Classification of Jet Fighters into Generations (by Air Marshal Anil Khosla)

Fighter jets are categorised into different generations based on their features, capabilities, performance and year of development. This method of classification is a very broad-based concept with hazy demarcation lines. Although dependent upon the advancement of technology it does not define specific features or capabilities and has a large scope for difference of opinion.

Genesis. The origin of the generational categorisation of jet combat aircraft is itself debatable. The usage appears to have first appeared in Russia during the mid-1990s when officials were planning a competitor to the American Joint Strike Fighter. They categorised previous fighters into four categories and concluded that the next one would be in the fifth generation. Aviation Week correspondent Bill Sweetman claims it originated from within Lockheed Martin’s business development machine shortly after the X-35 was declared the successful JSF solution in 2001. 

Previous Attempts at Classification. In 1990 air historian Richard P. Hallion proposed a classification of jet fighters into six generations up to that time. Some others classified them into five generations up to around the same period. Taylor and Guilmartin named four classifications based on the maximum speed; subsonic, transonic, supersonic and Mach 2, and added a fifth “new” generation with multi-mission capability. Russian and Chinese observers also categorise aircraft into generations, albeit with differing and broader definitions across fewer generations that relate more towards their platforms and capabilities.

Classification: Relevant Aspects.  Relevant aspects are as follows:-

• This method of categorisation is unofficial because there is no authorised classification concept based on the features or performance of aircraft.
• There is no clearly defined line between successive generations. Authorities have identified different technology jumps as the key ones, dividing fighter development into different numbers of generations.
• Each category represents a certain class of technology used in the aircraft: avionics, systems, design, features, engines, weapons etc. A higher generation means a more technologically advanced aircraft.
• A Generational shift in jet fighter aircraft occurs when a technological innovation cannot be incorporated into an existing aircraft through upgrades and retrospective fit-outs.
• The criteria for the various generations are not universally accepted and are subject to differing opinions.

Generations of Fighter Jets

Accepted Classification Norms. In 2004 Aerospaceweb listed division into five generations. The basic classification into five generations has since been widely accepted. Five generations are now widely recognised, with the development of a sixth underway. Some accounts have subdivided the 4th generation into 4 and 4.5, or 4+ and 4++.

First Generation Subsonic Jet Fighters (mid-1940s to mid-1950s). This category comprised the earliest subsonic jet fighters that appeared during and after the last years of World War II. They were similar in most aspects to their piston-engined contemporaries, having generally straight wings and being of wood and/or light alloy construction. The main feature of the Gen 1 fighter was their advance in speed over its piston-engine predecessors. The introduction of the swept wing allowed transonic speeds to be reached, but controllability was often limited at such speeds. The jet engines did not have afterburners and the aircraft operated in the subsonic regime. They had basic avionic systems. They had no radars or self-protection countermeasures and were armed with machine guns or cannons, as well as unguided bombs and rockets.  These aircraft were typically aimed at the air-superiority interceptor role.

According to available open sources, fighters in this generation could include the following:-

• Messerschmitt Me 262 Schwalbe
• Heinkel He 162 Salamander
• Messershmitt Me 162 Komet
• Gloster Meteor
• de Havilland Vampire
• de Havilland Venom
• Hawker Siddeley/Armstrong Whitworth Sea Hawk
• Supermarine Attacker
• Supermarine Swift
• Lockheed P-80 (F-80) Shooting Star
• Republic F-84 Thunderjet / Thunderstreak
• North American F-86 Sabre
• Northrop F-89 Scorpion
• Lockheed F-94 Starfire
• McDonnell FH-1 Phantom
• Vought F6U Pirate
• Vought F7U Cutlass
• North American FJ (F-1) Fury
• McDonnell F2H (F-2) Banshee
• McDonnell F3H (F-3) Demon
• Douglas F4D (F-6) Skyray
• Grumman F9F (F-9) Panther / Cougar
• Douglas F3D (F-10) Skyknight
• Mikoyan Gurevich MiG-15
• Mikoyan Gurevich MiG-17
• Lavochkin La-15
• Yakovlev Yak-15
• Yakovlev Yak-17
• Yakovlev Yak-23
• Dassault Ouragan
• Dassault Mystčre
• Saab J21R
• Saab J29
• Saab Lansen
• Avro Canada CF-100 Canuck

Second Generation Jet Fighters (mid-1950s to early 1960s). The second generation of fighter jets was a result of technological breakthroughs and experience gained during aerial warfare (mainly The Korean War of 1950-1953). The main features include higher speed (sustained transonic and supersonic dash capabilities), rudimentary fire control radar, and use of guided air-to-air missiles. This generation’s fighters also incorporated advances in engine design (afterburners) and aerodynamics (swept wings), which allowed them to reach and sustain supersonic speeds in level flight. The second generation fighters saw the introduction of air-to-air radar, infrared and semi-active guided missiles, as well as radar warning receivers. During this period, although air-to-air combat was still within visual range, radar-guided missiles started to extend the engagement ranges and accuracy. The aircraft were divided according to their roles into Interceptors (e.g. MiG-21F, SU-9, F-106) and fighter-bombers (e.g. F-105, SU-7) providing air superiority and ground attack.

 According to available open sources, fighters in this generation could include the following:-

• North American F-100 Super Sabre
• McDonnell F-101 Voodoo
• Convair F-102 Delta Dagger
• Lockheed F-104 Starfighter
• Republic F-105 Thunderchief
• Convair F-106 Delta Dart
• Vought F8U (F-8) Crusader
• Grumman F11F (F-11) Tiger
• Mikoyan Gurevich MiG-19
• Mikoyan Gurevich MiG-21
• Sukhoi Su-9 / Su-11
• Yakovlev Yak-25
• BAC Lightning
• de Havilland Sea Vixen
• Gloster Javelin
• Hawker Hunter
• Supermarine Scimitar
• Dassault Etendard
• Dassault Mirage III
• Saab Draken

Third Generation Jet Fighters (early 1960s to 1970). The Third generation of fighters were designed to be multirole fighters capable of performing both air defence and ground attack missions. They could 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. These aircraft were capable of sustained supersonic flight, carried improved fire control radars and semi-active air-to-air missiles and the first generation of tactical electronic warfare systems. The advent of more economical turbofan engines brought extended range and sortie times, increased thrust, better performance and manoeuvrability. Some designers even resorted to variable geometry or vectored thrust. This generation witnessed significant enhancements in the avionic suites and weapon systems.  The supporting avionics included pulse-doppler radar, off-sight targeting and terrain-warning systems. Doppler radar supported a ‘lookdown / shoot-down’ capability, and with off-bore-sight targeting and semi-active guided radio frequency missiles. The major change brought about by this generation aircraft was that it was no longer necessary to visually acquire opponents to neutralise them and gain control of the air.

According to available open sources, fighters in this generation could include the following:

• McDonnell Douglas F4H (F-4) Phantom II
• Northrop F-5 Freedom Fighter / Tiger II
• Mikoyan Gurevich MiG-23
• Mikoyan Gurevich MiG-25
• Sukhoi Su-15
• Sukhoi Su-17/20/22
• Tupolev Tu-28P
• Yakovlev Yak-28
• British Aerospace Harrier
• Dassault Mirage F.1
• Dassault Super Etendard
• Shenyang J-8II

Fourth Generation Jet Fighters (1970 to late 1980s). These fighters debuted in the mid-1970s and are still in use in most of the air forces of the world. This generation is the longest of the five generations so far. This generation fighter jets are mostly multirole aircraft with the ability to switch and swing roles between air-to-air and air-to-ground, as opposed to the previous role-dedicated aircraft. This in turn blurred the distinction between air defence and ground attack missions. Fly-by-wire control systems improved the manoeuvrability of these aircraft at the expense of aerodynamic instability. These aircraft introduced more efficient and powerful turbofan jet engines, allowing greater than one thrust-to-weight ratios. Use of composite materials in their construction revolutionised the stealth technology. Electronics was the most essential part of these aircraft including ‘look-down’ doppler fire-control radars, fly-by-wire flight control systems, integral and podded EO/IR targeting sensors, laser and GPS- guided precision weapons, active air-to-air missiles, heads-up displays, and improved electronic warfare systems.

According to available open sources, fighters in this generation could include the following:

• Grumman F-14 Tomcat
• McDonnell Douglas F-15 Eagle
• General Dynamics F-16 Fighting Falcon
• McDonnell Douglas F-18 Hornet
• McDonnell Douglas AV-8B Harrier II
• Mikoyan Gurevich MiG-29
• Mikoyan Gurevich MiG-31
• Sukhoi Su-27
• Yakovlev Yak-38
• Panavia Tornado
• Dassault Mirage 2000
• Saab Viggen
• Mitsubishi F-2
• AIDC Ching-Kuo
• Chengdu J-10
• Hindustan LCA

Four and Half Generation Jet Fighters (late 1980s and into the 90s). The concept of having a half generation increment stemmed from a forced reduction in military spending at the end of the Cold War, which in turn resulted in a restriction in aircraft development. It became more cost-effective to add new improved features to existing platforms. Later variants of 4^th gen aircraft progressively enhanced their characteristic technologies and incorporated some of the emerging fifth generation technologies (such as high-capacity digital communications), leading them to be classified as an intermediate generation (4.5 or 4+ or 4++). So 4.5 generation aircraft are basically fourth generation fighters with basic characteristics of fourth generation planes but with enhanced capabilities provided by more advanced technologies that might be seen in fifth generation fighters. Many of these types are in frontline service in 2021. These aircraft have advanced digital avionics based on microchip technology and highly integrated systems. They are adapted to operate in high-tech warfare where not only avionic but also super manoeuvrability are the key to success. Their features include stealth, radar absorbent materials, thrust vector controlled engines, greater weapons carriage capacity and extended range and endurance. The addition of an Active Electronically Scanned Array (AESA) radar is a significant enough game-changing combat capability. The AESA radar allows fighter aircraft to perform a limited Airborne Early Warning and Control function. Advances in computer technology and data links also allowed 4.5 generation fighters to be integrated into a network centric battle space where fighter aircraft have much greater scope to conduct multi-role missions.

According to available open sources, fighters in this generation could include the following:

• Boeing F-18E/F Super Hornet
• Sukhoi Su-30
• Sukhoi Su-33
• Sukhoi Su-35
• Eurofighter Typhoon
• Saab Gripen
• Dassault Rafale

Fifth Generation Jet Fighters (2005 to date). A fifth generation fighter is a jet fighter aircraft which includes major technologies developed during the first part of the 21st century. As on date these are the most advanced fighters in operation. A quantum improvement in the fighter’s lethality and survivability has been a qualifying requirement to achieve generational change in aircraft design. The characteristics of a fifth-generation fighter are not universally agreed. The technologies that best epitomize fifth generation fighters are advanced integrated avionics systems that provide the pilot with a complete picture of the battle space and the use of low observable “stealth” techniques. 5th Generation ac typically include stealth, low-probability-of-intercept radar (LPIR), agile airframes with super cruise performance, advanced avionics features, and highly integrated computer systems capable of networking with other elements within the battle space for situation awareness and C3 (command, control and communications) capabilities. Improved situational awareness is achieved through multi-spectral sensors located across all aspects of the airframe which allows the pilot to ‘look’ through the airframe of the aircraft without having to manoeuvre the fighter to obtain a 360 degree picture. These aircraft are also ‘born’ networked which allows them to receive, share and store information to enhance the battle space picture. Fifth generation fighter capabilities are largely defined by their software and it will be the ongoing development of their software that will ensure they maintain their edge against evolving threats. Fifth generation aircraft allows the pilot to maintain decision superiority over an adversary. This provides greater chances of survivability, which when combined with effective lethality, assures battle space dominance.

According to available open sources, fighters in this generation could include the following:

• Lockheed Martin F-22 Raptor
• Lockheed Martin F-35
• Sukhoi T-50 PAK FA / Sukhoi Su-57
• J- 20 (Claimed on Paper)

Sixth Generation Fighter Aircraft.   With the fifth generation slowly coming into service, attention is already turning to a replacement sixth generation. The requirements for such a fighter are under debate in the drawing board stage. 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 for 6th generation aircraft. These aircraft could feature hypersonic speed, dual-mode engines, and adaptive shapes. At this stage it is not clear as to what extent 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. Projects related to unmanned combat aircraft systems are in progress, such as the joint French- Swedish nEUROn, the UK’s BAE Taranis, Northrop Grumman’s X-47B and the US Navy’s follow-on UCLASS program. Similar unmanned combat aircraft projects are also underway in Russia and China.

References:-

1. https://www.airforce-technology.com/features/top-sixth-generation-fighter-jets/

2. https://www.sldinfo.com/wp-content/uploads/2014/05/Air-Combat-Seminar-summary-AndrewMcL.pdf

3. https://www.fighterworld.com.au/az-of-fighter-aircraft/five-generations-of-jets

4. http://www.codeonemagazine.com/archives/2005/articles/oct_05/

5. https://en.wikipedia.org/wiki/Fifth_generation_fighter

6. https://www.airforce-technology.com/features/top-sixth-generation-fighter-jets/?utm_source=Army%20Technology&utm_medium=website&utm_campaign=Must%20Read&utm_content=Image

7. https://migflug.com/jetflights/fighter-jet-generations/

8. http://www.aerospaceweb.org/question/history/q0182.shtml