Aside from turbine-driven, prop-driven, and saucers motivated by other means of propulsion, terrestrial aeronautics have given rise to other kinds of disc-shaped aircraft.
As early as 1925, according to Revista de Aeronautica y Astronáutica (Number 413, April 1975), Soviet designers had developed a glider with a semicircular wing (more practical than a circular wing) resembling a giant letter "D" with an enormous rudder in the aft section, which also doubled as an elevating plane throughout the rear perimeter. This device is known as Tscharanowsky's "Parabola" glider, which can be seen at the Leningrad (St. Petersburg) Aviation Museum, and is one of the first designs of this type, a spectacular example of Russian enthusiasm for gliding.
The Parabola was nothing more than the forerunner for other flying saucers built by the Soviets throughout history.
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