Messerschmitt Bf 109 109 was steadily being supplemented by the Focke-Wulf Fw 190. It was commonly called the Me 109, most often by Allied aircrew and even among the German aces themselves, even though this was not the official German designation. It was designed by Willy Messerschmitt and Robert Lusser, who worked at Bayerische Flugzeugwerke during the early to mid-1930s. Whilst the 109 was conceived as an interceptor, later models were developed to fulfill multiple tasks, serving as bomber escort, fighter-bomber, day-, night-, all-weather fighter, ground-attack aircraft, and as reconnaissance aircraft. It was supplied to and operated by several states during World War
Messerschmitt Bf 109 mounted on the firewall. The entire powerplant could be removed or replaced as a unit in a matter of minutes, a potential step to the eventual adoption of the unitized-powerplant "Kraftei" engine mounting concept used by many German combat aircraft designs, later in the war years. Another example of the Bf 109's advanced design was the use of a single, I-beam main spar in the wing, positioned more aft than usual (to give enough room for the retracted wheel), thus forming a stiff D-shaped torsion box. Most aircraft of the era used two spars, near the front and rear edges