Circular wing

In 1934, at Miami University (of Ohio), an aircraft called the Nemeth Umbrella Plane (aka Roundwing) was tested.

This aircraft had a parasol wing of circular form above a conventional fuselage and tail, and it was powered by propeller in a tractor configuration.

They were to be powered by a Pratt & Whitney R-4360-3 Wasp Major radial engine and capable of reaching speeds of 414 mph.

They were intended to be fighter planes, armed with 4 20mm cannons and underwing hardpoints that could carry 1,134 kg (2,500 lb) bombs or external fuel tanks.

The wing design had excellent short takeoff and landing (STOL) characteristics,[citation needed] that is preferred for fixed-wing aircraft carrier planes.

John Frost became interested in the Coandă effect to produce lift, eventually designing a disc-shape in which the thrust was directed downward around the entire disc by a flap ringing the aircraft, allowing it to take off and land vertically.

Little lift would be generated by conventional means; the engine thus would instead be used to build an "artificial wing" by directing the airflow around the craft.

The final outcome of Silver Bug was the Avrocar or VZ-9AV, effectively (and unintentionally) a prototype hovercraft rather than an aircraft, which was made public in 1961.

The Vought XF5U
The Avrocar under test
The Moller M200G Volantor