All changes made to the Flying Fortress were incorporated into the final production version, the B-17G. These included the
Bendix remotely-operated chin turret, bringing the bomber's defensive armament to thirteen machine guns. The waist gun windows were staggered to improve the gunner's freedom of movement, another carryover from the YB-40 "gunship" variant. The earliest B-17Gs lacked the "cheek" machine gun mounts, as it was believed that the chin turret provided sufficient forward firepower; they were quickly reintroduced. In a reversal of the B-17F's design, the starboard "cheek" machine gun mount was moved rearward and the port side mount was moved forward, just behind the edge of the bombardier's nose glazing to avoid interference with the storage of the chin turret's control yoke when it was not in use. For late production blocks of the G-series, the tail gun turret was revised. Referred to as the "Cheyenne" configuration (after the modification center where it was introduced, the United Airlines Modification Center in
Cheyenne, Wyoming), its guns were mounted in a new turret with a
reflector sight and a much greater field of fire. Some 8,680 were built, and dozens were converted for several different uses: •
CB-17G: Troop transport version, capable of carrying 64 troops. •
DB-17G: Drone variant •
DB-17P: Drone director •
EB-17G: Engine test-bed, company designation
Model 299Z. Two aircraft modified from Lockheed-built B-17Gs. Later redesignated
JB-17G. •
MB-17G: Missile launcher •
QB-17L: Target drone •
QB-17N: Target drone •
RB-17G: Reconnaissance variant •
SB-17G: Rescue version, later redesignated
B-17H: Featured
A-1 lifeboat under fuselage. After World War II, armament on the B-17Hs was removed; it was reinstated when the
Korean War began. •
TB-17G: Special duty training version •
TB-17H: Training version of B-17H •
VB-17G: VIP transport •
PB-1: This designation was given to one B-17F and one B-17G. They were used by the U.S. Navy for various test projects. •
PB-1G: This designation was given to 17 B-17Gs used by U.S. Coast Guard as air-sea rescue aircraft. •
PB-1W: This designation was given to 31 B-17Gs used by the U.S. Navy as the first airborne early warning aircraft (AWACS). •
Model 229AB: Single B-17G converted as a VIP transport for
Trans World Airlines. These carried an extensive array of electronic equipment including airborne Grocer air-interception jammers, the Jostle VHF jammer,
Monica tail-warning receiver,
Gee and
LORAN for navigation, and an
H2S radar which replaced the chin turret. They were also used as decoys during night bombing attacks. Fortress Mk.IIIs were operational until the units disbanded in July 1945. ==B-17H==