Northrop F-5B

The F-5B is the two-seat version of the F-5A Freedom Fighter. The approach was simple: take the tandem cockpit of the T-38 Talon trainer and fit it to the fighter's airframe, keeping the single-seater's external stores stations, leading-edge extensions and larger air intakes. What did not carry over were the two nose cannon, given up to make room for the second seat. The result was a conversion trainer that remained combat-capable, something the second-generation F-5F would later improve on by regaining one M39 cannon thanks to a lengthened nose.

The F-5B prototype first flew on 24 February 1964. Northrop built 200, alongside the single-seat F-5As and the RF-5A reconnaissance aircraft; the two-seaters later licence-built in Canada and Spain carry their own designations (CF-5D, NF-5B, SF-5B) and are not part of that figure.

The F-5B was literally the first F-5 in service. The first five were taken on in April 1964 by the 4441st Combat Crew Training Squadron at Williams Air Force Base, Arizona, which added seven F-5As in August. Although the squadron belonged to the USAF, its sole task was to train pilots and ground crews from customer nations, and the aircraft, despite their US markings, actually belonged to the Military Assistance Program states. The first course graduated in March 1965 with pilots from Iran and South Korea.

Airframe 72-0441, now at the Pima Air & Space Museum in Tucson, sums up that school life. It was built by Northrop at Palmdale and delivered to the USAF on 10 November 1972, joined the 58th Tactical Fighter Training Wing at Williams, moved in August 1979 to the 405th Tactical Training Wing at the same base, and in May 1984 became a ground training airframe designated GF-5B. In July 1984 it went to the Inter-American Air Force Academy at Albrook, Panama, in October 1989 to Homestead, Florida, and since May 2001 it has been on loan to the museum from the National Museum of the United States Air Force. The museum gives the type a wingspan of 7.70 m, a length of 14.12 m, a height of 3.99 m, a loaded weight of 9,379 kg, a maximum speed of 1,424 km/h and a service ceiling of 15,850 m, with two General Electric J85-GE-13 turbojets of 4,080 lbf (18.1 kN) thrust each.

Almost every F-5A operator received the two-seater with its first batches. Iran, the first export customer, received its first eleven F-5As and two F-5Bs in February 1965, declared operational that June; when it re-equipped with the F-5E it sold much of its A and B fleet, but kept several F-5Bs for training. Taiwan received two F-5Bs with its first 1965 batch and was operating eleven by 1971. South Korea received 30, Greece 20 within a fleet of about 120 F-5s flown from 1965 to 2002, and Saudi Arabia 20 between 1974 and 1985. Norway received 14 among its 108 Freedom Fighters; Ethiopia two alongside ten F-5As from 1966; Morocco another two; the Philippines three between 1965 and 1967, adding an ex-Taiwanese F-5B in 1989; and South Vietnam eight trainers. Malaysia took two alongside its F-5Es in 1975 and in 1982 transferred them to Thailand, where the type is designated B.Kh.18K. Brazil ordered six F-5Bs with its 36 F-5Es in October 1974 and retired the remaining five in 1990; FAB-4805 is displayed at Santa Cruz Air Force Base.

In Spain the F-5B shaped the programme from the start. During the evaluation an F-5B crashed near Torrejón, killing both occupants, a Northrop pilot and an Ejército del Aire pilot. Of the 70-aircraft contract, most of them built by CASA at Getafe, the first delivery came on 19 June 1969 and consisted entirely of two-seaters: two F-5Bs for Escuadrón 202 at Morón de la Frontera, with the F-5A and RF-5A following later. The F-5B was assigned to Ala 73 at Talavera la Real for training, and two were detached to Escuadrón 464 at Gando, in the Canary Islands, until the Mirage F1EE replaced the F-5s there in 1982. In 1989 an F-5B crashed after the structural failure of a wing and the entire fleet was grounded while crews searched for signs of fatigue. The surviving two-seaters were later modernised as the F-5BM (Spanish designation AE.9), a variant with its own page.

In several countries the two-seater outlived its single-seat stablemates. In 1979 Saudi Arabia transferred four F-5Bs to North Yemen, and on the night of 29–30 March 2015 at least one was destroyed on the ground at Sanaa airport by Saudi air strikes; even so, Yemen still had two F-5Bs operational in 2023. In Turkey, two F-5Bs upgraded to the 2000 standard still fly with the Turkish Stars aerobatic team. In Norway, eight F-5Bs were still for sale in 2011; two of them, stored in the United States, were approved for sale to Ross Perot Jr. in 2008, a deal the US government blocked until 2015. In Miami, 63-8447 is displayed fully chromed at the Phillip and Patricia Frost Museum of Science.

One F-5B also played a part beyond its trainer role: fitted with a 5,000 lbf (22.2 kN) General Electric J85-GE-21 engine, it served as the YF-5B prototype for the future F-5E Tiger II. That airframe was the testbed for the powerplant that would define the family's second generation.