The Northrop F-20 Tigershark (initially F-5G) was a privately financed fighter aircraft, designed and built by Northrop in the USA, starting in 1975 and offered for sale starting in the 1980s and formally ending in the early 1990s.
It began as a further evolution of Northrop's F-5 Freedom Fighter/Tiger II, although ultimately it shared little more than a strong family resemblance to that aircraft.
It was originally designated F-5G, which was approved by the USAF in May 1981. The initial request for F-20 was initially turned down in 1982, the USAF proposing F-19 which ended up not being used at all. The USAF gave approval for F-20 designation use in November 1982 and of the extra name Tigershark in March 1983.
The main change was the replacement of the F-5's two General Electric J85 engines with a single General Electric F404 turbofan, increasing its total thrust by 60%. Like the F-5, however, it was designed as a low-cost, high-performance fighter plane that was easy to maintain. It could reach speeds of Mach 2.1 and had a ferry range of 1,715 miles (2,760 km). The aircraft was armed with General Electric AN/APG-67 radar that offered significant performance improvement over the original Emerson AN/APQ-159 radar of the original F-5E/F.
The F-20 made its first flight on August 30, 1982, and a total of three prototypes were created. It was intended for sale to foreign countries and militaries, but the market for the plane never developed, as President Ronald Reagan relaxed the restrictions on selling fighters such as the F-16 Fighting Falcon to other countries. Also, the fact that the United States government had not placed an order for the aircraft had a large effect on the decisions of other countries to buy the F-20 or not. The Pakistan Air Force was offered the F-20 and A-10 Thunderbolt II, but insisted on choosing the F-16 because it was felt that it would give them a technological advantage.
After six years and no major buyers, Northrop cancelled the $1.2 billion project. Air forces that could afford the F-20 bought the F-16, while ones which could buy neither, purchased the cheaper F-5E/F Tiger II or the Russian MiG-21. While its performance was comparable to the Block 1/5/10 F-16 and superior to the turbojet-powered export-variant F-16/79, the F-20 airframe had virtually no remaining expansion capability, as it was built on essentially a 20 year old airframe at the limits of its capabilities. The F-20's low-set wing and wing-mounted undercarriage also limited the size and number (four underwing hardpoints on the F-20 vs. six on the F-16) of underwing stores that could be used; whereas the F-16 would often be seen with very large stores. The F-16 was a brand-new jet that had not even begun to approach its eventual capabilities. There was speculation within the F-20 development team that the US Air Force influenced foreign militaries to buy the F-16, in order to make spare parts more available.
The last existing F-20 is on display at the California Science Center. The other two prototypes were lost due to crashes during world sales tours. The crashes were caused by pilot error, and were not linked to any malfunction of the planes.
Aerospace legend Chuck Yeager, who worked as a spokesperson for Northrop during the F-20's development, frequently touted the plane and was regularly featured in its advertising.