The following is an extensive catalogue of the variants and specific unique elements of each variant and/or design stage of the Boeing B-17 Flying Fortress, a
heavy bomber
Heavy bombers are bomber aircraft capable of delivering the largest payload of air-to-ground weaponry (usually bombs) and longest range (takeoff to landing) of their era. Archetypal heavy bombers have therefore usually been among the larges ...
used by the
United States Army Air Forces
The United States Army Air Forces (USAAF or AAF) was the major land-based aerial warfare service component of the United States Army and ''de facto'' aerial warfare service branch of the United States during and immediately after World War II ...
and other
Allied
An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...
air forces during
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
.
Boeing Model 299 (XB-17)
The Model 299 was the original bomber design built by Boeing to fulfill an August 1934 requirement by the
United States Army Air Corps
The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical r ...
for a bomber capable of carrying 2,000 lb (907 kg) of bombs 2,000 mi (3,218 km) at 200 mph (322 km/h).
[Hess & Winchester ''Wings of Fame'' No. 6, 1997, p. 41.] The 299 was powered by four
Pratt & Whitney S1EG Hornet radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ca ...
s rated at each at , giving a maximum speed of and a maximum gross weight of . It carried a bomb load of eight bombs, with a defensive armament of five .30 caliber machine guns, with one in a nose turret and one each in dorsal and ventral mounts and two in waist blisters.
[Bowers 1989, pp. 291–292.][Hess & Winchester ''Wings of Fame'' No. 6, 1997, pp. 41–42.] In 1935, Boeing's Model 299 competed with several entries by other aircraft companies at an evaluation at
Wright Field
Wilbur Wright Field was a military installation and an airfield used as a World War I pilot, mechanic, and armorer training facility and, under different designations, conducted United States Army Air Corps and Air Forces flight testing. Lo ...
near Dayton, Ohio, USA.
On its flight from
Seattle
Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest regio ...
, Washington to Wright Field for the competition, the 299 set a nonstop speed record of 252 mph (406 km/h). Though it crashed and burned on takeoff during a demonstration, the crash was due to
flight-crew error, not from any flaw in the aircraft. Subsequent implementation of a mandatory pre-flight checklist prior to take-off ensured avoidance of flight crew error. Despite the crash (and more important, its much higher cost per unit), Army Air Corps leaders were impressed by the bomber's performance, so Boeing was awarded an initial development contract. The aircraft has since been referred to as the XB-17, but this designation is not contemporary or official.
Y1B-17 (YB-17)
Though still enthusiastic about the Boeing design, despite it being disqualified from the fly-off contest following the crash of the Model 299 prototype, the Army Air Corps cut its order from 65 service test YB-17s to just 13. On November 20, 1936, the bomber's normal acquisition funding was changed to "F-1" , and the heavy YB-17 bomber was redesignated "Y1B-17", as a result.
Unlike its predecessor, which had used
Pratt & Whitney R-1690
The Pratt & Whitney R-1690 Hornet was a widely used American aircraft engine. Developed by Pratt & Whitney, 2,944 were produced from 1926 through 1942. It first flew in 1927. It was a single-row, 9-cylinder air-cooled radial design. Displacem ...
Hornet radial engines, the Y1B-17 used the more powerful
Wright R-1820
The Wright R-1820 Cyclone 9 is an American radial engine developed by Curtiss-Wright, widely used on aircraft in the 1930s through 1950s. It was produced under license in France as the Hispano-Suiza 9V or Hispano-Wright 9V, and in the Soviet Uni ...
Cyclone that would become the standard power plant on all B-17s produced. Several changes were also made in the armament, and the crew was reduced from seven to six. Most changes were minor: the most notable was switching from double-wishbone to single-arm landing gear for ease of regular maintenance.
On 7 December 1936, five days after the first flight of the Y1B-17, the brakes on the bomber fused during landing, and it nosed over. Though damage was minimal, the cumulative impact of this event, combined with the crash of the Model 299, triggered a Congressional investigation. Following the crash, the Army Air Corps was put on notice: another such crash would mean the end of the bomber's "F-1" procurement program.
Though the heavy bombers were meant for testing, the commander of Army General Headquarters (Air Force), Major General
Frank Andrews, decided to assign twelve Y1B-17s to the
2nd Bomb Group
The 2nd Bomb Wing is a United States Air Force unit assigned to the Air Force Global Strike Command and the Eighth Air Force. It is stationed at Barksdale Air Force Base, Louisiana. The wing is also the host unit at Barksdale. The wing wa ...
located at
Langley Field Langley may refer to:
People
* Langley (surname), a common English surname, including a list of notable people with the name
* Dawn Langley Simmons (1922–2000), English author and biographer
* Elizabeth Langley (born 1933), Canadian perform ...
,
Virginia
Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...
. Andrews reasoned that it was best to develop heavy bombing techniques as quickly as possible. Of the thirteen Boeing aircraft built, one was assigned for stress testing.
In 1937, the twelve Y1B-17s at Langley Field represented the entire fleet of American heavy bombers. Most of the time spent with the bombers entailed eliminating problems with the aircraft. The most important development was the use of a detailed
checklist
A checklist is a type of job aid used in repetitive tasks to reduce failure by compensating for potential limits of human memory and attention. It helps to ensure consistency and completeness in carrying out a task. A basic example is the " to d ...
, to be reviewed by the pilot and copilot just prior to each takeoff. It was hoped that this procedure would prevent accidents similar to that which led to the loss of Boeing's Model 299 prototype.
In May 1938, the Y1B-17s (now redesignated just B-17) of the 2nd Bombardment Group, led by the lead bombers' navigator
Curtis LeMay
Curtis Emerson LeMay (November 15, 1906 – October 1, 1990) was an American Air Force general who implemented a controversial strategic bombing campaign in the Pacific theater of World War II. He later served as Chief of Staff of the U.S. Air ...
, took part in a demonstration in which they
intercepted the Italian liner ''Rex''. Coming into contact with the liner while it was still 610 mi (982 km) out at sea, the demonstration was meant to prove the range and navigational superiority of the B-17. It also showed that the bomber would be an effective tool for attacking a naval invasion force before it could reach the United States. The Navy was furious about the Army's intrusion into their mission, and forced the
War Department War Department may refer to:
* War Department (United Kingdom)
* United States Department of War (1789–1947)
See also
* War Office, a former department of the British Government
* Ministry of defence
* Ministry of War
* Ministry of Defence
* D ...
to issue an order restricting the Army Air Corps from operating more than a hundred miles from America's coastline.
After three years of flight, no serious incidents occurred with the B-17s. In October 1940, they were transferred to the 19th Bombardment Group at
March Field
March is the third month of the year in both the Julian and Gregorian calendars. It is the second of seven months to have a length of 31 days. In the Northern Hemisphere, the meteorological beginning of spring occurs on the first day of Ma ...
.
B-17A (Y1B-17A)
The aircraft that became the sole Y1B-17A was originally ordered as a static test bed. However, when one of the Y1B-17s survived an inadvertent violent spin during a flight in a
thunderhead, Army Air Corps leaders decided that the bomber was exceptionally robust and that there would be no need for static testing. Instead, it was used as a testbed for enhancing engine performance on the new bomber. After studying a variety of configurations, use of a ventral-nacelle-mount
turbocharger
In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...
position was settled on for each of its four engines. A successive series of
General Electric
General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
-manufactured turbochargers would equip B-17s as standard items, starting with the first production model, allowing it to fly higher and faster than the Y1B-17. When testing was completed, the Y1B-17A was reconfigured as the B-17A, serial number: 37-369.
B-17B
The B-17B (299M) was the first production model of the B-17 and was essentially a B-17A with a larger
rudder
A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally aircraft, air or watercraft, water). On an aircraft the rudder is used primarily to ...
, larger
flaps, and a redesigned nose and 1,200 hp (895 kW) R-1820-51 engines. The small, globe-like, machine gun turret used in the Y1B-17's upper nose blister was replaced with a .30 caliber (7.62 mm) machine gun, its barrel run through a ball-socket in the ten-panel
Perspex
Poly(methyl methacrylate) (PMMA) belongs to a group of materials called engineering plastics. It is a transparent thermoplastic. PMMA is also known as acrylic, acrylic glass, as well as by the trade names and brands Crylux, Plexiglas, Acrylite ...
nose glazing. This was held in place by both the socket's strength combined with a flexible interior support strap, which later became an aluminum-reinforced window pane. The Y1B-17's separate triangular-shaped bombardier's aiming window, located further back in the lower nose, was eliminated, replaced with a framed window panel in the lower portion of the nose glazing; this configuration was used on all Flying Fortress airframes up through the B-17E series. All B-17B aircraft were later modified at Boeing, being brought up to the B-17C/D production standard. While the new nose glazing still used only a single .30 caliber machine gun, two additional ball-sockets were installed in the nose, one in the upper left panel and another in a lower right. This three ball-socket layout was continued up through the B-17E series. During Army Air Corps service, the bulged teardrop-shaped machine gun blisters were replaced with flush-mounted Perspex side windows of the same type used in the B-17C/D series. Various aircraft had different levels of upgrades performed. Some of the "B" series Fortresses had only their bulged side blisters replaced with slide-out flush windows, while others also had their bulged upper blister changed to a much flatter, more aerodynamic Perspex window panel. In addition, some "B" series Fortresses also had ventral "bathtub turrets" (see the "C/D" section below) installed, replacing their lower, teardrop-shaped gun blisters.
Crew locations were rearranged, and the original
pneumatic
Pneumatics (from Greek ‘wind, breath’) is a branch of engineering that makes use of gas or pressurized air.
Pneumatic systems used in Industrial sector, industry are commonly powered by compressed air or compressed inert gases. A central ...
brake
A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.
Background ...
system was replaced with more efficient
hydraulic brake
A hydraulic brake is an arrangement of braking mechanism which uses brake fluid, typically containing glycol ethers or diethylene glycol, to transfer pressure from the controlling mechanism to the braking mechanism.
History
During 1904, Frederick ...
s.
In October 1942 all in-service B-17B aircraft were redesignated RB-17B, the "R" indicating "Restricted". These aircraft were now used only for training, transport, messenger, and liaison duties. The "R" prefix became a designation for combat obsolescence.
Many of these RB-17B aircraft, along with at least one still-airworthy YB-17, were stationed at Sebring Airfield, where the exterior scenes were filmed for the
Warner Bros.
Warner Bros. Entertainment Inc. (commonly known as Warner Bros. or abbreviated as WB) is an American film and entertainment studio headquartered at the Warner Bros. Studios complex in Burbank, California, and a subsidiary of Warner Bros. D ...
war drama ''
Air Force
An air force – in the broadest sense – is the national military branch that primarily conducts aerial warfare. More specifically, it is the branch of a nation's armed services that is responsible for aerial warfare as distinct from an a ...
'' (1943), directed by
Howard Hawks
Howard Winchester Hawks (May 30, 1896December 26, 1977) was an American film director, producer and screenwriter of the classic Hollywood era. Critic Leonard Maltin called him "the greatest American director who is not a household name."
A v ...
, and starring (among others)
John Garfield
John Garfield (born Jacob Julius Garfinkle, March 4, 1913 – May 21, 1952) was an American actor who played brooding, rebellious, working-class characters. He grew up in poverty in New York City. In the early 1930s, he became a member of ...
,
Arthur Kennedy,
Gig Young
Gig Young (born Byron Elsworth Barr; November 4, 1913 – October 19, 1978) was an American actor. He was nominated for the Academy Award for Best Supporting Actor for his performances in ''Come Fill the Cup'' (1952) and '' Teacher's Pet'' ...
, and
Harry Carey Harry Carey may refer to:
*Harry Carey (actor) (1878–1947), American actor
* Harry Carey Jr. (1921–2012), American actor
* Harry Carey (footballer) (1916–1991), Australian rules footballer
See also
* Henry Carey (disambiguation)
* Harry Car ...
. The film's real star, however, was an RB-17B (United States Army serial number 38-584), carrying on its upper rudder the "security-conscious" false serial number "05564". It passed as a later model B-17D Flying Fortress, having had its machine gun blisters replaced and a lower "bathtub" ventral gun turret installed. Many of these aircraft can still be seen in both ground and aerial scenes during the film.
The "B" series Flying Fortress made its maiden flight on 27 June 1939. 39 were built in a single production run, but Army Air Corps serial numbers were scattered over several batches. This was because of limited government funding: The Army Air Corps could only afford to purchase a few B-17Bs at a time.
B-17C
The B-17C was a B-17B with a number of improvements, including more powerful R-1820-65 engines. To boost crew safety, the waist-mounted machine gun blisters were replaced with teardrop-shaped, slide-out Perspex window panels flush with the fuselage, and the ventral blister was replaced by a lower metal housing dubbed a "bathtub turret", similar in appearance and general location on the lower fuselage, to the ''Bola'' ventral
gondola
The gondola (, ; vec, góndoła ) is a traditional, flat-bottomed Venetian rowing boat, well suited to the conditions of the Venetian lagoon. It is typically propelled by a gondolier, who uses a rowing oar, which is not fastened to the hull, ...
being used on Nazi Germany's
He 111P medium bomber. The most important additions made to the "C" series were
self-sealing fuel tank
A self-sealing fuel tank is a type of fuel tank, typically used in aircraft fuel tanks or fuel bladders, that prevents them from leaking fuel and igniting after being damaged.
Typical self-sealing tanks have multiple layers of rubber and reinforc ...
s and defensive armor plate added to vital areas.
With the passage of the
Lend-lease
Lend-Lease, formally the Lend-Lease Act and introduced as An Act to Promote the Defense of the United States (), was a policy under which the United States supplied the United Kingdom, the Soviet Union and other Allied nations with food, oil, ...
Act in 1941, the
Royal Air Force
The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
requested B-17s. At that time, the US Army Air Corps was suffering from shortages of the B-17, but hesitantly agreed to provide 20 examples to the RAF. Though the Air Corps did not consider the B-17 ready for offensive combat, the aircraft was still desperately needed in Britain. The 20 ferried bombers were Boeing production B-17Cs (company designation Model 299T). The aircraft's single .30 caliber nose-mounted machine guns were replaced with 0.5 inch Brownings.
Following their delivery, the 20 B-17C bombers were placed immediately into frontline service and designated RAF Fortress Mk I. They performed unremarkably while in British service. By September 1941,
three months after the Army Air Corps became the Army Air Forces, 39 sorties had made up 22 missions. Nearly half of those were aborted due to mechanical and electrical problems. Eight of the 20 aircraft were destroyed by September, half to various accidents. Their machine guns tended to freeze-up at high altitudes and were generally unable to effectively protect the Fortresses from German fighter attack. Their success as bombers were also limited, largely because they were unable to strike targets from the high altitudes at which the RAF flew its daylight bombing missions.
The first of the B-17C series flew in July 1940, with a total of 38 being built. The 18 remaining in Army Air Forces service, following the 20 transferred to the RAF, were upgraded to Boeing's new B-17D configuration. However, one of these bombers, B-17C 40-2047, crashed while being ferried from Salt Lake City, Utah, to
Mather Army Air Base, California, on November 2, 1941.
B-17D
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 gun
A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) a ...
s 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
The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is the ...
in
Dayton
Dayton () is the sixth-largest city in the U.S. state of Ohio and the county seat of Montgomery County. A small part of the city extends into Greene County. The 2020 U.S. census estimate put the city population at 137,644, while Greater Da ...
,
Ohio
Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...
. This B-17D was later renamed "
The Swoose
''The Swoose'' is a B-17D-BO Flying Fortress, USAAF Ser. No. "40-3097", that saw extensive use in the Southwest Pacific theatre of World War II and survived to become the oldest B-17 still intact. It is the only early "shark fin" B-17 known t ...
" by her last pilot Col.
Frank Kurtz
Colonel Frank Allen Kurtz Jr. (September 9, 1911 – October 31, 1996) was an American Olympic diver and an aviator in the United States Army Air Forces.
Life and career
Kurtz was born in Davenport, Iowa, the third child of Dora Lee (née Fe ...
, who after the war, kept the Fortress from being scrapped; he later named his daughter, actress
Swoosie Kurtz
Swoosie Kurtz ( ; born September 6, 1944) is an American actress. She is the recipient of an Emmy Award and two Tony Awards.
Kurtz made her Broadway theatre, Broadway debut in the 1975 revival of ''Ah, Wilderness''. She has received five Tony ...
, after the bomber.
B-17E
The B-17E (299-O) was an extensive redesign of the previous B-17D. The most obvious change was the larger, completely new vertical stabilizer, originally developed for the
Boeing 307 Stratoliner
The Boeing Model 307 Stratoliner (or Strato-Clipper in Pan American service, or C-75 in USAAF service) is an American stressed-skin four-engine low-wing tailwheel monoplane airliner derived from the B-17 Flying Fortress bomber, which entered co ...
by
George S. Schairer
George S. Schairer (May 19, 1913 – October 28, 2004) was an aerodynamicst at Consolidated Aircraft and Boeing whose design innovations became standard on virtually all types of military and passenger jet planes.
Early life
George Swift Schaire ...
. The new fin had a distinctive shape for the time, with the opposite end of the fuselage retaining the ten panel bombardier's nose glazing from the B-17D.
Because experience had shown that the Flying Fortress would be vulnerable to attack from behind, both a tail gunner's position and a powered, fully traversable dorsal turret behind the cockpit, (each armed with a pair of
"light-barrel" Browning AN/M2 .50 cal. machine guns), were added to the B-17E. Until this modification, aircrews had to devise elaborate maneuvers to deal with a direct attack from behind, including swinging the bomber laterally, allowing the waist gunners to alternate .50 caliber bursts at enemy fighters. (The configuration of a "3-window box" would later be implemented on the
B-29
The Boeing B-29 Superfortress is an American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the B-17 Fly ...
, and also adopted by Soviet bombers as late as the
Tupolev Tu-16
The Tupolev Tu-16 ( NATO reporting name: Badger) is a twin-engined jet strategic heavy bomber used by the Soviet Union. It has been flown for almost 70 years, and the Chinese license-built Xian H-6 remains in service with the People's Liberatio ...
Badger, and in different form on the USAF's
B-52
The Boeing B-52 Stratofortress is an American long-range, subsonic, jet-powered strategic bomber. The B-52 was designed and built by Boeing, which has continued to provide support and upgrades. It has been operated by the United States Air ...
). The teardrop-shaped sliding panels of the waist gunners were replaced by rectangular windows, located directly across the fuselage from each other, for better visibility. In the initial production run, the ventral "bathtub" machine gun emplacement of the B-17C/Ds was replaced by a remotely-sighted powered turret. It was similar to the one used as a ventral fuselage-mount Bendix remote turret of the
B-25B through -D Mitchell medium bomber variants, but was difficult to use and proved to be a failure in combat. This resulted in all remaining B-17E production being fitted with a powered
Sperry Sperry may refer to:
Places
In the United States:
*Sperry, Iowa, community in Des Moines County
*Sperry, Missouri
*Sperry, Oklahoma, town in Tulsa County
*Sperry Chalet, historic backcountry chalet, Glacier National Park, Montana
*Sperry Glacier, ...
ball turret
A ball turret was a spherical-shaped, altazimuth mount gun turret, fitted to some American-built aircraft during World War II. The name arose from the turret's spherical housing.
It was a manned turret, as distinct from remote-controlled turrets ...
, manually operated from inside. These ball turrets also equipped the "F" and "G" series Flying Fortresses that followed for ventral-quarter defense.
A total of 512 were built (possibly from the July 1940-dated order from the then-USAAC for B-17s being for that specific number of airframes) making the B-17E the first mass-produced version of the Boeing B-17. One of these was later converted to the
XB-38 Flying Fortress
The XB-38 Flying Fortress was a single example conversion of a production B-17E Flying Fortress, testing whether the Allison V-1710 V type engine could be substituted for the standard Wright R-1820 radial engine during early World War II.
Desig ...
, which proved to be a failure during flight tests. The B-17E production order was too large a quantity for Boeing to handle by itself, so the Vega division of
Lockheed and
Douglas
Douglas may refer to:
People
* Douglas (given name)
* Douglas (surname)
Animals
* Douglas (parrot), macaw that starred as the parrot ''Rosalinda'' in Pippi Longstocking
*Douglas the camel, a camel in the Confederate Army in the American Civi ...
assisted in the manufacture of the bomber. Boeing also built a new production plant, and Douglas added one specifically for building B-17s.
In the middle of 1942, 45 B-17Es were transferred to the RAF, where they served under the designation Fortress IIA. Likely because of the shortcomings experienced with the Fortress I (B-17C), the RAF decided not to use the Fortress IIA as a daylight, high-altitude precision bomber, the role for which it had been redesigned. Rather, the new aircraft were transferred to the
Coastal Command
RAF Coastal Command was a formation within the Royal Air Force (RAF). It was founded in 1936, when the RAF was restructured into Fighter, Bomber and Coastal Commands and played an important role during the Second World War. Maritime Aviation ...
for
anti-submarine
An anti-submarine weapon (ASW) is any one of a number of devices that are intended to act against a submarine and its crew, to destroy (sink) the vessel or reduce its capability as a weapon of war. In its simplest sense, an anti-submarine weapo ...
patrol.
Four known examples of B-17Es still exist in museums today, none of which is currently known to be airworthy.
B-17F
The B-17F was an upgrade of the B-17E. Outwardly, both types were distinguished primarily by the ten-panel fully-framed nose glazing on the "E" series. A molded, one-piece or two-piece all
plexiglas
Poly(methyl methacrylate) (PMMA) belongs to a group of materials called engineering plastics. It is a transparent thermoplastic. PMMA is also known as acrylic, acrylic glass, as well as by the trade names and brands Crylux, Plexiglas, Acrylite ...
nose cone replaced this framed glazing on the "F" series (the two-piece cone had a nearly-transparent diagonal seam). Fully-feathering paddle-blade propellers were also substituted. Many internal changes were also made to improve the effectiveness, range, and load capacity of the Flying Fortress. Once placed in combat service, however, the "F" series was found to be tail-heavy. The combined weight, when fully combat-loaded, of the four rear gunners and their heavy .50 caliber ammunition, moved the bomber's
center of gravity
In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weight function, weighted relative position (vector), position of the distributed mass sums to zero. Thi ...
rearward from its original design point. This forced the constant use of the bomber's
elevator
An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ...
trim tab
Trim tabs are small surfaces connected to the trailing edge of a larger control surface on a boat or aircraft, used to control the trim of the controls, i.e. to counteract hydro- or aerodynamic forces and stabilise the boat or aircraft in a pa ...
, stressing that component to eventual failure. In combat the B-17F also proved almost immediately to have inadequate defensive protection when being attacked directly from the front. Various armament configurations of two-to-four flexible machine guns were added to the plexiglas nose cone and side window positions (the starboard position was placed further forward). Late production "F" series Flying Fortresses received substantially-enlarged bulged "cheek" mounts for their .50 caliber machine guns, then located on each side of the nose. These replaced the previous side window-mounted .50s. These "cheek" mounts allowed for firing more directly ahead. An overhead bulged dome was also added on top of the nose for use by the navigator.
The problem of head-on defense was not adequately addressed until the introduction of a powered, Bendix-designed, remotely operated "chin" turret in the final production blocks of F-series Fortresses, starting with the last 65 (86 according to some sources) B-17Fs built by Douglas, from the B-17F-70-DL production block — directly derived from its debut on the
YB-40
The Boeing YB-40 Flying Fortress was a modification for operational testing purposes of the B-17 Flying Fortress bomber aircraft, converted to act as a heavily armed gunship to support other bombers during World War II. At the time of its de ...
experimental "gunship" version.
By using reinforced landing gear, the maximum bomb capacity was also increased from to . Though this modification reduced cruising speed by , increased bomb-carrying capacity was favored by decisionmakers over speed. A number of other modifications were made, including re-integrating external bomb racks; because of the negative impact on both rate-of-climb and high-altitude flight performance, this configuration was rarely used and the bomb racks were once again removed.
Range and combat radius were extended with the installation in mid-production of additional fuel cells in the wings. Called "
Tokyo tanks Tokyo tanks were internally mounted self-sealing fuel tanks used in the Boeing B-17 Flying Fortress and Consolidated B-24 Liberator bombers ", nine self-sealing rubber-composition fuel tanks were mounted inside each wing on each side of the reinforcing
joint
A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw ...
between the inner and outer wing spars. With an extra to the available on the first B-17Fs, the "Tokyo tanks" added approximately to the bomber's target capability.
3,405 "F" series Flying Fortresses were built: 2,300 by Boeing, 605 by Douglas, and 500 by Lockheed (Vega). These included the famous ''
Memphis Belle''. 19 were transferred to the RAF, where they served with
RAF Coastal Command
RAF Coastal Command was a formation within the Royal Air Force (RAF). It was founded in 1936, when the RAF was restructured into Fighter, Bomber and Coastal Commands and played an important role during the Second World War. Maritime Aviation ...
as the Fortress II. Three examples of the B-17F remain in existence, including the restored ''Memphis Belle''.
B-17G
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 .50 caliber machine guns. The waist gun windows were staggered, another carryover from the YB-40 "gunship" variant. This allowed more freedom of movement for the waist gunners. 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 when this proved untrue. 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 position was revised. Referred to as the "Cheyenne" configuration (after the modification center where it was introduced, the United Airlines Modification Center in
Cheyenne, Wyoming
Cheyenne ( or ) is the capital and most populous city of the U.S. state of Wyoming, as well as the county seat of Laramie County, with 65,132 residents, per the 2020 US Census. It is the principal city of the Cheyenne metropolitan statistical ...
), its guns were mounted in a new turret with a
reflector sight
A reflector sight or reflex sight is an optical sight that allows the user to look through a partially reflecting glass element and see an illuminated projection of an aiming point or some other image superimposed on the field of view. These sig ...
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
* JB-17G: Engine test-bed
* 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
The A-1 lifeboat was a powered lifeboat that was made to be dropped by fixed-wing aircraft into water to aid in air-sea rescue operations. The sturdy airborne lifeboat was to be carried by a heavy bomber specially modified to handle the external l ...
under fuselage. After World War II, armament on the B-17Hs was removed; it was reinstated when the
Korean War
, date = {{Ubl, 25 June 1950 – 27 July 1953 (''de facto'')({{Age in years, months, weeks and days, month1=6, day1=25, year1=1950, month2=7, day2=27, year2=1953), 25 June 1950 – present (''de jure'')({{Age in years, months, weeks a ...
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).
Fortress III
Eighty-five B-17Gs were transferred to the RAF, where they received the service designation Fortress III. Three were assigned to Coastal Command in the Azores and were fitted with radar before being reused by meteorological survey squadrons. The rest were operated from February 1944 by two squadrons of
Bomber Command
Bomber Command is an organisational military unit, generally subordinate to the air force of a country. The best known were in Britain and the United States. A Bomber Command is generally used for strategic bombing (although at times, e.g. during t ...
's
No. 100 Group RAF
No. 100 (Bomber Support) Group was a special duties group within RAF Bomber Command. The group was formed on 11 November 1943 to consolidate the increasingly complex business of electronic warfare and countermeasures in one organisation. The g ...
at
RAF Sculthorpe
The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
, where they were used to carry electronic
countermeasure
A countermeasure is a measure or action taken to counter or offset another one. As a general concept, it implies precision and is any technological or tactical solution or system designed to prevent an undesirable outcome in the process. The fi ...
s to confuse and jam enemy radar in support of bombing missions. These Fortress III (SD) would carry an extensive array of equipment: the
Monica tail-warning receiver, the Jostle VHF jammer, airborne Grocer air-interception jammers,
Gee and
LORAN
LORAN, short for long range navigation, was a hyperbolic radio navigation system developed in the United States during World War II. It was similar to the UK's Gee system but operated at lower frequencies in order to provide an improved range u ...
for navigation, and the
H2S radar
H2S was the first airborne, ground scanning radar system. It was developed for the Royal Air Force's Bomber Command during World War II to identify targets on the ground for night and all-weather bombing. This allowed attacks outside the range ...
in the lower nose position, replacing the chin turret. They were also used as decoys during night bombing attacks. Fortress IIIs took part in various such operations until the units were disbanded in July 1945.
XB-38
The XB-38 was a modification project undertaken primarily by the
Vega
Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, an ...
division of
Lockheed on the ninth B-17E built. Its primary purpose was testing the feasibility of liquid-cooled
Allison V-1710-89 engines. It was meant as an improved version of the B-17, and a variant that could be used if the
Wright R-1820
The Wright R-1820 Cyclone 9 is an American radial engine developed by Curtiss-Wright, widely used on aircraft in the 1930s through 1950s. It was produced under license in France as the Hispano-Suiza 9V or Hispano-Wright 9V, and in the Soviet Uni ...
engine became scarce. Completing the modifications took less than a year, and the XB-38 made its first flight on 19 May 1943. While it showed a slightly higher top speed, after just a few flights it had to be grounded due to a problem with engine manifold joints leaking exhaust. Following the fixing of this problem, testing continued until the ninth flight on 16 June 1943. During this flight, the starboard (third right) inboard engine caught fire, and the crew was forced to bail out. The XB-38 was destroyed and the project was cancelled. The gains in modification were minimal and would have been disruptive to the existing Flying Fortress production. Allison engines were also considered to be more badly needed for constructing fighter aircraft.
YB-40
Prior to the introduction of the
P-51 Mustang
The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts. The Mustang was designed in April 1940 by a team headed by James ...
, a B-17
"gunship" escort variant called the YB-40 was introduced. This aircraft differed from the standard B-17 in that a second dorsal turret was installed atop the radio operator's position between the forward dorsal turret and the waist guns, where only an upward firing single or double Browning M2 had been mounted; and a single 0.50 in (12.7 mm)
machine gun
A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) a ...
at each waist station was replaced by a pair of 0.50 in (12.7 mm) guns, of basically the same twin-mount design used for the tail guns. In addition, the
bombardier’s equipment was replaced with twin 0.50 in (12.7 mm) machine guns in a remotely operated "chin" turret directly under the bombardier's position, augmenting the existing "cheek" machine guns; and the bomb bay was converted to a .50 caliber
magazine
A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...
. The YB-40 would provide a heavily armed gunship escort capable of accompanying the bombers all the way to a target and back. The aircraft was deemed a failure, however, because it could not keep up with standard B-17s once they had dropped their heavy bomb loads. It was withdrawn from service after just fourteen missions. (Twenty-six were built: one XB-40 prototype, 21 YB-40 pre-production aircraft, four TB-40 training aircraft.)
C-108 Flying Fortress
Four B-17s were converted to serve as cargo carriers and V.I.P. transports under the designation C-108 Flying Fortress. (Many more served in the same roles under the designations CB-17 and VB-17, respectively.) The first of them, designated XC-108, was a B-17E partially stripped of military equipment and outfitted with various living accommodations. It served as a V.I.P. transport for General
Douglas MacArthur
Douglas MacArthur (26 January 18805 April 1964) was an American military leader who served as General of the Army for the United States, as well as a field marshal to the Philippine Army. He had served with distinction in World War I, was C ...
. A similar conversion was made on a B-17F, which was redesignated YC-108. The third plane, designated XC-108A, was made to test the feasibility of converting obsolete bombers to cargo aircraft. B-17E 41-2595 was chosen for the conversion. Based in
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
, it ferried supplies over the
Himalaya
The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 100 ...
to the base for the
B-29 Superfortress
The Boeing B-29 Superfortress is an American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the B-17 Fl ...
in
Chengdu
Chengdu (, ; Simplified Chinese characters, simplified Chinese: 成都; pinyin: ''Chéngdū''; Sichuanese dialects, Sichuanese pronunciation: , Standard Chinese pronunciation: ), Chinese postal romanization, alternatively Romanization of Chi ...
,
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
. It proved a difficult plane to maintain, due to lack of spare parts for the Cyclone engines, and was sent back to the United States, where it was based in Bangor, Maine, and flew a cargo route to Scotland until the end of the war. It was sold to a local dealer for scrap, but the airframe survived, and is currently being restored in Illinois. The final one was built under the designation XC-108B, and was used as a tanker to transport fuel from India to Chengdu.
F-9 Flying Fortress
![Boeing F-9](https://upload.wikimedia.org/wikipedia/commons/7/73/Boeing_F-9.jpg)
Several B-17s were converted to long-range photographic
reconnaissance aircraft
A reconnaissance aircraft (colloquially, a spy plane) is a military aircraft designed or adapted to perform aerial reconnaissance with roles including collection of imagery intelligence (including using photography), signals intelligence, as ...
, designated F-9 Flying Fortress. (The ''F-'' is for 'foto' and is not be confused with the post-1948 use of ''F-'' for 'fighter'.)
The first F-9 aircraft were sixteen
B-17Fs, with bombing equipment replaced by photographic equipment. Some of the defensive armament was kept. An uncertain number more were converted to a similar configuration to the F-9, but differed in minor details of their cameras, and received the designation F-9A. Some of these, along with more B-17Fs, received further camera alterations and became the F-9B. The last variant designation was the F-9C, which was given to ten
B-17G, converted in a similar fashion to the previous aircraft. Those surviving in 1948 were initially redesignated RB-17G (''R'' indicating 'reconnaissance').
*FB-17: Post-war redesignation of all F-9 photo-reconnaissance aircraft.
BQ-7 Aphrodite
Late in World War II, at least 25 B-17s were fitted with radio controls as BQ-7 drones for
Operation Aphrodite
Aphrodite and Anvil were the World War II code names of United States Army Air Forces and United States Navy operations to use Boeing B-17 Flying Fortress and Consolidated PB4Y bombers as precision-guided munitions against bunkers and other har ...
. Loaded with of
Torpex
Torpex is a secondary explosive, 50% more powerful than TNT by mass. Torpex comprises 42% RDX, 40% TNT and 18% powdered aluminium. It was used in the Second World War from late 1942, at which time some used the names Torpex and RDX interchange ...
high explosive and enough fuel for , they were to be used to attack Nazi
U-boat
U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role ...
pens,
V-1 flying bomb
The V-1 flying bomb (german: Vergeltungswaffe 1 "Vengeance Weapon 1") was an early cruise missile. Its official Ministry of Aviation (Nazi Germany), Reich Aviation Ministry () designation was Fi 103. It was also known to the Allies as the buz ...
sites, and bomb-resistant
fortification
A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''facere'' ...
s.
The BQ-7s would be taken up to by two volunteers before transferring control to another B-17 and bailing out while still over England. The controlling B-17 would follow the BQ-7, aim to at the target and set its controls for a collision course, before itself returning. The normal cockpit lost its roof and the fairing behind it was removed.
Because the remote-control hardware was inadequate, Operation Aphrodite was riddled with problems. Between August 1944 and January 1945, 15 BQ-7s were launched against Germany, but none hit their targets, and several crew were killed, many in parachuting accidents. One BQ-7 left a crater in Britain and another circled an English port out of control. The program was cancelled in early 1945.
PB-1 and PB-1W
![Boeing PB-1W in flight](https://upload.wikimedia.org/wikipedia/commons/c/c7/Boeing_PB-1W_in_flight.jpg)
The U.S. Navy (USN) received 48 B-17s towards the end of World War II, renamed PB-1 and used for maritime patrol missions. Post-war, the USN acquired 31 more B-17Gs, renamed PB-1W, and fitted with AN/APS-20 radar for Airborne Early Warning equipment and procedure development.
The Naval Air Material Center's
Naval Aircraft Modification Unit
Naval Air Warfare Center Warminster was a U.S. Navy military installation located in Warminster, Pennsylvania and Ivyland, Pennsylvania. For most of its existence (1949–1993), the base was known as the Naval Air Development Center (NADC) Wa ...
(NAMU) at
Johnsville, Pennsylvania modified the B-17s to PB-1W specification by sealing up the bomb bay doors and installing 300 gallon drop tanks on each wing, in addition to the "Tokyo Tanks" mounted in the outer wings, holding a total of 3,400 gallons of fuel, giving the PB-1W an endurance of 22+ hours. Initially PB-1W's retained the natural metal finish with a protective wax coat, but later the PB-1Ws were painted gloss
Navy Blue
Navy blue is a very dark shade of the color blue.
Navy blue got its name from the dark blue (contrasted with naval white) worn by officers in the Royal Navy since 1748 and subsequently adopted by other navies around the world. When this color n ...
overall.
The scanner for the one-megawatt
AN/APS-20
The AN/APS-20 was an airborne early warning, anti-submarine, maritime surveillance and weather radar developed in the United States in the 1940s. Entering service in 1945, it served for nearly half a century, finally being retired in 1991. Initi ...
Seasearch S-band Radio Detection and Ranging (RADAR), manufactured by
Hazeltine Corporation
Hazeltine Corporation was a defense electronics company which is now part of BAE Systems Inc.
History 1924–1986
The company was founded in 1924 by investors to exploit the Neutrodyne patent of Dr. Louis Alan Hazeltine. Headquartered in Gre ...
/
General Electric
General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
, was ventrally mounted in a bulbous housing below the redundant bomb bay, with the RADAR relay transmitter,
Identification friend or foe (IFF),
Radio Direction Finder
Direction finding (DF), or radio direction finding (RDF), isin accordance with International Telecommunication Union (ITU)defined as radio location that uses the reception of radio waves to determine the direction in which a radio station ...
(RDF),
Instrument Landing System
In aviation, the instrument landing system (ILS) is a precision radio navigation system that provides short-range guidance to aircraft to allow them to approach a runway at night or in bad weather. In its original form, it allows an aircraft to ...
(ILS), and
LOng RAnge Navigation (LORAN) also being installed during conversion.
The conversion introduced the following changes:
* Chin turret removed.
*
Norden bombsight
The Norden Mk. XV, known as the Norden M series in U.S. Army service, is a bombsight that was used by the United States Army Air Forces (USAAF) and the United States Navy during World War II, and the United States Air Force in the Korean and t ...
removed.
* Bombardier's station retained as a lookout post, while on ASW or airborne search and rescue (SAR) missions.
* Top forward turret removed.
* Cockpit armor removed.
* 300 U.S. gallon drop tanks fitted under the outer wings.
* Extra fuel tanks in the outer wings ("Tokyo Tanks").
*
AN/APS-20
The AN/APS-20 was an airborne early warning, anti-submarine, maritime surveillance and weather radar developed in the United States in the 1940s. Entering service in 1945, it served for nearly half a century, finally being retired in 1991. Initi ...
Seasearch S-band Radio Detection and Ranging (RADAR), with transmitter in the fuselage and aerial in a bulbous di-electric fairing under the former bomb-bay.
* Modernized Identification, Friend or Foe (IFF).
* Radio Direction Finder (RDF).
* Instrument Landing System (ILS).
* LOng RAnge Navigation (LORAN).
* 2 RADAR consoles facing aft in the former bomb-bay
* Radio operator's seat turned to face outboard.
* Waist gun positions and ball turret removed.
* Bench seats fitted for observers at the waist positions.
* Floating smoke markers carried.
* A latrine and a galley were fitted amidships.
* Tail guns and armor removed.
* Provision for spares and/or cargo to be carried in the tail section.
The crew for USN PB-1Ws consisted of six officers (Pilot in Command, Second in Command, Navigator, CIC Officer, and two RADAR Operators/Controllers) and five enlisted men (Plane Captain (now referred to as Crew Chief), 2nd Mechanic, Electronics Technician, and two Radio Operators).
First delivered to Patrol Bomber Squadron 101 (VPB-101) in the spring of 1946, the Navy was eventually to have twenty-two, out of thirty-one post-war B-17s, fully upgraded to PB-1W standard. Late in 1946, VPB-101 would move to
NAS Quonset Point
Quonset Point Air National Guard Station is the home base of the Rhode Island Air National Guard 143d Airlift Wing. Naval Air Station (NAS) Quonset Point was a United States Naval Base in Quonset Point, Rhode Island that was deactivated in 1974. ...
,
Rhode Island
Rhode Island (, like ''road'') is a U.S. state, state in the New England region of the Northeastern United States. It is the List of U.S. states by area, smallest U.S. state by area and the List of states and territories of the United States ...
, and be redesignated
Airborne Early Warning Development Squadron Four
Airborne or Airborn may refer to:
Arts, entertainment, and media
Films
* Airborne (1962 film), ''Airborne'' (1962 film), a 1962 American film directed by James Landis
* Airborne (1993 film), ''Airborne'' (1993 film), a comedy–drama film
* '' ...
(VX-4).
SB-17G and PB-1G
From 1943 to 1948, as part of
Dumbo missions, 12 B-17Gs were converted to SB-17G equipped with an airborne lifeboat and ASV radar for USAAF air-sea rescue duties. The US Coast Guard flew 17 similar aircraft as PB-1Gs.
PB-1Gs
See also
* List of surviving Boeing B-17 Flying Fortresses
The Boeing B-17 Flying Fortress is an American four-engine heavy bomber used by the United States Army Air Forces and other Allied air forces during World War II. Forty-five planes survive in complete form, including 38 in the United States. Few ...
* List of bomber aircraft
The following is a list of bomber airplanes and does not include bomber airships, organized by era and manufacturer. A bomber is a military aircraft designed to attack ground or sea targets.
, -
, , AEG G.I , , Germany , , , , Heavy bomber ...
* List of military aircraft of the United States
Lists of military aircraft of the United States cover current and former aircraft of the United States Armed Forces.
By designation
* List of United States Air Force aircraft designations (1919–1962)
* List of United States Navy aircraft desig ...
Notes
References
Bibliography
* Baugher,
Boeing B-17 Fortress
1999, American Military Aircraft
*
*
accessed on January 12, 2005
*
*
Model 299 Crash
Army press release
Intercepting the Rex
Y1B-17
Y1B-17A
B-17B
B-17C
B-17D
B-17D "The Swoose"
B-17F
B-17G
B-17E
XB-38
XB-40
* Freeman, Roger. ''The Mighty Eighth War Manual'' (1991) pp. 148–153.
* Bishop, Cliff T. ''Fortresses of the Big Triangle First'' (1986) p. 51,
* Bowers, Peter M. ''Boeing Aircraft Since 1916''. London: Putnam, 1989. .
* Hess, William N. ''Big Bombers of WWII''. Ann Arbor, Michigan: Lowe & B. Hould, 1998. .
* Hess, William N. and Jim Winchester. "Boeing B-17 Flying Fortress: Queen of the Skies" ''Wings Of Fame''. Volume 6, 1997, pp. 38–103. London: Aerospace Publishing. . .
*Hickey, Lawrence J. (with Birdsall, Steve; Jonas, Madison D.; Rogers, Edwards M.; and Tagaya, Osamu). ''Ken’s Men Against the Empire: The Illustrated History of the 43rd Bombardment Group During World War II'' (Volume I: Prewar to October 1943, The B-17 Era). International Historical Research Associates, 2016. .
* Jablonski, Edward. ''Flying Fortress''. New York: Doubleday, 1965. .
* Johnson, Frederick A. ''Boeing B-17 Flying Fortress'' (Warbird Tech Series, Volume 7). Stillwater, Minnesota: Voyageur Press, 2001. .
*Listemann, Phil H. ''Allied Wings No. 7 Boeing Fortress Mk. I''. www.raf-in-combat.com, 2009. First edition. .
* Lloyd, Alwyn T. ''B-17 Flying Fortress in Detail and Scale''. Fallbrook, California: Aero Publishers, 1986. .
* O'Leary, Michael. ''Boeing B-17 Flying Fortress'' (Osprey Production Line to Frontline 2). Botley, Oxford, United Kingdom: Osprey Publishing, 1999. .
* Andrade, John M. . ''U.S Military Aircraft Designations and Serials since 1909''. Leicester: Midland Counties Publications, First edition 1979. .
* Swanborough, Gordon and Peter M. Bowers. ''United States Navy Aircraft since 1911''. London: Putnam, Second edition 1976. .
* Swanborough, F. G. and Peter M. Bowers. ''United States Military aircraft since 1909''. London: Putnam, 1963
External links
USAF Museum
* ttp://www.lonesentry.com/blog/bendix-chin-turret.html Lone Sentry's page on the B-17's Bendix Chin Turret
{{DEFAULTSORT:B-17 Flying Fortress Variants
Variants
Variant may refer to:
In arts and entertainment
* ''Variant'' (magazine), a former British cultural magazine
* Variant cover, an issue of comic books with varying cover art
* ''Variant'' (novel), a novel by Robison Wells
* " The Variant", 2021 e ...
Lists of aircraft variants