B-17 Flying Fortress - Liberty BelleB 17 Liberty Belle airplane model. The B 17G was the result of an almost continuous improvement program of earlier B 17 models. The G model was basically the production version of the B 17F after the modifications and improvements were incorporated into the design. Although the Bendix chin turret is the most obvious improvement incorporated into the B 17G, it was actually first used on late model B 17Fs. More than 8,500 Gs were built by three