A weirdly shaped, not very aesthetic plane that looks like a saucer that can never fly. This is the Vought V-173, an American prototype with a circular airfoil with large-diameter propellers on the wingtips.
Developed in 1940 for the Navy, it is an aircraft with capabilities of short take-off and landing, it can fly at very low speeds and has the characteristics of an all-wing aircraft since all its surfaces can generate lift. In addition, the engine nacelles are embedded in the flying wing very smoothly.
The design and development are credited to the work of Charles H. Zimmerman, an aeronautical engineer working at NACA (National Advisory Committee for Aeronautics). He is known for his works and research regarding flat circular bodies, sans wings, as their lifting surface. He realized that drag created by the airflow on wingtips of conventional wings could be minimized by placing the propeller at the wingtip. Furthermore, this type of wing could maintain a uniform airflow on the entire wing, improving the aerodynamic performance.
The prototype of the plane Flying Pancake was constructed of wood and canvas and contained in the wing a symmetrical airfoil section (NACA 0015). It has a circular wing 23.3 feet in diameter and is powered by two Continental engines of 80 hp. The traction is provided by driving 16-foot diameter propellers through cross shafting and 90-degree gearboxes.
The pitch control and elevation are generated by two normal-looking horizontal stabilizers and elevators on tips and elevators on the mid-rear fuselage. The aircraft made its first flight on November 23, 1942, with 199 flight tests until 1947.
The tests of the V-173 proved Zimmerman’s ideas to be practical but unfortunately the useful potential of high-speed performance with turbojet engines was greater than the remarkable low-speed performance attainable with the flying wingNational Air and Space Museum, Smithsonian Institution.
As seen the weird shape of this plane, in the place where test flights were performed, many concerned residents in Connecticut, called in reports of UFOs to authorities and media. An event that was pretty common at that time.
The aircraft can be seen in Smithsonian National Air & Space Museum, USA.