Northrop F-5

F-5A/B Freedom Fighter F-5E/F Tiger II
An F-5E of the Swiss Air Force
General information
Type	Light fighter
National origin	United States
Manufacturer	Northrop Corporation
Status	In service
Primary users	United States Navy Republic of China Air Force (historical) Republic of Korea Air Force Islamic Republic of Iran Air Force
Number built	A/B/C/D: 1,204 E/F: 1,399
History
Manufactured	1959–1987
Introduction date	1964
First flight	F-5A: 30 July 1959 F-5E: 11 August 1972
Developed from	Northrop T-38 Talon
Variants	Canadair CF-5 Shaped Sonic Boom Demonstration
Developed into	Northrop YF-17 Northrop F-20 Tigershark HESA Azarakhsh HESA Saeqeh HESA Kowsar

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 (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.

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.

The first Northrop YF-5A prototype

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 F-5 earned a reputation for a jet that was hard to discern in the air and when one finally saw it, it was often after a missile or guns kill [by F-5] had already been called.

— —Singapore's former Chief of Air Force and F-5 pilot, Major General Ng Chee Khern.

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, (along with the Douglas A-4 Skyhawk and Fiat G.91) 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

Official roll-out of first USAF F-5E Tiger II

F-5E Tiger II with B83 nuclear bomb at Hill Aerospace Museum

In 1970, Northrop won the International Fighter Aircraft (IFA) 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 3,600 lbf (16 kN) dry thrust and 5,000 lbf (22 kN) 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 (initially the Emerson Electric AN/APQ-153) (F-5A and B had no 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.

An early series F-5E

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.

Upgrades

The F-5E experienced numerous upgrades in its service life, with the most significant one being adopting a new planar array radar, Emerson AN/APQ-159 with a range of 20 nmi to replace the original AN/APQ-153. Similar radar upgrades were also proposed for F-5F, with the derivative of AN/APQ-159, the AN/APQ-167, to replace the AN/APQ-157, but that was cancelled. The latest radar upgrade included the Emerson AN/APG-69, which was the successor of AN/APQ-159, incorporating mapping capability. However, most nations chose not to upgrade for financial reasons, and the radar saw very little service in USAF aggressor squadrons and Swiss Air Force.

Various F-5 versions remain in service with many nations. Having taken delivery of its first F-5 Tigers in 1979, Singapore operated approximately 49 modernized and re-designated F-5S (single-seat) and F-5T (two-seat) aircraft until the early 2010s when they were retired from service. Upgrades included new FIAR Grifo-F X-band radar from Galileo Avionica (similar in performance to the AN/APG-69), updated cockpits with multi-function displays, and compatibility with the AIM-120 AMRAAM and Rafael Python air-to-air missiles.

NASA F-5E modified for DARPA sonic boom tests

One National Aeronautics and Space Administration (NASA) F-5E was given a modified fuselage shape for its employment in the Shaped Sonic Boom Demonstration program carried out by Defense Advanced Research Projects Agency (DARPA). It is preserved in the Valiant Air Command Warbird Museum at Titusville, Florida.

The Royal Thai Air Force (RTAF) had their F-5s undergo an extensive upgrade program, resulting in the aircraft re-designated as F-5T Tigris. They are armed with Python III and IV missiles; and equipped with the Dash helmet-mounted cueing system.

Similar programs have been carried out in Chile and Brazil with the help of Elbit. The Chilean upgrade, called the F-5 Tiger III Plus, incorporated a new Elta EL/M-2032 radar and other improvements. The Brazilian program, re-designated as F-5M, adds a new Grifo-F radar along with several avionics and cockpit refurbishments, including the Dash helmet. The F-5M has been equipped with new weapon systems such as the Beyond Visual Range Derby missile, Python IV short-range air-to-air missile, SMKB "smart" bombs, and several other weapons.

Operational history

United States

An F-5B of 602d TFS at Bien Hoa, 1966

The F-5 entered service with the USAF's 4441st Combat Crew Training Squadron at Williams Air Force Base, which had the role of training pilots and ground crew for customer nations, including Norway, on 30 April 1964. At that point, it was still not intended that the aircraft be used in significant numbers by the USAF itself.

USAF doctrine with regard to the F-5 changed following operational testing and limited deployment in 1965. Preliminary combat evaluation of the F-5A began at the Air Proving Ground Center, Eglin Air Force Base, Florida, in mid-1965 under the code name Project Sparrow Hawk. One airframe was lost in the course of the project, through pilot error, on 24 June.

In October 1965, the USAF began a five-month combat evaluation of the F-5A titled Skoshi Tiger. A total of 12 aircraft were delivered for trials to the 4503rd Tactical Fighter Squadron, and after modification with probe and drogue aerial refueling equipment, armor and improved instruments, were redesignated F-5C. Over the next six months, they flew in combat in the Vietnam War, flying more than 2,600 sorties, both from the 3rd Tactical Fighter Wing at Bien Hoa Air Base over South Vietnam and from Da Nang Air Base, where operations were flown over Laos. One aircraft was lost in combat, killing the pilot, USAF Major Joe Baggett.

Operations were declared a success, with the F-5 generally rated as being as capable a ground-attacker as the F-100, albeit having a shorter range. However, the program was more a political gesture that was intended to aid the export of F-5s than a serious consideration of the type for US service. (Following Skoshi Tiger the Philippine Air Force acquired 23 F-5A and B models in 1965. These aircraft, along with remanufactured Vought F-8 Crusaders, eventually replaced the Philippine Air Force's F-86 Sabres in the air defense and ground attack roles.)

From April 1966, the USAF aircraft continued operations under the auspices of the 10th Fighter Squadron, Commando, with their number boosted to 17 aircraft. 7300 more sorties were flown by the 10th FSC. Combining the missions flown by the 4503rd TFS and the 10th FSC; nine aircraft were lost in Vietnam, seven to enemy ground fire and two to operational causes.

USAF F-5F with AIM-9J Sidewinder, AGM-65 Maverick missiles and auxiliary fuel tanks over Edwards Air Force Base, 1976.

In June 1967, the surviving aircraft of the 10th Fighter Squadron, Commando, were transferred to the Republic of Vietnam Air Force (RVNAF). In view of the performance, agility and size of the F-5, it might have appeared to be a good match against the similar MiG-21 in air combat; however, US doctrine was to use heavy, faster and longer-range aircraft like the Republic F-105 Thunderchief and McDonnell Douglas F-4 Phantom II over North Vietnam.

The F-5 was also adopted as an opposing forces (OPFOR) "aggressor" for dissimilar training role because of its small size and performance similarities to the Soviet MiG-21. In realistic trials at Nellis AFB in 1977, called ACEVAL/AIMVAL, the F-14 reportedly scored slightly better than a 2:1 kill ratio against the simpler F-5, while the F-15 scored slightly less. There is some contradiction of these reports, another source reports that "For the first three weeks of the test, the F-14s and F-15s were hopelessly outclassed and demoralized"; after adapting to qualities of the F-5 carrying the new all aspect AIM-9L missile and implementing rule changes to artificially favor long range radar-guided missiles, "the F-14s did slightly better than breaking even with the F-5s in non-1 v 1 engagements; the F-15s got almost 2:1". A 2012 Discovery Channel documentary Great Planes reported that in USAF exercises, F-5 aggressor aircraft were competitive enough with more modern and expensive fighters to only be at small disadvantage in Within Visual Range (WVR) combat.

USMC F-5N Tiger IIs from VMFT-401 on standby at the Marine Corps Air Station Beaufort

The F-5E served with the US Air Force from 1975 until 1990, in the 64th Aggressor Squadron and 65th Aggressor Squadron at Nellis Air Force Base in Nevada, and with the 527th Aggressor Squadron at RAF Alconbury in the UK and the 26th Aggressor Squadron at Clark Air Force Base in the Philippines. The US Marines purchased used F-5s from the Air Force in 1989 to replace their F-21s, which served with VMFT-401 at Marine Corps Air Station Yuma. The US Navy used the F-5E extensively at the Naval Fighter Weapons School (TOPGUN) when it was located at NAS Miramar, California. When TOPGUN relocated to become part of the Naval Strike and Air Warfare Center at NAS Fallon, Nevada, the command divested itself of the F-5, choosing to rely on VC-13 (redesignated VFC-13 and which already used F-5s) to employ their F-5s as adversary aircraft. Former adversary squadrons such as VF-43 at NAS Oceana, VF-45 at NAS Key West, VF-126 at NAS Miramar, and VFA-127 at NAS Lemoore have also operated the F-5 along with other aircraft types in support of Dissimilar Air Combat Training (DACT).

The US Navy F-5 fleet continues to be modernized with 36 low-hour F-5E/Fs purchased from Switzerland in 2006. These were updated as F-5N/Fs with modernized avionics and other improved systems. Currently, VFC-111 operates 18 Northrop F-5N/F Tiger IIs. 17 of these are single-seater F-5Ns and the last is a twin-seater F-5F "FrankenTiger", the product of grafting the older front-half fuselage of an F-5F into the back-half fuselage of a newer low-hours F-5E acquired from the Swiss Air Force. A total of three "FrankenTigers" were made.

According to the FAA, there are 18 privately owned F-5s in the US, including Canadair CF-5Ds.

Brazil

A Brazilian Air Force F-5M

Brazilian F-5 in 2016

In October 1974, the Brazilian Air Force (FAB) ordered 36 F-5E and 6 F-5B aircraft from Northrop for $72 million. The first three aircraft arrived on 12 March 1975. In 1988, FAB acquired 22 F-5E and four F-5F second-hand USAF "aggressor" fighters. A total of 15 of these aircraft were part of the initial batch of 30 aircraft produced by Northrop. In 1990, FAB retired all remaining five F-5Bs; later, they were sent to Brazilian museums around the country.

In 2001, Elbit Systems and Embraer started work on a $230 million Brazilian F-5 modernization program, performed over an eight-year period, upgrading 46 F-5E/F aircraft, re-designated as F-5EM and F-5FM. The modernization centered on several areas: new electronic warfare systems, the Grifo F radar, an air-to-air refueling system, INS/GPS-based navigation, support for new weapons, targeting and self-defense systems, HOTAS, LCD screens, helmet-mounted displays (HMDs), Radar Warning Receiver, encrypted communications, cockpit compatibility for night vision goggles, On-Board Oxygen Generation System (OBOGS) and various new onboard computer upgrades. One important capability is the secure communication with R-99 airborne early warning platforms and ground stations.

Externally, the new aircraft features a larger nose cone that accommodates the larger radar equipment. The first F-5EM was handed over on 21 September 2005. On 7 July 2003, four Rafael Litening III targeting pods were ordered at a cost of US$13 million, to be used on F-5M together with three Rafael Sky Shield jamming pods ordered on 5 July 2006 at a cost of US$42 million.

In 2009, FAB bought eight single-seat and three twin-seat F-5F used aircraft from Jordan in a US$21 million deal. These aircraft were built between 1975 and 1980. On 14 April 2011, a contract of $153 million was signed with Embraer and Elbit to modernize the additional F-5s bought from Jordan, and to supply one more flight simulator as a continuation of the contract signed in 2000. These F-5s will receive the same configuration as those from the initial 46 F-5s currently completing the upgrade process. The first delivery of this second batch of upgraded jet fighters is scheduled for 2013 with expected use to 2030.

In 2020, the FAB started implementing the new proprietary Datalink System of the Brazilian Armed Forces on the F-5EM, for integrated communication and real-time sharing battlefield/warfare data with AEW&C R-99/E-99 FAB/Embraer aircraft, other aircraft, ships, helicopters, tanks and front/back-ends battlefield control centers, called Link-BR2.

Ethiopia

Ethiopia received 10 F-5As and two F-5Bs from the US starting in 1966. In addition to these, Ethiopia had a training squadron equipped with at least eight Lockheed T-33 Shooting Stars. In 1970, Iran transferred at least three F-5As and Bs to Ethiopia. In 1975, another agreement was reached with the US to deliver a number of military aircraft, including 14 F-5Es and three F-5Fs; later in the same year eight F-5Es were transferred while the others were embargoed and delivered to a USAF aggressor Squadron due to the changed political situation. The US also withdrew its personnel and cut diplomatic relations. Ethiopian officers contracted a number of Israelis to maintain American equipment.

The Ethiopian F-5 fighters saw combat action against Somali forces during the Ogaden War (1977–1978). The main Somali fighter aircraft was the MiG-21MF delivered in the 1970s, supported by Mikoyan-Gurevich MiG-17s delivered in the 1960s by the Soviet Union. Ethiopian F-5E aircraft were used to gain air superiority because they could use the AIM-9B air-to-air missile, while the F-5As were kept for air interdiction and airstrike. During this period Ethiopian F-5Es went on training against Ethiopian F-5As and F-86 Sabres (simulating Somali MiG-21s and MiG-17s).

On 17 July 1977, two F-5s were on combat air patrol near Harer, when four Somali MiG-21MFs were detected nearby. In the engagement, two MiG-21s were shot down while the other two had a midair collision while avoiding an AIM-9B missile. The better-trained F-5 pilots swiftly gained air superiority over the Somali Air Force, shooting down a number of aircraft, while other Somali aircraft were lost to air defense and to incidents. Records indicate that Ethiopian F-5s of the 9th Fighter Squadron "shot down 13 MiGs-17 and 12 MiGs-21 from 20th July until 1st September 1977. All aircraft were hit by Sidewinders (AIM-9)." However at least three F-5s were shot down by air defense forces during attacks against supply bases in western Somalia.

Ethiopian pilots who had flown both the F-5E and the MiG-21 considered the F-5E to be the superior fighter because of its manoeuvrability at low to medium speeds and the fact that it was far easier to fly, allowing the pilot to focus on combat rather than controlling his airplane. This effect was enhanced by the poor quality of pilot training provided by the Soviets, which provided limited flight time and focused exclusively on taking off and landing, with no practical training in air combat.

Ethiopia's ace pilot and national hero was Legesse Tefera who is credited with shooting down 6 (or 7) Somali MiGs, thus making him the most successful F-5 pilot.

Greece

Retired Greek NF-5A on display near Edessa, Greece

The Hellenic Air Force was the first European air force to receive the Freedom Fighter. The first F-5As were delivered in 1965, and over the next 8 years a total of about 70 F-5A/Bs were operational. The Hellenic Air Force bought an additional 10 F-5A/Bs from Iran in 1975, and around the same period another batch of 10 F-5A/Bs were acquired from Jordan. Another 10 were acquired from Norway in 1986, and a final 10 NF-5As were purchased from the Netherlands in 1991. The total number of F-5s in operation (including the ex-Iranian machines, 34 RF-5As, and 20 F-5Bs) in the Hellenic Air Force was about 120 aircraft, from 1965 to 2002, when the last F-5 was decommissioned and the type went out of operation in the Hellenic Air Force.

Units that used the F-5 in Greek service:

• 337th Day Interceptor Squadron (1967–1978)
• 341st Day Interceptor Squadron (1965–1993)
• 343rd Day Interceptor Squadron (1966–2001)
• 349th Day Interceptor Squadron (1970–1997)

Iran

F-5A Freedom Fighters of the Imperial Iranian Air Force

An F-5E of the Islamic Republic of Iran Air Force

The Imperial Iranian Air Force (IIAF) received extensive US equipment in the 1960s and 1970s. Iran received its first 11 F-5As and two F-5Bs in February 1965 which were then declared operational in June 1965. Ultimately, Iran received 104 F-5As and 23 F-5Bs by 1972. From January 1974 with the first squadron of 28 F-5Fs, Iran received a total of 166 F-5E/Fs and 15 additional RF-5As with deliveries ending in 1976. While receiving the F-5E and F, Iran began to sell its F-5A and B inventory to other countries, including Ethiopia, Turkey, Greece and South Vietnam; by 1976, many had been sold, except for several F-5Bs retained for training purposes. F-5s were also used by the IIAF's aerobatic display team, the Golden Crown.

After the Iranian revolution in 1979, the new Islamic Republic of Iran Air Force (IRIAF) was partially successful at keeping Western fighters in service during the