All have the characteristic cranked wing.

But unlike the cranked wings of these earlier aircraft, the wings of the R.3140 have constant dihedral.

One advantage of the cranked wing was, it reduced the length of the undercarriage, making retraction easier.

Tests throughout the first half of the year resulted in a number of changes to the design, including a cranked wing and beefed-up fuselage, fin and control surfaces.

Instead, two Percival Proctor training aircraft were converted into half-scale Stukas, with a cranked wing, as "Proctukas", though in the event they were not used on screen.

Built in a conventional fashion using wood throughout, fabric covering and steel for highly stressed parts and fittings the SZD-6x was a cantilever monoplane with the cranked wing attached to a short fuselage pod at the mid position.