"F-20" redirects here. For other uses, see F20
The Northrop F-20 Tigershark (initially F-5G) was a privately financed light fighter, designed and built by Northrop. Its development began in 1975 as a further evolution of Northrop's F-5E Tiger II, featuring a new engine that greatly improved overall performance, and a modern avionics suite including a powerful and flexible radar. Compared with the F-5E, the F-20 was much faster, gained beyond-visual-range air-to-air capability, and had a full suite of air-to-ground modes capable of firing most U.S. weapons. With these improved capabilities, the F-20 became competitive with contemporary fighter designs such as the General Dynamics F-16 Fighting Falcon, but was much less expensive to purchase and operate.
Much of the F-20's development was carried out under a US Department of Defense (DoD) project called "FX". FX sought to develop fighters that would be capable in combat with the latest Soviet aircraft, but excluding sensitive front-line technologies used by the United States Air Force's own aircraft. FX was a product of the Carter administration's military export policies, which aimed to provide foreign nations with high quality equipment without the risk of US front-line technology falling into Soviet hands. Northrop had high hopes for the F-20 in the international market, but policy changes following Ronald Reagan's election meant the F-20 had to compete for sales against aircraft like the F-16, the USAF's latest fighter design. The development program was abandoned in 1986 after three prototypes had been built and a fourth partially completed.
When the Kennedy administration entered office in 1961, the U.S. Department of Defense was instructed to find an inexpensive fighter aircraft that the United States could offer to its allies through the Mutual Defense Assistance Act. A number of designs were studied, including stripped-down versions of the Lockheed F-104 Starfighter and Vought F-8 Crusader, and the newly designed Northrop N-156F. On 23 April 1962, the United States Air Force (USAF) informed the United States Secretary of Defense that the N-156F had been selected, under the designation F-5 and given the name "Freedom Fighter." 847 F-5's of various early marks would be produced.
As the Mikoyan-Gurevich MiG-21 became more common, the U.S. Air Force initiated the International Fighter Aircraft (IFA) program to provide an equivalent to allies. The USAF desired a light weight fighter with competitive performance to the MiG, inexpensive when purchased in large numbers, and with reasonable operating costs for prospective customer nations. Although numerous companies entered designs, Northrop's existing F-5 put them in a leading position. They submitted an upgrade, the F-5E Tiger II, with the AN/APQ-153radar and other changes to allow the AIM-9 Sidewinder missile to be fired from wing-tip rails. On 20 November 1970, Northrop's entry was announced as the IFA winner. Northrop produced a total of 1,399 F-5E/F Tiger IIs by the time manufacturing ended in 1986.
F-5G and export limitations
In the late 1970s, the Republic of China (Taiwan) Air Force started looking for a fighter aircraft to match improvements made in mainland People's Republic of China (PRC)'s air force. In particular, they wanted a platform capable of firing the AIM-7 Sparrow long-range missile. At the time, the US was in the process of opening up ties with the People's Republic of China after President Nixon's famous visit in 1972. China considered US support of Taiwan against their interests, and the US State Department wanted to tread carefully. They blocked export of all of the AIM-7 capable aircraft, even otherwise outdated early models of the McDonnell Douglas F-4 Phantom II. The State Department suggested the Israeli IAI Kfir instead; however, it was rejected. Taiwan was already producing the F-5E under license, so the Department of Defense asked Northrop to study adding an AIM-7 capable radar to the Tiger II as an alternative. This effort became the first of several F-5G studies.
In the spring of 1977, Jimmy Carter's administration had announced a new military export policy that limited sales of front line designs to countries within NATO, along with Australia and Japan. Carter stated at the time that the U.S. could not be "both the world's champion of peace and the world's leading supplier of the weapons of war." Previously, there was no coherent export policy, fueling concerns that the US's latest technologies might quickly end up in Soviet hands.
Numerous exceptions were made; Israel and Egypt could buy advanced designs under the Camp David Agreements, Israel was even allowed to buy McDonnell Douglas F-15 Eagles, a key component in U.S. air-defense technology. Iran was already receiving the Grumman F-14 Tomcat, and this demonstrated the problem with advanced exports in February 1979 when reports emerged that Iran had sold an AIM-54 Phoenix missile to the Soviets. South Korea's F-16 order was initially blocked under this policy, but later allowed in the context of strengthening relations. Despite exceptions, the export policy was implemented, covering many potential and current customers. As the F-5G was a relatively modest upgrade to the F-5E, the F-5G appeared to be in a strong position for sales given the limitations placed on rival designs, however Carter personally blocked the sales of the F-5G to Taiwan.
In 1979, problems with the export policy were becoming apparent. The Soviets continued to sell newer aircraft designs to their clients, placing allies of the U.S. at a disadvantage. Denied by the U.S., countries were turning to other vendors for modern fighters, notably France's Dassault Mirage 2000. Barry N. Blechman, Assistant Director of the Arms Control and Disarmament Agency, testified that the US reductions in foreign arms transfers had actually encouraged other nations and increased worldwide arms sales. At the same time, there was considerable pressure to provide a suitable aircraft for Taiwan.
The State Department argued that the U.S. needed a modern counterpart for the role the F-5E had occupied in the 1960s and 1970s. In light of Carter's concerns, they suggested that a new aircraft be designed for the role, based on technology that would not pose a threat to the U.S. After a lengthy study, in January 1980, President Carter allowed the development of a new export fighter: "FX." The FX would have to outperform the F-5E; however, it could not use any advanced avionics systems that were also used in US aircraft. Unlike the Mutual Defense Assistance Act programs that led to the F-5E, FX would be entirely privately financed. Moreover, the companies could not market the aircraft directly; all sales would be handled by the Secretary of Defense.
Both Northrop and General Dynamics (GD) responded to the FX requirement. GD's F-16/79 was a variant of the F-16A, replacing the Pratt & Whitney F100 turbofan engine with the J79 turbojet and equipping it with downgraded avionics; Northrop responded with the F-5G.
FX stumbles and F-20 emerges
When Ronald Reagan's administration took power in 1981, the export restrictions put in place by the Carter administration were slowly relaxed. At first, the FX program continued as normal, but a number of events eroded the value of the program and limit the F-5G's potential sales. The signing of the 1982 US-PRC Joint Communiqué was a major agreement on arms sales, which continued blocking sales of the F-5G to Taiwan. By this point the Taiwanese had started their own light-fighter project, the AIDC F-CK-1 Ching-kuo. In signing the Communiqué, the U.S. was signaling that Taiwan would not receive modern aircraft, therefore the Ching-kuo became Taiwan's primary focus. As a result, the F-5G's sales potential remained unestablished.
In the summer of 1982, Deputy Secretary of Defense Frank Carlucci sent a memorandum to the Air Force and Navy, encouraging them to seek out potential foreign customers to procure FX aircraft. However, four months later Carlucci sent a classified memo to the same services to abandon the FX, and green-lighting the exporting of front-line fighters overseas. In December, after prompting from the White House, Carlucci reversed his position again, and directed the Air Force to fund a small number of F-20s in the fiscal year 1984 budget.
The future of the FX program seemed doubtful. Following an agreement to sell F-16s to Pakistan, Northrop felt that the F-5G needed to match the performance of F-16. This would require not only better performance from the engine, but a new and comparable avionics suite as well. Northrop saw that the F-5G was still being viewed as the "FX fighter", a low-cost option for second-tier air forces. To combat this perception, Northrop requested the designation "F-20"; the USAF approved in late 1982, and of the name Tigershark in March 1983.