:04 AM UTC-8, wrote:
Bob,

Define "straight and square". Most wings have leading edges
that are swept back and/or trailing edges that are swept forward.

Parallel with the fuselage longitudinal axis, orthogonal to the plane containing the leading and trailing edges. In the absence of sweep reference, splitting the difference between the leading and trailing edges will get you plenty close enough. Which is to say, closer than the difference between the right and left wings on your glider.

--Bob K.