New J57-43 engines took the place of the B-52E's J57-P-19s or P-29s. Alternators, attached to the left-hand unit of each pair of the J57-P-43W engines replaced the air-driven turbines and alternators in the B-52E's fuselage. The B-52F's only other new feature was a more efficient water injection system.
Continued improvements of the J57 engine series prompted the November 1954 initiation of the B-52F design. Incorporation of the J57-P-43W engines had to entail some changes. A slight modification of the wing structure also had to be planned in order to install 2 additional wing tanks, which would give the B-52F's injection system an increased water capacity-the system's main overall advancement.
B-52F procurement was accomplished by 2 B-52E contracts AF33(600)-32863 and AF33(600)-32834. One contract called for 44 Seattle B-52Fs; the other, for 45 B-52Fs from Wichita.
The Seattle-built B-52F first flew on 6 May 1958; the Wichita-built model, on 14 May.
Whether from Seattle or Wichita, B-52F deliveries lagged a few months behind schedule because authorized overtime for Boeing personnel was curtailed. Fiscal limitations, imposed by the Office of the Secretary of Defense in late 1957 were the cause (Charles E. Wilson was sworn in as Secretary of Defense on 28 January 1953, and served until 8 October 1957. He was succeeded by Neil H. McElroy, who resigned on 1 December 1959.).
B-52Fs did not start reaching the Strategic Air Command until June 1958. By the end of the month, SAC's 93d Bomb Wing counted 6 B-52Fs.
Fuel leaks, occurring in the B-52Fs and preceding B-52s, proved difficult to stop. The problem manifested itself from the start. Marman clamps, the flexible fuel couplets interconnecting fuel lines between tanks, broke down on several occasions during the first few weeks of B-52 operation. This caused fuel gushers that obviously created serious flying hazards. Blue Band, a September 1957 project, put new clamps (CF-14s) in all B-52s. Depot assistance field teams did the retrofit well, but Blue Band did not work. The CF-14 aluminum clamps soon showed signs of stress corrosion and were likely to fall after 100 days of service. Highly concerned, the Air Force and Boeing began replacing the aluminum clamps with a Boeing-developed stainless steel strap clamp, the CF-17. Hard Shell, a high-priority retrofit program, put CF-17 clamps in all in-service B-52s. Completed in January 1958, the Hard Shell retrofit was not a fool-proof solution. B-52 operations were again restricted, as several CF-17 clamps ruptured, this time because of deficient latch pins. CF-17A couplings, CF-17 clamps that had been modified to strengthen their latch pins, were used to correct the problem. But neither Boeing nor the Air Force put too much credence on the new modification. This gave way to Quickclip, a new retrofit project started in mid-1958. All B-52s went through Quickclip, which installed a safety strap around the modified clamps. Several cases of broken latch pins were reported before the end of 1958. However, the safety straps prevented the fuel from leaking out, which was Quickclip's whole purpose. Additional B-52Fs, entering the inventory after the fall of 1958, therefore were also fitted with Quickclip safety straps.
Fuel system icing posed another initial and long-lasting B-52 problem which had been shared for several years by other jet aircraft. However, little was known about its cause and effect. A B-52 accident in 1958 brought the problem to a climax, while providing a few definite findings. In many previous crashes, icing of the fuel system had been recognized as a probable cause of accident, but the ice had melted in ensuing fires, leaving no concrete evidence. This time, the Air Force could ascertain that icing of the fuel system strut filters and fuel pump screens had caused the engine to flame out and lose thrust. As a remedial step, B-52s were immediately fitted with filters and screens which promised to be less susceptible to icing. The Air Force in addition initiated new fuel draining procures and directed use of the driest fuel available. A new fuel booster transfer valve came under development during the same period. The B-52 accident of 1958 also speeded research on fuel additives that would prevent the formation of ice in fuel system components. The Air Force, Boeing, and fuel vendors participated in the intensified research program. Nevertheless, progress was likely to be slow. In the meantime, the only meaningful solution was to put fuel heaters in every B-52 and to do so as quickly as possible. Despite troubles encountered during the thermal shock and vibration tests of the heaters, this retrofit project proceeded according to schedule in late 1959. Concurrently, however, a new problem arose. The fuel additive program, after going on unabated, came to a sudden stop because the additives were damaging the fuel cell's inner coating. But this latest problem was resolved in due time. In October 1962, jet fuel additives had proven so successful in eliminating icing problems that SAC was disconnecting the fuel heaters on its latest B-52s (B-52Hs).
The B-52F, after participating in the High Stress and Big Four modification programs, was further improved. Again the improvement covered all B-52s, even the early B-52Bs. It consisted of installing the equipment necessary to detect and locate actual and incipient malfunctions in the bombing-navigation and autopilot systems. This equipment was known as MADREC, an acronym for Malfunction Detection and Recording (B47Es were also due to be fitted with MADREC equipment.). The requirement for MADREC had been established in 1961, and its installation was part of a long-range program. The first stage involved the B-52B, B-52C, and B-52D bombers and was completed by mid-1963. The second stage was directed at the more complicated ASQ-38 bombing-navigation system of the B-52E, B-52F, and subsequent B-52s. In essence, the program was closely associated with the Big Four package. MADREC equipment would play an important role in monitoring the Hound Dog missiles that were carried by almost every B-52, as a result of Big Four. The program neared completion by 1965.
The revised strategy of the early sixties, calling for a greater nonnuclear retaliatory force, did not leave the B-52 untouched. In June 1964, the Air Staff approved the modification of 28 B-52Fs under a project known as South Bay. Completed in October of the same year, the modification program allowed selected B-52Fs to carry twenty-four 750-pound bombs externally-almost doubling the aircraft's original conventional bombload. In June 1965, as the tempo of activities in Southeast Asia began to escalate, Secretary of Defense McNamara requested that 46 other B-52Fs receive similar modifications. Referred to as Sun Bath, the project this time carried a 1-month deadline. Some problems arose. Multiple ejection racks, beams, kits, and supporting aerospace ground equipment were in short supply. To fulfill its many commitments, Air Force Logistics Command's Oklahoma Air Materiel Area, the project's prime coordinator, had to borrow assets from war reserve materiel and from units of the Tactical Air Command. Just the same, Sun Bath was completed 1 week ahead of schedule.
The first B-52 bombers that entered the war in Southeast Asia were B-52Fs. On 18 June 1965, the initial Arc Light bombing mission was carried out from Guam by 27 B-52Fs of the 7th and 320th Bomb Wings. B-52FS were the only SAC bombers committed to the Vietnam conflict throughout 1965. Even though all deployed B-52Fs had received ahead of time the South Bay or Sun Bath modifications to increase their bombload to 38,250 pounds, they were replaced before mid-1966 by modified B-52Ds.
B-52F participation in Southeast Asian operations accounted for the loss of 2 of the planes. The 2 collided in mid-air on 18 June 1965, on their way to the first Arc Light mission.
Production of the B-52F, the last model of the B-52 series built in Seattle, ended in November 1958. The Seattle plant, after manufacturing nearly one-half of the B-52F productions, transferred all B-52 engineering responsibility to Wichita. The Air Force accepted 44 B-52Fs from Seattle; 45 from Wichita. The Air Force accepted 10 B-52Fs in FY 58 (all in June 1958), and 79 in FY 59 (between July 1958 and February 1959). Cost per aircraft was: $6.48 million: Airframe, $3,772,247; engines (installed), $1,787,191; electronics, $60,111; ordnance, $3,016; armament (and others), $862,839.
Although the 93d Bomb Wing retained every one of its B-52Fs, 1971 marked the beginning of the aircraft's phaseout. The Air Force retired a few B-52Fs in 1967. As in the B-52E's case, these planes were retired only because they had exceeded their service life criteria. Retired planes went to Davis-Monthan for storage. In mid-1973, the Air Force still possessed 62 B-52Fs. Thirty-six of these aircraft were in the inactive inventory. Other B-52Fs were used for training.
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