THE STORY OF THE BOEING B-52 STRATOFORTRESS
The Boeing B-52 Stratofortress, in service today, almost seventy years after its first test flight, is one of the most versatile and successful aircraft ever designed.
Originally conceived as a replacement for the Convair B-36, with a long-range, high altitude, free-fall nuclear delivery mission, it has adapted over the years to changing technological and political conditions, assuming a wide variety of tasks and requiring tactics unforeseen by the engineers and airmen responsible for its design and procurement in the late 1940s.
Today, it is still flying and fighting, and will probably do so until 2040 or longer. One saying that is popular with today's aircrews is: "The last B-52 pilot hasn't been born!"
The requirement for a heavy bomber with intercontinental range dates back to the darkest days of World War Two, when it was feared that England might fall and the bases it provided be lost, necessitating a transatlantic continuation of the war against Hitler.
Although not delivered until after the war, in 1948, the Convair B-36 was the eventual response to this requirement, and to the previously unforeseen challenge posed by the Soviet Union.
By the time it entered service, however, technology—especially the emergence of jet fighters—had already dictated its early obsolescence, and the requirement for its replacement had already been stated in early 1946, calling for an unrefueled range of 8000 miles with a 10,000 lb bomb load and a top speed of 450 mph.
A preliminary design contract was awarded to the Boeing Company that year. Boeing had earned an impressive reputation and considerable expertise in the heavy bomber field with its highly successful B-17s and B-29s.
Initially, both Boeing and the Air Force envisioned this second generation intercontinental bomber as a turboprop, since pure jet development had not yet produced an engine powerful enough, and because the turboprop was more fuel efficient, translating into greater range. The company was, in fact, working on a jet-powered medium bomber—the B-47—but its smaller size and expected performance did not satisfy the new requirement.
The design with which Boeing won this new contract was a conventional one, essentially a B-29 scaled up to B-36 size with straight wings and six turboprop engines.
By the Fall of 1948, a number of refinements to this original design had been made, but the projected performance was still not much better than that of the improved B-36 it was to replace.
SEVERAL EVENTS CHANGED THE COURSE OF B-47 DEVELOPMENT
The company responsible for the engine intended for the aircraft had encountered difficulties in its development, causing the program to fall behind.
Concurrently, the Pratt and Whitney Company was making unexpected progress with a new jet engine, the J-57, with 10,000 lbs of thrust, a significant advance.
Finally, the potential of in-flight refueling was greatly increased with the development of the “flying boom” by Boeing. This rendered the fuel savings of the turboprop less critical.
During a visit by senior Boeing officials to Wright-Patterson AFB to review progress, the Air Force chief of bomber development asked the Boeing team to look at the possibility of substituting pure jet power.
This was on Thursday, 21 October 1948. By coincidence, the Boeing staff present that weekend included just the right combination of skills and knowledge to respond to this opportunity.
Closeting themselves in a Dayton hotel room, with an open line back to the engineering staff and analysts in Seattle, they hammered out a new design which was surprisingly like the prototype which was to roll out of the factory some three years later.
This was submitted to the Air Force on Monday, and the B-52 as it flies today was truly born.
Equally responsible for the dramatic change in direction of the B-52 design was the unexpected success Boeing was having with the independent development of the B-47 medium bomber. The B- 47 had used essentially off-the-shelf technology in a radical design which incorporated two World War Two innovations:
- jet engine
- swept wings
Flight testing going on at that time was revealing accomplishments beyond all expectations in reducing drag. The confidence instilled by this success encouraged Boeing engineers to push the technology envelope with the B-52.
One lesson learned was that the thin wing used on the B-47 for stability at transonic speeds was not essential, allowing the new design to include a tapered wing—thick and wide at the root, thin and flexible further out—and a greatly enlarged wing area.
This, combined with major weight savings throughout, resulted in a very high lift over drag ratio, the major factor in the continuing growth potential of the aircraft.
DEVELOPMENT AND PRODUCTION
The first B-52, the XB-52, rolled out on 29 November 1951, and the first flight, by the second aircraft built, was on 15 April 1952.
The initial production aircraft, the B-52A, was delivered to the Air Force a little over two years later, in June 1954, but only three of this model were built, none of which found their way to operational units. They were used as test beds for further type development and one, the first, became the launch vehicle for the X-15 rocket-powered experimental plane.
The first operational model, the B-52B—built in both bomber and reconnaissance versions — entered the Air Force operational inventory on 29 June 1955, when 52-8711 was delivered to the 93rd Bomb Wing at Castle AFB, California.
The B-model was almost identical to the A, but had an improved bombing-navigation system in the MA-6A, a generation beyond the K-system in the B-47 and the B- 52A. Fifty B-52Bs were built before the final one was delivered on 31 August 1956. It continued to serve along with later models until 1966.
While the B-52B was still in production, a follow-on version, the B-52C, made its first flight on 9 March 1956, with delivery to the Air Force some three months later.
There was little external change from the B-model, but two large 3,000 gallon wing tanks were added. In addition, the avionics and bomb-nav systems, the heart of a bomber aircraft, were significantly upgraded.
Only 35 B-52Cs were built, and seven months before the last one was delivered, the B-52D had made its first flight on 14 May 1956. The only difference between the two was a series of strengthening structural changes.
The D-model was the core of the Strategic Air Command (SAC) fleet for a number of years in the late ‘50s and later carried the burden of the conventional bombing campaign in Southeast Asia.
Changes from the D- to the E-model, first flown on 3 October 1957, were again internal and primarily in the bomb-nav systems, giving the aircraft an improved capability to fly and bomb from low altitude, reflecting new tactics made necessary by improving Soviet air defenses.
One hundred Es were built, followed in 1958 by another 89 F-models, with an upgraded J-57 engine delivering 13,750 lb of thrust (vice 12,100 for the B- through E-models).
The delivery of the last D-model to the Aerospace Maintenance and Regeneration Center in Tucson in October 1983 marked the end of the first generation of B-52s, all of the earlier models having been previously retired.
THE B-52G AND H - The 2nd Generation
The second generation had begun with a Boeing proposal in the Spring of 1956, initiating a program to capitalize on the proven soundness and growth possibilities of the B-52 design. In many ways, what was envisioned was a new airplane, incorporating the basic airframe structure, but with new concepts, materials, and systems.
The result was to be increased range, improved defenses, lower empty weight, and a decreased maintenance requirement, The B-52G made its first flight on 31 August 1958. A total of 193 were built, the largest number of any model of the B-52.
G Model major modernizations incorporated
- the “wet wing,” eliminating fuel bladders in favor of a sealed wing structure and adding more than 10,000 gallons of internal fuel
- an eight-foot shorter vertical tail, and
- moving the gunner from his separate pressurized tail compartment to the forward crew area, with radar and closed circuit TV operation of his guns.
- Ailerons were eliminated and lateral control provided by wing spoilers
- The large external wing tanks of earlier models were replaced by smaller, 700 gallon versions
- A wide variety of internal changes were also made from new hydraulic and fuel management controls to enhanced crew comfort for long flights
- The G-model was designed to be a missile platform as well as a gravity bomb carrier with the new GAM-77 (later AGM-28) Hound Dog as its intended standoff weapon and the GAM- 72 (ADM-20) Quail decoy missile to improve its defense penetration capability.
The B-52Gs were withdrawn from service in the early 1990s, with the last one being delivered to the salvage yard in Arizona on 5 May 1994. They were subsequently destroyed in compliance with the Strategic Arms Limitation Treaty of 1991.
The final version of the Stratofortress, the B-52H, first flew on 6 March 1961, and was produced until June 1962, when the 102nd was completed, the newest of the 742 B-52s built.
MAJOR H MODEL CHANGES
- the adoption of the Pratt and Whitney TF-33 fanjet engine to replace the J-57 which had been used on every earlier B-52, and
- the replacement of the four machine guns in the tail by a six-barrel, 20 mm M61 (T-171 model) Vulcan Gatling gun.
- In addition, advanced avionics were incorporated to permit lower, more precise terrain-hugging penetration of defenses and target acquisition.
Over its long operational life, the B-52 has undergone an extensive series of retrofits and modernizations. As its role changed from high altitude bomber to low level penetrator, the additional stress of prolonged flight in turbulent air required a number of structural modifications to strengthen the airframe.
In a rapidly advancing technological environment, the Stratofortress has gone through several generations of electronic countermeasures systems, and the G- and H-model B-52s had dual chin turrets added housing low-light television and infrared sensors which allow precise navigation and bombing under any light conditions.
The Hound Dog standoff missile was supplanted in the early ‘70s by the AGM-69 Short Range Attack Missile (SRAM). In the ‘80s, large segments of the fleet were configured to carry the AGM-86 Air-Launched Cruise Missile (ALCM).
Subsequent weapons upgrades
- AGM-84 Harpoon
- AGM-142 Have Nap
- AGM-86B conventional warhead version of the ALCM
- AGM-129A Advanced Cruise Missile
- CBU- 87/89/97 family of cluster munitions
- CBU-103-105 Wind Corrected Munitions Dispensers
- GBU-31/32 Joint Direct Attack Munition
- AGM-154 Joint Standoff Weapon, and
- AGM-158 Joint Air-to-Surface Stand-Off Missile to the BUF’s arsenal
In addition, there have been significant improvements in both offensive and defensive avionics.
The B-52 was initially fielded as a long-range nuclear bomber, and that was its primary role from 1955 to 1991. Tactics have changed from high altitude to low altitude penetration to standoff attack, and the aircraft’s inherent flexibility has enabled it to meet these changing demands.
Although never called upon to execute this nuclear mission, its capability and destructive potential are recognized as the key elements in the Western Alliance’s success in waging the Cold War.
For several generations of aircrew, the physical demands of extended training missions in its cramped confines under all flight conditions, alternating with the stress and boredom of 15-minute response ground alert, involving as high as 50 percent of the force at all times, was a way of life.
Beginning in 1958, SAC practiced an airborne alert concept which kept some B-52s, fully loaded with weapons, in the air at all times on flights as long as 26 hours, supported by multiple aerial refuelings.
The tactic ensured the survival of a retaliatory force regardless of the degree of surprise achieved by an enemy attack. A month-long, intensified airborne alert during the Cuban missile crisis in 1962 was the significant factor in preventing its escalation into a U.S.-Soviet confrontation. Armed airborne alert flights were terminated in 1968.
On June 18, 1965, the B-52 dropped its first bomb in anger when a force of 27 B-52Fs struck an enemy stronghold known as the Iron Triangle in South Vietnam. This began the eight-year-long Arclight operation in support of the war in Southeast Asia.
Before the final mission by B-52Gs against a storage area in Cambodia on August 15, 1973, 126,615 B-52 sorties were flown from Guam and Thailand.
The majority of these were against targets in South Vietnam and employed carpet bombing by, typically, two three-ship cells releasing together, saturating an area a mile and a half long long and a half mile wide with more than 80 tons of high explosive bombs. The effect on the ground was dramatic, and enemy prisoners repeatedly cited this as the attack they feared the most. The F models which initiated the campaign were soon withdrawn and replaced by the D, which contributed the bulk of the effort, supplemented by B-52Gs for major operations.
During 1966, the B-52Ds received the “Big Belly” modification which provided for denser loading of the bomb bay, increasing the internal weapon load from 27 to 84 500 lb bombs. With the 24 carried on wing pylons, this gave it a total capacity of 108, or 54,000 pounds—compared to 17,600 pounds for the B- 17G of World War Two.
The Vietnam War culminated with the so-called Eleven-Day War, or Linebacker II, a concentrated bombing campaign against military targets in the Haiphong-Hanoi area of North Vietnam, from December 18-29, 1972. A force of B-52Ds and Gs flow a total of 729 sorties against 24 target complexes delivering 15,000 tons of bombs. Fifteen B-52s were shot down by surface-to-air missiles, and B-52 gunners were credited with two MiGs destroyed and three more claimed, but not confirmed. Twenty-seven days after the final mission of Linebacker II, the North Vietnamese signed the peace accords that led eventually to the end of American participation in the War in Southeast Asia.
The last B-52 strike in South Vietnam was on 28 January 1973, though operations continued over Laos and then Cambodia for another seven months. Throughout the Vietnam/Southeast Asia conflict, the Cold War continued. While their sister ships flew hot missions in Asia, other BUFs—mostly Gs and Hs—continued their deterrent nuclear alert. And this continued through the ‘80s as the aircraft and their weapons were modernized to keep pace with advancing technology.
The dedication and steadfastness of the SAC crew members who had been the tip of our nuclear sword for forty years was rewarded in November 1989 with the opening of the wall separating east and west Germany, the symbolic sign of their victory in the long conflict.
On 27 September 1991, the B-52 bomber force stood down from nuclear alert. Ever since its first use in a conventional delivery capacity early in the Vietnam War, however, this potential in the B-52 had been increasingly explored and developed.
It wasn’t long after the end of the prolonged confrontation with the Soviet Union that it would be employed again. In August of 1990, less than a year after the wall came down in Germany, Iraq invaded its neighbor, Kuwait. After a period of build up by U.S. led Coalition forces, including the deployment of twenty B-52Gs to Diego Garcia in the Indian Ocean, and repeated demands for Iraqi withdrawal, hostilities to restore the independence of Kuwait were initiated on the night of 17 January 1991. Seven B-52s took off from Barksdale AFB armed with conventional warhead air launched cruise missiles (CALCM), flew to the Middle East, launched their weapons against command and control facilities in Baghdad, and returned to their home base.
During the war that followed, Desert Storm, B-52s operating from Diego Garcia, RAF Fairford in England, Moron AB in Spain, and Jeddah AB in Saudi Arabia flew 1741 sorties, delivering more than 27,000 tons of bombs. Seventy-four out of the 90 G-models active at the time participated, attacking strategic targets, SCUD missile sites, and enemy infantry/armor formations. They were also given a new mission: “breaching operations,” in which their string of concentrated high explosive bombs were used to blast passages through the minefields through which attacking Coalition forces had to pass.
At home, the modernization program described above continued, as well as a drawdown of Cold War forces. The Strategic Air Command was inactivated in June 1992, with the B-52s transferred to the new Combat Air Command. In May, as noted above, the Gs were gone from the force, and in November, the last Stratofortress departed from KI Sawyer AFB, leaving only two B-52 fields open, Barksdale in Louisiana and Minot in North Dakota.
Following the First Persian Gulf War, the USAF retained a presence in the Middle East and on Diego Garcia.
The principle mission
- to compel Iraq to comply with UN Security Council Resolution 687, which called for UN inspections of Iraqi weapons-making potential
- to prevent a threatening Iraqi military buildup in the southern and northern areas of their territory.
B-52s were called into action again in 1996 when two B-52Hs flying from Guam launched 13 CALCMs against the Iraqi air defense network. This was the first employment of the H-model in combat.
Meanwhile, in the adjustments to the breakup of the Soviet Bloc, another hot spot was created in the Balkans. In the former Yugoslavia, old ethnic divisions were resurfacing. In order to retain control of Kosovo, the Serbs were applying increasing force to suppress the Albanian and Moslem majorities in the province.
In early 1998, full scale fighting began, and the UN intervened, arranging a cease fire and “safe havens.” Violence continued, however, and a peace conference aimed at a permanent solution broke up on 19 March 1999.
In response, NATO set in motion Operation Allied Force (Noble Anvil was the American component action) on 24 March. In preparation, eight B-52Hs had arrived at RAF Fairford on 21/22 February. On the morning of 24 March, hostilities were commenced with the launch of eight BUFs from Fairford (including two spares) to strike the Serb armed forces in Kosovo with CALCMs.
As the war progressed, B-52 operations switched from missile launches to conventional freefall bombs. Heavy B-52 raids continued until the signing of a peace agreement on 9 June.
The War on Terrorism, which had been building up for two decades, was launched suddenly on the morning of 11 September 2001 with the destruction of the Trade Center and the attack on the Pentagon. Once again, the B-52 was in the vanguard of America’s response.
Operation Enduring Freedom was begun on 7 October to destroy al-Qaeda bases in Afghanistan and to bring down the oppressive Taliban regime which harbored them.
In the first day’s strike, B-52s were employed along with B-1s and B-2s, carrier based air, and ship launched Tomahawk missiles. In the following months, which would stretch into years, B-52s based on Diego Garcia struck known Taliban positions and targets of opportunity, and carried out close air support and propaganda leaflet drops.
Further west, the confrontation with the Iraqi government over disarmament and weapons inspections continued. Finally, there was a United Nations coalition decision to invade the country and replace the regime. Hostilities commenced during the night of 21 March 2003, when more than 1000 air strikes were carried out within the first few hours.
The B-52 was again a major contributor to the “shock and awe” punch. During the 28 days of the air war leading to the fall of Baghdad, 28 B-52s took part, taking off from Fairford and Diego Garcia to deliver CALCMs, conventional bombs, precision guided bombs (including the first combat release of a laser guided bomb using the Litening Pod), and leaflets.