Boeing B-52 Stratofortress
High-Altitude, Long-Range Strategic Heavy Bomber
Despite its early Cold War-era upbringing, the Boeing B-52 Stratofortress continues as the USAF heavy bomber-of-choice.
Authored By: Staff Writer | Last Edited:
The B-52 has been the preeminent American heavy bomber of the last 54 years. The massive aircraft served throughout the heightened periods of the Cold War as a nuclear deterrent, as a dedicated bomber and reconnaissance platform in the Vietnam War and as a carpet-bombing nightmare for the Iraqi Army in the 1991 Persian Gulf War. More recently, the B-52 has seen combat actions in the 2001 assault on Afghanistan (Operation Enduring Freedom) and the 2003 Invasion of Iraq (Operation Iraqi Freedom). The Stratofortress aircraft has evolved into a multi-role aircraft equally capable of dedicated bombing, strategic bombing, anti-shipping, nuclear warfare, mine-laying, close-support, reconnaissance, electronic warfare and maritime surveillance sorties. Upon its inception into the USAF inventory, the B-52 became America's first long-range, swept-wing heavy bomber and currently maintains the title of longest serving bomber in United States military history.
The Boeing firm had made a name for itself beginning with its aircraft developments throughout the interwar years following World War 1. By World War 2, the company would become a household name thanks to its development of the stellar B-17 "Flying Fortress", serving in both the Pacific and European Theaters, as well as its follow-up design - the B-29 "Superfortress" long range, high-altitude heavy bomber charged with dropping the two atomic bombs on Japan. The commercial "Stratocruiser" appeared in the post-war years as did the military B-47 "Stratojet" bomber. It was no surprise then that the designation of "Stratofortress" was selected for what would become one of the Boeing's biggest successes to date.
Origins of the B-52 stemmed from a specification issued through the forward-looking Air Material Command (AMC) on November 23rd, 1945. AMC fell under the branch of the United States Air Force at the end of World War 2 though it originally began service in 1917 as part of the US Army Signal Corps. This new specification called for a next generation long-range, intercontinental, high-altitude strategic bomber to replace the already-in-development Convair B-36 Peacemakers. In February of 1946, the Boeing Aircraft Company, Consolidated Aircraft Corporation and the Glenn L. Martin Company all jumped into the fray with their respective responses. Boeing's team devised the Model 462 as a straight-wing, multi-engine design powered by 6 x Wright T35 Typhoon turboprop engines rated at 5,500shp each. On June 5th, 1946, Model 462 was selected ahead of the pack and the legacy of the B-52 was born in the designation of XB-52. A full-scale mockup contract was then awarded.
By now, the USAAF (United States Army Air Forces) was already looking beyond the qualities of the Model 462, fearing that the aircraft was already rendered obsolete in its conventional design approach and could never reach the intended goals of the original specification - especially in terms of its range. As such, the USAAF cancelled their contract with Boeing and the Model 462 was dead.
Boeing chief engineer Ed Wells took the Model 462 and evolved a pair of smaller concepts with four turboprops each appearing in their respective 464-16 and 464-17 forms. Essentially, the 464-16 was a short-range bomber made to carry a greater bombload while the 464-17 was a long-range bomber made to carry a smaller bombload. Neither idea stuck with the USAAF as a replacement for the B-36 though interest did center on the 464-17 design. Several more concepts were developed but interest on the part of the Air Force was waning. The Model 464-29 appeared, complete with swept-back wings at 20 degrees and fitting 4 x Pratt & Whitney turboprop engines. Again, this concept failed to answer the key points of the specification which, by now, was ever-changing to include increased performance specs along with long range.
The Model 464-35 was another Boeing design team proposal fitting 4 x turboprop engines with contra-rotating propellers. Wing sweep was increased moreso than previous attempts, beginning to define the look of the Stratofortress. With in-flight refueling becoming more of a USAF operational norm, the design team now had some leeway in the overall size of their aircraft. Events in Europe in the latter part of the 1940's pushed the XB-52 project forward, rewarding the Boeing Company with a hard-earned contract for a single mock-up and at least two flyable prototypes.
Upon a visit to Wright-Patterson AFB by the Boeing design team, it was learned that the USSAF was now more interested in a jet-powered solution, seeing it as the only way to achieve the desired performance specs it required of the XB-52. In the course of a single weekend in a Dayton hotel room Ed Wells company set to work on new ideas for a Monday morning presentation. The resulting design combined elements of their Model 464-35 design with a four-engine, jet-powered medium bomber concept that had been brought along. The new aircraft became an eight-engine, Pratt & Whitney JT3 jet-powered heavy bomber with 35-degree swept wings. A small balsa wood model was constructed to further develop the idea and accompanied a detailed Model 464-49 design document of some 33 pages. The weekend effort paid off for Boeing as the USAF became greatly interested in the aircraft after Monday morning. The design was revised into the Model 464-67 accepted the new aircraft for construction as two prototypes. Despite this progress, the USAF was still looking at alternatives to their next generation bomber design including modifying B-36's (as the YB-60) and B-47's (as the B-47Z) still in development.
Thanks to the vision of General Curtis LeMay to see the XB-52 program come to fruition, USAF commander of SAC (Strategic Air Command), the XB-52 production contract finally landed in the lap of Boeing executives on February 14th, 1951. The contract called for 13 B-52A models.
The USAF still batted around the main goal for the XB-52 program however, and was now calling for a reconnaissance aircraft in the form of the RB-52 though General LeMay and SAC still saw value in a bomber/reconnaissance hybrid. Despite the disagreements, the XB-52 team forged on. The XB-52 became the first prototype constructed and this was followed by the YB-52. The YB-52 received this evaluation due to the funding coming from the Air Force's Logistics Command, a department not truly allowed to fund experimental aircraft projects such as this.
The YB-52 beat the XB-52 to flight testing on March 15th, 1952. The XB-52 was rolled out on November 29th, 1951, under the cover of night for secrecy's sake but a pneumatic system failure caused enough damage to the wing trailing edge for the aircraft to be rolled back inside for lengthy repairs. As such, the YB-52 achieved its first flight on April 15th, 1952 and did not experience any grand setbacks. The XB-52 finally made it airborne on October 2nd, 1952. Both the XB-52 and the YB-52 featured tandem seating cockpits with upward firing ejection seats.
At its core, the B-52 design sported a distinctly long and slim fuselage, nearly rectangular in shape when viewed from the front. Wings were shoulder-mounted monoplanes affixed to the forward portion of the fuselage and swept back at 35 degrees. The sag inherent in the massive size of the wing span forced both wings to slope downward towards the ends when the aircraft was at rest. This required the use of smaller support landing gears (called outriggers) outboard of the outermost engine grouping. Wings could flex an impressive 22 feet up and 10 feet down. Each wing contained four engines in two engine pairings. If an engine were to feature an uncontrollable fire, the entire pod would eventually come loose and drop off, detaching itself from the aircraft wing and in effect saving the aircraft - and "unexpected benefit" as noted by Boeing designers. The flight deck would be situated behind and above a short nose and feature windowed surfaces for views forward, above and to the sides. The cockpit itself was made up of two separate floors with the pilot and co-pilot on upper floor. The bomb bays took up most of the lower central fuselage while the undercarriage followed suit with the Boeing B-47 - consisting of four independently retracting trucks with double-wheels at the forward and middle underfuselage positions - forward and aft of the bomb bay doors. These trucks could also be steered up to 20 degrees left or right to compensate in crosswinds. The empennage was dominated by a single large vertical tail fin and conventional horizontal surfaces.
Modern B-52's (B-52H models) operate an electro-optical, forward-looking infrared (FLIR) sensor paired with high-resolution, low-light-level television in targeting and battle assessing for low- and high-level operations. Pilots can utilize night vision optics to enhance low-light flying operations while global positioning systems (GPS) allow for visual travel assistance to anywhere in the world. In-flight refueling, along with engine improvements, has considerably and consistently enhanced the range of the Stratofortress. Improvements to crew comfort, general crew safety and versatility to mount high volume internal and external loads have all benefitted in making the B-52 relevant on today's battlefield.
With its bomber origins, Stratofortress armament naturally centered exclusively on the ability to field a large quantity of various types of conventional and nuclear munitions. The H-models, for example, sport a bombload of up to 70,000lbs. Munitions can range from conventional drop bombs, precision-guided guided bombs and mine dispensing units. The Stratofortress eventually tested and was accepted to fire even more advanced munitions and guided weapons including nuclear-tipped types. External mountings of these weapons would become a part of the B-52 armament arrangement within time. Today the B-52 is cleared to use more munition types in the American inventory than any other USAF aircraft.
While original B-52's featured a 4 x 12.7mm collection of Browning M3 heavy machine guns in a rear turret, later production models switched over to a remote-controlled 1 x 20mm M61 cannon for self-defense. The tail armament was altogether removed in more modern Stratofortress forms with the onset of the missile age. However, it should noted that at least 2 Mikoyan-Gurevich MiG-21 "Fishbed" aircraft were destroyed in the Vietnam War by the tail gunner, with these aircraft kills credited to SSgt Samuel O. Turner and A1C Albert E. Moore - both kills achieved just days apart in December of 1972 from B-52D's. In B-52D models as the example, the tail gunner externally accessed the rear portion of the aircraft via an entry hatch. Once inside, he could scoot into his position, feet-first, then settle in with his headset and helmet. A seat back, initially folded, could be raised for additional relative comfort. In the revised G-models, the gunner was allocated to the main crew cabin (complete with an ejection seat fitted to the upper flight deck and facing aft with the ECM operator) and operated the tail gun via the AGS-15 Fire Control System and radar.
Modern B-52H's sport 8 x Pratt & Whitney TF33-P-3/103 series turbofans positioned in pairs with four to a wing. These engines were a performance improvement over the initial turbojet types used in earlier Stratofortresses though they did have their growing pains. Performance specifications for H-models list the maximum speed at 650 miles per hour with a combat radius of 4,480 miles while ferry range is listed at 10,145 miles. The aircraft's service ceiling is limited to roughly 50,000 feet while a rate-of-climb of 6,270 feet per minute is possible. The B-52H relies on a crew of five personnel made up of the pilot, co-pilot, navigator, Electronic Warfare Officer and the radar navigator/bombardier. Reconnaissance versions in the aircrafts history required up to eight personnel.
Despite its far-reaching history, the B-52 was actually produced in less than a dozen variants beginning with the aforementioned developmental limited production B-52A model. From the original order of 13 B-52A's, ten were later earmarked for production as B-52B models. Compared to the twin prototypes, the three B-52A's now featured the more conventional side-by-side cockpit seating arrangement in a revised forward fuselage along with the tail armament of 4 x 12.7mm Browning M3 machine guns. A distinguishing feature of A-models to B-models was the lack of a fully operational avionics suite. These aircraft were fitted with Pratt & Whitney J57-9W engines of 10,000lbf thrust each. The split-level cockpit featured seating for three on the upper deck and seating for two in the lower. The lower occupants were given downward-firing ejection seats. The tail gunner was removed from the rest of the crew and seated in his rear-facing turret station sans any type of ejection seat though the tail system could be ejected in the event of an accident. An unpressurized crawlspace was his only link to the front of the aircraft. In-flight refueling was accomplished via a boom connection above and behind the main flight deck. Other key additions included wing-mounted external fuel tanks to increase range and decrease "wing-flexing" across the span. Water injection was introduced to the J57 to assist in take-off. The two prototypes lacked the side-by-side cockpit seating arrangement and the in-flight refueling arrangement of the A-models and seating for the third upper deck crewmember (Electronic Warfare Officer - EWO). NB-52A - aka "The High and Mighty One" - was developed from the third B-52A flight test model. This aircraft (s/n 52-0003) was modified to act as the mothership in the launching of the experimental North American X-15 hot rod aircraft.
The B-52B was, in actuality, the first true Stratofortress production model and was already in development while the previous aircraft forms were being refined. They more essentially A-models with fully operational avionics suites and Pratt & Whitney J57-P-29W, J57-P-29WA or J57-P-19W series engines all rated at 10,500lbf thrust. The J57-P-19W's were differentiated by having their compressor blades made of titanium instead of steel. First flight of these aircraft was achieved in December of 1954. B-models were the first model in the series to achieve operational service on June 29th in 1955, this occurring with the 93rd Bombardment Wing (themselves achieving operational status on March 12th, 1956) of the United States Air Force and coming in the form of an RB-52B reconnaissance model. The defensive tail armament remained the 4 x 12.7mm machine gun mounts for a time though some 16 B-52B and 18 RB-52B models were fitted with a more potent 2 x M24A-1 20mm cannon array and an different fire control system. When this proved ineffective, the final production B-52B's reverted back to the 4 x 12.7mm formation.
The B-52B was tested with atomic weapons on May 21st, 1956 - dropping a four megaton Mark 15 "Zombie" hydrogen bomb on the Bikini Atoll. Fifty B-52B models were produced in whole, with 27 of these being modified as special RB-52's. RB-52's represented reconnaissance-capable B-52B production models. These aircraft sported a crew of eight personnel and were fitted to accept specialized reconnaissance equipment in the form of a 300lb pod in their bomb bays. The NB-52B (aka "Balls 8") was another single example Stratofortress (this being a B-model) again modified to carry the experimental North American X-15 for research with NASA. NB-52B went on to become the longest flying B-52B airframe, ultimately seeing retirement in 2004.
B-model combat load performance netted a top speed of 628 miles per hour with a service ceiling of 47,300 feet. The operational radius was equal to 3,576 miles.
The B-52C first flew on March 9, 1956 and officially came online in June of 1956 with 35 of the type seeing delivery. B-52C's arrived with increased range thanks to improved fuel capacity made possible through larger external tanks. They were similar to B-models and operated with the same engine series. As this was the Cold War and the use of B-52's in an all-out nuclear strike seemed all but imminent, the underside fuselage of B-52C models were painted over in an all-white scheme in an effort to reflect the thermal radiation inherent in a nuclear-induced explosion while their "tops" remained a natural metal finish. B-52B models were retrofitted with this white underside scheme. Bombloads for C-models topped 24,000lbs. B-52C's were also reconnaissance capable though the RB-52C designation was never truly adopted for the type. Production of all C-models lasted through 1956.
The B-52D became the first definitive high-quantity production Stratofortress ultimately produced in 170 examples and achieving first flight on May 14th, 1956. D-models entered service in December of 1956 as dedicated long-range bombers and, unlike previous Stratofortress offerings, these aircraft would not feature the ability to carry the reconnaissance pod so there were no RB-52D designations handed out. B-52D's were used extensively in the Vietnam air war where their expansive bomb bays could be put to good use. Vietnam-based B-52D models were distinguished by their overall forest camouflage schemes and black-colored, anti-searchlight fuselage undersides. Production was split between Seattle and Wichita plants.
The B-52E first flew on October 17th, 1957, and followed D-models into operational service as improved Stratofortresses though they were quite similar to their predecessor. Improved air defenses across the Soviet Union forces a change to the high-level bombing strategy of early B-52's. Therefore, the B-52E was developed into a low-level bomber. Additions included a revised bombing and navigation suite (AN/ASQ-38 - Raytheon AN/ASB-4 navigation and bombing radar) that would become standard on future Stratofortress production models. One hundred B-52E models were produced with the initial examples entering service in December of 1957. A single E-model was set aside for use as an in-flight test airframe and featured stabilizing canards.
The B-52F was similar to the preceding B-52E but sported Pratt & Whitney J57-43W series engines of 11,200lbf. Engine pods on each wing were revised to include their own water injection systems. F-models represented 89 production examples split between Seattle and Wichita to begin service in June of 1958. Among other refinements, these Stratofortresses featured new Pratt & Whitney J57-P-43W series turbojet engines. First flight was achieved on May 6th, 1958.
The B-52G model was originally a near-complete redesign of the base B-52 but a simpler modified design was accepted instead. G-models featured the all-important "wet wing" arrangement in which the internal spaces of the wing were utilized for the storage of fuel cells for increased overall fuel capacity and thus operational range. Several tons were shaved off of the aircraft and crew accommodations were improved. The tail gunner was relocated to a new station within the main cabin area in the forward fuselage where the rest of the crew resided and given remote control of the turret. The vertical tail fin was shortened while the nose radome was lengthened and ailerons completely eliminated in favor of seven spoilers to provide for roll control. Production of all G-models totaled 193 examples representing the most produced B-52 models in the series seeing first flight on August 31st, 1958 and entering service on February 13th, 1959. G-models (55th production onwards) were outfitted with underwing pylons to accept the AGM-28/GAM-77 Hound Dog nuclear-tipped cruise missile - a feature also retrofitted on earlier production G-models. These Superfortresses were also later cleared to use 20 x AGM-69 SRAM nuclear missiles beginning in 1971. Four ADM-20 Quails (aircraft shaped decoys) were added in the bomb bay. Many B-52G's would be sacrificed as part of the nuclear proliferation agreements between the United States and the Soviet Union beginning in 1992 while the surviving models were relegated to museum work. Production of G-models was handled by Wichita.
The B-52H model was first flown on March 6th, 1961 and introduced into service on May 9th, 1961. It was never meant to be produced for the USAF had its eyes on the North American Mach 3-capable XB-70 Valkyrie to take the Superfortresses place. When the Valkyrie project folded, the USAF turned to Boeing for another "final" B-52 - this in the B-52H model and designed to carry the new GAM-87 Skybolt ballistic missile on four external pylons. Though essentially similar to the G-models it replaced, the B-52H sported improved performance and fuel efficient Pratt & Whitney TF33-P-3 turbofan engines of 17,000lbf and a reinforced understructure for improved low-level bombing. Major systems and subsystems were revised or improved as well and the 4 x 12.7mm tail gun armament was officially replaced by the remote-controlled 1 x 20mm General Electric M61 Vulcan six-barrel Gatling cannon system (6,000rpm) tied to an Emerson ASG-21 fire control system. Ammunition supply was 1,242 rounds. The B-52H went on to utilize cruise missiles (the Skybolt missile was eventually cancelled before production), anti-ship missiles and unmanned drones in this fashion thanks to its heavy duty wing pylons. Light duty pylons were added later between the two engine pods on either wings and retrofitted to earlier H- and G-models. Like her G-model sisters, B-52H's were cleared to use 20 x AGM-69 SRAM nuclear missiles beginning in 1971. Low-level operations became another improvement of this model type. In 2004, a B-52H was tabbed to replace the long-running NB-52B research model mentioned previously. H-models now represent the only Stratofortress models in operational service.
The EB-52H was a proposed electronic warfare variant of the base B-52H model. The plan was to convert 16 of the production G-models into this new platform though lack of funding nixed the program altogether - twice.
Cold War Service
The B-52 performed a valuable deterrent role during the Cold War years, stationed for a time in "quick response" air patterns to provide for a rapid response to any Soviet nuclear attack. These aircraft formed the "Dirty Dozen". The B-52 is generally known more for her involvement and contributions in the Vietnam War. Her bombing ability proved unmatched in her thousands of sorties over Vietnam. First combat missions occurred via B-52F'ss on June 18th, 1965. B-52D models were also utilized and modified to take on even more of a combat load than F-models, whom they replaced. D-models made their presence known on April 1966 and became the standard Stratofortress of the war. D- and G-models participated in "Operation Linebacker II" (18th - 29th December 1972) - a non-stop, nearly two-week long, bombing campaign against Vietcong targets with ten Stratofortresses lost in the ensuing action. B-52D and G-models (55 and 98 respectively) were flown from Anderson Air Force Base in Guam while some 54 further D-models also originated from U-Tapao Rayong International Airport in Thailand during the action.
Persian Gulf War
The B-52G models were a fixture of the Persian Gulf War in 1991. Originating from bases within the United States, Stratofortresses made their way to the other side of the globe to hit targets within Iraq. Later missions would see B-52G's originating from bases about the region for equally effective results. Their high-capacity bombing ability no doubt proved a tremendous psychological effect on Iraq army units and Stratofortresses could be called upon to complete both low-level and high-level sorties as needed. According to the USAF, B-52's accounted for 40% of munitions dropped by Coalition forces, covering some 1,620 total sorties in the war with no combat-related losses. Targets included bunkers, buildings of interest and troop concentrations. B-52's conducted the longest strike mission ever during the conflict, beginning from Barksdale AFB in Louisiana and covering some 35 hours of non-stop flight time before delivering lethal cruise missiles against Iraq targets.
The B-52 in H-model form was called to action in the 2001 American invasion of Afghanistan following 9/11. Stratofortress elements utilized their extensive loiter times and large payloads to offer on-the-spot assistance to ground forces, this through guided munition deliveries. Although other smaller multi-role aircraft would have sufficed in the role, nothing in the American inventory could truly match the B-52 in terms of concentrated and quantitative firepower. Carpet bombing suspected Taliban locations in the northern mountain areas were also the forte of B-52's over Afghanistan.
The 2003 American invasion of Iraq was another modern theater for the B-52 to showcase its worth to the modern air force. In the opening assault, Stratofortresses unleashed over 100 cruise missiles on targets of opportunity throughout Iraq.
No End to this Road
Despite its long history, the United States Air Force - try as they might - have no immediate plans to retire this beast any time soon. Over the years, the B-52 faced threats of replacement from the likes of the ill-fated North American Valkyrie, the supersonic Rockwell B-1 Lancer and the Northrop B-2 Spirit stealth bomber. Though the B-1 and B-2 bombers entered production in some quantity, their real strength remained in their ability to deliver precision payloads while utilizing speed or stealth practices to avoid enemy air defenses. The B-52 remains potent today because it can be utilized to terrific effect after these enemy air defenses have been vanquished - as shown in Persian Gulf 1991, in the 2001 war in Afghanistan and finally in the 2003 invasion of Iraq.
Modernization and refurbish programs have no doubt played a role in keeping the Stratofortress relevant these past decades and the intention is to keep it as such for decades to come. According to the USAF, it is expected that the B-52 can remain in service well up to 2040, which is an astonishing thought given that the aircraft was a design first flown in the 1950's. During its peak involvement with Strategic Air Command, no fewer than 650 B-52 bombers made up 42 SAC bomber squadrons at 38 bases. As of this writing, the Air Force maintains approximately 76 active and 20 reserve B-52's from the 744 total that were produced. Production of all B-52's lasted from 1952 through 1962 and handled at the Boeing Seattle, Washington and Wichita, Kansas plants, marking some 47 years since the last Stratofortress rolled off of the assembly lines.
It is easy for one to forget that this massive aircraft was a record setter in its day. A world air speed record was set on September 26th, 1958, in a B-52D reaching 560.705 miles per hour on a closed circuit covering 6,210 miles. The same day netted another air speed record of 597.675 miles per hour over a 3,105 mile course. On December 14th, 1960, a B-52G set a world air distance record by traveling 10,078.84 miles without refueling. This record was bested several years later on January 10th/11th, 1962, when a B-52H achieved 12,532.28 miles of unrefueled flight time in a journey from Japan to Spain. According to Boeing, this single flight alone broke some 11 speed and distance records.
In Pop Culture
The B-52 has also made it into pop culture as it was the aircraft featured in the 1964 Stanley Kubrick film "Dr Strangelove". The Stratofortress is commonly known by the unflattering nickname of "BUFF", standing for "Big Ugly Fat F%%ker".