(B2431) wrote in message ...
The U.S. built and flew a few disc aircraft during WW2. The Chance Vought V-173
first flew 23 November 1942, which had excellent STOL capabilities and was
apparently impossible to stall. The Navy ordered two XF5U-1 which didn't get
their propellers until 1947 and were not proceded with since the Navy decided
jets were the way to go.

Dan, U.S. Air Force, retired

Actually, the idea was researched in the US since 1932 (Patent
2,108,093). It was based om the theories of physicist Charles H.
Zimmermann, compiled in technical report NACA 431. In 1939, The US
Navy provided the funding for the prototype which flew on 11/23/42 as
the Chance-Vought V-173.
Previous aerodynamic tests had already revealed the instability and
low maneuverability of the plane, so the designers were forced to
install big conventional empennages, spoiling the very concept of the
circular wing aircraft (hint: not a true disc).
Low speed performances were considered worse than in other models in
service of the time. So, the next step was a proposal for a VTO recon
plane with tilting rotors repacing the prop blades.
Other protoypes were made (series XF5U-1) equipped with 1359 hp
engines but their performance was also inadequate for the postwar
needs of the US Navy and the project was cancelled in the spring of
1948.
The Soviets also tested two circular gliders based on the German
A.S.6- the Diskoplan I with a Kreisflugel J1253 wing (investigated by
Dr. Alexander Lippisch in 1940-41 at the AVA Gottingen wind tunnel and
Messerschmitt AG laboratories). It was presented at the Moscow Airport
at Tushino in 1958. A Diskoplan II flew in 1962, but no data is
available for a powered version. It is not known if a high-performance
powered version was ever built.

Rob