The Northrop F-5 is a family of supersonic light fighter aircraft initially designed as a privately funded project in the late 1950s by Northrop Corporation. There are two main models: the original F-5A and F-5B Freedom Fighter variants, and the extensively updated F-5E and F-5F Tiger II variants. The design team wrapped a small, highly aerodynamic fighter around two compact and high-thrust General Electric J85 engines, focusing on performance and a low cost of maintenance. Smaller and simpler than contemporaries such as the McDonnell Douglas F-4 Phantom II, the F-5 costs less to procure and operate, making it a popular export aircraft. Though primarily designed for a day air superiority role, the aircraft is also a capable ground-attack platform. The F-5A entered service in the early 1960s. During the Cold War, over 800 were produced through 1972 for US allies. Despite the United States Air Force (USAF) not needing a light fighter at the time, it did procure approximately 1,200 Northrop T-38 Talon trainer aircraft, which were based on Northrop's N-156 fighter design.