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 G-6s were converted to two-seat trainers, known as G-12s. An instructor's cockpit was added behind the original cockpit and both were covered by an elongated, glazed canopy. The final production version of the Bf 109 was the K series, or "Kurfürst", introduced in late 1944, powered by the DB 605D engine with up to 2,000 PS (1,973 HP). Though externally akin to the late production Bf 109G series, a large number of internal changes and aerodynamic improvements was incorporated that improved its effectiveness and remedied existing flaws, keeping it competitive with the latest Allied and Soviet fighters. The Bf 109's