by Bill Yenne
Other detail differences between the two prototypes and the production aircraft included provisions for 1,000-gallon external fuel tanks and inflight refueling. Boeing had become a pioneer in the practical application of the latter in routine operations and had earlier adapted its piston-engine C-97 Stratofreighter (Model 367) to serve as the U.S. Air Force’s principal aerial tanker.
By the time that the Stratofortress entered production, Boeing had developed a jet refueling aircraft, the KC-135 (Model 717) Stratotanker. The KC-135 and B-52 would enter service at the same time and would be inexorably linked with one another in SAC operations for decades.
The external fuel tanks, built by Fairchild, meanwhile, would become an issue in the early stages of Stratofortress production when they did not fit. The first reaction from Art Carlsen, the production man who was now the B-52 project chief, was to make Fairchild fix the problem. However, Thorton Arnold “T” Wilson, an MIT-trained engineer who had been with the Model 464 program since the early days, suggested that this solution would adversely impact the schedule and that Boeing itself had the expertise to fix the problem. He was right. T Wilson succeeded Bill Allen as Boeing president in 1968.
Seated side by side as required by LeMay, the pilot and copilot of the production series Stratofortresses shared the upper level of the pressurized flight deck with the Electronic Countermeasures (ECM) operator, while two bombardier-navigators were in the lower deck below them. The gunner was positioned in the tail turret.
The crew positions on the upper flight deck—pilot, copilot, and ECM officer—were equipped with ejection seats that ejected upward. Lower-deck crew positions used downward-ejecting seats that could not be safely used below 200 feet. To escape, the tail gunner would jettison the tail gun assembly and bail out through the resulting hole.
Offensive armament comprised up to 43,000 pounds of ordnance in the 28-foot bomb bay, though a smaller load was typical in order to achieve optimal range. The payload included twenty-seven 1,000-pound conventional bombs, or a nuclear load. Initially, the Stratofortress carried an 8,500-pound Mk 6 uranium fission atomic bomb and, later, a pair of 7,600-pound Mk 15 thermonuclear bombs, also known as hydrogen bombs, or H-bombs. Thermonuclear weapons derive their destructive force from the fusion of hydrogen atoms (deuterium and tritium) and are more powerful than fission weapons.
Pratt & Whitney J57 turbojet engines are hung on the wings of a B-52B. Examples of this variant were delivered with a wide range of water-injected J57 models.
The first of the three B-52A Stratofortresses made its debut flight on August 5, 1954. The series served as a service test, rather than operational, series. USAF
The RB-52B was the only Stratofortress variant to be specifically designated as a reconnaissance aircraft, although in practice, the aircraft were mostly configured as bombers. USAF
B-52C forward fuselages take shape on the factory floor. Note the open doors into which the ejection seats will be lowered.
The B-52C Stratofortresses are said to have been the first that were all delivered from the factory with gloss white paint on their undersurfaces. The paint was intended to reflect the radiation of the nuclear blast from the bombs they dropped. USAF
A detail view of the manned tail turret of a B-52D. Most early model Stratofortresses were equipped with four .50-caliber machine guns in this quad-fifty arrangement.
The B-52A Stratofortress, the first production model of a series of long-range bombers, takes off from Boeing Field, Washington, on its maiden flight August 5, 1954. USAF
All B-52s were delivered from the factory in natural metal finish, but, beginning with the B-52C, the Stratofortresses were delivered with their undersides painted gloss white to reflect the thermal radiation expected from the blast from the nuclear weapon that the aircraft dropped. B-52Bs seen with white bellies were painted after delivery.
On May 21, 1956, a B-52B became the first aircraft to drop a thermonuclear weapon when it released a Mk 15 at Bikini Atoll in a test code-named Cherokee, which was part of Operation Redwing. The Mk 15 was in service with SAC fleet for about a decade, beginning in 1955.
It was superseded from 1957 by several other types. They included the 15,000-pound Mk 21, which had a destructive force of up to five megatons, and the 6,750-pound Mk 39 (later W39), with a 3.8-megaton yield. The B-52s also flew with the smaller Mk 28 (later B28), which had a maximum yield, depending on variant, of 1.45 megatons. In the 1960s, more advanced thermonuclear weapons such as the 9-megaton B53 and the variable-yield B61 became available for the B-52 arsenal and earlier types were phased out.
Beginning with the B-52D series (Model 464-201-7), Boeing opened a second source of Stratofortress production. Back in 1946, when Boeing was first thinking about the airplane that became the Stratofortress, the factory complex at Seattle and Renton was a ghost town. By the time that the B-52C was on the assembly line, this “town” was becoming very crowded. Boeing was beginning production of the KC-135, as well its revolutionary Model 707 jetliner. Meanwhile, however, Boeing’s other center of production was winding down. The facility in Wichita, Kansas, which Boeing had acquired when it bought Stearman Aircraft in 1934, had been a major center of B-29 production during World War II, and Boeing had built all the production B-47s there. With B-47 production ending, and a large workforce in place, Boeing began shifting Stratofortress manufacturing to Wichita.
Seattle would build 101 B-52Ds, while Wichita produced 69. There were 42 B-52Es (Model 464-259) and 44 B-52Fs (Model 464-260) built in Seattle, while Wichita produced 58 and 45, respectively. Externally, the early-production series Stratofortresses, from B-52B through B-52F were virtually indistinguishable. Internally, upgrades to electronic equipment that were introduced in new models were often retrofitted in some examples of earlier models.
The first flight of a B-52D was at Wichita on May 14, 1956, more than four months ahead of the first Seattle B-52D. The B-52E first flew on October 3, 1957, and the B-52F made its debut on May 6, 1958. The former used the same J57-P-19W and J57-P-29W engines as its predecessors, while the latter was powered by J57-P-43W engines.
An important innovation first seen in the B-52E was the advanced, automated IBM AN/ASQ-38 bombing-navigation system, which permitted low-level operations. This included an improved search radar receiver-transmitter and newly developed terrain avoidance compute with terrain avoidance displays and controls for the pilot and copilot. Though it caused problems initially, when the bugs were worked out the AN/ASQ-38 was a significant improvement over the mechanical analog Sperry K-System, dating from the late 1940s, that was used in earlier model Stratofortresses.
The New Generation
As the initial six B-52 models were in production and appearing in rapid succession—with an average of just nine months between model introductions—Boeing engineers were thinking ahead toward the Model 464-253, a substantially improved second generation of Stratofortresses.
The presentation to the Air Force of this new generation aircraft took place in March 1956 and included a number of proposed technical upgrades aimed at improving performance and reducing airframe weight. Among other things, the Boeing proposal promised a 30 percent increase in unrefueled range, along with a 25 percent decrease in maintenance man-hours.
After months of consideration and back-and-forth, the U.S. Air Force approved Boeing’s proposal with a letter contract dated August 29, 1957. A big part of the Air Force decision is said to have been the problems and delays in the development of the Convair B-58 Hustler supersonic strategic bomber.
A series of three orders, issued through April 28, 1959, called for a total of 193 Boeing Model 464-253 aircraft to be delivered under the designation B-52G. This was by far the largest number of Stratofortresses of any model. With B-52 production now terminated in Seattle, all of the B-52Gs would be built at Wichita.
A Block 60 Seattle-built B-52D is seen over snowcapped western mountains as it might have appeared over snowcapped Siberian mountains had the Cold War tu
rned hot.
Though the B-52G was designed for the same J57-P-43W engines introduced on the B-52F, the aircraft was substantially different in many other ways.
The most outwardly apparent change was in the size of the tail, which, at 40 feet 8 inches, was a full 8 feet shorter than those of the “tall-tailed” first generation of B-52s. However, this was only the tip of the proverbial iceberg. Combined with the elimination of the aileron system in a newly redesigned wing, this reduced the overall empty weight by an amazing 6 tons. Another 3 tons was saved in the wing redesign by making it a “wet wing” through the inclusion of integral fuel tanks.
Conversely, the gross weight increased by 19 tons, as the weight savings were more than offset by the increased fuel capacity of nearly 7,000 gallons. This increased the range capability of the B-52G by better than 30 percent.
Other revisions in the new design concerned provisions for the crew, notably the relocation of the tail gunner from his lonely outpost in the tail to a seat adjacent to the ECM operator in the forward fuselage. Here, he operated the new Avco-Crosley AN/ASG-15 fire control system by remote control.
The most welcome change, so far as the other crewmembers were concerned, was a revision of the climate control system. A long-standing complaint was that while the pilot and copilot roasted in the sun, the crewmembers below shivered in the cold. The B-52G afforded separate climate control options.
The first Seattle-built B-52E during low-level flight testing off the coast of the Pacific Northwest, circa 1957. The B-52E and B-52F were both factory-equipped with radar that permitted low-altitude operations. USAF
A Block 75 Wichita-built B-52G is refueled by a KC-135A high over a snow-covered Midwestern landscape. The first B-52G entered service in February 1959. USAF
The IBM AN/ASQ-38 bombing-navigation system introduced on the B-52F was also retained in the B-52G as built, but this would be subject to numerous electronics upgrades through the coming decades.
The B-52G made its first flight on August 31, 1958, and the type entered service with the Strategic Air Command’s 5th Bombardment Wing at Travis AFB on February 13, 1959.
By then, Boeing was already working on the aircraft that would be the “ultimate Stratofortress,” the Model 464-261. The final B-52 type, it was first ordered on May 6, 1960, under the designation B-52H. A subsequent order, issued six weeks later, brought the total number of B-52Hs to 102, all of which were built at Wichita. This also brought the total number of Stratofortresses of all types to 744.
Structurally, the B-52H was like the B-52G, with the wet wing and shorter tail. What made it such a significant improvement, and what set it apart visually, were the engines. The water-injected J57 turbojets were now superseded by eight Pratt & Whitney TF33-P-3 turbofans. This engine was based on the commercial JT3D turbofan, which was then becoming the turbojet replacement of choice for many airlines.
The greater thrust of the turbofan engine type provides improved takeoff performance at higher gross weights, while being significantly quieter and more fuel efficient. Of particular interest to SAC was a 20 percent increase in range over that of the B-52G.
The broader engine nacelles of the TF33s were a notable difference in appearance between the B-52G and B-52H, as was the revised tail armament. The quad-fifty arrangement and AN/ASG-15 fire control system were superseded by a six-barreled General Electric M61 rotary cannon with 1,242 rounds of 20mm ammunition and an Emerson AN/ASG-21 fire control system.
An inflight photo of the fourth B-52G, to be built at Wichita, a Block 75 bird.
A photographer arrives at Boeing Field in Seattle in his Austin Healey to watch the rollout of a Block 110 B-52F. The first of the F models made its debut in May 1958.
Digital electronics to allow routine low-level operations, which had been introduced in the B-52E and B-52F, continued to be a key part of the factory equipment on the B-52G and B-52H, and it would be subject to further in-service upgrades through the years on both aircraft.
The B-52H made its first flight on July 20, 1960, although the TF33 turbofan engines had previously been tested on a B-52G, making this aircraft a “virtual B-52H.”
The first delivery of a B-52H to SAC went to the 379th Bombardment Wing at Wurtsmith AFB in Michigan on May 9, 1961, and the last of the 102 B-52H aircraft was received by the 4136th Strategic Wing at Minot AFB on October 26, 1962.
In the meantime, wing cracks were identified on a small number of B-52H aircraft. These were traced to fasteners at the wing roots that were prone to corrosion, and the issue was corrected.
No Friend of Manned Bombers
On the same day that SAC received its last B-52H, the last Convair B-58 was delivered to the 305th Bombardment Wing at Bunker Hill AFB in Indiana. This brought production of both aircraft to an end. As the official SAC history reports, “for the first time since 1946 there was no bomber being produced or developed for SAC. The XB-70 was the only bomber-type aircraft under development and it had been excluded from consideration as a bomber. In September, an Air Force recommendation to expand the XB-70 program into a full-scale weapon system development was rejected by the Department of Defense.”
The narrative goes on to say that four days after the final deliveries, “Secretary of Defense [Robert] McNamara requested the Air Force ‘consider an alternative bombing system’ as a follow-on [from] the B-52, something that could serve as an airborne missile launching platform for the period beyond 1970.”
Robert Strange McNamara came to Washington in 1961 as defense secretary under President John F. Kennedy and remained in that post under Lyndon B. Johnson until 1968. In this role, he was historically instrumental in guiding the shape of weapons acquisition—and in guiding American involvement in the Vietnam War.
He was greatly fascinated by strategic missiles and had little enthusiasm for strategic bombers. A strong proponent of ICBMs over manned bombers in a nuclear deterrent force, he fast-tracked the Minuteman solid-fuel ICBM, while ordering the termination of XB-70 development, as well as other manned programs—such as the Boeing X-20, which would have been America’s first space shuttle.
Nevertheless, the Air Force did undertake a number of manned bomber feasibility studies during his tenure. These included the Low-Altitude Manned Penetrator (LAMP) and the Advanced Manned Precision Strike System (AMPSS) projects in 1963, which culminated in the Advanced Manned Strategic Aircraft (AMSA) program of 1964. Ironically, the man most responsible for AMSA was Harold Brown, who had been chief of research and engineering at the Pentagon since 1961 and who had been instrumental in killing the XB-70 program. In 1965, Lyndon Johnson named him as Secretary of the Air Force, directly under McNamara.
Stratofortress Production by Model Number
(See Appendix 2 for more detail)
XB-52 (Boeing Model 464-67) 1 built in Seattle
YB-52 (Boeing Model 464-67) 1 built in Seattle
B-52A (Boeing Model 464-201-0) 3 built in Seattle
B-52B (Boeing Model 464-201-4) 23 built in Seattle in 3 blocks
RB-52B (Boeing Model 464-201-3) 27 built in Seattle in 6 blocks
B-52C (Boeing Model 464-201-6) 35 built in Seattle in 3 blocks
B-52D (Boeing Model 464-201-7) 101 built in Seattle in 6 blocks 69 built in Wichita in 10 blocks
B-52E 59 (Boeing Model 464-259) 42 built in Seattle in 4 blocks 58 built in Wichita in 4 blocks
B-52F (Boeing Model 464-260) 44 built in Seattle in 3 blocks 45 built in Wichita in 2 blocks
B-52G (Boeing Model 464-253) 193 built in Wichita in 12 blocks
B-52H (Boeing Model 464-261) 102 built in Wichita in 9 blocks
Total: 774
Production Close-Up Boeing B-52 Stratofortress
The second of 102 Wichita-built B-52Hs. The H Model was visually distinguishable by its low tail, its turbofan engines, and the Vulcan cannon in its tail turret.
The winning AMSA proposal, submitted by North American Rockwell, appeared after McNamara and Brown had left office and was ordered i
nto production by the Nixon administration under the designation B-1A. This aircraft made its first flight on December 23, 1974, but the program was terminated by the Carter administration after only four were built.
The Air Force resumed studies of a new strategic bomber in 1979 under the Long-Range Combat Aircraft (LRCA) project. A Rockwell proposal based on the B-1A was approved by the Reagan administration in October 1981, and the first of 100 B-1Bs made its debut on March 23, 1983. The B-1B reached its initial operational capability on October 1, 1986, twenty-four years after the last delivery of a B-52H.
The SAC war room deep inside the bomb-proof bowels of Offutt AFB. USAF
ON JUNE 29, 1955, SAC’s first B-52B was flown from Seattle to Castle AFB, piloted by Brig. Gen. William E. Eubank, commander of the 93rd Bombardment Wing. Located near Merced in California’s San Joaquin Valley, Castle would remain as a center of B-52 crew training base for several decades.
In June 1956, the 42nd Bombardment Wing at Loring AFB in Maine became the second wing to be equipped with B-52s, and the first B-36 unit to convert to the Stratofortress. The 99th Bombardment Wing at Westover AFB, Massachusetts, became the third B-52 wing in December 1956. From here, the incorporation of the Stratofortress into the U.S. Air Force proceeded quickly. The 92nd Bombardment Wing at Fairchild AFB in Washington and the 28th at Ellsworth AFB, South Dakota, came next, in 1957.
From 18 B-52s in the Strategic Air Command fleet at the end of 1955, the inventory grew to 97 at the end of 1956 and to 243 in December of 1957, the last year that Curtis LeMay was in charge of SAC. When LeMay moved up the ladder to assume the post of Air Force Vice Chief of Staff, he handed SAC off to his handpicked successor, Gen. Thomas S. Power, who would remain in that post until 1964.
