<p>With the outbreak of the Korean War in 1950, the US Air Force was in desperate need of a jet bomber replacement for its aging tactical bomber force, which was limited to the Douglas B-26 Invader of World War II. These Invaders were being used primarily as night intruders against the supply lines in North Korea. Because of their high attrition rate and already limited numbers, new equipment was needed desperately and in quick order.
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<p>To solve this problem, the US Air Force wanted this replacement aircraft to be an existing and proved design in order to shorten procurement time. Even to come close to the performance specifications, few aircraft flying at the time could be considered. The strongest contender was the Martin XB-51 trijet that was in the test stage for the tactical bomber mission. The North American B-45 four-jet medium bomber was in service but seemed limited by its World War II structural design philosophy. The US Navy was operating the carrier-based North American AJ-1 Savage twin-engined propeller-driven attack bomber that had a J33 turbojet embedded in the fuselage. Its growth potential was deemed very limited.
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<p>Foreign designs included the Avro Canada CF-100 Canuck. Its all-weather capability was impressive for the night mission work intended, but this fighter had limited growth capability as a bomber. The English Electric Canberra also had possibilities. The USAF had sent staff members to England as early as 1949 to witness early flights of the first Canberra, but they went away seemingly unimpressed. Like the de Havilland Mosquito bomber of World War II, the Americans found the Canberra difficult to compare with any US aircraft types.
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<p>Fly-offs between the possible aircraft were held at Andrews AFB in November 1950, and the Canberra came out the winner in flying the prescribed maneuvers, plus more, within the allotted time. For the most part, the decision to adopt the Canberra had already been reached, sparking a fierce conflagration for not having selected the Martin XB-51 that many had favored. Martin still came out in front, because it received an initial order for 250 Canberras to be built under a licence agreement with English Electric.
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<p>The Canberra met the off-the-shelf aircraft requirement, but this was not a simple solution for procurement as first envisaged. British production tolerances were too tight to comply with American mass production techniques. As a consequence, the entire aircraft had to be re-engineered to match American standard hardware, dimensions and production standards. This cost time, and production schedules slipped. When these details were overcome, the first of the new American-built bombers was flown on 20 July 1953, two years and eight months after the fly-off acceptance decision.
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<p>Initial tests with the B-57A were not as promising as expected. While performances matched or exceeded those of the Canberra B.Mk 2, the B-57A was found to be unsuitable for the air-to-ground ordnance delivery phase for which it was intended to serve. Little thought had been given to the fact that a gun sight had to be installed behind the round glass of the bubble canopy; this all-curved windshield flexed during rapid temperature and pressure changes during ground-attack maneuvers, and made it impossible to harmonize the guns accurately with the gunsight. A flat glass panel had to be substituted in the canopy.
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<p>This and other changes resulted in the B-57B, which had as its most dominant feature a fully redesigned nose section that had all the traits of American design for that time. It was a tandem arrangement for the crew of two which raised the navigator out of the lower part of the fuselage so that he could see to navigate. Another unique feature of the Americanized bomber was its one-piece rotating bomb bay door. Attached by two pivot points fore and aft, it rotated 180 degrees to expose the bombs attached to it. This innovation eliminated the need to reduce the speed of the B-57 when opening the door, which is often the case when opening conventional clamshell doors. Also introduced were speed brakes to the sides of the fuselage for added control in descents.
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<hi style=hdr1>B-57s in Service</hi>
<p>Deliveries to squadrons began in 1955 to equip four bomber groups and one reconnaissance group along with supplemental RB-57As in smaller quantities to other reconnaissance units. The 345th Tactical Bomb Group at Langley AFB, Virginia, and the 461st TBG at Hill AFB, Utah, which later moved to Blytheville, Arkansas, were the two units in the United States to have the B-57B. Overseas units were the 38th Bomb Group at Laon, France and the 3rd Bomb Group at Johnson AB, Japan. RB-57As went to the 361st Tactical Reconnaissance Wing at Shaw AFB, South Carolina, completing the initial allotments.
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<p>In the early years of the B-57s, far too many were mysteriously lost in operational accidents. The most common cause was an unrecoverable pitchdown at high speed and low altitude. Runaway trim seemed the cause, but the reason could never be positively determined. A number of system changes were made to the aircraft in hopes that one of them might eliminate the problem. Presumably one did, for safety with the type sharply improved and the only treacherous aspect was a critical single-engine airspeed of 178 mph (286 km/h) at full power. This was later reduced to 155 mph (249 km/h) when all the B-57As, B-57Bs and B-57Cs (this version being a trainer variant of the B-57B) were equipped with hydraulic assist that came into effect upon demand by heavy rudder pressure. Early versions produced by conversion included the EB-57A/B for electronic warfare training, RB-57B/C reconnaissance aircraft used by the ANG and JB/NB-57s used for a variety of test work. The B-57E was built as a general purpose bomber which had provision for target-towing, and most were converted to EB-57E, JB-57E, NB-57E, RB-57E or TB-57E standards.
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<hi style=hdr1>High-Altitude Missions</hi>
<p>The B-57 appeared in other configurations as well. There were the 'long-wing' versions, namely the RB-57D and RB-57F high-altitude models. The D model first appeared in service, almost secretly, as early as April 1956, with deliveries to the Strategic Air Command. Their increased wing area allowed them to compete in altitude and range with the Lockheed U-2, and they used their high-resolution cameras to good advantage along the Iron and Bamboo Curtains. When their use as weather and special reconnaissance aircraft drew to an end, they were converted as EB-57Ds for ECM (electronic countermeasures) missions and used as high-flying target aircraft for interceptor fighter training. These RB-57Ds (along with the standard-wing Canberras) were also used in gathering upper air data during nuclear detonation tests in the Pacific.
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<p>Still another version for the high-altitude reconnaissance and air-sampling mission followed in the form of the RB-57F, later redesignated WB-57F. General Dynamics re-engineered the B-57 design beginning in 1962, and from components of existing Canberras eventually built 21 of these 122-ft (37.19-m) span models. This nearly doubled the wing area and span over that of the standard model. These machines operated from bases throughout the world wherever their mission dictated. They were withdrawn from US Air Force service in 1974 (the last flying Martin B-57—a WB-57F—still operates in 1995 from Johnson Space Center on behalf of NASA and the Department of Energy on high-altitude sampling missions).
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<p>No sooner did it seem that the Canberras were well implanted in the USAF units than the tactical bomb groups began to be deactivated. In rapid order the 38th TBW in France, and the 461st and 345th in the United States were deactivated, all by June 1959. Their bomber assets were farmed out to other units including reconnaissance and ECM units, many of which were Air National Guard organizations.
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<p>With the deactivation of the 345th Bomb Group, most of its aircraft were transferred to the Pakistan air force at Mauripur Air Base, Karachi. This was in support of a Military Defense Assistance Plan that the USA had with Pakistan beginning in September 1959. The aircraft outfitted the 7th and 8th Squadrons of the 31st Wing. Modifications were made to these B-57Bs by installing an all-weather bombing system.
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<p>The inevitable war between India and Pakistan did erupt in September 1965. The conflicting reports about gains and losses by India and Pakistan in the 23-day war were so controversial that claims cannot be substantiated. However, it is interesting to note that the exchange of combat sorties by Canberras came from both sides; Martin B-57Bs for the PAF, and English Electric Canberras of several models flown by the IAF.
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<p>Within the USAF, one bombardment unit that did prevail long after the others ceased to exist was the 3rd Bomb Wing in Japan. It continued with its important mission during those unsettled years by maintaining quick-strike capability against targets on the mainland of China, North Korea and the USSR. A squadron-strength detachment was always on 15-minute quick-strike alert at Kunsan, Korea as the primary mission of the 3rd Bomb Wing.
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<p>In 1964 this mission was no longer necessary for the Canberras, and the 3rd Bomb Wing was scheduled to close. However, with the escalating war situation in Southeast Asia, the future of the B-57 changed once more. Two squadrons of the 3rd Bomb Wing, the 8th and 13th Bomb Squadrons, remained active and the bomber force consisting of 47 B-57s moved to Clark AB in the Philippines on 9 April 1964. On 4 August of that year, a detachment from these units was deployed to Bien Hoa AB, South Vietnam in the event that they be needed. On the first day that US jets were allowed to drop bombs in this war which was rapidly getting out of hand, B-57s of these two squadrons were the first to do so. This attack upon Viet Cong guerrilla forces on 19 February 1965 marked the beginning of combat engagements for the Canberras, which would not let up until 1972.
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<hi style=hdr1>Patricia Lynn</hi>
<p>These bombers of the 8th and 13th Bomb Squadrons were not the first of the American-built Canberras to see service in Vietnam. That time began as early as May 1963, when two specially modified B-57s were ferried to Tan Son Nhut AB at Saigon with special reconnaissance sensing equipment tucked away in their unusually shaped noses. These were RB-57Es sent to the war zone to field test this new equipment under actual combat conditions as part of a project named Patricia Lynn. The crews were meant only to ferry the aircraft to Vietnam, but began flying reconnaissance missions immediately. So effective were their results they continued with actual combat support and their test requirements appeared to be secondary. When permanently assigned crews arrived, Patricia Lynn was subsequently assigned to the 33rd Tactical Group, 6250th Combat Support Group and finally the 460th Reconnaissance Wing.
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<p>These aircraft were not only the first military jets to arrive in Vietnam, but were also the last to leave. When the Patricia Lynn operation was terminated after mid-1971, one ('245) or more of the five RB-57Es had nearly reached the 8,000 flying hour mark. Two of the aircraft had been lost to enemy ground fire, but with no loss of crew members.
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<p>The bomber crews of the 8th and 13th BS were not so fortunate in regard to losses. Of the 95 Canberra bombers that were assigned over their five and a half year period in Vietnam, 63 (two-thirds of the force) were lost. Most of the losses were sustained on single- and two-aircraft missions, and were the victims of ground fire. Battle damage was frequent, but the rugged structure of the aircraft held together remarkably well. Two disastrous events, marked by a pair of ground explosions separated by only six months, destroyed five and 10 B-57s respectively and caused the greatest devastation to the Canberra force.
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<hi style=hdr1>The 'Screaming Bird'</hi>
<p>Despite these losses, the aircraft performed admirably in combat and was one of the three best weapons-delivery aircraft for this type of work during that war, the other two being the McDonnell Douglas A-4 and Cessna A-37. They had the advantages of seemingly limitless staying time in the target area, and a large and varying bomb load for target selection, and they were very stable platforms for weapons delivery. The second set of eyes (of the navigator in the backseat) aided immeasurably. Interrogations of captured Viet Cong quickly revealed that the Canberra was one of the most dreaded aircraft overhead. They called it the 'screaming bird'. To them, 'it stayed over the target too long, and never ran out of bombs!'
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<p>As the American forces began disengaging from the war, the 13th Bomb Squadron was deactivated in 1967, and by late 1969 the B-57s of the 8th Bomb Squadron were also on their way out; the last left Phan Rang AB on 15 October.
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<p>This was not the last that the enemy would see of the B-57 Canberra bombers, however. Many of the assets of the 13th Bomb Squadron that had been returned to the United States were being converted into B-57G models. This version was developed to fill the requirement of a completely self-contained night attack system specifically designed to interrupt the flow of enemy resupply traffic.
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<p>Sixteen of these B-57Bs were modified by Martin Marietta to carry special equipment developed and installed by Westinghouse. When completed, the unusually shaped nose contained newly developed sensing and target-tracking systems. This consisted of a forward-looking radar, infra-red and low-light-level television sensors, plus a lasing device. This equipment became the electronic seeing eyes for the crew. Once the target was sighted, the pilot received direction from a heading indicator for target alignment. With the laser beam locked on the target, a 500-lb (227-kg) laser-guided bomb followed the beam to the target, usually with 15-ft (4.6-m) accuracy.
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<p>These B-57Gs of the reactivated 13th Bomb Squadron were based at Ubon AB in Thailand beginning in September 1970, as part of the 8th Tactical Fighter Wing. While the 11 aircraft assigned were there primarily as a test program of this sensing equipment in combat, they gave a good account of themselves in the night interdiction mission. Before having the use of electronic sensors now built into the B-57G Canberras, the aircraft had been no better at picking up targets in the dark than the human eyes of the pilot. Only then, after 15 years of service and with this completely self-contained night attack system specifically designed to interrupt enemy supply lines, was the B-57 able satisfactorily to perform the night intruder mission for which it was originally intended. In Stateside trials, one B-57G was fitted with the Pave Gat system, with a downward-firing three-barrel 20-mm cannon housed in the weapons bay. This gunship configuration never reached the war zone.
<item><hi format=bold>Powerplant:</hi> two Wright J65-W-5F turbojets, each rated at 7,200 lb thrust
<item><hi format=bold>Performance:</hi> maximum speed 598 mph at 2,500 ft; service ceiling 40,100 ft; range 2,300 miles
<item><hi format=bold>Weights:</hi> empty 27,090 lb; maximum take-off 58,800 lb
<item><hi format=bold>Dimensions:</hi> wing span 64 ft 0 in; length 65 ft 6 in; height 15 ft 7 in; wing area 960 sq ft
<item><hi format=bold>Armament:</hi> eight 0.5-in machine-guns or four 20-mm cannon in nose; up to 5,200 lb of bombs in internal bay and up to 4,000 lb of stores on underwing hardpoints
<item><hi format=bold>Powerplant:</hi> two Pratt & Whitney TF33-P-11A turbofans rated at 16,500 lb thrust each and two Pratt & Whitney J60-P-9 turbojets rated at 2,900 lb thrust each
<item><hi format=bold>Performance:</hi> maximum speed 483 mph at 63,500 ft; service ceiling 64,000 ft; range 3,910 miles
<item><hi format=bold>Weights:</hi> empty 36,876 lb; maximum take-off 63,000 lb
<item><hi format=bold>Dimensions:</hi> wing span 122 ft 5 in; length 68 ft 8 in; height 20 ft 5 in; wing area 2,000 sq ft
