In the autumn, 1944, JG 1 began partial equipment with the Fw 190 D (nicknamed the Dora; or Long-Nose Dora, "Langnasen-Dora"). The first major production D model was the Fw 190 D-9. With the D version the power plant was changed from the radial engine of earlier models to a 12-cylinder inverted-V liquid-cooled inline Jumo 213A with MW 50 injection. The fighter lacked the high rate of roll of its predecessor, but was faster all around, with a maximum speed of at . The new power plant and alterations to the airframe, which lengthened it, gave it the performance at high altitude necessary to combat US heavy bombers. The operational circumstances by late, 1944, however, had changed to the Fw 190 D rarely engaged the bomber streams and instead served in the fighter-versus-fighter combat role over the frontline and in protection of Messerschmitt Me 262 jet airfields.