World War 2 In Review: Boeing B-17D Flying Fortress

Early B-17D at Wright Field. The "D" model was the last B-17 series to have a small "shark-fin" tail and underside "bathtub" gun position; circa 1941.

Though changes in the design made the Army Air Force decide that the B-17D was worthy of a new sub designation, the B-17C and B-17D were very similar. In fact, both were given the same sub designation (299H) by Boeing.

Minor changes were made, both internally and externally. Outside, the engines received a set of adjustable cowl flaps for improved cooling, and the externally-mounted bomb racks were removed. On the interior, the electrical system was revised, and another crew position was added, bringing the total number to ten. In the aft-dorsal radio compartment was a new overhead twin-.50s machine gun mount; in the central-aft section's ventral "bathtub" gun position, twin .50s were also added, as was additional armor plating. Nose gun ball sockets were added to the side windows for the first time, in a longitudinally staggered layout (the starboard ball socket was further forward than the port-side ball socket). The number of machine guns aboard brought the total armament to seven: one portable nose .30 in (7.62 mm) and six .50 in (12.7 mm). The B-17D also featured more extensive armored plate protection. A total of 42 "D" series were built, and the 18 remaining B-17Cs were converted to Boeing's new B-17D standard. The sole-surviving example of the "D" series (originally built in 1940 and nicknamed Ole Betsy by her original aircrew) is currently undergoing restoration at the National Museum of the United States Air Force in Dayton, Ohio. This B-17D was later renamed "The Swoose" by her last pilot Col. Frank Kurtz, who after the war, kept the Fortress from being scrapped; he later named his daughter, actress Swoosie Kurtz, after the bomber.

Boeing B-17D with engines running, right front quarter view; 3 February 1941.

Boeing B-17D, left rear quarter view; circa 1941.

Boeing B-17D, serial number 40-3065, front view; circa 1941.

Boeing B-17D, Wright Field.

Boeing B-17D Flying Fortress.

Boeing B-17D in flight; circa 1941.

A 19th Bombardment Group B-17D being loaded with 100 and 500-pound bombs probably at Del Monte Field, Mindanao, Philippines, early in 1942. Note the Fortress is parked in a rough, dirt area and the early M1917 helmet and pre-war uniform worn by one of the ground crew indicating the photo was taken in a combat area in the first few weeks of the war.

B-17Ds of the 5th Bombardment Group overfly the main gate at Hickam Field, Hawaii Territory during the summer of 1941. 21 B-17C/Ds had been flown out to Hawaii during May to reinforce the defenses of Hawaii.