The genesis of the F.6 design was the desire to adapt the airframe of the Caproni Vizzola F.5 fighter to mount the German Daimler-Benz DB 605A liquid-cooled inverted V12 engine. Shortly after Caproni began to design the F.6M, it began work on a second F.6 prototype, this one designed to use the Isotta-Fraschini R.C.25/60 Zeta 24-cylinder X-type engine and designated the F.6Z, with "Z" standing for Zeta.