|A Boeing B-50D|
|National origin||United States|
|First flight||25 June 1947|
|Primary user||United States Air Force|
|Developed from||Boeing B-29 Superfortress|
|Developed into||Boeing C-97 Stratofreighter|
The Boeing B-50 Superfortress is an American strategic bomber. A post–World War II revision of the Boeing B-29 Superfortress, it was fitted with more powerful Pratt & Whitney R-4360 radial engines, stronger structure, a taller tail fin, and other improvements. It was the last piston-engined bomber built by Boeing for the United States Air Force, and was further refined into Boeing's final such design, the B-54. Not as well known as its direct predecessor, the B-50 was in USAF service for nearly 20 years.
World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries. The major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 50 to 85 million fatalities, most of whom were civilians in the Soviet Union and China. It included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, and the only use of nuclear weapons in war.
The Boeing B-29 Superfortress is a four-engine propeller-driven heavy bomber designed by Boeing, which was flown primarily by the United States during World War II and the Korean War. It was one of the largest aircraft operational during World War II and featured state-of-the-art technology. Including design and production, at over $3 billion it was the most expensive weapons project in the war, exceeding the $1.9 billion cost of the Manhattan Project—using the value of dollars in 1945. Innovations introduced included a pressurized cabin, dual-wheeled, tricycle landing gear, and an analog computer-controlled fire-control system directing four remote machine gun turrets that could be operated by one gunner and a fire-control officer. A manned tail gun installation was semi-remote. The name "Superfortress" continued the pattern Boeing started with its well-known predecessor, the B-17 Flying Fortress. Designed for the high-altitude strategic bombing, the B-29 also excelled in low-altitude night incendiary bombing. One of the B-29's final roles during World War II was carrying out the atomic bomb attacks on Hiroshima and Nagasaki.
The Pratt & Whitney R-4360 Wasp Major is an American 28-cylinder four-row radial piston aircraft engine designed and built during World War II, and the largest-displacement aviation piston engine to be mass-produced in the United States. It was the last of the Pratt & Whitney Wasp family, and the culmination of its maker's piston engine technology, but the war was over before it could power airplanes into combat. It did, however, power many of the last generation of large piston-engined aircraft before turbojets, and equivalent horsepower turboprops, supplanted it. Its main rival was the Wright R-3350 Duplex-Cyclone.
After its primary service with SAC ended, B-50 airframes were modified into aerial tankers for Tactical Air Command (KB-50) and as weather reconnaissance aircraft (WB-50) for the Air Weather Service. Both the tanker and hurricane hunter versions were retired in March 1965 due to metal fatigue and corrosion found in the wreckage of KB-50J, 48-065, which crashed on 14 October 1964.
Strategic Air Command (SAC) was both a United States Department of Defense (DoD) Specified Command and a United States Air Force (USAF) Major Command (MAJCOM), responsible for Cold War command and control of two of the three components of the U.S. military's strategic nuclear strike forces, the so-called "nuclear triad," with SAC having control of land-based strategic bomber aircraft and intercontinental ballistic missiles or ICBMs.
Tactical Air Command (TAC) is an inactive United States Air Force organization. It was a Major Command of the United States Air Force, established on 21 March 1946 and headquartered at Langley Air Force Base, Virginia. It was inactivated on 1 June 1992 and its personnel and equipment absorbed by Air Combat Command (ACC).
In materials science, fatigue is the weakening of a material caused by repeatedly applied loads. It is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The nominal maximum stress values that cause such damage may be much less than the strength of the material typically quoted as the ultimate tensile stress limit, or the yield stress limit.
Development of an improved B-29 started in 1944, with the desire to replace the unreliable Wright R-3350 Duplex-Cyclone engines with the more powerful four-row, 28-cylinder Pratt & Whitney R-4360 Wasp Major radial engine, America's largest-ever displacement aircraft piston engine in large-scale production. 3,000- horsepower (2,200 kW ) R-4360-33s replacing the 2,200-horsepower (1,600 kW) R-3350s. The modified aircraft, designated XB-44 Superfortress, first flew in May 1945. The planned Wasp-Major powered bomber, the B-29D, was to incorporate considerable changes in addition to the engine installation tested in the XB-44. The use of a new alloy of aluminum, 75-S rather than the existing 24ST, gave a wing that was both stronger and lighter, while the undercarriage was strengthened to allow the aircraft to operate at weights of up to 40,000 pounds (18,000 kg) greater than the B-29. A larger vertical fin and rudder (which could fold to allow the aircraft to fit into existing hangars) and enlarged flaps were provided to deal with the increased engine power and weight, respectively. Armament was similar to that of the B-29, with two bomb bays carrying 20,000 pounds (9,100 kg) of bombs, and a further 8,000 pounds (3,600 kg) externally. Defensive armament was 13 × 13 mm (.50 in) machine guns (or 12 machine guns and one 20 mm (0.8 in) cannon) in five turrets.A B-29A-5-BN (serial number 42-93845) was modified by Pratt & Whitney as a testbed for the installation of the R-4360 in the B-29, with four
The Wright R-3350 Duplex-Cyclone is a twin-row, supercharged, air-cooled, radial aircraft engine with 18 cylinders displacing nearly 55 L. Power ranged from 2,200 to over 3,700 hp, depending on the model. Developed before World War II, the R-3350's design required a long time to mature before finally being used to power the Boeing B-29 Superfortress. After the war, the engine had matured sufficiently to become a major civilian airliner design, notably in its turbo-compound forms, and was used in the Lockheed L-1049 Super Constellation airliners into the 1990s. The engine is now commonly used on Hawker Sea Fury and Grumman F8F Bearcat Unlimited Class Racers at the Reno Air Races.
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 called a "star engine" in some languages. The radial configuration was commonly used for aircraft engines before gas turbine engines became predominant.
In the United States, all military aircraft display a serial number to identify individual aircraft. These numbers are located on the aircraft tail, so they are sometimes referred to unofficially as "tail numbers". On the Northrop Grumman B-2 Spirit bomber, lacking a tail, the number appears on the nose gear door. Individual agencies have each evolved their own system of serial number identification. Aircraft serials are part of the Aircraft Visual Identification System, which also includes the aircraft's tail code and Modex.
First flying in May 1945, the sole XB-44 proved 50–60 mph (80–100 km/h) faster than the standard B-29, although existing sources do not indicate how much of this increased speed was due to differing aircraft weight due to deleted armament or increased power due to the R-4360-33 engines.
An order for 200 B-29Ds was placed in July 1945, but the ending of World War II in August 1945 prompted mass cancellations of outstanding orders for military equipment, with over 5,000 B-29s canceled in September 1945.In December that year, B-29D orders were cut from 200 to 60, while at the same time the designation of the aircraft was changed to B-50.
Officially, the aircraft's new designation was justified by the changes incorporated into the revised aircraft, but according to Peter M. Bowers, a long-time Boeing employee and aircraft designer, and a well-known authority on Boeing aircraft, "the re-designation was an outright military ruse to win appropriations for the procurement of an airplane that by its B-29D designation appeared to be merely a later version of an existing model that was being canceled wholesale, with many existing examples being put into dead storage."
Peter M. Bowers was a journalist specializing in the field of aviation.
The first production B-50A (there were no prototypes, as the aircraft's engines and new tail had already been tested) made its maiden flight on 25 June 1947, with a further 78 B-50As following.The last airframe of the initial order was held back for modification to the prototype YB-50C, a planned version to be powered by R-4360-43 turbo-compound engines. It was to have a longer fuselage, allowing the two small bomb bays of the B-29 and the B-50A to be replaced by a single large bomb bay, more suited to carrying large nuclear weapons. It would also have longer span wings, which required additional outrigger wheels to stabilize the aircraft on the ground. Orders for 43 B-54s, the planned production version of the YB-50C, were placed in 1948, but the program was unpopular with Curtis LeMay, commander of Strategic Air Command (SAC), as being inferior to the Convair B-36 Peacemaker and having little capacity for further improvement, while requiring an expensive redevelopment of air bases owing to the type's undercarriage. The B-54 program was therefore canceled in April 1949, work on the YB-50C being stopped prior to it being completed.
While the B-54 was canceled, production of less elaborate developments continued as a stopgap until jet bombers like the Boeing B-47 and B-52 could enter service. Forty-five B-50Bs, fitted with lightweight fuel tanks and capable of operating at higher weights, were built, followed by 222 B-50Ds, capable of carrying underwing fuel tanks and distinguished by a one-piece plastic nose dome.To give the Superfortress the range to reach the Soviet Union, B-50s were fitted to be refueled in flight. Most (but not all) of the B-50As were fitted with the early "looped hose" refueling system, developed by the British company Flight Refuelling Limited, in which the receiving aircraft would use a grapple to catch a line trailed by the tanker aircraft (normally a Boeing KB-29) before hauling over the fuel line to allow transfer of fuel to begin. While this system worked, it was clumsy, and Boeing designed the alternative Flying Boom method to refuel SAC's bombers, with most B-50Ds being fitted with receptacles for Flying Boom refueling.
Revisions to the B-50 (from its predecessor B-29) would boost top speed to just under 400 miles per hour (640 km/h). Changes included:
The C-97 military transport was, in its 1944 prototype, essentially a large upper fuselage tube attached to a B-29 lower fuselage and wings, with an inverted figure-eight cross-section. In its production version it incorporated the key elements of the B-50 platform including, after the first 10 in production, the enlarged tailfin of the B-50. The B-29 and B-50 were phased out with introduction of the jet-powered B-47 Stratojet. The B-50 was nicknamed "Andy Gump", because the redesigned engine nacelles reminded aircrew of the chinless newspaper comic character popular at the time.
Boeing built 370 of the various B-50 models and variants between 1947 and 1953, the tanker and weather reconnaissance versions remaining in service until 1965.
The first B-50As were delivered in June 1948 to the Strategic Air Command's 43d Bombardment Wing, based at Davis–Monthan Air Force Base, Arizona. The 2d Bombardment Wing at Chatham Air Force Base, Georgia also received B-50As; the 93d Bombardment Wing at Castle Air Force Base, California and the 509th Bombardment Wing at Walker Air Force Base, New Mexico received B-50Ds in 1949. The fifth and last SAC wing to receive B-50Ds was the 97th Bombardment Wing at Biggs Air Force Base, Texas in December 1950.
The mission of these wings was to be nuclear-capable and, in wartime, be able to deliver the atomic bomb on enemy targets if ordered by the president.
The 301st Bombardment Wing at MacDill Air Force Base, Florida received some B-50As reassigned from Davis–Monthan in early 1951, but used them for non-operational training pending the delivery of B-47A Stratojets in June 1951. The B-50 was built as an interim strategic bomber to be replaced by the B-47 Stratojet, but delays to the Stratojet forced the B-50 to soldier on until well into the 1950s.
A strategic reconnaissance version of the B-50B, the RB-50 was developed in 1949 to replace the aging RB-29s used by SAC in its intelligence gathering operations against the Soviet Union. Three different configurations were produced, which were later redesignated RB-50E, RB-50F, and RG-50G respectively. The RB-50E was earmarked for photographic reconnaissance and observation missions; The RB-50F resembled the RB-50E but carried the SHORAN radar navigation system designed to conduct mapping, charting, and geodetic surveys, and the mission of the RB-50G was electronic reconnaissance. These aircraft were operated primarily by the 55th Strategic Reconnaissance Wing. RB-50Es were also operated by the 91st Strategic Reconnaissance Wing as a replacement for RB-29 photographic reconnaissance aircraft flown over North Korea during the Korean War.
The vast northern borders of the Soviet Union were wide open in many places during the early Cold War years with little defensive radar coverage, and limited detection capability. RB-50 aircraft of the 55th SRW flew many sorties along the periphery, and where necessary into the interior. Initially, there was little opposition from the Soviet forces as radar coverage was limited and, if the overflying aircraft were detected, the World War II era Soviet fighters could not intercept the RB-50s at their high altitude.
The deployment of the MiG-15 interceptor in the early 1950s made these flights exceedingly hazardous, with several being shot down by Soviet air defenses and the wreckage being examined by intelligence personnel. RB-50 missions over Soviet territory ended by 1954, replaced by RB-47 Stratojet intelligence aircraft that could fly higher near supersonic speed.
The Boeing B-47 Stratojet was manufactured in large numbers beginning in 1953 and eventually replaced the B-50Ds in SAC service; the last being retired in 1955. With its retirement from the nuclear-bomber mission, many B-50 airframes were converted to aerial refueling tankers.
The B-50, with more powerful engines than the KB-29s in use by Tactical Air Command, was much more suitable to refuel tactical jet fighter aircraft, such as the F-100 Super Sabre. As tankers, KB-50s would feature extensively reinforced outer wing panels, the necessary equipment to air refuel simultaneously three fighter-type aircraft by the probe and drogue method, and removal of defensive armament.
The first KB-50 flew in December 1955 and was accepted by the Air Force in January 1956. The tankers steadily entered the operational inventory of Tactical Air Command (TAC) supplanting TACs KB-29s. By the end of 1957, all of the command's aerial refuling squadrons had their full complement of KB-50s. KB-50s, and later KB-50Js with two General Electric J47 jet engines were used by TAC, and also by USAFE and PACAF overseas as aerial tankers. Some were deployed to Thailand and flew refueling missions over Indochina in the early years of the Vietnam War until being retired in March 1965 due to metal fatigue and corrosion.
In addition to the aerial tanker conversion, the Air Weather Service by 1955 had worn out the WB-29s used for hurricane hunting and other weather reconnaissance missions. Thirty-six former SAC B-50Ds were stripped of their armament and equipped for long-range weather reconnaissance missions. The WB-50 could fly higher and faster and longer than the WB-29. However, between 1956 and 1960 it experienced 13 major operational accidents, six of them involving the loss of the entire crew, and 66 crew member fatalities. After the weather reconnaissance fleet was grounded in May 1960 because of fuel leaks, plans were set in motion in 1962 to modify Boeing B-47 Stratojets being phased out of SAC to replace it in the role. The WB-50 had an important role during the Cuban Missile Crisis, when it monitored the weather around Cuba to plan photo-reconnaissance flights. The WB-50 was finally retired in 1965 due to metal fatigue and corrosion.
From the 370 produced only five B-50 aircraft survive today, :
AF Ser. No. 46-0010 Lucky Lady II – The first plane to fly around the world nonstop, between February 26 and March 2, 1949. Was refueled four times in air by KB-29 tanker planes of the 43rd Air Refuelling Squadron, over the Azores, Saudi Arabia, the Philippines and Hawaii. The circumnavigation took 94 hours and 1 minute, and covered 37,743 km (23,452 miles) at an average speed of 398 km/h (249 mph). Lucky Lady II was disassembled after a serious accident and its forward fuselage is stored outside at Planes of Fame Air Museum in Chino, California.
AF Ser. No. 49-0310 – National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio.
AF Ser. No. 49-0351 Flight Of The Phoenix – Castle Air Museum at the former Castle Air Force Base in Atwater, California. This was the last B-50 to be flown, being delivered to MASDC at Davis–Monthan Air Force Base, Arizona, on 6 October 1965. It was put on display at the Castle Air Museum in 1980.
AF Ser No. 49-0372 – Pima Air & Space Museum adjacent to Davis-Monthan Air Force Base in Tucson, Arizona.
AF Ser. No. 49-0389 – Air Mobility Command Museum in Dover, Delaware. Formerly an outdoor display at MacDill Memorial Park at MacDill Air Force Base in Tampa, Florida. In 2018, 49–0389 was dismantled and moved a thousand miles to the Air Mobility Command Museum in Dover, Delaware, where the air frame is being repaired before reassembly.
Data from Encyclopedia of U.S. Air Force Aircraft and Missile Systems: Volume II: Post-World War II Bombers, 1945–1973
Aircraft of comparable role, configuration and era
The Boeing B-47 Stratojet is a retired American long-range, six-engined, turbojet-powered strategic bomber designed to fly at high subsonic speed and at high altitude to avoid enemy interceptor aircraft. The B-47's primary mission was as a nuclear bomber capable of striking the Soviet Union. With its engines carried in nacelles under the swept wing, the B-47 was a major innovation in post-World War II combat jet design, and contributed to the development of modern jet airliners.
The Convair B-36 "Peacemaker" is a strategic bomber 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 wingspan of any combat aircraft ever built, at 230 ft (70.1 m). The B-36 was the first bomber capable of delivering any of the nuclear weapons in the U.S. arsenal from inside its four bomb bays without aircraft modifications. With a range of 10,000 mi (16,000 km) and a maximum payload of 87,200 lb (39,600 kg), the B-36 was capable of intercontinental flight without refuelling.
The North American B-45 Tornado was the United States Air Force's (USAF) first operational jet bomber, and the first multiengine jet bomber in the world to be refueled in midair. The B-45 was an important part of the United States's nuclear deterrent for several years in the early 1950s, but was soon superseded by the Boeing B-47 Stratojet. B-45s and RB-45s served in the United States Air Force's Strategic Air Command from 1950 until 1959.
The Boeing B-29 Superfortress was produced in a large number of experimental and production models.
The Boeing B-54 was an American strategic bomber designed by Boeing for use by the United States Air Force. Derived from the YB-50C Superfortress, construction of the prototype was canceled before completion, and the aircraft was never flown.
The Boeing KB-29 was a modified Boeing B-29 Superfortress for air refueling needs by the USAF. Two primary versions were developed and produced: KB-29M and KB-29P.
The 58th Reconnaissance Squadron is an inactive United States Air Force squadron. Its last was assigned to the 9th Weather Reconnaissance Wing at Kirtland Air Force Base, New Mexico, where it was inactivated in 1974.
The 358th Fighter Squadron is part of the 495th Fighter Group at Whiteman Air Force Base, Missouri. The squadron was reactivated there in 2015. The squadron was formerly part of the 355th Operations Group at Davis-Monthan Air Force Base, Arizona, operating the Fairchild Republic A-10 Thunderbolt II aircraft conducting close air support missions, until its 2014 inactivation.
The 38th Reconnaissance Squadron is part of the 55th Wing at Offutt Air Force Base, Nebraska. It operates the Boeing RC-135 aircraft conducting reconnaissance missions.
The 91st Air Refueling Squadron is part of the 6th Air Mobility Wing at MacDill Air Force Base, Florida. It operates the Boeing KC-135R Stratotanker aircraft conducting air refueling missions.
The 810th Strategic Aerospace Division is an inactive United States Air Force organization. Its last assignment was with Strategic Air Command (SAC), assigned to Fifteenth Air Force at Minot Air Force Base, North Dakota, where it was inactivated on 30 June 1971.
The 801st Air Division is an inactive United States Air Force organization. It was assigned to Strategic Air Command (SAC)'s Eighth Air Force at Lockbourne Air Force Base, Ohio, where it was inactivated on 15 March 1965.
The 57th Weather Reconnaissance Squadron is an inactive United States Air Force squadron. Its last assignment was with the 9th Weather Reconnaissance Wing at Hickam Air Force Base, Hawaii, where it was inactivated on 10 November 1969.
The 421st Air Refueling Squadron is an inactive United States Air Force unit. It was last assigned to the 41st Air Division at Yokota Air Base, Japan, where it was inactivated on 18 February 1965.
The 427th Air Refueling Squadron is an inactive United States Air Force unit. It was last assigned to the 4505th Air Refueling Wing at Langley Air Force Base, Virginia, where it was inactivated on 1 April 1963.
The 429th Air Refueling Squadron is an inactive United States Air Force unit. It was last assigned to the 4505th Air Refueling Wing at Langley Air Force Base, Virginia, where it was inactivated on 8 October 1963.
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