In the pre-World War 2 period, F. Fabrizi of Italy led a design team that engineered several lesser-known fighter prototypes for the Kingdom of Italy. This work netted the "F.4", an all-modern monoplane seating one in an enclosed cockpit, offering a wholly retractable undercarriage, and armed with twin machine guns. Engine decisions meant that this model was passed on in favor of another fighter being designed in parallel - the "F.5'.
While the F.4 was intended to fit an Isotta-Fraschini liquid-cooled inline, the F.5 was to feature the Fiat A.74 R.C.38 twin-row, 14-cylinder air-cooled radial piston engine of 870 horsepower. This was used to drive a three-bladed propeller unit at the nose. Both aircraft used the same low-wing monoplane layout and both were designed to carry 2 x 12.7mm Breda-SAFAT heavy machine guns as primary armament. The availability of the German Daimler-Benz DB601 inline engine for Italy in the summer of 1939 changed the fortunes of the F.4 some but this model, slated to become the "F.5bis" prototype, managed little before being given up for good in 1942.
The F.5 itself flew in prototype form on February 19th, 1939 with its Fiat powerplant in place. It was showcased to Italian authorities who were sold enough on the type to order a second flyable prototype for further evaluation and this was followed by a contract for twelve pre-series airframes (subsequent events then led to the final pre-series F.5 airframe being used to develop the F.4/F.5bis mentioned earlier as that program was revitalized by the arrival of the German inline engines).
The eleven pre-series F.5 were delivered to 300 Squadriglia and, by 1942, were formed as part of the night-fighting contingent of 167 Gruppo. Beyond this, it appears that little more was had with the F.5. Like the F.4, the F.5 ended its days most likely in 1942.
The F.5 "Gamma" was a proposed two-seat trainer being planned for the series. It was to be powered by an Isotta-Fraschini "Gamma" R.C.35 IS air-cooled radial piston engine instead. A single 7.7mm Breda-SAFAT machine gun was to make up its armament load for gunnery training. Little was realized of this project.
As flown, the F.5 managed a maximum speed of 317 miles per hour with a range out to 480 miles. Its service ceiling reached 31,200 feet.