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 operational history comparative trials were held at the "Erprobungsstelle Rechlin" central Luftwaffe air test facility, with the leading Luftwaffe ace Werner Mölders being one of the participants. The tests concluded that the Bf 109 had superior level and climb speed to the Spitfire and Hurricane at all altitudes, but also noted the significantly smaller turning circle of the British fighters (more than one British pilots combat reports bear this out, having used the tighter turning circle of their aircraft to get into firing position, or conversely used it to get out of the way of a 109). It was advised not to