Cockpit and top turret of the Boeing B-17G Flying Fortress Duxford Aero Museum - part of the Imperial War Museum. The B-17G (the major production version), was the first production variant of the B17 to have a chin turret installed, under the nose. The Bendix turret held two .50-cal. guns, which increased the armament to thirteen guns. In all, there were 8,680 B-17Gs built by Boeing, Vega, and Douglas. B-17G had a wingspan of 103 feet 9 inches (31.6 m), length of 74 feet 4 inches (22.6 m), and a height of 19 feet 1 inch (5.8 m). The four supercharged Wright R-1820-97 Cyclones delivered 1,200 hp (895 kW) and gave a top speed of 287 mph (462 km/h), cruising at 182 mph (293 km/h). Service ceiling was 35,800 ft. (10,850 m), with a max. range of 3,400 miles (5,471 km). Empty and gross weights were 36,135 lb (16,390 kg)and 65,500 lb (29,710 kg). Maximum fuel load was 3,630 gallons (13,741 liters).