Northrop F-5
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 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 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.
After winning the International Fighter Aircraft Competition, a program aimed at providing effective low-cost fighters to American allies, in 1972 Northrop introduced the second-generation F-5E Tiger II. This upgrade included more powerful engines, larger fuel capacity, greater wing area and improved leading-edge extensions for better turn rates, optional air-to-air refueling, and improved avionics, including air-to-air radar. Primarily used by American allies, it remains in US service to support training exercises. It has served in a wide array of roles, being able to perform both air and ground attack duties; the type was used extensively in the Vietnam War. A total of 1,400 Tiger IIs were built before production ended in 1987. More than 3,800 F-5s and the closely related T-38 advanced trainer aircraft were produced in Hawthorne, California. The F-5N/F variants are in service with the United States Navy and United States Marine Corps as adversary trainers. Over 400 aircraft were in service as of 2021.
The F-5 was also developed into a dedicated reconnaissance aircraft, the RF-5 Tigereye. The F-5 also served as a starting point for a series of design studies which resulted in the Northrop YF-17 and the F/A-18 naval fighter aircraft. The Northrop F-20 Tigershark was an advanced variant to succeed the F-5E which was ultimately canceled when export customers did not emerge.
Design and development
Origins
The design effort was led by Northrop vice president of engineering and aircraft designer Edgar Schmued, who previously at North American Aviation had been the chief designer of the successful North American P-51 Mustang and F-86 Sabre fighters. Schmued recruited a strong engineering team to Northrop.In December 1953, NATO issued NBMR-1, calling for a lightweight tactical fighter capable of carrying conventional and nuclear weapons and operating from rough airfields. In late 1954, a Northrop team toured Europe and Asia to examine both the NBMR-1 and the needs of SEATO members. From this tour, Schmued gave his team the goal of reversing the trend in fighter development towards greater size and weight in order to deliver an aircraft with high performance, enhanced maneuverability, and high reliability, while still delivering a cost advantage over contemporary fighters. Recognizing that expensive jet aircraft could not viably be replaced every few years, he also demanded "engineered growth potential" allowing service longevity in excess of 10 years.
The design began to firm up in 1955 with the introduction of the General Electric J85 turbojet engine. Originally developed for McDonnell's ADM-20 Quail decoy for use on the Boeing B-52 Stratofortress, the J85 had a thrust-to-weight ratio of 6.25 to 7.5 depending on the version, giving it a notable advantage over contemporaries such as the 4.7 ratio of the J79 engine used in the F-4 Phantom.
Design evolution
Using a pair of J85s as the baseline, the team began considering a series of prospective designs. Among the earliest concepts was the N-156TX of March 1955. This mounted the engines in pods, one under each wing about mid-span. The fuselage was quite slim compared to the final design, with a crew of two under a narrow cockpit canopy.That year, the US Navy expressed an interest in a fighter to operate from its escort carriers, which were too small to operate the Navy's existing jet fighters. Northrop responded with a radical redesign, PD-2706, which placed the engines against the fuselage in short ducts exiting in front of the tail area, like the F-4, and moved the elevator up to form a T-tail. The resulting design had a much shorter fuselage and was quite compact. Development along these lines ended when the Navy decided to withdraw the escort carriers. Northrop continued development of the N-156, both as a two-seat advanced trainer, designated as N-156T, and a single-seat fighter, designated as N-156F.
Another highly influential figure was chief engineer Welko Gasich, who convinced Schmued that the engines must be located within the fuselage for maximum performance. This led to the January 1956 PD-2812 version which began to look a lot like the final product, although this version had a long-span low-mounted elevator with notable anhedral. March 1956's PD-2832 moved to a more conventional elevator and had a strongly swept vertical stabilizer. The design underwent several further versions over the next year which experimented with different nose designs and continued to lengthen the fuselage. The final design, PD-2879D, emerged in December 1956.
Gasich also introduced the concept of "life cycle cost" into fighter design, which provided the foundation for the F-5's low operating cost and long service life. A Northrop design study stated "The application of advanced technology was used to provide maximum force effectiveness at minimum cost. This became the Northrop philosophy in the development of the T-38 and F-5 lightweight trainer and fighter aircraft."
Into production
The N-156T was quickly selected by the United States Air Force as a replacement for the T-33 in July 1956. On 10 April 1959, the first prototype aircraft, which was subsequently designated as YT-38 Talon, performed its first flight. By the time production had ended in January 1972, a total of 1,189 Talons had been produced. Development of the N-156F continued at a lower priority as a private venture by Northrop; on 25 February 1958, an order for three prototypes was issued for a prospective low-cost fighter that could be supplied under the Military Assistance Program for distribution to less-developed nations. The first N-156F flew at Edwards Air Force Base on 30 July 1959, exceeding the speed of sound on its first flight.Although testing of the N-156F was successful, demonstrating unprecedented reliability and proving superior in the ground-attack role to the USAF's existing North American F-100 Super Sabres, official interest in the Northrop type waned, and by 1960 it looked as if the program was a failure. Interest revived in 1961 when the United States Army tested it, for reconnaissance and close-support. Although all three types proved capable during army testing, operating fixed-wing combat aircraft was legally the responsibility of the Air Force, which would not agree to allow the Army to operate fixed-wing combat aircraft, a situation repeated with the C-7 Caribou.
In 1962, the Kennedy Administration revived the requirement for a low-cost export fighter, selecting the N-156F as winner of the F-X competition on 23 April 1962, subsequently becoming the "F-5A", and was ordered into production in October that year. It was named under the 1962 United States Tri-Service aircraft designation system, which included a re-set of the fighter number series. Northrop manufactured a total of 624 F-5As, including three YF-5A prototypes, before production ended in 1972. A further 200 F-5B two-seat trainer aircraft, lacking nose-mounted cannons but otherwise combat-capable, and 86 RF-5A reconnaissance aircraft, fitted with four-camera noses, were also built. In addition, Canadair built 240 first generation F-5s under license, CASA in Spain built 70 more aircraft.
The Royal Norwegian Air Force placed the first international order on 28 February 1964.
F-5E and F-5F Tiger II
In 1970, Northrop won the International Fighter Aircraft competition to replace the F-5A, with better air-to-air performance against aircraft like the Soviet MiG-21. The resulting aircraft, initially known as F-5A-21, subsequently became the F-5E. It had two more powerful GE J85-21 engines, each with dry thrust and in afterburner, and had a lengthened and enlarged fuselage to accommodate more fuel. Its wings were fitted with enlarged leading edge extensions, giving an increased wing area and improved maneuverability. The aircraft's avionics were more sophisticated, crucially including a radar . It retained the gun armament of two M39 cannons, one on either side of the nose of the F-5A. Various specific avionics fits could be accommodated at a customer's request, including an inertial navigation system, TACAN and ECM equipment. Additionally the two position nose landing gear from the Canadian CF-5 was incorporated to reduce takeoff distance.The first F-5E flew on 11 August 1972. A two-seat combat-capable trainer, the F-5F, was offered, first flying on 25 September 1974, at Edwards Air Force Base, with a new nose, that was three feet longer, which, unlike the F-5B that did not mount a gun, allowed it to retain a single M39 cannon, albeit with a reduced ammunition capacity. The two-seater was equipped with the Emerson AN/APQ-157 radar, which is a derivative of the AN/APQ-153 radar, with dual control and display systems to accommodate the two-men crew, and the radar has the same range of AN/APQ-153, around 10 nmi. On 6 April 1973, the 425th TFS at Williams Air Force Base, Arizona, received the first F-5E Tiger II.
A reconnaissance version, the RF-5E Tigereye, with a sensor package in the nose displacing the radar and one cannon, was also offered.
The F-5E eventually received the official name Tiger II; 792 F-5Es, 146 F-5Fs and 12 RF-5Es were eventually built by Northrop. More were built under license overseas: 91 F-5Es and F-5Fs in Switzerland, 68 by Korean Air in South Korea, and 308 in Taiwan.
The F-5E proved to be a successful combat aircraft in service with US allies, but had no combat service with the US Air Force, though the F-5A with modifications, designated F-5C, was flown by the US in Vietnam. The F-5E evolved into the single-engine F-5G, which was rebranded the F-20 Tigershark. It lost out on export sales to the F-16 Fighting Falcon in the 1980s.