Freedom Tiger
Skoshi F-5C Tigers topping up from a KC-135 tanker prior to hitting North Vietnamese positions. Photo: USAF
Text: Richard Plos
Sleek and compact, the twin-engine fighter developed by Northrop gave many countries access to modern supersonic technology. Modernized F-5Es fly under different designations in the air forces of several countries to this day, although the origins of the type can be traced back to the mid-1950s.
In 1954, the Northrop company team went on a long journey through NATO countries. Aviation was just entering the supersonic age, and the American manufacturer wanted to determine what kind of aircraft was deemed most suitable for Allied nations. The team returned with a number of findings, on the basis of which the study of a light supersonic aircraft was started in 1955, which would be relatively cheap, low-maintenance and capable of operating from short runways.
Development began in 1956, under project designation N-156F with two non-afterburning YJ-85-GE-1 engines (9.34 kN or 2100lbs thrust each) being chosen to power it. The first prototype took off on July 30, 1959, at Palmdale Airport in California with factory pilot Lew Nelson at the controls, and the speed of sound was already broken during that flight. Other prototypes were subsequently involved in the tests, which were equipped with a fire control radar and five hardpoints for missiles, though these aircraft lacked guns. This was reconsidered and a pair of 20mm cannon were installed instead of the radar. The lack of a radar made the production F-5A aircraft suitable primarily for attacking ground targets with limited options for engaging enemy aircraft, yet the US Department of Defense announced that it had selected this aircraft for its Military Assistance to Allies (MAP) program. The aircraft received the official designation F-5A Freedom Fighter on August 9, 1962, and the two seat counterpart was designated F-5B. The US Air Force itself was not interested in the project, until someone realized that the USAF could use a two-seat version to replace the aging T-33. So in June 1956 it was announced that the USAF would purchase the F-5B export version, to be designated as the T-38. Additionally, the USAF borrowed twelve F-5As from the MAP program in October 1965 and equipped the 4503rd TFW with them, which then moved to Vietnam to test these aircraft under combat conditions. The program was named Skoshi Tiger (Little Tiger) and its pilots used a slightly modified F-5A, designated F-5C. They undertook more than 3,500 combat sorties from Bien Hoa Air Base, losing two aircraft in the process. Although the program was considered a success, it was more of a political gesture than a serious consideration for the type's inclusion among USAF types. From April 1966 the aircraft continued operations with the 10th Fighter Commando Squadron, with the number of aircraft increasing to seventeen. Aircraft from the Skoshi Tiger program were then acquired by the Philippine Air Force. Another user of the F-5A in the conflict was the South Vietnamese Air Force, which received 100 F-5As and F-5Bs.
One of the first F-5Es, serial number 11420. Photo: USAF
MiG-21 Adversary
However, the absence of a radar represented a fundamental limitation of the F-5A's capabilities, and the advent of the MiG-21 made it necessary to arm America’s allies with sufficiently powerful aircraft capable of air combat. Therefore, the International Fighter Aircraft (IFA) program was announced, for which Northrop prepared a thorough modernization of the F-5A. The prototype designated F-5A-21 received more powerful GE J85-21 engines, each with a maximum thrust of 19.12 kN (4,300 lbs). These, together with the need for more voluminous fuel tanks, required a lengthening and widening of the fuselage. The wings received an increase in area by way of the addition of the LERX, or Leading Edge Root Extension, which improved the maneuverability of the aircraft. Modeled after the Canadian license built and modified CF-5, a two-position front landing gear was introduced. In the extended position, the wing angle of attack was de facto increased and thus the take-off run was shortened.
Another significant change was the installation of the Emerson Electric AN/APQ-153 fire control radar, which significantly expanded the possibilities of combat use against aerial targets. It was also possible to install other avionics equipment according to customer requirements
The first F-5E, as the aircraft was now designated, took to the air on August 11, 1972, and a two-seat variant designated F-5F was also developed. It flew for the first time on September 25, 1974 and received an extended nose, which, unlike the F-5B, allowed for the installation of at least one cannon. The two-seat version received the Emerson AN/APQ-157 radar, which was a development of the AN/APQ-153 intended for two-seat aircraft with dual controls. Both radars have the same range of approximately 18 km (11 miles).
Following the Skoshi Tiger program, the F-5E was named ‘Tiger II’ and the Williams Based 425th TFS received its first aircraft on April 6, 1973. This unit was reactivated in 1969 and tasked with training Vietnamese personnel for the F-5A and subsequently the F-5E. After the US withdrew from Vietnam, it continued to train personnel from countries that purchased the F-5E/F. The unit continued in this mission until 1989, when sales of the Tiger II were discontinued.
An RF-5E ‘Tigereye’ reconnaissance version was also developed, with appropriate equipment in the nose displacing the radar and one of the cannons. Subsequent upgrades to the F-5E included the Emerson AN/APG-69 radar, which was a successor to the AN/APQ-159, however most users chose not to use this option for financial reasons. The exception was the Swiss Air Force and USAF aggressor squadrons.
A trio of F-5Es of the 527th TFTS operating in 1983 out of RAF Alconbury. Photo: USAF
Continuous Improvements
The F-5E underwent a number of upgrades, the most significant of which was the introduction of the new Emerson AN/APQ-159 radar with a range of about 36 km (22 miles), replacing the original AN/APQ-153. A similar radar upgrade was also proposed for the F-5F, with a derivative AN/APQ-159 type to replace the AN/APQ-157. However, this upgrade was not implemented.
In total, Northrop produced 792 F-5Es, 140 F-5Fs and a dozen RF-5Es. Other aircraft were assembled overseas from components supplied by Northrop. In Malaysia, 56 were manufactured in this way, in Switzerland 90, in South Korea 68 and in Taiwan, 308.
Various versions of the F-5 remain in service with several air forces. Singapore has approximately 49 modernized and redesignated F-5S (single-seat) and F-5T (two-seat) aircraft. The upgrade includes a new GRIFO radar, upgraded cockpits with multi-function displays and compatibility with the Rafael Python and AIM-120 AMRAAM air-to-air missiles.
With the help of Elbit, modernization programs were implemented in Chile and Brazil. Called the F-5 Plus, the Chilean upgrade included the new Elta 2032 radar and other improvements. The Brazilian program, the result being designated F-5M (Modernized), is armed with Python Vs coupled with the DASH helmet system and the new GRIFO radar, cockpit displays and navigation electronics. Brazilian F-5Ms can also carry Israeli Derby missiles.
Switzerland sold a portion of their F-5E/Fs to the United States, retaining the rest to this day. Photo: Wikimedia
Aggressors
No branch of the US military uses the F-5 in combat, but this type has proven itself very well in the role of enemy aircraft for advanced pilot training. It is operationally very efficient, the price per flight hour is roughly one-third that of the F/A-18, and it has similar dimensions to the MiG-21.
F-5Es served with the US Air Force from 1975 to 1990, the Marine Corps purchased former USAF aircraft in 1989, and the US Navy operated F-5Es at The Naval Fighter Weapons School at NAS Miramar, with VF-127, VF- 43 and VF-45. ‘Top Gun’ received a total of ten F-5Es and three F-5Fs for the enemy aircraft role.
The F-5E/F was gradually renewed and modernized, including machines bought from Switzerland. These were designated F-5N after modernization and received upgraded avionics and other improvements. Gradually they received enlarged LERXs and also a new radome, nicknamed ‘sharknose’ for its flatter shape. This was introduced primarily to improve flight characteristics at high angles of attack and to improve spin recovery.