The Boeing B-47 Stratojet (Boeing company designation Model 450) is a retired American long-

range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...

, six-engined,

turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...

-powered

strategic bomber A strategic bomber is a medium- to long-range penetration bomber aircraft designed to drop large amounts of air-to-ground weaponry onto a distant target for the purposes of debilitating the enemy's capacity to wage war. Unlike tactical bombers, ...

designed to fly at high subsonic speed and at high altitude to avoid enemy

interceptor aircraft An interceptor aircraft, or simply interceptor, is a type of fighter aircraft designed specifically for the defensive interception role against an attacking enemy aircraft, particularly bombers and reconnaissance aircraft. Aircraft that are cap ...

. The primary mission of the B-47 was as a nuclear bomber capable of striking targets within the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...

. Development of the B-47 can be traced back to a requirement expressed 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 ...

(USAAF) in 1943 for a reconnaissance bomber that harnessed newly developed

jet propulsion Jet propulsion is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law, the moving body is propelled in the opposite direction to the jet. Reaction engines operating o ...

. Another key innovation adopted during the development process was the

swept wing A swept wing is a wing that angles either backward or occasionally forward from its root rather than in a straight sideways direction. Swept wings have been flown since the pioneer days of aviation. Wing sweep at high speeds was first investigate ...

, drawing upon captured German research. With its engines carried in

nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...

s underneath the wing, the B-47 represented a major innovation in post-

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 ...

combat jet design, and contributed to the development of modern

jet airliner A jet airliner or jetliner is an airliner powered by jet engines (passenger jet aircraft). Airliners usually have two or four jet engines; three-engined designs were popular in the 1970s but are less common today. Airliners are commonly cl ...

s. Suitably impressed, in April 1946, the USAAF ordered two prototypes, designated "XB-47"; on 17 December 1947, the first prototype performed its

maiden flight The maiden flight, also known as first flight, of an aircraft is the first occasion on which it leaves the ground under its own power. The same term is also used for the first launch of rockets. The maiden flight of a new aircraft type is alwa ...

. Facing off competition such as the North American XB-45,

Convair XB-46 The Convair XB-46 was a single example of an experimental medium jet bomber which was developed in the mid-1940s but which never saw production or active duty. It competed with similar designs, the North American XB-45 and Martin XB-48, all of ...

and

Martin XB-48 The Martin XB-48 was an American medium jet bomber developed in the mid-1940s. It competed with the Boeing B-47 Stratojet, which proved to be a superior design, and was largely considered as a backup plan in case the B-47 ran into development p ...

, a formal contract for 10 B-47A bombers was signed on 3 September 1948. This would be soon followed by much larger contracts. During 1951, the B-47 entered operational service with the

United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...

Strategic Air Command Strategic Air Command (SAC) was both a United States Department of Defense Specified Command and a United States Air Force (USAF) Major Command responsible for command and control of the strategic bomber and intercontinental ballistic missile ...

(SAC), becoming a mainstay of its bomber strength by the late 1950s. Over 2,000 were manufactured to meet the Air Force's demands, driven by the tensions of the

Cold War The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because the ...

. The B-47 was in service as a strategic bomber until 1965, at which point it had largely been supplanted by more capable aircraft, such as the

Boeing B-52 Stratofortress 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 B-47 was also adapted to perform a number of other roles and functions, including

photographic reconnaissance Imagery intelligence (IMINT), pronounced as either as ''Im-Int'' or ''I-Mint'', is an intelligence gathering discipline wherein imagery is analyzed (or "exploited") to identify information of intelligence value. Imagery used for defense intel ...

electronic intelligence Signals intelligence (SIGINT) is intelligence-gathering by interception of ''signals'', whether communications between people (communications intelligence—abbreviated to COMINT) or from electronic signals not directly used in communication ( ...

, and weather reconnaissance. While never seeing combat as a bomber, reconnaissance RB-47s would occasionally come under fire near or within Soviet air space. The type remained in service as a

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 ...

until 1969. A few served as flying testbeds up until 1977.

Development

Origins

The B-47 arose from an informal 1943 requirement for a

jet-powered Jet propulsion is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law, the moving body is propelled in the opposite direction to the jet. Reaction engines operating o ...

reconnaissance bomber, drawn up by the

(USAAF) to prompt manufacturers to start research into jet bombers. Boeing was among several companies to respond to the request; one of its designs, the Model 424, was basically a scaled-down version of the

piston-engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common featu ...

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 ...

equipped with four jet engines.Peacock 1989, p. 31.Gunston and Gilchrist 1993, pp. 38–39. In 1944, this initial concept evolved into a formal request-for-proposal to design a new bomber with a maximum speed of , a cruise speed of , a range of , and a service ceiling of .Knaack 1988, p. 101.Gunston and Gilchrist 1993, p. 39. In December 1944,

North American Aviation North American Aviation (NAA) was a major American aerospace manufacturer that designed and built several notable aircraft and spacecraft. Its products included: the T-6 Texan trainer, the P-51 Mustang fighter, the B-25 Mitchell bomber, the F ...

Convair Convair, previously Consolidated Vultee, was an American aircraft manufacturing company that later expanded into rockets and spacecraft. The company was formed in 1943 by the merger of Consolidated Aircraft and Vultee Aircraft. In 1953, it ...

Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...

and the

Glenn Martin Company The Glenn L. Martin Company—also known as The Martin Company from 1957-1961—was an American aircraft and aerospace manufacturing company founded by aviation pioneer Glenn L. Martin, and operated between 1917-1961. The Martin Company produc ...

submitted proposals for the new long-range jet bomber. Wind tunnel testing had shown that the drag from the engine installation of the Model 424 was too high, so Boeing's entry was a revised design, the Model 432, with the four engines buried in the forward fuselage.Peacock 1989, p. 33. The USAAF awarded study contracts to all four companies, requiring that North American and Convair concentrate on four-engined designs (to become B-45 and XB-46), while Boeing and Martin were to build six-engined aircraft (the B-47 and XB-48). The powerplant was to be General Electric's new TG-180 turbojet engine.

Swept wings

In May 1945, the von Kármán mission of the Army Air Forces inspected the secret German aeronautics laboratory near

Braunschweig Braunschweig () or Brunswick ( , from Low German ''Brunswiek'' , Braunschweig dialect: ''Bronswiek'') is a city in Lower Saxony, Germany, north of the Harz Mountains at the farthest navigable point of the river Oker, which connects it to the Nor ...

. Von Kármán's team included the chief of the technical staff at Boeing,

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 ...

. He had heard about the controversial swept-wing theory of R. T. Jones at Langley, but seeing German models of swept-wing aircraft and extensive supersonic wind-tunnel data, the concept was decisively confirmed. He wired his home office: "Stop the bomber design" and changed the wing design.Gunston and Gilchrist 1993, pp. 39–40. Analysis by Boeing engineer Vic Ganzer suggested an optimum sweepback angle of about 35 degrees. Boeing's aeronautical engineers modified the Model 432 with swept wings and

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, r ...

to produce the "Model 448", which was presented to the USAAF in September 1945. It retained the four TG-180 jet engines in its forward fuselage, with two more TG-180s in the rear fuselage. The flush-mounted air intakes for the rear engines were inadequate while the USAAF considered the engine installation within the fuselage to be a fire hazard.Knaack 1988, p. 102.Gunston and Gilchrist 1993, p. 40. The engines were moved to streamlined pylon-mounted pods under the wings, leading to the next iteration, the ''Model 450'', which featured two TG-180s in a twin pod mounted on a pylon about a third of the way outboard on each wing, plus another engine at each wingtip. The Army Air Force liked this new configuration, so Boeing's engineers refined it, moving the outer engines further inboard to about of the

wingspan The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the other wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingspan of ...

. The thin wings provided no space for tricycle main gear to retract so it would have needed a considerable bulge in the fuselage aft of the bomb bay for lateral stability. The only way to get a bomb-bay long enough for an A-bomb was to use a "bicycle landing gear", the two main gear assemblies arranged in a tandem configuration and outrigger struts fitted to the inboard engine pods. As the landing gear arrangement made

rotation Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional ...

impossible, it was designed so that the aircraft rested on the ground at the proper angle for takeoff.Bowers 1989, p. 383.Gunston and Gilchrist 1993, p. 42. Pleased with the refined Model 450 design, in April 1946, the USAAF ordered two prototypes, to be designated "XB-47".Knaack 1988, pp. 102–103. Assembly began in June 1947. The first XB-47 was rolled out on 12 September 1947, a few days before the USAAF became a separate service, the

(USAF), on 18 September 1947. According to aviation authors Bill Gunston and Peter Gilchrist, Boeing subjected the first prototype to "one of the most comprehensive ground-test programmes ever undertaken".

Flight test phase

The XB-47 prototype flew its first flight on 17 December 1947 (the anniversary of the Wright Brothers' first four flights on 17 December 1903), with test pilots Robert Robbins and Scott Osler at the controls. It lasted 27 minutes, flying from

Boeing Field Boeing Field, officially King County International Airport , is a public airport owned and operated by King County, five miles south of downtown Seattle, Washington. The airport is sometimes referred to as KCIA (King County International Airpo ...

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 ...

to Moses Lake Airfield in central

Washington state Washington (), officially the State of Washington, is a state in the Pacific Northwest region of the Western United States. Named for George Washington—the first U.S. president—the state was formed from the western part of the Washington ...

.Yenne 2002, p. 158.Peacock 1989, p. 34. While not experiencing major problems, the emergency hot wire system was needed to raise the flaps and the engine fire warning indicators falsely illuminated. Robbins stated that it had good flight characteristics.Natola 2002, pp. 17–24. Robbins had been skeptical about the XB-47, saying that before his first flight he had prayed, "Oh God, please help me through the next two hours." Robbins soon realized that he had an extraordinary aircraft.

Chuck Yeager Brigadier General Charles Elwood Yeager ( , February 13, 1923December 7, 2020) was a United States Air Force officer, flying ace, and record-setting test pilot who in October 1947 became the first pilot in history confirmed to have exceeded the ...

also flew the XB-47, noting it was so aerodynamically clean that he had difficulty landing on the Edwards lakebed.Yeager 1985, pp. 177–178. In February 1949, Russ Schleeh and Joe Howell "broke all coast-to-coast speed records" flying from

Moses Lake Air Force Base Larson Air Force Base is a former United States Air Force base located five miles (8 km) northwest of the central business district (CBD) of Moses Lake, in Grant County, Washington. After its closure in 1966, the airport facility became G ...

Andrews Air Force Base Andrews Air Force Base (Andrews AFB, AAFB) is the airfield portion of Joint Base Andrews, which is under the jurisdiction of the United States Air Force. In 2009, Andrews Air Force Base merged with Naval Air Facility Washington to form Joint B ...

, averaging .Natola 2002, pp. 34–36. During an early test flight, the canopy came off at high speed, killing pilot Scott Osler; the aircraft was safely landed by the copilot.Boyne, Walter J. "Flying the B-47: An inside look at the USAF's first jet bomber".''Flight Journal'', April 2002. Retrieved 31 March 2010. The accident resulted in a canopy redesign and the hiring of pilot

Tex Johnston Alvin Melvin "Tex" Johnston (August 18, 1914 – October 29, 1998) was an American jet-age test pilot for Bell Aircraft and the Boeing Company. Early life Johnston was born August 18, 1914, in Admire, Kansas, to farmers Alva and Ella Johnst ...

as chief test pilot. The second XB-47 (46-066) prototype first flew on 21 July 1948 and, following its delivery to the USAF in December of that year, served as a flying test bed until 1954. Its final destination was

Chanute AFB Chanute Air Force Base is a decommissioned United States Air Force facility, located in Champaign County, Illinois, south of and adjacent to Rantoul, Illinois, about south of Chicago. Its primary mission throughout its existence was Air Force t ...

where it was used as a maintenance and familiarization aircraft. The second prototype was equipped with more powerful General Electric J47-GE-3 turbojets with of static thrust each.Yenne 2002, p. 165. The J47 or "TG-190" was a redesigned version of the TG-180/J35. The first prototype was later retrofitted with these engines. Flight testing of the prototypes was careful and methodical since the design was new in so many ways. They initially suffered from "

Dutch roll Dutch roll is a type of aircraft motion consisting of an out-of-phase combination of "tail-wagging" (yaw) and rocking from side to side (roll). This yaw-roll coupling is one of the basic flight dynamic modes (others include phugoid, short per ...

", an instability that caused it to weave in widening "S" turns, remedied by the addition of a "

yaw damper A yaw damper (sometimes referred to as a stability augmentation system) is a system used to reduce (or damp) the undesirable tendencies of an aircraft to oscillate in a repetitive rolling and yawing motion, a phenomenon known as the Dutch roll. ...

" control system to automatically deflect the

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 ...

to damp out the weaving motion. Wind tunnel tests had shown it would pitch up at maximum speed due to wing stall on the outboard section of the wing. This was confirmed during flight tests so small vanes called "

vortex generator A vortex generator (VG) is an aerodynamic device, consisting of a small vane usually attached to a lifting surface (or airfoil, such as an aircraft wing) or a rotor blade of a wind turbine.airflow separation. Both XB-47 prototypes were test flown at Edwards AFB; the first XB-47 (46-065) was disassembled and scrapped in 1954, making the second prototype (46-066) the sole surviving XB-47. Upon retirement, XB-47 (46-066) was restored and placed on display at the

Octave Chanute Aerospace Museum The Octave Chanute Aerospace Museum, the largest aviation museum in Illinois, occupied part of the grounds of the decommissioned Chanute Air Force Base in Rantoul, Illinois. It and the base were named for Octave Chanute, railroad engineer and a ...

Rantoul, Illinois Rantoul is a village in Champaign County, Illinois, United States. The population was 12,371 at the 2020 census. History The community was named after Robert Rantoul, Jr., a U.S. representative from Massachusetts, and a director of the Illino ...

, remaining there until the museum announced its closure due to financial difficulties in April 2015. In late 2015, the Flight Test Historical Foundation began fundraising to purchase XB-47 (46-066) for relocation to the

Flight Test Museum Flight or flying is the process by which an object moves through a space without contacting any planetary surface, either within an atmosphere (i.e. air flight or aviation) or through the vacuum of outer space (i.e. spaceflight). This can be a ...

at Edwards AFB. The purchase was completed in August 2016 and on 21 September 2016 the aircraft arrived at Edwards AFB for reassembly, restoration and eventual display at the Flight Test Museum.

X-model competitions

By mid-1948, the USAF's bomber competition had already been through one iteration, pitting the North American XB-45 against the Convair XB-46. The North American design won that round of the competition. As an interim measure, the USAF decided to put the North American bomber into production on a limited basis as the B-45 Tornado. The expectation was that B-45 production would be terminated if either of the remaining two designs in the competition, the Boeing XB-47 and the Martin XB-48, proved superior. It is sometimes claimed that the final production decision was made as a result of Boeing president Bill Allen inviting USAF General K.B. Wolfe, in charge of bomber production, for a ride in the XB-47.Yenne 2002, p. 160. A formal contract for 10 aircraft was signed on 3 September 1948.Knaack 1988, p. 107.Gunston and Gilchrist 1993, pp. 43–44.

Production

The total number of B-47s built was 2,042.

Design

Overview

The XB-47, which looked nothing like contemporary bombers, was described by Boyne as a "sleek, beautiful outcome that was highly advanced". The 35-degree

s were shoulder-mounted, the inboard turbojet engines mounted in twin pods, at about a third of the span, and the outboard engines singly near the wing tip. This arrangement reduced the bending moment at the wing roots, saving structural weight. The engines' mass acted as counter- flutter weights.Fraser November 1949, p. 141. The wing airfoil was identified by Boeing as the BAC 145, also known as the NACA 64A(.225)12 mod airfoil. Wing flexibility was a concern, flexing as much as at the tip;Gunston and Gilchrist 1993, pp. 40–41. major effort was expended to ensure that flight control could be maintained as the wing moved up and down; these worries proved to be mostly unfounded. Its maximum speed was limited to

IAS IAS may refer to: Science * Institute for Advanced Study, in Princeton, New Jersey, United States * Image Analysis & Stereology, the official journal of the International Society for Stereology & Image Analysis. * Iowa Archeological Society, Uni ...

to avoid

control reversal Control reversal is an adverse effect on the controllability of aircraft. The flight controls reverse themselves in a way that is not intuitive, so pilots may not be aware of the situation and therefore provide the wrong inputs; in order to roll to ...

, where aileron deflections would cause the wings to twist and produce a roll in the opposite direction to that desired by the pilot. The wings were fitted with a set of

Fowler flap A flap is a high-lift device used to reduce the stalling speed of an aircraft wing at a given weight. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used to reduce the take-off distance and the landi ...

s that extended well behind the wing to enhance lift at slow speeds.Natola 2002, pp. 19, 47, 54, 207, 213. The

flight control surface Aircraft flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude. Development of an effective set of flight control surfaces was a critical advance in the development of aircraft. Ea ...

s were powered, augmenting the pilot's inputs and reducing the exertion required to overcome the forces involved.Fraser November 1949, pp. 139–140. The XB-47 was designed to carry a crew of three in a

pressurized {{Wiktionary Pressurization or pressurisation is the application of pressure in a given situation or environment. Industrial Industrial equipment is often maintained at pressures above or below atmospheric. Atmospheric This is the process by ...

forward compartment: a pilot and copilot, in

tandem Tandem, or in tandem, is an arrangement in which a team of machines, animals or people are lined up one behind another, all facing in the same direction. The original use of the term in English was in ''tandem harness'', which is used for two ...

, in a long fighter-style

bubble canopy A bubble canopy is an aircraft canopy constructed without bracing, for the purpose of providing a wider unobstructed field of view to the pilot, often providing 360° all-round visibility. The designs of bubble canopies can drastically vary; so ...

, and a

navigator A navigator is the person on board a ship or aircraft responsible for its navigation.Grierson, MikeAviation History—Demise of the Flight Navigator FrancoFlyers.org website, October 14, 2008. Retrieved August 31, 2014. The navigator's primar ...

/ bombardier in a compartment in the nose. The

copilot In aviation, the first officer (FO), also called co-pilot, is the pilot who is second-in-command of the aircraft to the captain, who is the legal commander. In the event of incapacitation of the captain, the first officer will assume command of ...

doubled as

tail gunner A tail gunner or rear gunner is a crewman on a military aircraft who functions as a gunner defending against enemy fighter or interceptor attacks from the rear, or "tail", of the plane. The tail gunner operates a flexible machine gun or aut ...

(using a remotely controlled,

radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...

-directed tail gun), and the navigator as bombardier.Gunston and Gilchrist 1993, p. 43. The bubble canopy, which provided a high level of visibility to the pilots, pitched up and slid backward; as the cockpit was high off the ground, the crew entered via a door and ladder on the underside of the nose.Fraser November 1949, pp. 140–141. The extreme front of the nose was initially glazed for visual navigation and bomb sighting, but this requirement was soon deleted together with the glazing. Most production versions had a metal nose with no windows. A K-series

bombsight A bombsight is a device used by military aircraft to drop bombs accurately. Bombsights, a feature of combat aircraft since World War I, were first found on purpose-designed bomber aircraft and then moved to fighter-bombers and modern tactical ...

provided integrated

radar navigation Radar navigation is the utilization of marine and aviation radar systems for vessel and aircraft navigation. When a craft is within radar range of land or special radar aids to navigation, the navigator can take distances and angular bearings ...

and visual navigation, the optical portion extending through the nose in a small dome. For greater comfort, both

heater Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HV ...

s and

refrigeration The term refrigeration refers to the process of removing heat from an enclosed space or substance for the purpose of lowering the temperature.International Dictionary of Refrigeration, http://dictionary.iifiir.org/search.phpASHRAE Terminology, ht ...

systems were present in the cockpit to manage the cockpit environment. There was little vibration compared to prior bombers powered by

reciprocating engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common featu ...

Engines and performance

During the late 1940s, the bomber was hailed as the fastest of its class in the world.Fraser November 1949, p. 139. The first prototypes were fitted with General Electric J35 turbojets, the production version of the TG-180, with of thrust. Early jet engines did not develop good thrust at low speeds, so to assist take off when heavily loaded, the B-47 had provisions for fitting solid-fuel rocket-assisted takeoff (RATO) rockets, each generating roughly of static thrust.Fraser November 1949, p. 142. Early aircraft had mounts for nine RATO units built into each side of the rear fuselage, arranged in three rows of three bottles. Most of the space within the upper fuselage was taken up by

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, the wing having been deemed unsuitable for storing fuel.Gunston and Gilchrist 1993, pp. 41–43. The performance of the Model 450 was projected to be so good that the bomber would be as fast as fighters then on the drawing board;Gunston and Gilchrist 1993, p. 38. thus the only defensive armament was to be a tail turret with two .50 in (12.7 mm) AN/M2 Browning machine guns, which would in principle be directed by an automatic

fire-control system A fire-control system (FCS) is a number of components working together, usually a gun data computer, a director, and radar, which is designed to assist a ranged weapon system to target, track, and hit a target. It performs the same task as a ...

.Gunston and Gilchrist 1993, pp. 42–43. The two XB-47s were neither fitted with combat equipment nor tail turrets as they were engineering and flight test aircraft only. The total bombload capacity was to be . Production aircraft were to be equipped with modern electronics for navigation, bombing, countermeasures and turret fire control. Navigation was more difficult than on earlier aircraft due to the higher speed involved.Fraser November 1949, p. 140. One problem with the aircraft was that at higher altitudes, where the pure turbojet engines could produce good fuel economy, the wing was very compromised. At the top of the B-47's envelope, about , it was in " coffin corner".Natola 2002, p. 184. That means that at this level, which produced the most range at most weights due to fuel consumption, there was an envelope of between maximum mach and stall speed. For the B-47 to cross the Atlantic Ocean, it had to be flown this high. Due to its rudimentary autopilot, the pilot had to leave it turned off and spend up to eight hours diligently monitoring the airspeed and adjusting the throttles to avoid going into a stall. For perspective, a modern Boeing 757 has over of difference at even a very heavy weight at . Fuel capacity was enormous, at , more than triple the on the B-29 Superfortress, and meant that maintaining fuel trim to ensure a stable

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 ...

was a critical copilot duty.

Drogue chutes

The aircraft was so aerodynamically clean that rapid descent ("penetration") from high

cruise A cruise is any travel on a cruise ship. Cruise or Cruises may also refer to: Tourism * Booze cruise * Music cruise * River cruise Aeronautics and aircraft * Cruise (aeronautics), a distinct stage of an aircraft's flight * Aviasouz Cruise, a R ...

altitude to the landing pattern required dragging the deployed rear landing gear. The relatively high

wing loading In aerodynamics, wing loading is the total mass of an aircraft or flying animal divided by the area of its wing. The stalling speed of an aircraft in straight, level flight is partly determined by its wing loading. An aircraft or animal with a ...

(weight/wing area) required a high landing speed of . To shorten the landing roll, USAF test pilot Major Guy Townsend promoted the addition of a German-invented "ribbon" drag chute (

thrust reverser Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's thrust for it to act against the forward travel of the aircraft, providing deceleration. Thrust reverser systems are featured on many jet aircraft ...

s had not then been developed). For the same reason, the B-47 was the first mass-produced aircraft to be equipped with an anti-skid braking system. A related problem was that the aircraft's engines would have to be throttled down on landing approach. Since it could take as long as 20 seconds to throttle them back up to full power, the bomber could not easily do a " touch and go" momentary landing. A 16-foot "approach chute" (

drogue parachute A drogue parachute is a parachute designed for deployment from a rapidly-moving object. It can be used for various purposes, such as to decrease speed, to provide control and stability, or as a pilot parachute to deploy a larger parachute. ...

) provided

aerodynamic drag In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fl ...

so that the aircraft could be flown at approach speeds with the engines throttled at ready-to-spool-up medium power. On the ground, the pilots used the 32-foot "brake chute". The brake chute could be deployed to stop the aircraft from "porpoising", or bouncing, after a hard landing on the front nose gear.Natola 2002, pp. 58–59, 151–153, 206, 211, 219. Training typically included an hour of dragging the approach chute around the landing pattern for multiple practice landings.

Operational history

Early years

The

USAF The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Sign ...

operated multiple B-47 models (B-47s, EB-47s, RB-47s and YRB-47s) from 1951 through 1965. Upon entry to service, its performance was closer to that of contemporary fighters than SAC's extant

B-36 Peacemaker The Convair B-36 "Peacemaker" is a strategic bomber that was built by Convair and operated by the United States Air Force (USAF) from 1949 to 1959. The B-36 is the largest mass-produced piston-engined aircraft ever built. It had the longest wing ...

bomber, setting multiple records with ease. It handled well in flight, the controls having a fighter-like light touch. The large bubble canopy enhanced the flying crew's vision and gave a fighter-like feel, but also caused internal temperature variations for the crew. The three-man crew consisted of the commander, copilot and a navigator/bombardier or a crew chief.Natola 2002, pp. 44–45, 136, 156. In 1953 the B-47 became operational. It was sluggish on takeoff and too fast on landings, an unpleasant combination. If landed at the wrong angle, the B-47 would "porpoise", bouncing fore-and-aft. If the pilot did not lift off for another go-around, instability would quickly cause it to skid onto one wing and cartwheel. Because the wings and surfaces flexed in flight, low-altitude speed restrictions were necessary to ensure effective flight control. The B-47 was regarded as a maintenance "hog". General reliability was good, the only major issuing relating to the

avionics Avionics (a blend word, blend of ''aviation'' and ''electronics'') are the Electronics, electronic systems used on aircraft. Avionic systems include communications, Air navigation, navigation, the display and management of multiple systems, ...

, typical of the

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...

technology used and the placement of equipment outside the pressurized crew compartment. Much work was done to improve avionics reliability, but avionics remained troublesome throughout the B-47's operational life. Starting in 1950, several models of the B-47 included a fuel tank

inerting system An inerting system decreases the probability of combustion of flammable materials stored in a confined space. The most common such system is a fuel tank containing a combustible liquid, such as gasoline, diesel fuel, aviation fuel, jet fuel, or ro ...

, in which

dry ice Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimates directly from the solid state to the gas state. It is used primarily a ...

was sublimed into

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

vapor while the fuel pumps operated or while the in-flight refueling system was in use. The carbon dioxide was pumped into both the fuel tanks and the fuel system to ensure low oxygen levels throughout. It was implemented largely to reduce the probability of an explosion from

static electricity Static electricity is an imbalance of electric charges within or on the surface of a material or between materials. The charge remains until it is able to move away by means of an electric current or electrical discharge. Static electricity is na ...

discharges. Strategic Air Command B-47 Stratojets - 020903-o-9999r-001

Initial mission profiles included the loft bombing of nuclear weapons. As the training for this imposes repeated high stress on the aircraft, the airframe lifetime would have been severely limited by

metal fatigue In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts o ...

, and this maneuver was eliminated. Improved training led to a good safety record, and few crews felt the aircraft was unsafe or too demanding, but apparently there were some aircrews who had little affection for the B-47. Crew workload was high, having only three crew members to operate it.Fraser November 1949, pp. 141–142. Boeing's

B-52 Stratofortress 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 ...

, in contrast, generally had six crewmen, five officers and one enlisted, with more internal cabin space.

Prime years

An XB-47 was flown in the 1951

Operation Greenhouse Operation Greenhouse was the fifth American nuclear test series, the second conducted in 1951 and the first to test principles that would lead to developing thermonuclear weapons (''hydrogen bombs''). Conducted at the new Pacific Proving Grou ...

nuclear weapons test Nuclear weapons tests are experiments carried out to determine nuclear weapons' effectiveness, yield, and explosive capability. Testing nuclear weapons offers practical information about how the weapons function, how detonations are affected by ...

. This was followed by a B-47B being flown in the 1952 test,

Operation Ivy Operation Ivy was the eighth series of American nuclear tests, coming after '' Tumbler-Snapper'' and before '' Upshot–Knothole''. The two explosions were staged in late 1952 at Enewetak Atoll in the Pacific Proving Ground in the Marshall Is ...

and the 1954 test, Operation Castle. A B-47E was then flown in the 1956 test, Operation Redwing.Natola 2002, pp. 98–109. "Reflex" missions proved the long-endurance (eighteen hours) and long range capability of the B-47 and aircrews. These were "simulated strike missions against the then Soviet enemy".Natola 2002, pp. 110, 163, 194, 199. Three B-47s flew cross country from March Air Force Base to the Philadelphia International Airport as participants in the 1955 Labor Day National Air Races, race. In the 1956 event, three B-47s participated in the G.E. Trophy race for Jet Bombers, flying from Kindley Field, Bermuda, to Oklahoma City. One of these set a course speed record of .Natola 2002, pp. 126–131. By 1956, the USAF had 28 wings of B-47 bombers and five wings of RB-47 reconnaissance aircraft. The B-47 was the first line of America's strategic nuclear deterrent, often operating from forward bases in the UK, Morocco, Spain, Alaska, Greenland and Guam. B-47s were often set up on "one-third" alert, with a third of operational aircraft available sitting on hardstands or an alert ramp adjacent to the runway, loaded with fuel and nuclear weapons, crews on standby, ready to attack the Soviet Union, USSR at short notice. Crews were trained to perform "Minimum Interval Take Offs (MITO)",Natola 2002, pp. 36, 44–45, 162, 193. one bomber following another into the air at intervals of as little as 15 seconds to launch as fast as possible. MITO could be hazardous, as the bombers left wingtip vortices and general turbulence behind them; the first generation turbojet engines, fitted with Water injection (engines), water-injection systems, also created dense black smoke.Natola 2002, p. 180. The B-47 was the backbone of SAC into 1959, when the B-52 began to assume nuclear alert duties and the number of B-47 bomber wings started to be reduced. B-47 production ceased in 1957, though modifications and rebuilds continued. Operational practice for B-47 bomber operations during this time went from high-altitude bombing to low-altitude strike, which was judged more likely to penetrate Soviet defenses. Crews were trained in "pop-up" attacks, coming in at low level at and then climbing abruptly near the target before releasing a nuclear weapon.Natola 2002, pp. 131–134, 212.

Later years

Stress and fatigue incurred in low-altitude operations led to a number of wing failures and crashes, and an extensive refit program was begun in 1958 to strengthen the wing mountings. The program was known as "Milk Bottle", named after the big connecting pins that were replaced in the wing roots. One of the more notable mishaps involving a B-47 occurred on 5 February 1958 near Savannah, Georgia, in the so-called 1958 Tybee Island B-47 crash. A B-47 based at Homestead AFB, Florida, was engaged in a simulated combat exercise against an North American F-86 Sabre, F-86 fighter. As was the practice at the time, the B-47 was carrying a single Mark 15 nuclear bomb, without its core. During this exercise, the two aircraft collided. The F-86 crashed after the pilot ejected, while the B-47 suffered substantial damage, including loss of power in one outboard engine. After three unsuccessful landing attempts at Hunter Air Force Base, the bomber pilot had to "safe" soft drop the Mark 15 weapon off the coast of Savannah, Georgia near Tybee Island, after which the B-47 landed safely. Despite an extensive nine-month search, the unarmed bomb was never found. In 1963, the Kennedy administration offered 24 B-47E bombers as an interim English Electric Canberra, Canberra Mk 20 replacement for the Royal Australian Air Force (RAAF), pending delivery of the much delayed General Dynamics F-111C, F-111C aircraft. Three B-47E aircraft flew to Australia for demonstration purposes, but RAAF declined the B-47E as technically outdated and too resource-intensive. During 1963, final phaseout of B-47 bomber wings began, the last were out of SAC service by 1966. The last USAF operational aircraft, WB-47Es assigned to the Air Weather Service, were withdrawn from use in September 1969. Shortly before, a B-47E, USAF Serial Number 53-2280, was used as a testbed for a newly developed fly-by-wire system. The United States Navy, U.S. Navy kept specialized EB-47E test aircraft from USAF inventory in occasional use to support the ''Fleet Electronic Warfare Systems Group (FEWSG)'' until December 1977, being replaced by government owned/contractor operated (GOCO) Boeing NC-135, NKC-135 modified Stratotankers also loaned from the USAF. B47 DF-ST-88-01015

The final recorded flight of a B-47 was on 17 June 1986, when a B-47E was restored to flightworthy condition for a one-time ferry flight. This aircraft was flown from Naval Air Weapons Station China Lake, California, to Castle Air Force Base, California, for static display at the Castle Air Museum, where it presently resides.Natola 2002, pp. 217–219.

Reconnaissance

The only B-47s to see anything close to combat were the aerial reconnaissance variants. The first overflight of Soviet territory with a B-47B, fitted with special radar and cameras in the bomb bay, occurred on 15 October 1952, overflying Soviet airfields in Northeastern Siberia.Natola 2002, pp. 90–97. RB-47s operated from almost every airfield that gave them access to the USSR and routinely probed Soviet airspace. Occasionally, they would avoid confrontations with speed and evasion. At least five aircraft were fired upon and three were shot down. The RB-47s returned fire with their tail turrets, although it is uncertain if they scored any kills; these were the only shots fired in anger by any B-47. On 8 May 1954, after a top secret reconnaissance mission near the Kola Peninsula, a 4th Air Division / 91st Missile Wing, 91st Strategic Reconnaissance Wing RB-47E, flown by then-Capt (later Col) Harold "Hal" Austin, overflew the Soviet Union at high altitude, out of reach of Mikoyan-Gurevich MiG-15, MiG-15s. Unknown to USAF intelligence, Mikoyan-Gurevich MiG-17, MiG-17s capable of intercepting it had been stationed nearby. The RB-47E was chased by several MiG-17s, firing upon it with their guns over Soviet and Finnish airspace. While taking damage, the RB-47E escaped over Sweden to its home base at RAF Fairford, Gloucestershire. Its top speed and combat radius superiority to the fighter jets were decisive factors. The mission marked the first time a jet aircraft equipped with modern aerial photography equipment, K-17 and K-38 cameras, was used for USAF reconnaissance over the Soviet Union. The incident was kept secret by all parties.Natola 2002, pp. 85–89. Other interceptions resulted in losses. An RB-47 flying from Alaska was scouting the Kamchatka Peninsula on 17 April 1955, when it was intercepted by Soviet MiG-15s in international airspace before disappearing. Between 21 March and 10 May 1956, 16 RB-47Es and five RB-47Hs operating from Thule performed overflights the length of Siberia 156 times under Project HOMERUN. The Soviets filed a complaint with the US government, which attributed the overflights to "navigational difficulties". MiGs intercepted RB-47s on three separate occasions in late 1958: over the Black Sea on 31 October, over the Baltic on 7 November, and over the Sea of Japan on 17 November. On 1 July 1960, a PVO Strany Mikoyan-Gurevich MiG-19, MiG-19 1960 RB-47 shootdown incident, shot down an RB-47H (AF Serial No. 53-4281) in international airspace over the Barents Sea,Powers 2004, pp. 152, 159. killing four of the crew while two were captured by the Soviets and released in 1961. The co-pilot reported that the MiG-19 jammed his MD-4 FCS (that aimed the tail guns), rendering it defenseless. The last known confrontation between MiGs and RB-47s occurred on 28 April 1965, when an ERB-47H was intercepted by two North Korean MiG-17s over the Sea of Japan. While hit by the MiGs, it returned to Yokota Air Base in Japan with three engines out.Natola 2002, pp. 208–211. A few operated during the Vietnam War on missions such as relaying Signals intelligence, ELINT data, but were replaced by more efficient and capable Boeing Boeing RC-135, RC-135s. The last RB-47H was retired on 29 December 1967. The final 15 RB-47s, built from December 1955, were fitted with additional equipment, including the AN/APD "side looking airborne radar" (SLAR) system, and gear to sample the air for Nuclear fallout, fallout from Nuclear testing, nuclear tests. These were given the designation RB-47K and generally used for weather reconnaissance missions, carrying a load of eight "dropsonde" weather sensors that were released at various checkpoints along the flight path. Data radioed back from the dropsondes was logged by the navigator. The RB-47Ks were in service until 1963.Gunston and Gilchrist 1993, p. 45. The type was succeeded by dedicated reconnaissance aircraft such as the Lockheed U-2.

Variants

:''Section source: Baugher.'' ; XB-47 :Two prototype aircraft, Model 450-1-1 and 450-2-2 respectively,(46-065 and 46-066); powered by six Allison J-35-GE-7 turbojet engines on early flights. The second XB-47 was powered by General Electric J-47-GE-3 engines, the first was retrofitted as such.Lloyd 2005. . ;B-47A B-47A

:The first 10 aircraft were designated B-47A and were evaluation aircraft, the first delivered in December 1950. While the XB-47s had been built at Boeing's Seattle plant, all B-47s were built at a government-owned factory in Wichita, Kansas that had previously built B-29s. Their configuration was akin to the XB-47. All were powered by J47-GE-11 turbojets, offering the same thrust as the earlier J47-GE-3, and had built-in rocket-assisted-take-off (JATO, RATO) bottles. Four were fitted with the K-2 bombing and navigation system (BNS), HD-21D autopilot, an analog computer, APS-23 radar, and a Y-4 or Y-4A bombsight. Two were fitted with the tail turret mounting two Hispano-Suiza HS.404, 20mm cannons; one of them used an Emerson A-2 fire-control system, fire control system (FCS), another a General Electric A-5 FCS. The eight other B-47As lacked defensive armament. :The B-47As were fitted with ejection seats. The pilot and copilot ejected upward, while the navigator had a downward ejection seat built by Stanley Aviation. Minimum safe ejection altitude was about 500 ft (150 m). In the 1950s, there were no suitable "dummies" to test ejection seats, thus live people were used. Several volunteers were injured testing the downward ejection seat. The first person to successfully use it was USAF Colonel Arthur M. Henderson who ejected over Choctawhatchee Bay, near Eglin Air Force Base, Florida, on 7 October 1953. Most B-47As were retired by 1952, though one performed flight tests for NACA for a few more years. ;B-47B B47B with chute

:In November 1949, prior to the B-47A's first flight, the USAF ordered 87 B-47Bs, the first operational model. The first flew on 26 April 1951. A total of 399 were built, including eight assembled by Lockheed Corporation, Lockheed and 10 assembled by Douglas Aircraft Company, Douglas using Boeing-built parts. To quickly receive B-47s in quantity, the USAF contracted both Lockheed and Douglas for additional production;Gunston and Gilchrist 1993, p. 44. Lockheed-built aircraft were designated by a "-LM (Lockheed Marietta)" suffix and Douglas-built aircraft given a "-DT (Douglas Tulsa)" suffix. Boeing production was designated by a "-BW (Boeing Wichita)" suffix, except for the Seattle-built XB-47s and B-47As, which had a "-BO" suffix. :The initial 87 B-47Bs used the same J47-GE-11 engines as the B-47A, subsequent deliveries had uprated J47-GE-23 units with thrust; early aircraft were later retrofitted. It had a built-in RATO system, as used on the B-47A, along with full combat systems. Early aircraft retained the K-2 BNS installed on some B-47As, but most featured the K-4A BNS, incorporating an AN/APS-54 warning radar and an AN/APT-5 electronic countermeasures (ECM) system. The K-4A used a nose-mounted periscopic bombsight. Ejection seats were deleted as a weight reduction measure; a windbreak panel on the main door made for a difficult escape. :The bomb bay was shorter than the B-47A's as nuclear weapons had shrunk in the interim; the B-47B could carry a larger bombload of up to . All B-47Bs had a tail turret with twin 20 mm (0.79 in) guns and the B-4 radar-guided FCS. Due to issues, this FCS was often replaced with an N-6 optical sight; the copilot could swivel his seat to face backward and sight the guns directly. A nose-mounted in-flight refueling (IFR) receptacle enabled flying boom refueling from Boeing KB-50, KB-50 and KC-97 tankers, requiring the plexiglas nose cone's replacement by a metal nose cone with four small windows, two on either side of the nose. The B-47B was also fitted with a pair of jettisonable external tanks, carried between the inboard and outboard engine assemblies, with a capacity of . Another visible change was the vertical tailplane's squared-off top instead of a rounded top. :Between 1955 and 1956, Boeing modified surviving B-47Bs from line numbers 235 to 399 to the B-47E standard under program ''High Noon''; this included fitting ejection seats. It was followed by the ''Ebb Tide'' program covering early line numbers from 1 to 234; this included 66 aircraft from the 135 to 234 batch to the same standard as the ''High Noon'' aircraft. Another 30 in the same range had additional modification as drone directors DB-47Bs, and the 1 to 134 range which had the same ''High Noon'' modification, but lacked some non-combat changes. Following these programs, they were sometimes referred to as B-47B-II. ;;YRB-47B :The USAF considered building a specialized RB-47B reconnaissance variant, but schedule slips ensured that the RB-47E was the first such variant. As an interim measure, 91 B-47B bombers were fitted with a heated pod stowed in the forward bomb bay that housed eight cameras. These were designated YRB-47Bs and were capable of daylight reconnaissance only. Once the RB-47E arrived, they returned to the bomber role. ;;TB-47B :A total of 66 of the 87 non-combat B-47Bs were re-designated TB-47B in 1953 to alleviate logistics problems due to different engines and systems. Most were used as trainers; some were modified for Air Training Command by Douglas at Tulsa under the ''Field Goal'' program, adding a fourth seat for an instructor and removing the tail turret. They were upgraded to B-47E standard in 1956 under the ''Ebb Tide'' program, joined by 41 more early build aircraft, also designated TB-47B. Used for training through the 1950s. ;;MB-47B :With the introduction of the hydrogen bomb, the USAF studied converting a few B-47Bs into MB-47B drones, essentially huge cruise missiles, under the Project Brass Ring, Brass Ring program. Due to impracticality, it was canceled on 1 April 1953. ;;YDB-47B / DB-47B :There were flight tests through the 1950s for using the B-47B as a launcher for the 31 ft (9.5 m) GAM-63 Rascal missile, and one B-47B was modified into a YDB-47B Rascal launcher. The Rascal never became operational; a total of 74 B-47Bs were modified into DB-74Bs before cancellation. ;;WB-47B :In 1956, a B-47B was converted into a WB-47B weather reconnaissance model and operated by the Military Air Transportation Service (MATS), one of a few B-47s not operated by SAC. It was used by the Air Weather Service until the mid-1960s. ;;KB-47B :In 1953, two B-47Bs were modified to test the Aerial refueling, probe-and-drogue refueling system. The tanker, fitted with Cobham plc, British-built tanker kit, was given the designation KB-47G and was known as "Maw" by flightcrews. The receiver aircraft was designated YB-47F and was known as "Paw", though other aircraft (including the Boeing B-52 Stratofortress, YB-52 prototype) were also used as refueling targets. The program was cancelled in 1954 as the KB-47G could not carry a practical fuel load. The idea of fielding B-47 tanker conversions was re-examined, but unfavorable economics meant that it was again discarded in 1957. In parallel to the KB-47, Boeing tested its aerial refueling system aboard its Dash 80, later evolving into the Boeing KC-135 Stratotanker, KC-135 Stratotanker, which had greater fuel capacity. ;;Canadair CL-52 :An unusual conversion was the Canadair CL-52: a B-47B (USAF S/N 51-2059 RCAF S/N 059X) loaned in 1956 to the Royal Canadian Air Force to test the new, powerful Orenda Iroquois turbojet (rated at dry, afterburning) for the Avro Arrow, Avro Canada CF-105 Arrow interceptor aircraft, interceptor. Canadair attached the Iroquois engine to the right side of the rear fuselage; due to the large exterior diameter of the engine, no other location was feasible. Flying the CL-52 was reportedly a nightmare. After the Arrow was canceled in early 1959, the B-47B/CL-52, which saw 35 hours of engine flight tests, was returned. Some sources claimed it was bent out of shape; it was scrapped. The CL-52 was the only B-47 to be used by any foreign service. ;YB-47C / RB-47C / B-47Z / B-56 Boeing B-56A drawing 061025-F-1234P-001

:A four-engined variant of the B-47, the YB-47C, was proposed by Boeing in 1950 to be powered by four Allison J35-A-23 turbojet engines, providing thrust each, in place of the six GE J47s. The J35 was being developed at the time, and was provisionally rated at (with afterburner) or thrust without AB. Thus 4 * 8500 = using that engine, as compared to 6 * = in the production B-47, making it lighter, simpler and more powerful.Jones 1969, . Allison J71, J71-A-5 A contract was signed in January 1950 for the rework of one B-47B. The first flight was projected for April 1951. :Due to the J35's less-than-expected performance and delays, other engines were considered, such as the proposed Allison J71, however engine problems meant that it was not feasible for the by-then redesignated B-56A. The Pratt & Whitney J57, eventually rated at thrust, was also considered, but was still in development. The Boeing B-52 Stratofortress, which was being concurrently developed, had priority for this engine. Thus, the B-56 was cancelled in December 1952 before the prototype's conversion had started. The donor fuselage intended for the XB-56 was reused as a ground instructional airframe. Boeing XB-47D propjet

;XB-47D :Starting in 1951, two XB-47Ds were modified from B-47Bs as experimental platforms, replacing each inboard two-jet pod with a Wright T49, Wright YT49-W-1 turboprop engine spinning a huge four-bladed prop.Natola 2002, pp. 38–42. Engine development issues delayed the XB-47D's first flight until 26 August 1955. Performance was comparable to a conventional B-47, and its reversible propellers shortened the landing roll, but the idea was not pursued. ;B-47E B47E in flight

:The designations B-47C and B-47D applied to variants that were never produced, thus the next production model was the definitive B-47E, first flying on 30 January 1953. Four "blocks" or "phases" were built, each incorporating refinements on the previous block; changes sometimes occurred mid-block. The B-47 incorporated the radar-controlled rear tail turret. A total of 1,341 B-47Es were produced; 691 built by Boeing, 386 built by Lockheed, and 264 built by Douglas. Most B-47Bs were rebuilt to B-47E standards and given the designation of B-47B-II, though they were often called B-47Es. :Early B-47E-Is had General Electric J47, J47-GE-25 turbojets with thrust, these were changed to J47-GE-25A engines with water-methanol injection, which increased mass flow rate, mass flow to temporarily raise thrust to and produce much black smoke when engaged. Jet-Assisted Take Off (JATO) was installed on early B-47E-Is, integrating 18 JATO bottles, but was removed due to its proximity to fuel tanks. A later JATO system used an external jettisonable "split V" or "horse collar" rack fitted under the rear fuselage, carrying 33 JATO bottles in three rows of 11 bottles;Natola 2002, pp. 31, 36–37, 191, 195. the expendable racks were dropped over specific range areas after takeoff. Early B-47Es had a lower internal fuel capacity of to save weight, which was considered acceptable due to large external tanks and mid-air refueling becoming common practice. A welcome change was the return of ejection seats. The twin .50 in guns (12.7 mm) in the tail turret were replaced with twin 20 mm (0.79 in) cannon for more firepower, backed up by an A-5 FCS in early production and an MD-4 FCS in later production. :The B-47E-II had only minor changes from later-built B-47E-Is. The B-47E-III featured an ECM suite, consisting of a radar jammer in a bulge under the fuselage plus a Chaff (radar countermeasure), chaff dispenser, as well as improved electrical alternators. The B-47E-IV was a major update, featuring stronger landing gear, airframe reinforcement, greater fuel capacity, and an uprated bombload of while the bomb bay was again shortened as nuclear weapons became more compact. Another addition was the MA-7A BNS, which included the AN/APS-64 radar, having a range of up to and could be used as a long range "identification friend or foe (IFF) transponder" interrogator to locate other B-47s or tankers, or as a high-resolution ground-targeting radar. The B-47E-IV retained the rarely-used optical bombsight. Most nose windows were deleted; only one remained on each side. ;;TEE TOWN B-47E :In 1955, 100 B-47E-Is were modified to carry two removable external pods, one mounted on either side of the bomb bay, with each pod containing four AN/ALT-6B jammers. The pods were known as "Tee Town pods" (for Topeka, Kansas, location of Forbes AFB) and so these aircraft were known as "Tee Town B-47s". All retained their bombing capability. ;;EB-47E :The Tee Town B-47Es led to a specialized ECM conversion, the EB-47E. "Phase IV" or "Blue Cradle" aircraft used a removable cradle housing 16 jammers in the bomb bay, plus radar warning receivers and chaff dispensers. The advanced "Phase V" EB-47E had a pressurized module holding 13 jammers stowed in the bomb bay controlled by two Electronic Warfare Officers (EWOs), also known as "Crows" or "Ravens".Natola 2002, pp. 146, 164–165, 182, 192, 208–211, 214. While the Phase IV jammer was "broadband", covering a wide frequency range to jam radars operating within that range, the Phase V jammer could be selectively tuned to specific radar frequencies, enabling higher jammer power on the most effective frequencies. About 40 B-47Es were converted to EB-47Es; they could not carry bombs but retained tail turrets. :B-47E ''52-0410'' and ''52-0412'' were converted to EB-47Es in the mid-1960s for the U.S. Navy's Fleet Electronic Warfare Support Group (FEWSG). Considered to be on indefinite loan, they differed from USAF EB-47Es in that some podded ECM gear was mounted on the external fuel tank pylons. Used as "electronic aggressors" to test ECM systems, they were the last B-47s in service, ''52-0410'' performed its last flight on 20 December 1977. ;;EB-47E(TT) :Three B-47Es were converted to the specialized EB-47E(TT) "Tell Two" configuration to be used for "telemetry intelligence", picking up radio signals from Soviet missile tests and space launches, being a precursor to the RC-135S Rivet Ball and Cobra Ball. It featured two ECM operators, a "Crow capsule" in the bomb bay loaded with gear, and distinctive antennas below each side of the cockpit. All three aircraft were operated out of Turkey until 1967. Crews often made up stories about their purpose, such as a "return to fighter" defensive system that made air-to-air missiles loop back and attack their own launch fighters. ;;ETB-47E :As with the B-47B, a few B-47Es were converted to trainers, with a fourth seat for an instructor, and designated ETB-47E. They replaced older TB-47Bs, serving into the early 1960s. ;;DB-47E / YDB-47E :Two B-47Es were converted to YDB-47Es to support the GAM-63 RASCAL stand-off missile program; two more B-47Es were converted to DB-47Es in preparation for the missile's introduction before it was axed and were reused as drone controller aircraft. ;;JB-47E :Several B-47Es were assigned to other specialized test duties and given the blanket designation of JB-47E. One was used in the late 1960s to test "fly by wire" control system concepts. ;;JTB-47E :Two B-47Es were also used for secret flight experiments in the early 1960s and given the designation JTB-47E, and a third modified B-47E was given the designation JRB-47E. They appear to have been test platforms for ECM systems. ;;NB-47E :A B-47E was loaned to the US Navy to test the GE General Electric TF34, TF34-2 turbofan for the Lockheed S-3 Viking. It was given the designation NB-47E and performed test flights from 1969 through 1975. ;;QB-47E :A total of 14 RB-47Es were converted to QB-47E target drones in 1959 and 1960. These aircraft were radio-controlled and included self-destruct charges, arresting gear to assist landings, and carried pods on the external tank pylons to help in scoring weapons tests. Apparently most missiles fired on them were directed for a near-miss, but the QB-47Es were nonetheless eventually whittled down to two survivors that were retired in the early 1970s. ;;RB-47E : Reconnaissance from Thule Air Base

:The B-47E was the basis for several reconnaissance models, the only B-47s to see anything resembling combat. They operated from most airfields that gave access to the USSR and often probed Soviet airspace. Boeing built 240 RB-47Es, similar to the B-47E but with a nose stretched by , giving an arguably more elegant appearance. The long nose accommodated up to 11 cameras, possibly including an O-15

camera for low-altitude work, a forward oblique camera for low-altitude work, a K-17 trimetrogon (three-angle) camera for Panorama, panoramic shots and K-36 Telephoto lens, telescopic cameras. Cameras were controlled by the "navigator-photographer". Photoflash flares were carried for night photography. While it could be refueled in flight, fuel capacity was increased to a total of . ;;WB-47E WB 47E 55 BW Stratojet HAFB

:Following the single WB-47B conversion, in the early 1960s, 34 B-47Es were converted by Lockheed into WB-47Es for weather reconnaissance to replace 44 Boeing B-50 Superfortress, WB-50D Superfortresses that had suffered several fatal crashes between 1956 and 1960. Stripped of combat gear, they were fitted with nose cameras to photograph cloud formations and a meteorological instrument pod in the bomb bay. Initially assigned to the Air Weather Service of the Military Air Transport Service (MATS), they became part of the Military Airlift Command (MAC) upon its establishment. The WB-47Es, the last B-47s in USAF service, were retired in October 1969. :The 53d Weather Reconnaissance Squadron, of the 9th Weather Reconnaissance Wing, operated WB-47Es from Hunter Air Force Base and Ramey Air Force Base. These assets were transferred to the 57th Weather Reconnaissance Squadron for Operation Arc Light, operating from Clark Air Base.Natola 2002, pp. 177–179. ;RB-47H/ERB-47H National Museum of the United States Air Force marker for the RB-47H

National Museum of the United States Air Force marker for the RB-47H

:A total of 32 RB-47H models were built for electronic intelligence (ELINT) missions, as well as three more specialized "ERB-47Hs". Featuring a distinctive blunt, rounded nose and sported blisters and pods for intelligence-gathering antennas and gear, they were designed to probe defenses and collect data on radar and communications signals. The bomb bay was replaced by a Cabin pressurization, pressurized compartment, which accommodated "Crows", or Electronic Warfare Officers (EWOs). There were three Crows on board the RB-47H and two on the ERB-47H. A distinctive bulged radome fairing replaced the bomb bay doors. They retained the tail turret and were fitted with jammers and chaff dispensers. A recognizable difference between the RB-47H and ERB-47H was the latter's distinctive antenna fairing under the rounded nose. :The first RB-47H was delivered in August 1955 to Forbes AFB, Kansas. They received a "Mod 44" or "Silver King" program in 1961 to update electronics systems and was recognizable by a large teardrop pod for ELINT antennas upon a pylon under the belly and offset to one side, as well as a pylon-style antenna under each wing beyond the outboard engine. The EWO compartment was cramped with sitting room only and had both poor noise insulation and climate control, making 12-hour missions uncomfortable and tiring. Successful ejection downward through the belly radome was impossible near the ground. Crews sat bobsled-like on the pilot compartment's floor for takeoff and landing. They then crawled encumbered with Arctic clothing and parachute to and from their compartment along an unpressurized maintenance shelf during a temporary level-off at . RB-47H with F-111 nose

:Operations were generally flown at night and classified Top Secret.Natola 2002, pp. 179–181. The final RB-47H to be retired from service, ''53-4296'', was reactivated and fitted with an F-111-style nose to test avionics for the General Dynamics F-111, General Dynamics FB-111 in the early 1970s. It was not given any special designation. It is now on display at the Air Force Armament Museum at Eglin Air Force Base, fitted with a bomber nose. ;YB-47J :A single B-47E was modified to test the MA-2 BNS for the B-52, and given the designation YB-47J. ;RB-47K :The RB-47K was a photo and weather reconnaissance variant based on the RB-47E generally used for weather reconnaissance missions, carrying eight dropsonde weather sensors that were released at various checkpoints along its flight path. Data radioed from the dropsondes was logged by the navigator. Fifteen RB-47Ks were built, the variant was in service until 1963. ;EB-47L :Between 1961 and 1963, 36 B-47Es were modified to carry a communications relay system and were designated EB-47L. Used to support US flying command post aircraft in case of a nuclear attack on the US, the EB-47Ls were only briefly in service as improved communications technologies made them redundant by 1965.

Operators

; *

* United States Navy ; * Royal Canadian Air Force – 1 B-47B loaned to Canada and converted by Canadair with the designation CL-52 to test the CF-105 Avro Arrow's Orenda engines in 1956; returned to the U.S. Air Force and scrapped (1957)

Surviving aircraft

Boeing B-47 at Mighty 8th Air Force Museum, Pooler, GA, US

Twenty-three surviving airframes exist in museum collections; all are located in the United States.

Accidents and incidents

National Museum of the United States Air Force display of McKone and Olmstead artifacts

Over the operating history of the B-47, 203 aircraft were lost in crashes, with 464 deaths. This represents approximately 10% of the total number produced. On 8 February 1954, a B-47 of the 22nd Bomber Wing, March AFB, California, crashed in Stoke Wood, a mile and a half short of the runway at RAF Upper Heyford, England, while on a training run. All three crew were killed. On 28 February 1955, a crippled B-47 crashed into a trailer park in Lake Charles, Louisiana, killing the three crewmen and two people on the ground. On 10 March 1956, four B-47s left MacDill Air Force Base in Florida for a non-stop flight to Ben Guerir Air Base in Morocco. After descending through clouds to begin their second round of aerial refueling over the Mediterranean Sea at 14,000 feet, one of the four aircraft, 1956 B-47 disappearance, serial number 52-0534, failed to make contact with the tanker; neither the aircraft, its two nuclear weapon Pit (nuclear weapon), cores, nor its personnel were ever found. On 28 March 1956, a B-47 exploded near Wichita, Kansas, with an instructor and two student pilots on board. It crashed four miles northeast of the city, killing its crew of three. The office of information services at McConnell Air Force Base said the explosion occurred after takeoff, probably at about 2,000 feet altitude. Wreckage was strewn along the countryside for several miles as the wings sheared off and the fuselage tumbled to earth. On 27 July 1956, a B-47 of the 307th Bombardment Wing crashed at RAF Lakenheath killing its crew and causing a near radioactive incident when it hit a storage igloo containing three Mark 6 nuclear bomb, MK-6 nuclear weapons. Although the bombs involved lacked their Pit (nuclear weapon), fissile cores, each carried about 8,000 pounds of high explosives for their trigger mechanism. The crash and ensuing fire did not ignite the high explosives and no detonation occurred. In November 1956, B-47E serial number 51-2421 of the 96th Bombardment Wing, flying from Altus AFB, crashed on a farm near Hobart, Oklahoma, following engine problems. Four crewmen were killed in the incident. On 9 October 1957, B-47 serial number 51-2177A, of the 447th Missile Squadron, 447th Bomb Squadron, 321st Air Expeditionary Wing, 321st Bomb Wing at Pinecastle Air Force Base suffered wing failure and crashed northwest of Orlando, Florida, and west of Winter Park, Florida, while conducting a practice demonstration for the annual Strategic Air Command Bombing Navigation and Reconnaissance Competition at Pinecastle AFB. The wing commander, Colonel Michael Norman Wright McCoy, was killed in the crash; Pinecastle AFB was later renamed McCoy Air Force Base, McCoy AFB in his honor. On 4 December 1957, a MacDill Air Force Base B-47 exploded in mid-air over Choctawhatchee Bay, Okaloosa County, Florida. Parts were scattered over a wide underwater area that varied in depth from 20 to 30 feet. Assistance from US Navy divers from the Mine Detection Laboratory, Panama City, Florida, the Underwater Demolition Team No. 21 from Little Creek, Va., the 3201st Boat Squadron, APGC, recovered most of the plane. The three crew were killed. On 5 February 1958, a B-47 was involved in a mid-air collision with an F-86 fighter over Georgia, known as 1958 Tybee Island mid-air collision.Natola 2002, pp. 77–80. On 26 February 1958, RB-47E serial number 52-0720 crashed six miles south of Lancaster, OH on approach to Lockbourne AFB, OH, hitting the ground at an angle of 50 degrees. It was determined that the aircraft attained an unusual attitude and/or high speed through disorientation, from which there was no recovery. In actuality, a wheel door had broken away and prevented the control surfaces being fully active. On 13 March 1958, two B-47s crashed on the same date in separate incidents when the lower wing skin failed at the same structural location. One exploded over southeast Tulsa, Oklahoma, killing one crewman and raining debris over at least 8 square miles, witnessed by thousands of people on the ground. Two of the three men on a training mission from McConnell Air Force Base in Wichita, Kansas, parachuted to safety. The third was trapped in the nose of the plane and died. On 10 April 1958, a B-47 from Lockbourne Air Force Base, Ohio, exploded mid-flight behind the Boeing KC-97 Stratofreighter, KC-97G tanker that was to refuel it. The KC-97 was unharmed, but the wreckage fell within a half-mile of a highway and none of the crew survived. On 15 April 1958, a B-47 from Walker Air Force Base in New Mexico, United States military aircraft serials, serial number 52–0562, crashed on takeoff at Pease Air Force Base in New Hampshire; all four crewmen were killed. On 22 November 1958, a B-47B crashed while taking off from Loring Air Force Base in Maine, killing all four crew members on board. The plane belonged to a unit at McCoy Air Force Base in Orlando, Florida. The plane was described as having veered sharply to the right while two-thirds of the way down the runway, eventually crashing 400 feet north of the runway. On 25 November 1958, a KC-135 of the 42d Air Refueling Squadron crashed on takeoff roughly in the same area as the B-47 three days before. On 4 April 1959, B-47 serial number 52-0320 crashed in the Santa Rita mountains, south of Tucson, Arizona, while attempting to land at Davis-Monthan AFB. All three crew were killed. Investigators noted that a faulty altimeter was a contributing factor. On 24 April 1959, Captain John S. Lappo, operating from Lockbourne AFB flew a B-47 with two crewmen on board under the Mackinac Bridge in Michigan. Following a Courts-martial in the United States#General court-martial, general court-martial, he was grounded for life. On 30 December 1959, a B-47B crashed at Torrejón Air Base, Spain one minute after takeoff. All four crew members were killed. On 31 March 1960, B-47E serial number 52-1414, of the 384th Bomb Wing (SAC), 545th Bombardment Squadron, Little Rock AFB, exploded inflight over Little Rock, Arkansas. Three of the four crew and two civilians on the ground were killed. On 4 January 1961, B-47 serial number 53-4244, based at Pease Air Force Base, crashed on takeoff; all four crewmen were killed. On 24 February 1961, a B-47 crashed 10 miles southwest of Hurley, Wisconsin, while on a practice bombing mission from the 40th Bomb Wing at Forbes Air Force Base, Topeka, Kansas. Its four crew were killed. An engine was found 600 yards from the point of impact, indicating it detached prior to the crash. On 2 May 1961, a B-47 crashed eight miles southwest of Hurley, Wisconsin, only a few miles from the scene of a prior B-47 crash on 24 February 1961. Two of four crew survived. Evidence showed that it was steeply diving when the crash occurred. In January 1962, a B-47 based at Plattsburgh Air Force Base on a training mission crashed into the side of Wright Peak in the Adirondack High Peaks, High Peaks in the Adirondacks of New York. All four crew were killed. It had veered about 30 miles east due to inclement weather. Wreckage can still be found at the summit, including a landing gear strut and a partial engine. On 23 July 1962, a B-47 based at Dyess Air Force Base near Abilene, Texas, departed on a training mission through Montana. After crossing into Paradise Valley (Montana), Paradise Valley, it crashed into Emigrant Peak and exploded while turning toward the northwest. All four crew were killed. On 3 August 1962, B-47 serial number 52-0526, based at Pease Air Force Base, crashed on takeoff; all three crew were killed. On 22 August 1962, B-47 serial number 52-0553, based at Davis–Monthan Air Force Base near Tucson, Arizona, crashed on a training mission shortly before midnight in the Idaho mountains south of Smiths Ferry, Idaho, Smiths Ferry; controlled flight into terrain started a Wildfire, forest fire, and all three crew were killed. On 20 February 1963, a B-47 of the 98th Bomb Wing based at Lincoln Air National Guard Base, Lincoln AFB, Nebraska, crashed in Bashaw Township, Brown County, Minnesota, Bashaw Township, approximately three miles north of the town of Comfrey, Minnesota. All four crew were killed. It had just completed a low-altitude simulated bombing run near the town of Heron Lake, Minnesota, when the sixth engine failed, causing it to crash in a field, resulting in a 25-foot deep by 50-foot wide crater. On 20 August 1963, a QB-47 veered off course on its landing approach at Eglin Air Force Base and crash landed on a road parallel to the runway. It was used for Bomarc Missile Program tests, normally operated from Eglin Air Force Base Auxiliary Field Number Three (Duke Field), approximately north of the main base. Two cars were crushed, killing two occupants and injuring a third. On 8 December 1964, B-47 serial number 52-0339, based at Pease Air Force Base, crashed in Newington, New Hampshire, shortly after takeoff; all four crewmen were killed.

Specifications (B-47E)

Notable appearances in media

References

Citations

Bibliography

* Walter J. Boyne, Boyne, Walter J.]
"Airpower Classics: B-47 Stratojet."
''Air Force Magazine'', August 2007, Air Force Association. Retrieved 4 June 2009. * Walter J. Boyne, Boyne, Walter J. "The Long Reach Of The Stratojet." ''Air Force Magazine'' Vol. 66, issue 71, December 1997. * Bowers, Peter M. "The Boeing B-47" ''Aircraft in Profile, Volume 4''. Windsor, Berkshire, UK: Profile Publications Ltd., 2nd revised and enlarged edition, 1970. . * Peter M. Bowers, Bowers, Peter M. ''Boeing Aircraft since 1916''. London: Putnam, 1989. . * Cook, William H. ''The Road to the 707: The Inside Story of Designing the 707.'' Bellevue, Washington: TYC Publishing, 1991. . * Dennison, Robert C. "Stratojet!" ''Air Combat'', July /August 1997. (Dennison is a retired USAF officer and B-47 pilot who works with the B-47 Stratojet Association.) * Fraser, Jim
"I Fly The World's Fastest Bomber."
''Popular Science'', November 1949. Vol. 155, No. 5. pp. 139–142. . * Grant, R.G. and John R. Dailey. ''Flight: 100 Years of Aviation''. Harlow, Essex, UK: DK Adult, 2007. . * Gunston, Bill. ''Bombers of the West''. London: Ian Allan Ltd., 1973, pp. 126–153. . * Gunston, Bill and Peter Gilchrist. ''Jet Bombers: From the Messerschmitt Me 262 to the Stealth B-2''. Osprey, 1993. . * Johnston, A.M. ''Tex Johnston: Jet-Age Test Pilot''. Washington D.C.: Smithsonian Institution Press, 2000. . * Jones, Lloyd S. ''U.S. Bombers, B-1 1928 to B-1 1980s''. Fallbrook, California: Aero Publishers, 1962, second edition 1974. . * Jones, Lloyd S. ''U.S. Bombers: 1928-1980s''. Fallbrook, California: Aero Publishers, Inc., 1981. . * Knaack, Marcelle Size
''Post-World War II Bombers, 1945–1973''(PDF).
Washington, D.C.: Office of Air Force History, 1988. . * Lloyd, Alwyn T. "Boeing's B-47 Stratojet". North Branch Minnesota: Specialty Press, 2005. . * Loftin, Laurence K. Jr

''NASA Scientific and Technical Information Branch'', 2004. * Natola, Mark. "Boeing B-47 Stratojet." ''Schiffer Publishing Ltd'', 2002. . * Peacock, Lindsay. "Stratojet...Progenitor of a Dynasty". ''Air Enthusiast'', Thirty-eight, January–April 1989, pp. 31–44, 63. Bromley, UK: FineScroll. ISSN 0143-5450. * Powers, Francis. "Operation Overflight: A Memoir of the U-2 Incident." ''Potomac Books Inc'', 2004. . * Tegler, Jan. ''B-47 Stratojet: Boeing's Brilliant Bomber''. New York: McGraw-Hill, 2000. . * Yeager, Chuck. "Yeager." ''Bantam Book'', 1985. . * Yenne, Bill. "Variant Briefing: Boeing B-47 Stratojet". ''International Air Power Review'', Volume Six, Autumn/Fall 2002, pp. 156–171. Norwalk, Connecticut: AIRtime Publishing. . ISSN 1473-9917.

External links

* *
National Museum fact sheet Boeing B-56E

* [https://web.archive.org/web/20121206030916/http://www.millionmonkeytheater.com/B-47.html Forgotten Jets – Boeing B-47 Stratojet series] – status of all 2,032 produced
B-47 Stratojet Association
{{Authority control Boeing military aircraft, B-47 Stratojet 1940s United States bomber aircraft, Boeing B-47 1950s United States bomber aircraft, Boeing B-56 Six-engined jet aircraft Articles containing video clips High-wing aircraft Aircraft first flown in 1947