Military disc-shaped aircraft

Military disc-shaped aircraft development dates back to before World War II. A number of disc-shaped aircraft have been proposed over the years, and a few have been built.

Nemeth Umbrella Plane
In 1934, at Miami University (of Ohio), an aircraft called the Nemeth Umbrella Plane (aka Roundwing) was tested. (Nemeth is sometimes spelled Nuneth.) This aircraft had a circular wing on top of the rectangular fuselage, a propeller in front, wheels underneath the fuselage and a rudder with tail fins. There were no wings extending from the middle of the fuselage. The aircraft looked like the AWAC plane, except for the missing middle wings. The aircraft is named in the 1976 reference book "Airplanes of the World" as the "Flying Saucer" plane, (the book also mentions the Avro Avrocar, the Vought V-173, and the Vought XF5U).

Sack AS.6
During World War II, a number of disc-shaped aircraft were proposed by aircraft designers in Nazi Germany. One of the few to make it further than the drawing board was the Sack AS-6, an experimental light plane with a round-winged planform that first flew in 1944. The aircraft proved unsuccessful, and was scrapped in early 1945.

Vought Flying Flapjack
During WWII some research was carried out by a number of designers on circular wings. Led by design-engineer Charles Zimmerman, Chance-Vought led a series of designs that eventually resulted in the Vought Flying Flapjack, perhaps the first aircraft explicitly designed as a disc for aerodynamic reasons. The Flapjack had a huge wing and very low wing loading, allowing it to take off easily from aircraft carriers. As with the earlier Vought V-173, the Flapjack's contra-rotating propellers were located at the ends of the wings to help counteract the drag-inducing vortices that would normally result from a wing of such a low aspect ratio. By the time the design was flying in the post-war era, jet engines had rendered the design obsolete and the US Navy lost interest.

In 1943, the Boeing Aircraft built 3 scale model aircraft whose designs had saucer-shaped wings with a propellor in the front, and a rudder in the back. The cockpit was to be in front of the wings. There was no actual fuselage in the center. The aircraft model numbers were 390, 391, and 396. 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 2 500 lb. bombs or external fuel tanks. Boeing submitted the proposals to the US Navy. The wing design had excellent Short TakeOff and Landing characteristics, and STOL is preferred for fixed-wing aircraft carrier planes. The Navy rejected the Boeing designs in favor of the similar-shaped Chance-Vought V-173/XF5U-1 aircraft.

Avrocar
In the US, a number of experimental saucer shaped craft were apparently developed as black projects by Lockheed Corporation for the USAF, and by Convair for the CIA. The saucer had the advantages of being a Vertical take-off and landing design (so avoiding the need for easily damaged runways), while the shape was well suited to diffusing radar making the craft stealthy. These early designs were apparently powered by turbojets, which powered a horizontal rotor to provide lift using the Coandă effect.



In an apparent attempt to quell speculation about the military nature of flying saucers, a press conference was held in July 1952, at which Major John A. Sandford denied any knowledge of the craft, and retired Major Donald E. Keyhoe declared his belief that they were of alien origin. In 1957 Keyhoe became head of the civilian UFO group NICAP (National Investigations Committee on Aerial Phenomena).

Meanwhile in Canada, the Avro Canada company was also attempting to develop saucer shaped craft, funded (initially) by the Canadian government. John Frost had initiated the design while experimenting with different ways to build more efficient jet engines, eventually settling on a large disc-shaped device with the exhaust towards the outside. He then wrapped the smallest possible airframe around the engine, piping the exhausts to the rear. For VTOL the aircraft sat on its tail for takeoff and landing, generating lift in forward flight as a large delta wing.



Frost also became interested in the Coandă effect to produce lift, eventually abandoning the original delta wing design and replacing it with a true disc. In this model the exhaust was directed downward around the entire disc by a flap ringing the aircraft, allowing it to take off and land "flat". Once in flight the flap would be angled slightly, producing a small downforce while being directed to the rear. Little lift would be generated by conventional means, the engine exhaust would instead be used to build an "artificial wing" by directing the airflow around the craft. He offered a number of increasingly dramatic performance estimates, generally claiming Mach 4 performance at 80,000 ft (24,000 m), at which point the USAF took over funding under Weapon System 606A. The result was a 29-foot (8.9 m) diameter supersonic Project Y2.

Testing soon revealed that the entire concept was unworkable; the craft would be highly unstable at supersonic speeds. Avro nevertheless continued work on the project as a subsonic design known as Project Silver Bug. Silver Bug was of interest to the US Army, who was looking for solutions for battlefield transport and support, and they took over most of the project funding. 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. After Avro experienced financial difficulties in 1959, funding for future projects was apparently directed to the Bell Aircraft Corporation. Meanwhile the helicopter had proven to be the solution the Army was looking for.

Other
The Sikorsky Cypher is a doughnut-shaped, experimental, prototype unmanned vertical takeoff and landing aerial vehicle. The Sikorsky Cypher II, (a.k.a. Sikorsky Mariner), follow-up aircraft has wings extending from the left and right sides of the aircraft

Books

 * Rose, Bill; Tony Buttler. Secret Projects: Flying Saucer Aircraft, Midland Publishing, 2004 ISBN 978-1-85780-233-7