Monday, March 21, 2011

The F-5A/B Freedom Fighter and F-5E/F Tiger II by Northrop

The Northrop F-5A/B Freedom Fighter and F-5E/F Tiger II are part of a family of widely used light supersonic fighter aircraft, designed and built by Northrop in the United States, beginning in the 1960s. Hundreds remain in service in air forces around the world in the early 21st Century, and the type has also been the basis for a number of other aircraft.

The first Northrop YF-5A prototype aircraft.

The F-5 started life as a privately funded light fighter program by Northrop in the 1950s. The first generation F-5A Freedom Fighter entered service in the 1960s. Over 800 were produced through 1972 for U.S. allies during the Cold War. The USAF had no need for a light fighter, but it did specify a requirement for a supersonic trainer and procured about 1,200 of a derivative airframe for this purpose, the T-38 Talon.

NASA F-5E modified for DARPA sonic boom tests.

The improved second-generation F-5E Tiger II was also primarily used by American Cold War allies and, in limited quantities, served in US military aviation as a training and aggressor aircraft; Tiger II production amounted to 1,400 of all versions, with production ending in 1987. Many F-5s continuing in service into the 1990s and 2000s have undergone a wide variety of upgrade programs to keep pace with the changing combat environment. The F-5 was also developed into a dedicated reconnaissance version, the RF-5 Tigereye.

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

The F-5 served as a starting point for a series of design studies which resulted in the twin-tailed Northrop YF-17 and the F/A-18 series of carrier-based fighters. The F-20 Tigershark was an advanced version of the F-5E that did not find a market. The F-5N/F variants remain in service with the United States Navy and United States Marine Corps as an adversary trainer.

Early series F-5E.

In the mid-1950s, Northrop started development on a low-cost, low-maintenance fighter, with the company designation N-156, partly to meet a US Navy requirement for a jet fighter to operate from its Escort Carriers, which were too small to operate the Navy's existing jet fighters. This requirement disappeared when the Navy decided to withdraw the Escort Carriers, but Northrop continued development of the N-156, with both a two seat advanced trainer (the N-156T), and a single-seat fighter (the N-156F) planned. The N-156 was based on the use of a pair of an afterburning version of the General Electric J85 engine which was originally designed to power the tiny McDonnell ADM-20 Quail decoy, then carried by the B-52 bomber. This requirement created a very small engine with a very high thrust-to-weight ratio.

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

The N-156T was selected by the United States Air Force as a replacement for the T-33 in July 1965, allowing development of the trainer to progress at full speed, the first example, later designated YT-38 Talon, flying on 12 June 1959 with a total of 1,158 Talons being built by the time production ended in January 1972.

Development of the N-156F continued at a lower priority as a private venture by Northrop, which was rewarded by an order for three prototypes on 25 February 1958 as 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.

Imperial Iranian Air Force Golden Crown F-5E.

Although testing of the N-156F was successful, demonstrating unprecedented reliability and proving superior in the ground-attack role to the USAF's existing 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, however, when the U.S. Army tested it, (along with the A-4 Skyhawk and Fiat G.91) for reconnaissance and close-support, but although all three types proved capable during Army testing, operating fixed-wing combat aircraft was legally the responsibility of the Air Force, which would neither agree to operate the N-156 nor to allow the Army to operate fixed-wing combat aircraft (a situation repeated with the C-7 Caribou). In 1962, however, 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, being 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 (the General Dynamics F-111 was the highest sequentially numbered P/F-aircraft to enter service under the old number sequence).

F-5As of Islamic Republic of Iran Air Force.

Northrop built 636 F-5As (including the YF-5A prototype) before production ended in 1972. These were accompanied by 200 two-seat F-5B aircraft. These were operational trainers, lacking the nose-mounted cannon but otherwise combat-capable, while 86 RF-5A reconnaissance variants of the F-5A, fitted with a four camera nose were also built. In addition Canadair built 240 first generation F-5s under license, with CASA in Spain adding a further 70 aircraft.

In 1970 Northrop won a competition for an improved International Fighter Aircraft (IFA) to replace the F-5A, with better air-to-air performance against aircraft like the Soviet MiG 21. The resultant aircraft, initially known as F-5A-21, subsequently became the F-5E. It had more powerful (5,000 lbf) General Electric J85-21 engines, and had a lengthened and enlarged fuselage, accommodating 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) (the F-5A and B had no radar). It retained the gun armament of two M39 cannon, one on either side of the nose) of the F-5A. Various specific avionics fits could be accommodated at customer request, including an inertial navigation system, TACAN and ECM equipment. The first F-5E flew on 11 August 1972.

A 602d TFS F-5B at Bien Hoa, 1966.

A two-seat combat-capable trainer, the F-5F, was offered, first flying on 25 September 1974, with a new, longer nose, which, unlike the F-5B which 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. A reconnaissance version, the RF-5E Tigereye, with a sensor package in the nose displacing the radar and one cannon, was also offered. 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 due to financial reasons, and the radar only saw very limited service in USAF aggressor squadrons and Swiss air force.

VNAF F-5C Bien Hoa Air Base, 1971.

The F-5E eventually received the official name Tiger II. 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 was never carried out.

 A former Swiss F-5N in service with US Navy aggressor squadron VFC-111.

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

RTAF F-5 and USAF F-15 in the background.

Northrop built 792 F-5Es, 140 F-5Fs and 12 RF-5Es. More were built under license overseas: 91 F-5Es and -Fs in Switzerland; 68 by Korean Air in South Korea, and 308 in Taiwan.

A Canadian Forces Air Command's CF-116.

The F-5 proved to be a successful combat aircraft for US allies, but had only limited combat service with the US Air Force 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 in the 1980s.

Kenya Air Force F-5E Tiger II and an USAF C-5 Galaxy in the background.

Various F-5 versions remain in service with many nations. Singapore has approximately 49 modernized and re-designated F-5S (single-seat) and F-5T (two-seat) aircraft. Upgrades include 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.

Mexican Air Force F-5 jets.

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, whose product is called the F-5M (Modernized), is armed with Python V coupled to the DASH helmet-mounted cue system, and new GRIFO radar, cockpit displays and navigation electronics. The Brazilian F-5M is also equipped with the Israeli Derby missile and can operate in a BVR environment. In the Cruzex 2006 multinational war games, a Brazilian F-5 made simulated kills on two French Dassault Mirage 2000N aircraft, which were supported by an E-3 Sentry and escorted by other two Mirage 2000C. This result was achieved by using the Derby and the information relayed by datalink from an AEW&C plane, the Embraer R-99, fitted with the Erieye AESA radar.

NF-5B of the Turkish Stars aerobatic team at RIAT 2008, England.

Other upgrade programs have been carried out in Royal Thai Air Force by Israel being called the F-5T Tigris, armed with Python III and 4 (with the Dash helmet-mounted cueing system). Unlike other F-5s which have undergone updates, the RTAF aircraft cannot use BVR missiles.

An F-5S belonging to 144 Squadron, Republic of Singapore Air Force prepares for takeoff.

One NASA F-5E was given a modified fuselage shape for its employment in the Shaped Sonic Boom Demonstration program carried out by DARPA. It is preserved in the Valiant Air Command Museum at Titusville, Florida.

 A civilian F-5B (restored to include a U.S. Air Force paint scheme) flies a low pass down Runway 30 at the Mojave Spaceport.


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