The Farman F.1020 was an experimental aircraft built in France in 1933 to investigate the behaviour of a semi-circular wing fitted with unconventional controls.
Such a wing has high induced drag but was thought to offer good transverse stability and low speed behaviour.
The leading edge was a little further forward than the diameter of the idealised semicircle would have been and was slightly swept; it was also extended beyond the rest of the wing, carrying conventional ailerons.
The trailing edge carried deep chord control surfaces, two per side: the outer pair were used differentially like ailerons and the inner ones as flaps.
[1] This wing was mounted on the fuselage of a Farman F.402, retaining the empennage, undercarriage and the 110 hp (82 kW) Lorraine 5-cylinder radial engine.