The Martin B-57 Canberra is an American-built, twin-engined tactical bomber and reconnaissance aircraft that entered service with the United States Air Force (USAF) in 1953.

Initial Martin-built models were virtually identical to their British-built twinjet counterparts; Martin later modified the design to incorporate larger quantities of US-sourced components and produced the aircraft in several variants.

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.

The existing inventory of piston-engined Douglas B-26 Invaders had been dispatched in this capacity at the very start of the conflict; within a few months in the theatre, the B-26 had suffered a very high rate of attrition and successes with the type were typically limited.

[2] The USAF requested that the British government provide a private demonstration of the English Electric Canberra, a newly developed jet-powered bomber.

[2] On 16 September 1950, the USAF formally issued a request for a jet-powered bomber; the sought aircraft had to possess a top speed of 630 mph (1,010 km/h), ceiling of 40,000 ft (12,000 m), and range of 1,150 mi (1,850 km).

Aviation authors Bill Gunston and Peter Gilchrist commented that "It seems likely that this first batch of trials convinced the Americans that the Canberra was ideal for the job, but in order to satisfy the US Senate a competitive evaluation of all likely contenders had to be arranged".

On 21 February 1951, a Canberra B.2 (WD932), flown by Roland Beamont, made the transatlantic journey, arriving in the United States to participate in the competition; by making this journey, the Canberra became the first jet aircraft to perform a non-stop unrefueled flight across the Atlantic Ocean, travelling from Warton, England, to Gander, Newfoundland and Labrador, Canada, in the record time of 4 hours 37 minutes.

[2] In March 1951, many of these questions were answered; with production lines already at full capacity meeting Royal Air Force orders and those emerging from other export customers, English Electric entered into discussions with Glenn L. Martin Company.

[5] One noticeable exception was the adoption of more powerful Armstrong Siddeley Sapphire engines capable of producing 7,200 lbf (32 kN) of thrust, which were license-built in the United States as the Wright J65.

Having a more lengthy development time, this model incorporated the structural and system changes that had been recommended by WADC, which resulted in the aircraft being more adaptable than its B-57A predecessor.

[5] Of the external changes, the most significant was the adoption of a fighter-style canopy accompanied by a flat-panel windshield and a tandem seating arrangement, providing for greater transparency and an improved view for both the pilot and navigator, as well as allowing it to be equipped with a gunsight.

In terms of armaments, a total of four hardpoints attached to the outer wing panels were installed on this variant, capable of mounting external bombs and rockets.

Gunston and Gilchrist stated of the consequences to the program: "This was clearly not the manufacturer's fault, but the money effectively ran out after 177 of the planned 250-aircraft order had been completed".

[11] In 1954, in response to the sound performance offered by the B-57B, the USAF elected to place a large second order; this included a further 100 B-57B bombers, 38 B-57C trainers, and 20 RB-57D high-altitude reconnaissance aircraft.

[11] In 1969, in response to demands for a capable night interdiction aircraft for combat operations in Southeast Asia, a total of 16 B-57B Canberras were substantially rebuilt during a lengthy upgrade program.

A laser rangefinder/designator was also installed, and the wing pylons modified to accommodate laser-guided Paveway bombs, while all the guns were removed to save weight.

Particularly contentious were the cockpit arrangement and the lack of guns, the Canberra having been designed as a high-speed, high altitude bomber rather than for close air support.

The USAF came to consider the B-57B as being inadequate for the night intruder role and thus Martin put all aircraft through an extensive avionics upgrade in response.

A number of modified RB-57As were used by the 7499th Support Group at Wiesbaden AB, West Germany in Operation "Heart Throb" reconnaissance missions over Europe.

[21] In 2011 it was determined that a third aircraft was needed to satisfy mission requirements and an additional WB-57 was removed from the 309th AMARG after over 40 years at Davis-Monthan AFB and returned to flight status in August 2013 as NASA 927.

The Detachment flew nighttime reconnaissance missions to identify Viet Cong (VC) base camps, small arms factories and storage and training areas.

The nighttime imagery showed VC training and base camps; small, hidden factories and storage dumps that RF-101 Voodoo crews had flown over during the day and had been unable to locate from the air.

The United States began Operation Steel Tiger over the Laos Panhandle and the Vietnamese Demilitarized Zone (DMZ) on 3 April 1965, to locate and destroy enemy forces and materiel being moved southward at night into South Vietnam, and to fly bomb damage assessment reconnaissance runs over targets attacked in the secret war the United States fought there.

[27] The deployment of actual combat capable B-57Bs from 8th and 13th Bomb Squadrons to Bien Hoa Air Base in August 1964 began with two aircraft lost and one damaged in collisions on arrival.

In April, Canberras began flying night intruder missions supported by USAF's Fairchild C-123 Provider or C-130 Hercules flare ships and USN's EF-10B Skyknight electronic warfare aircraft.

These weapons combined with their bomb loads and four hours of flight time made them excellent ground support aircraft, as well as exceptional truck killers along the Ho Chi Minh trail.

[31] On 16 May 1965, an armed B-57B exploded on the runway at Biên Hòa, setting off a chain reaction that destroyed 10 other Canberras, 11 Douglas A-1 Skyraiders, and one Vought F-8 Crusader.

[35] An attempt to combine both led to one B-57G being modified to house a special bomb bay installation of one Emerson TAT-161 turret with a single M61 20mm cannon as a gunship under project Pave Gat.

Deployment to SEA was resisted, however, by the Seventh and Thirteenth Air Forces and others as the decision had been made in August 1971 to return the B-57G squadron to the U.S. in early 1972, leaving insufficient evaluation time.