During the spring and summer of 1942 the assembly lines began to switch to the production of the Bf 109 G-series. With the introduction of the Bf 109 G-series the constant operational demands for increased fire power and additional equipment brought with them a serious deterioration in the fighter's flying characteristics. The most important change denoted by the introduction of the Bf 109 G was the installation of the more powerful Daimler Benz DB 605 A engine in which the cylinder block had been re-designed to obtain the maximum possible bore with the existing cylinder centers.Bf109 G-2 was produced in parallel with the Bf109 G-1, and differed in lacking the pressure cabin and GM-1 nitrous oxide boost. It was used primarily in the fighter reconnaissance role, and the service test group at Guyana court, France, experimented with a ventral gun pack in which two rear-firing MG 17 machine guns were fitted (Schraege Musik).The Bf-109G-2 was built in substantially larger numbers than the Bf-109G-1, and was produced in a wide range of modifications. Bf 109 G-2 fitted with an older type ETC 500 IX b bomb rack for 250 or 500 kg bomb. The tail wheel is not retractable due to a larger tyre (350 x 135) and there is no locking device, either. The head armour plate has been moved backwards to the rear line of canopy’s swinging part. The tailplane and fin have no cast leading edges any more. The cooling air intakes for sparking plugs and deeper cooler under the nose are also new. Oil cooler is a bit deeper than in F-1/2 and early F-4.