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.

[1] 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.

Problems with engine development greatly delayed the F.6Z, but it finally flew in August 1943.

Testing in August and September 1943 showed that the Zeta engine, although rated at 1,100 kilowatts (1,500 horsepower), was producing only 900 kilowatts (1,200 horsepower), and this problem was not solved before the World War II Italian armistice with the Allies on 8 September 1943.