>>1735892I would guess they have gone for ease of construction and the greatest amount of lift at the lowest possible speed,
there are some high aspect gliders with a slight sweep to their wing, but apparently this is not so good at lower speeds, and the yaw stability it brings can be achieved by dihedral.
in theory a shape of wing could be used to reduce but not completely eliminate the need for a tail plane,
the benefit being that although there will be less control over pitch, there will also be less drag generated.
a blended wing body has the fuselage as a lifting body and the outer wings supercritical,
but this type seems to be more about the internal volume of the craft rather than its surface area.
