Jet fighter generations

First

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. They had little or no avionics, with their primary armament being manually-controlled guns. The Messerschmitt Me 262, Heinkel He 162, and Gloster Meteor saw wartime service, while types such as the de Havilland Vampire and Lockheed F-80 had yet to see 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 geared towards an air superiority interceptor role.^[16] Notable types which took part in the Korean War of 1950–1953 include the Mikoyan-Gurevich MiG-15 and the North American F-86 Sabre. The Hawker Hunter appeared too late for the war but was widely used in subsequent wars. All of these aircraft, however, did not use missiles or rotary cannons.

Second

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 afterburning engines to reach Mach 2, 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.^[17]

Third

Many third generation fighters were designed with multirole capabilities from the outset. Aircraft of this era were expected to carry a wide range of weapons and other ordnance, such as air-to-surface 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 with it extended range and sortie times, while increasing 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.^[18]

Fourth

Following the 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), supermaneuverability, 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 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 multirole 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 attack aircraft introduced stealth as a design concept.^[19]

The Chinese People's Liberation Army (PLA), with a different generation system, classifies most fourth-generation fighters as third-generation.^[13][20]

4.5th

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:^[21]

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

These partial upgrades to 5th-generation capability have led some commentators to identify these 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.^[22] Many of these types remain in frontline service as of 2025.

Fifth

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,^[23] Shenyang J-35, and Sukhoi Su-57.^[24] Some other fifth-generation fighter programs in development are the Tai TF Kaan, AMCA, and KAI KF-21 Boramae.

Sixth

With the fifth generation slowly coming into service, attention has 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^[25] 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.^[26][27] Specific requirements are anticipated by some observers to crystalize around 2025.^[28]