Messerschmitt Bf 109 11 July 1938 when Erhard Milch finally allowed Willy Messerschmitt to acquire the company. All Messerschmitt aircraft that originated after that date, such as the Me 210, were to carry the "Me" designation. Despite regulations by the RLM, wartime documents from Messerschmitt AG, RLM and "Luftwaffe" loss and strength reports continued to use both designations, sometimes even on the same page. All extant airframes bear the official "Bf 109" designation on their identification plates, including the final K-4 models. The aircraft was often referred to by the folk-designation, 'Me 109', particularly by the Allies. The aircraft was often nicknamed "Messer"
Messerschmitt Bf 109 variants first Bf 109 in serial production, the Bf 109 B-1, was fitted with the 670 PS (661 hp, 493 kW) Jumo 210D engine driving a two-bladed fixed-pitch propeller. During the production run a variable-pitch propeller was introduced and often retrofitted to older aircraft; these were then unofficially known as B-2s. The Bf 109B saw combat with the "Legion Condor" during the Spanish Civil War, although it was apparent that the armament was still inadequate. Several aircraft were produced with an engine-mounted machine gun but it was very unreliable, most likely because of engine vibrations and overheating. Thus the Bf 109