Caproni Vizzola F.4

The Caproni Vizzola F.4 was an Italian fighter prototype designed in 1937 and built from 1939, a single-seat low-wing cantilever monoplane with retractable landing gear. It was developed in parallel with the Vizzola F.5 and shared its airframe, with design begun in late 1937 by a team led by F. Fabrizi, the F.4 standing for Fabrizi 4. The fuselage was welded steel tube covered with flush-riveted duralumin and the wing was wooden with a stressed plywood skin. Fabrizi intended an Isotta Fraschini Asso water-cooled engine, but the Air Ministry preferred that the Asso not be used in fighters, so the project was halted in favour of the radial-engined F.5. The last of 12 pre-production F.5 aircraft was later converted into the F.4 prototype with a German Daimler-Benz DB 601A, and the Regia Aeronautica assigned it to the 303a Squadriglia, which operated it experimentally in 1942.