F.6M as originally built with a deep
radiator under the nose. It was later removed and replaced by a ventral radiator in order to reduce
aerodynamic drag. The F.6 design was the result of a project to adapt the airframe of the Italian
Caproni Vizzola F.5 fighter with the
German Daimler-Benz DB 605A liquid-cooled inverted V-12 engine. To accomplish this, the Caproni company retained the F.5
fuselage but designed metal wings to replace the wood wings of the F.5. The new aircraft was designated F.6M, with "F" standing for Fabrizi, the designer of the F.5, and "M" for
Metallico. It was designed to carry twice the offensive armament of the F.5, with four instead of two
Breda-SAFAT machine guns; the prototype F.6M flew with two of these mounted in the fuselage and provision for two more in the wings, although the wing guns were never mounted. The F.6M prototype first flew in September 1941, using a large radiator mounted under the nose, just behind the propeller. Flight testing showed that this location produced significant
aerodynamic drag, and the prototype was reworked to mount the radiator on the belly, aft of the pilot position. One other fighter type, the
Reggiane Re.2004 was also planned with this engine, but was not realized. ==Operators==