Messerschmitt Bf 109 Bf 109 F-4

The Bf 109 F-4 was the highest-production sub-variant of the Friedrich series, with 1,841 units built between May 1941 and May 1942, including the F-4/R1 derivative (underwing gondolas), the F-4/Z (high-altitude, with GM-1 boost) and the F-4 trop (tropicalized). It introduced the 20 mm MG151/20 Motorkanone through the propeller hub, replacing the F-2's 15 mm MG151, firing alongside the two 7.92 mm MG17s above the engine. Powered by the Daimler-Benz DB 601E engine, it reached 659 km/h at 6,200 m once full power of 1,350 hp (993 kW) was cleared in February 1942; with initial power restricted to 1,200 hp it reached 635 km/h. It was the basis on which the following series, the Gustav, was developed.