Jet fighter generations

In 1990, air historian Richard P. Hallion proposed a classification of jet fighters into six generations up to that time. These may be broadly described as subsonic, transonic, supersonic, Mach 2, multi-mission, and high-maneuverability.{{citation |url= http://www.airpower.au.af.mil/airchronicles/apj/apj90/win90/1win90.htm |title= Air Force Fighter Acquisition since 1945 |author= Dr Richard P. Hallion |work= Air Power Journal |date= Winter 1990 |access-date= 2012-02-07 |archive-url= https://web.archive.org/web/20161211062747/http://www.airpower.au.af.mil/airchronicles/apj/apj90/win90/1win90.htm |archive-date= 2016-12-11 |url-status= dead }} Other schemes comprising five generations up to around the same period have since been described, although the demarcation lines between generations differ. John W.R. Taylor and John F. Guilmartin (Encyclopedia Britannica) follow Hallion, except that they condense the last two into one.John W.R. Taylor and John F. Guilmartin; "[https://www.britannica.com/technology/military-aircraft/The-jet-age Military Aircraft: The Jet Age]", britannica.com. (Retrieved 3 January 2021) A NASA web publication divides jet development, up to 2004, into five stages; pioneer (straight wing), swept wing, transonic, the 1960s and 1970s on, culminating in types such as the F-15, F-16, and AV-8A.Steve Garber; Quest for Performance: The Evolution of Modern Aircraft, NASA SP-468, NASA History Office, [https://history.nasa.gov/SP-468/cover.htm Updated August 6, 2004] Chapter 11, Pages 2-6. (Retrieved 3 January 2021)

In the 1990s, a different division came into use in Russia, in which a "fifth generation" fighter was proposed as a counter to the Lockheed Martin F-22 Raptor. In contrast, a preceding fourth generation filled in the gap since the F-15/16 era.Winchester 2011, pages 5, 83. This effectively condensed the previous classifications to three generations. In 2004, Aerospaceweb listed one such division into five generations.{{cite web |url= http://www.aerospaceweb.org/question/history/q0182.shtml |title= Fighter Generations |author= Joe Yoon |author-link= Joe Yoon |date= 27 June 2004 |publisher= Aerospaceweb}} Although details differ, the basic classification into five generations has since been widely adopted.{{cite book |title= The Modern Defense Industry: Political, Economic, and Technological Issues|editor= Richard A. Bitzinger|editor-link= Richard A. Bitzinger|publisher= Praeger |year= 2009 |url= https://books.google.com/books?id=4n5oyaPnqm0C |page= 307|isbn= 9781567207491}}{{cite web |title= Five Generations of Jets |publisher= Fighter World Aviation Museum, Australia |url= http://www.fighterworld.com.au/az-of-fighter-aircraft/five-generations-of-jets}}{{cite web|title=Five Generations of Jet Fighter Aircraft |publisher=Royal Australian Air Force |work=Air Power Development Centre Bulletin |date=January 2012 |url=https://airpower.airforce.gov.au/sites/default/files/2021-03/PFV05-Pathfinder-Collection-Volume-5.pdf }}

The exact criteria for the various generation steps are not universally agreed on 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 GmbH and Boeing IDS.{{cite web |url= http://www.eurofighter.com/fileadmin/web_data/downloads/extpub/02_5thGenFighter.pdf |archive-url= https://web.archive.org/web/20121102122645/http://www.eurofighter.com/fileadmin/web_data/downloads/extpub/02_5thGenFighter.pdf |archive-date=2012-11-02|title= What is a 5th generation fighter |work= Eurofighter World |date= February 2010 |page= 16}} (archive date inferred from archive URL){{cite news |title= War heats up between Lockheed Martin and Boeing in bid to replace jets |author= Daniel Leblanc |publisher= "The Globe and Mail" |date= 18 October 2013 |url= https://www.theglobeandmail.com/news/politics/war-heats-up-between-lockheed-martin-and-boeing-in-bid-to-replace-canadas-fighter-jets/article14945766/}} 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".{{cite web |title= Is Saab's New Gripen The Future Of Fighters? |date= 24 March 2014 |author= Bill Sweetman |author-link= Bill Sweetman |work= Aviation Week & Space Technology |url= http://aviationweek.com/defense/saab-s-new-gripen-future-fighters}} 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, progressively since 1990.

Five generations are now commonly recognised, with the fifth representing the latest generation in service (as of 2018).Winchester 2011{{cite web|title=Does China's J-20 rival other stealth fighters?|url=http://chinapower.csis.org/china-chengdu-j-20/|website=China Power|publisher=CSIS|access-date=30 April 2017}} Future types at an early stage of development are expected to have even further enhanced capabilities and have become known as a sixth generation.{{cite web|title=The Sixth Generation Fighter |date=October 2009 |work=Air Force Magazine |author=John A. Tirpak |author-link=John A. Tirpak |url=https://www.airforcemag.com/MagazineArchive/Pages/2009/October%202009/1009fighter.aspx |url-status=bot: unknown |archive-url=https://web.archive.org/web/20160303225547/http://www.airforcemag.com/MagazineArchive/Pages/2009/October%202009/1009fighter.aspx |archive-date=2016-03-03 }} The rest of this article broadly follows the analysis of Baker.

File:Messerschmitt Me 262A at the National Museum of the USAF.jpg was the first operational jet fighter.]]

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, effectively 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 a significant aerodynamic effect.{{Cn|date=January 2021|reason=Needs to be verified}}) 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.

The 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.Baker 2018, Chapter 1: "Genesis of the Generations". Notable types which took part in the Korean War of 1950–1953 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.

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File:Croatian MiG-21 (cropped).jpg was the most widely produced jet fighter in history.]]

The Korean War of 1950–1953 forced a major reconsideration of aircraft design. Guns proved unsuitable at such high speeds, while the need for multirole capability in battlefield support was rediscovered. Interceptor-type aircraft emerging after the war used after-burning engines to give Mach 2 performance, while radar and infrared homing missiles greatly improved their accuracy and firepower. The U.S. 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.Baker 2018, Chapter 2: Generation Gap.

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File:Spanish Hawker Siddeley AV-8S Matador in flight over the Mediterranean Sea, 1 June 1988 (6430231).jpg was the first operational attack aircraft with vertical/short takeoff and landing (V/STOL) capabilities.]]

Many third generation fighters were designed with the intent of having multi-role capabilities. Aircraft of this era were expected to carry a wide range of weapons and other ordnance, such as air-to-ground missiles and laser-guided bombs, while also being able to engage in air-to-air interception beyond visual range. This generation of fighters also brought forth numerous improvements in supporting avionics, including 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 maneuvrability across the speed range. Some designers resorted to variable geometry or vectored thrust in an attempt to reconcile these opposites. Types such as the McDonnell Douglas F-4 Phantom, Mikoyan-Gurevich MiG-23, Sukhoi Su-17, Shenyang J-8, and Hawker Siddeley Harrier had varying degrees of success.Baker 2018, Chapter 3: Generation Rising.

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File:US Navy 051105-F-5480T-005 An F-14D Tomcat conducts a mission over the Persian Gulf-region.jpg was one of the first operational fourth-generation jet fighters.]]

{{Main|Fourth-generation fighter}}

Following the undeniable successes of the multirole generation, advanced technologies were being developed, such as fly-by-wire, composite materials, thrust-to-weight ratios greater than one (enabling the plane to climb vertically), hypermaneuverability, 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 Soviet Sukhoi Su-27 highlighted extreme maneuvrability 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 and 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.Baker 2018, Chapters 4 to 6. The Chinese People's Liberation Army (PLA), with a different generation system, classifies most fourth-generation fighters as the third generation.{{cite web|url=https://www.theweek.in/news/world/2020/08/01/did-china-downgrade-its-j-20-stealth-fighter-from-5th-generation-to-4th.html |title=Did China downgrade its J-20 stealth fighter from 5th generation to 4th? |website=The Week | date= 1 August 2020 }}

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:{{Cite web |title=Ask Us - Fighter Generations |url=https://aerospaceweb.org/question/history/q0182.shtml |access-date=2023-01-20 |website=aerospaceweb.org}}

• Active electronically scanned array radar
• Low-probability-of-intercept radar
• Electro-optical targeting systems
• Sensor fusion
• Supercruise ability
• Link 16-like, high-capacity digital network communications
• use of composite materials to reduce the radar cross-section

These partial upgrades to 5th generation capability have led some commentators to identify intermediate generations as 4.5 or 4+ and 4++. In some cases, such as the Mikoyan-Gurevich MiG-35 developed from the MiG-29 with fifth-generation avionics, the upgrade has been classed as fully fifth generation (meeting all fifth gen requirements except stealth).Baker 2018. Chapter 9: MiG-35 Many of these types remain in frontline service as of 2025.

A number of new 4.5 generation types are being developed in the 2020s, post the emergence of the true 5th generation and contemporaneous with 6th generation aircraft development, these include the HAL Tejas MK 1A, CAC/PAC JF-17 Thunder Block 3, and KAI KF-21 Boramae.{{Cite web|last=admin2|date=2020-09-18|title=HAL Tejas, the strongest fighter plane of its generation, developed indigenously by India. - Thecompares.net|url=https://thecompares.net/hal-tejas-the-strongest-fighter-plane/,%20https://thecompares.net/hal-tejas-the-strongest-fighter-plane/|access-date=2021-08-24|language=en-US}}{{Dead link|date=October 2024 |bot=InternetArchiveBot |fix-attempted=yes }}

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File:F-22 Raptor edit1 (cropped).jpg was the first operational fifth-generation jet fighter.]]

{{main|Fifth-generation fighter}}

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. 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 made 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, Chengdu J-20,{{cite news |last1=Seidel |first1=Jamie |title=With the J20 stealth fighter in fully operation service, China leaps ahead in Asian arms race |url=http://www.news.com.au/technology/innovation/with-the-j20-stealth-fighter-in-fully-operational-military-service-china-leaps-ahead-in-asian-arms-race/news-story/d5a65bfd8da252a1bb0240026591d575 |work=Australian News|date=20 October 2017|language=en}} Shenyang J-35, and Sukhoi Su-57.Baker 2018, Chapters 7 to14.

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{{main|Sixth-generation fighter}}

With the fifth generation slowly coming into service, attention turned to a replacement sixth generation. The requirements for such a fighter remain under debate. Fifth-generation abilities for battlefield survivability, air superiority and ground support are being enhanced and adapted to the future threat environment. Development time and cost are proving major factors in laying out practical roadmaps. Drones and other remote unmanned technologies are being increasingly deployed on the battlefields of the new millennium, and projects are underway to use them as semi-autonomous "wingmen". They may be integrated with sixth-generation fighter avionics, 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 U.S. F-47{{Cite web |last=Rogoway |first=Thomas Newdick, Tyler |date=2025-03-21 |title=Boeing Wins F-47 Next Generation Air Dominance Fighter Contract |url=https://www.twz.com/air/boeing-wins-air-forces-next-generation-air-dominance-fighter-contract |access-date=2025-03-21 |website=The War Zone |language=en-US}} and F/A-XX programs, the European Future Combat Air System (FCAS), the multinational Global Combat Air Programme (GCAP), and Chinese Chengdu J-36 and Shenyang J-50 development are ongoing.{{cite web |last=Kadidal |first=Akhil |date=30 December 2024 |title=Update: Two Chinese stealth aircraft programmes emerge unexpectedly |url=https://www.janes.com/osint-insights/defence-news/defence/update-two-chinese-stealth-aircraft-programmes-emerge-unexpectedly |website=Janes}}{{cite web |last1=Honrada |first1=Gabriel |date=2 January 2025 |title=China's J-36 stealth fighter another blow to US air superiority |url=https://asiatimes.com/2025/01/chinas-j-36-stealth-fighter-another-blow-to-us-air-superiority/ |access-date=2025-01-05 |website=Asia Times}} Specific requirements are anticipated by some observers to crystalize around 2025.Baker 2018, Chapter 18.

• Northrop Grumman B-21 Raider: U.S. 6th generation bomber project{{cite web|url= https://news.yahoo.com/first-sixth-generation-aircraft-ever-181800238.html|title= The First Sixth-Generation Aircraft Ever, the B-21 Raider Is "a Bomber Like No Other"|access-date= 5 December 2022|last= Mizokami|first= Kyle|work= Yahoo News|date= 5 December 2022|archive-url= https://web.archive.org/web/20221210233510/https://news.yahoo.com/first-sixth-generation-aircraft-ever-181800238.html|archive-date= 10 December 2022|url-status= live}}

{{Reflist}}

• David Baker; Fifth Generation Fighters, Mortons, 2018.
• {{cite book |author= Jim Winchester |title=Jet Fighters Inside & Out |url=https://books.google.com/books?id=3shgcJXesN0C|series=Weapons of War |date=December 15, 2011 |publisher= The Rosen Publishing Group |location=New York |isbn= 978-1448859825}}

{{Jet Fighter Generations}}