In March 1951, the USAF contracted Martin to build the British Canberra under license in the United States, designation B-57 Canberra
During the Vietnam War, the US used a large number of bombers for air raids, few remember the B-57, because it was completely overshadowed by the B-52 Stratofortress. Ironically, the B-57s were originally brought to Vietnam to serve reconnaissance missions, not attack. It was not until Operation Rolling Thunder in 1964, the US sent B-57 bombers to carry out air strikes against North Vietnam.
After the Korean War, the United States Air Force searched for a jet-powered medium bomber to quickly replace the aging, propeller-driven Douglas B-26 Invader. In March 1951, the USAF contracted Martin to build the British Canberra under license in the United States, designation B-57 Canberra. The B-57 made its maiden flight in July 1953 and by the end of production in 1959, a total of 403 Canberras had been produced for the US Air Force.
The B-57B is a definitive production version of the Martin B-57 with an external length of 65 ft 6 in (20.0 m), a height of 14 ft 10 in (4.52 m), and a Wingspan of 64 ft 0 in (19.5 m). It featured a fighter-style canopy and has a tandem cockpit that seats a pilot and a navigator. The empty weight is 27,090 lb (12,285 kg), and the maximum takeoff weight is 53,720 lb (24,365 kg).
The B-models brought about use of four underwing hardpoints in addition to the internal bomb bay and relocation of the airbrakes from the wings to the fuselage. Standard armament included 8 x 0.50 caliber M2 Browning heavy machine guns. The bomb bay held up to 4,500lbs of ordnance while the four external hardpoints managed up to 2,800lbs of ordnance. The underwing hardpoints also support the launching of unguided rockets.
As a tactical bomber and reconnaissance aircraft, the B-57 was powered by two Wright J65-W-5 turbojets, with 7,220 lbf (32.1 kN) thrust each. It can achieve a top speed of 598 mph (960 km/h), a range of 950 mi (1,530 km), a service ceiling of 45,100 ft (13,745 m), and a rate of climb of 6,180 ft/min (31.4 m/s).
Although intended as a bomber and never before deployed by the USAF to a combat zone, the first B-57s to be deployed to South Vietnam were not operated in an offensive role. The need for additional reconnaissance assets, especially those capable of operating at night. Dedicated versions were produced and served as high-altitude aerial reconnaissance platforms (the Martin RB-57D Canberra), and as electronic warfare aircraft.
The B-57 Canberra was also sold to export customers abroad; further combat use was seen by the Pakistani Air Force during the Indo-Pakistani War of 1965 and the Indo-Pakistani War of 1971.
In 1983, the USAF opted to retire the type; the B-57 Canberra’s retirement marked the ending of the era of the tactical bomber. The three remaining flightworthy WB-57Fs are technically assigned to the NASA Johnson Space Center, next to Ellington Field in Houston, as high-altitude scientific research aircraft, but have also been used for testing and electronic communications in the U.S. and Afghanistan.