Unsolicited Concepts

Initially intended to serve a need that Northrop perceived for a cheap, lightweight and supersonic fighter that could operate from short runways. The USAF had no need for such a fighter at that time but since it needed a two-seat trainer to replace the Lockheed T-33 Shooting Star, Northrop pushed ahead designing an aircraft to meet this role, and delivered the T-38 Talon.

This complete, Northrop continued privately with its program to develop a lightweight fighter, and based it strongly around the T-38. When the USAF inspected a mockup in 1958 they saw the F-5 as a great opportunity for exports to countries who could not afford the more sophisticated fighters the United States was currently using.

Continuing with the venture (having taken an order from the USAF for three prototypes and a static test airframe), Northrop entered discussions with many overseas manufacturers about producing the F-5 under license. Although European manufacturers chose the Lockheed F-104 Starfighter instead, licenses to produce the F-5 were eventually sold to companies in Canada, Switzerland, Taiwan and South Korea.

The USAF takes on the F-5

In 1962 the USAF announced it would be using the F-5A/B for its Military Assistance Program (MAP) - in effect a discount program for American allies to purchase military hardware. The F-5A was seen as suitable due to its simplicity (or low sophistication, as one might choose to term it) - it had and has no fly-by-wire system, and was optimised for an air-to-ground role, with no fire control radar and only a basic optical aiming system for weapons. Added to this, it had no guns installed. Subsequent to the F-5's acceptance into MAP, prototypes underwent extensive flight testing. As a result the powerplants were upgraded. Initially the F-5As were powered by two General Electric J85-GE-5 afterburning turbojets (which themselves replaced non-afterburning - or 'dry' - YJ85-GE-1 turbojets that were installed in the first F-5). After testing these were replaced with uprated J85-GE-13 turbojets. These offered around 15% more thrust, producing 3050lbs dry and 4080lbs at afterburn. As well as this, the wing structure and undercarriage were strengthened to support a wider variety of payloads and payload configurations.

The USAF requested 200 F-5As for use in Vietnam, due to higher than expected rates of attrition. Although in this role it was the lightest, least sophisticated and most lightly-armed aircraft of those in use (the other workhorses being the F-4 Phantom and the F-105 Thunderchief) it turned out to be the least vulnerable, due to its ability to dodge ground fire during attack runs.

Modifications

Noting the F-5's relatively poor air-to-air combat performance, Northrop took design steps to improve things. The F-5E, the most notable re-issue of the F-5, was the result. The proposal for this was actually unsolicited as far as the USAF was concerned, but after the installation of the more powerful versions of the J85 turbojets (the J85-GE-21) in the late model F-5As it was agreed that these engines would, as Northrop suggested, work much better in a new variant of the F-5.

The USAF announced a competition for an International Fighter Aircraft to succeed the F-5A, whose production run was concluding. Northrop also suggested the F-5E concept to them at around this time. The competition placed an emphasis on aircraft fulfilling an air superiority rather than a tactical fighter role. The F-5E won the contract, beating off competition from Vought, Lockheed, and McDonnell Douglas.

The F-5E was longer and wider than the F-5A, partly due to the more powerful engines but also to increase fuel capacity and enhance survivability (the larger fuel tanks were lined with reticulated foam). The performance of the F-5E was pretty much universally superior to the F-5A/B. Its turn rate was higher (sustained and instantaneous), and its turn radius was substantially smaller. Climbing from sea-level was quicker, as was the top speed at mach 1.6 (the F-5A/B was capable of mach 1.4). Interestingly the replacement nose landing gear shortened the aicraft's takeoff run because it was larger the original and thus increased the angle of attack of the wings whilst on the ground.

The F-5E's first flight was in 1972. It experienced great export success, with buyers including Iran, Saudi Arabia and Brazil. It became known as the 'Tiger II', referring to the name 'Tiger' that the F-5A acquired in Vietnam during its participation in the 'Skoshi Tiger' program. A further development of the F-5, the F-5G (also known as the F-20 Tigershark), never found buyer success.

International Service

More than 2000 F-5s of various variants have been supplied by the USAF to nations allied with the United States. 799 were F-5As, and 1166 were F-5E Tiger IIs. The remainder were manufactured under license. The F-5 has never actually had widespread use with the USAF itself. However, because it shares many flight characteristics with the Russian MiG-21, the F-5E has had consistent duties simulating aggressors for pilot training, and several squadrons of F-5Es exist for that sole purpose. In fact it was F-5Es that took the role of the (entirely fictional) 'MiG-28' in the film 'Top Gun'.

• Baugher, Joe; "Northrop F-5";
  <http://www.fitertown.com/f5/history.html>
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