Jet fighter generations
Jet fighter generations classify the major technology leaps in the historical development of the jet fighter. Different authorities have identified different technology jumps as the key ones, dividing fighter development into different numbers of generations. Five generations are now widely recognised, with development of a sixth under way.
In 1990 air historian Richard P. Hallion proposed a classification of jet fighters into six generations up to that time. Other schemes comprising five generations up to around the same period have since been described, although the demarcation lines between generations differ. Taylor and Guilmartin name four; subsonic, transonic, supersonic and Mach 2, and add a fifth "new" generation with multimission capability and culminating in types such as the F-16 and MiG-29. A NASA web publication divides jet development into five stages; pioneer (straight wing), swept wing, transonic, 1960s and 1970s on, culminating in types such as the F-15, F-16 and AV-8A.
In the 1990s a different division came into use in Russia, where a "fifth generation" fighter was proposed as a counter to the Lockheed Martin F-35, while a preceding fourth generation filled in the gap since the F-15/16 era. This effectively condensed the previous classifications to three generations. In 2004 Aerospaceweb listed one such division into five generations. Although details differ, the basic classification into five generations has since been widely adopted.
The exact criteria for the various generation steps are not universally agreed and are subject to some controversy. For example Lockheed Martin has applied the term "fifth generation" to its F-22 and F-35 aircraft, but this has been challenged by its competitors Eurofighter and Boeing IDS. It has been suggested that Lockheed Martin "labeled the F-35 a 'fifth-generation' fighter in 2005, a term it borrowed from Russia in 2004 to describe the F-22", or that the post–Cold War era, low-cost approach of the Saab Gripen should qualify it as a sixth generation jet.[clarification needed] Some accounts have subdivided the 4th generation into 4 and 4.5, or 4+ and 4++.
The table below shows how some authors have divided up the generations.
|Period||Description||Example aircraft||Hallion (1990)||Aerospaceweb (2004)||Air Force Magazine (2009)||Air Power Development Centre (2012)||People's Liberation Army (2007)|
|1943–50||High subsonic conventional armament||Me 262, DH Vampire, P-80, MiG-9||1||1||1||1|
|1953–55||Transonic air-to-air missiles, radar||F-86, MiG-15, Dassault Mystère IV, Hawker Hunter||2||2||1|
|1953–60||Early supersonic radar, air-to-air missiles||F-100, MiG-19, Super Mystère B2||3||2||3||2|
|1955–70||Supersonic (limited purpose), Mach 2 air-air missiles only||F-104, MiG-21, Mirage III, Shenyang J-8||4||3|
|1960–70||multi-purpose fighter-bombers||F-4, MiG-23, Mirage F1||5||3|
|1970–80||Supersonic (multirole)||Panavia Tornado||4||4||4||3|
|1974–1990||Supersonic multirole, high efficiency. High manoeuvrability||F-14, F-16, MiG-29, Mirage 2000||6|
|1990-2000||enhanced capabilities, advanced avionics, limited stealth||F/A-18, Su-30, Rafale, Eurofighter Typhoon||4.5||4+||4.5||3.5|
|2000-present||Advanced integrated avionics, low observable stealth||Su-35||4++|
|F-22, F-35, J-20, Su-57||5||5||5||4|
The rest of this article broadly follows the analysis of Baker.
The earliest jet fighters appeared during and after the last years of World War II. They were similar in most respects to their piston-engined contemporaries, having straight, unswept wings and being of wood and/or light alloy construction (the Me 262 had a lightly swept wing, but this was done principally to achieve balance and the sweep was deliberately kept too little to have significant aerodynamic effect.) They had little or no avionics, with their primary armament being manually-controlled guns. The Heinkel He 162 and Gloster Meteor also saw wartime service, while types such as the de Havilland Vampire and Lockheed F-80 were still working up to operational service when the war ended.
Introduction of the swept wing allowed transonic speeds to be reached, but controllability was often limited at such speeds. These aircraft were typically aimed at the air-superiority interceptor role. Notable types which took part in the Korean War of 1950-53 include the Soviet Mikoyan-Gurevich MiG-15 and the North American F-86 Sabre. The Hawker Hunter appeared too late for the war but was widely used and took part in several later ones.
The Korean War of 1950-1953 forced a major rethink. Guns proved unsuitable at such high speeds, while the need for multirole capability in battlefield support was rediscovered. Interceptor types emerging after the war made use of afterburning engines to give Mach 2 performance, while radar and infrared homing missiles greatly improved their accuracy and firepower. The American Century series such as the Lockheed F-104 Starfighter, as well as the Russian MiG-21, English Electric Lightning and French Dassault Mirage III were typical of this era. Many types were soon compromised by adaptations for battlefield support roles and some of these would persist in new variants for multiple generations.
The next generation of fighters were designed from the start to be multirole. They were expected to carry a wide range of weapons and other ordnance such as air-to-ground missiles and laser-guided bombs, while also able to engage in air-to-air interception beyond visual range. Their supporting avionics included pulse-doppler radar, off-sight targeting and terrain-warning systems.
The advent of more economical turbofan engines brought extended range and sortie times, while increased thrust could only partly deliver better performance and maneuverability across the speed range. Some designers resorted to variable geometry or vectored thrust in the attempt to reconcile these opposites. Types such as the McDonnell Douglas F-4 Phantom, General Dynamics F-111, Mikoyan-Gurevich MiG-23, Sukhoi Su-17 and Hawker Siddeley Harrier had varying degrees of success.
Following the mixed successes of the multirole generation, advanced technologies were being developed, such as fly-by-wire, composite materials, thrust-to-weight ratios greater than unity, hypermaneuvrability, advanced digital avionics and sensors such as synthetic radar and infrared search-and-track, and stealth. As these appeared piecemeal, designers returned to the fighter first and foremost, but with support roles mapped out as anticipated developments. The General Dynamics F-16 introduced electronic flight control and wing-body blending, while the Saab 37 Viggen broke new ground in aerodynamic configuration with its canard foreplanes. The Anglo-American Harrier II and Russian Sukhoi Su-27 highlighted extreme maneuverability with, respectively, strengthened exhaust nozzles for viffing (vectoring in forward flight) and maneuvering control at high angles of attack as in Pugachev's Cobra. The Panavia Tornado remained multi-role but developed a defensive/offensive sensor, avionics and weapons suite especially capable of anti-radar and anti-missile ground attack, while the Lockheed F-117 introduced stealth as a design concept. Chinese People's Liberation Army (PLA) with a different generation system classifies most fourth generation fighter as the third generation.
Later variants of these and other aircraft progressively enhanced their characteristic technologies and increasingly incorporated aspects of each other's, as well as adopting some emerging fifth generation technologies such as high-capacity digital communications, leading some commentators to identify intermediate generations as 4.5 or 4+ and 4++. The Mikoyan-Gurevich MiG-35 is a development of the MiG-29 with fifth-generation avionics, leading some commentators to class it as fully fifth generation. Wholly new 4.5 generation types include the CAC/PAC JF-17 Thunder, Eurofighter Typhoon, Dassault Rafale, Sukhoi Su-35 and Saab Gripen. Many of these types remain in frontline service in 2021.
The huge advance of digital computation and mobile networking which began in the 1990s led to a new model of sophisticated forward C3 (command, control and communications) presence above the battlefield. Such aircraft had previously been large transport types adapted for the role, but information technology had advanced to the point that a much smaller and more agile plane could now carry the necessary data systems. Sophisticated automation and human interfaces could greatly reduce crew workload and it was now possible to combine the C3, fighter and ground support roles in a single, agile aircraft. Such a fighter—and its pilot—would need to be able to loiter for long periods, hold its own in combat, maintain battlefield awareness and seamlessly switch roles as the situation developed.
Parallel advances in materials, engine technology and electronics were making such a machine possible. From the start of the new millennium, advanced systems concepts such as smart helmets, sensor/data fusion and subsidiary attack drones were becoming realities. Bringing together and integrating such advances, along with those of the fourth generation, created what has become known as the fifth generation of fighters. The first of these is generally acknowledged to be the Lockheed Martin F-22. Subsequent types include the Lockheed Martin F-35, Sukhoi Su-57, Chengdu J-20 and Shenyang FC-31. Chinese People's Liberation Army fighter classification system refers to this fighter generation as the fourth generation.
With the fifth generation only slowly coming into service, attention is already turning to a replacement sixth generation. The requirements for such a fighter are under debate. The fifth-generation abilities for battlefield survivability, air superiority and ground support will need to be enhanced and adapted to the future threat environment. Development time and cost are likely to prove major factors in laying out practical roadmaps. One big unknown is the extent to which drones and other remote unmanned technologies will be able to participate, either as satellite aircraft under a sixth generation command fighter, or even replacing the pilot in an autonomous or semi-autonomous command aircraft. Studies such as the US F/A-XX program and UK-led BAE Systems Tempest are ongoing. Specific requirements are anticipated by some observers to crystallize around 2025.
- Baker 2018
- Dr Richard P. Hallion (Winter 1990), Air Force Fighter Acquisition since 1945, "Air Power Journal", archived from the original on 11 December 2016, retrieved 7 February 2012
- John W.R. Taylor and John F. Guilmartin; "Military Aircraft: The Jet Age", britannica.com. (Retrieved 3 January 2021)
- Steve Garber; Quest for Performance: The Evolution of Modern Aircraft, NASA SP-468, NASA History Office, Updated August 6, 2004 Chapter 11, Pages 2-6. (Retrieved 3 January 2021)
- Winchester 2011, pages 5, 83.
- Joe Yoon (27 June 2004). "Fighter Generations". Aerospaceweb.
- Richard A. Bitzinger, ed. (2009). The Modern Defense Industry: Political, Economic, and Technological Issues. Praeger. p. 307.
- "Five Generations of Jets". Fighter World Aviation Museum, Australia.
- "Five Generations of Jet Fighter Aircraft" (PDF). Air Power Development Centre Bulletin. Royal Australian Air Force. January 2012.
- "What is a 5th generation fighter" (PDF). Eurofighter World. February 2010. p. 16. Archived from the original (PDF) on 2 November 2012. (archive date inferred from archive URL)
- Daniel Leblanc (18 October 2013). "War heats up between Lockheed Martin and Boeing in bid to replace jets". "The Globe and Mail".
- Bill Sweetman (24 March 2014). "Is Saab's New Gripen The Future Of Fighters?". "Aviation Week & Space Technology".
- John A. Tirpak (October 2009). "The Sixth Generation Fighter". "Air Force Magazine". Archived from the original on 3 March 2016.CS1 maint: bot: original URL status unknown (link)
- "Does China's J-20 Rival Other Stealth Fighters?". CSIS.
- Winchester 2011
- "Does China's J-20 rival other stealth fighters?". China Power. CSIS. Retrieved 30 April 2017.
- Baker 2018, Chapter 1: Genesis of the Generations.
- Baker 2018, Chapter 2: Generation Gap.
- Baker 2018, Chapter 3: Generation Rising.
- Baker 2018, Chapters 4 to 6.
- "Did China downgrade its J-20 stealth fighter from 5th generation to 4th?". The Week. 1 August 2020.
- Baker 2018. Chapter 9: MiG-35
- Baker 2018, Chapters 7 to14.
- Baker 2018, Chapter 18.