6th-Generation Fighters
The 6th-generation aircraft -- and the next generation air warfare -- remain conceptual, especially given that armed forces around the globe are still striving to digest the 5th-generation (i.e. the F-22, the F-35, and the Chinese J-20) novelties that have recently entered into service. In essence, the forthcoming 6th-generation platforms and air warfare systems will probably enjoy the 5th-generation aircraft’s revolutionary features along with some groundbreaking technological leaps.
Generally speaking, the American F-111, F-104 and the Russian MiG-21 are called second-generation fighter jets. The American F-14, F-15, the Soviet MiG-23, MiG-25, the French Mirage-2000, etc. are called third-generation fighter jets. The fourth-generation fighter jets generally include the American F-15EX, F-16, the Russian Su-27, MiG-29, etc., and the typical fifth-generation fighter jets include the American F-22, F-35 and the Russian Su-57, etc. Among the fifth-generation fighters represented by the US Air Force F-22 and F-35 and the Russian Aerospace Forces Su-57, the F-22, which was the first to be mass-produced and put into actual combat, has been in service for nearly 20 years. According to the characteristics that the main combat equipment of the air force is updated every 20 years or so, many countries, such as the United States, Russia and European countries, are independently or jointly developing the sixth-generation fighters. At present, the development of the sixth-generation fighters in the world presents a situation of many heroes emerging. The term "6th generation fighter" refers to the next generation of advanced military aircraft that are currently in development by several countries, including the United States, Russia, China, and European nations. These fighters are expected to feature a range of cutting-edge technologies that will significantly surpass the capabilities of existing 5th generation fighters like the F-22 Raptor, F-35 Lightning II, and the Sukhoi Su-57.
Key features and technologies expected in 6th generation fighters include:
- Stealth and Low Observability: Enhanced stealth capabilities that make the aircraft nearly invisible to radar and other detection systems.
- Advanced Avionics and Sensor Fusion: Integration of advanced sensors and avionics systems that provide superior situational awareness and target tracking. This includes improved radar, infrared, and electronic warfare systems.
- Artificial Intelligence (AI) and Autonomy: Incorporation of AI for decision-making, threat analysis, and potentially autonomous or semi-autonomous operations, reducing pilot workload and enhancing mission effectiveness.
- Directed Energy Weapons: Potential integration of laser weapons or other directed energy systems for defensive and offensive capabilities.
- Enhanced Networking and Connectivity: Advanced communication systems enabling seamless data sharing and coordination with other aircraft, ground forces, and command centers.
- Improved Propulsion and Speed: More powerful and efficient engines capable of higher speeds, extended range, and better fuel efficiency.
- Manned-Unmanned Teaming (MUM-T): The ability to control and coordinate with unmanned aerial vehicles (UAVs) or drones, expanding the tactical options available during missions.
- Advanced Materials and Structures: Use of next-generation materials for construction, which could provide better durability, reduced weight, and improved performance.
Several programs and concepts are currently being developed under various names:
- United States: The U.S. Air Force is working on the Next Generation Air Dominance (NGAD) program.
- United Kingdom: The Tempest program aims to deliver a 6th generation fighter by the mid-2030s.
- France, Germany, and Spain: These countries are collaborating on the Future Combat Air System (FCAS).
- Japan: The F-X program is Japan's effort to develop its own 6th generation fighter.
- China and Russia: Both countries are also reportedly working on their respective 6th generation fighter projects.
These advanced aircraft are expected to enter service in the 2030s and will play a critical role in the future of aerial combat, maintaining air superiority, and ensuring national security in an increasingly complex and technologically advanced global landscape.
What would the 5th-generation aircraft bring to warfighting and what should one expect from the 6th generation? The F-35’s design philosophy gives important clues in this respect. The essence of the 5th-generation aircraft are stealth capabilities, increased capacity of penetrating into denied airspaces, and multi-domain connectivity. Manufacturers of these assets focus on minimizing the radar signature, equipping the platforms with state-of-the-art sensors, boosting onboard and offboard features, and providing the aircraft with unprecedented situational awareness. More importantly, the 5th-generation air forces will master network-centric warfare and joint coalition operations. Information superiority remains at the epicenter of the 5th-generation understanding. On a separate note, the combination of stealth technologies and swiftly developing beyond-visual-range air-to-air missiles is already making air warfare more complex than ever.
The 6th-generation, theoretically, will go beyond the 5th-generation aircraft’s skills in many aspects. The present literature suggests that the 6th-generation platforms will be “optionally-manned”, meaning they could fly with or without a pilot onboard. If achieved, such an advancement would mark a critical transition in the world’s air forces’ orders of battle. Besides, since optionally-manned or unmanned squadrons will completely alter our understanding of managing the risk of casualties, they could drastically re-shape the known concept of operations and rules of engagement in many corners of the world. Again, available writings on the 6th-generation aircraft predict that these platforms would further advance the 5th generation’s connectivity by enabling sensor fusion with drones and satellites. Notably, the 6th-generation aircraft could function as a platform for launching swarming drone strikes. They will probably carry directed energy weapons (DEWs) too.
Without a doubt, managing such complicated tasks and dealing with a huge amount of data are beyond the human cognitive capabilities. Before the 5th-generation aircraft, defense industry and aviation experts tended to solve this problem by multi-crewing some platforms of the 3rd and 4th generations, and thereby introducing new roles into the cockpit. What the 5th generation has so far brought, however, are single-seat designs. If the 6th generation follows suit at large, and because it will deal with a huge amount of data and multi-tasking in a more complex battle space, the only way forward is to foster artificial intelligence (AI) capacity and human-machine teaming.
Although the fifth-generation fighters such as the F-22 have a certain integrated information fusion capability and can use advanced external sensor networks and airborne fire control systems to detect and destroy incoming enemy aircraft or missiles outside the detection range of enemy aircraft, the F-22 was designed in the 1980s, the F-35 was designed in 1994, and the U.S. Department of Defense submitted the "Network-Centric Warfare" report to Congress in July 2001. This determines that the fifth-generation fighters such as the F-22 and F-35 are inherently insufficient in terms of network-centric warfare and integration into integrated network information systems. After the Gulf War, the U.S. military began to strengthen the integrated construction of military information networks. So far, a basically mature military information network system has been built. In the network information system, each combat unit and combat platform is a node in the network. Since some previously designed and manufactured combat platforms do not have network capabilities, they must be transformed to adapt to combat needs. As the latest designed and manufactured sixth-generation fighter, it is inevitable that the network information system will be integrated into the design stage to achieve interconnection and interoperability with other platforms in the combat network and share tactical information in real time. The generational update of fighter jets is based on significant technological updates, but it will not completely eliminate the original technology. The emergence of the sixth-generation fighter jets coincides with the extensive and in-depth application of artificial intelligence technology in the military field. While the sixth-generation aircraft engines are widely used, and the full wing-body fusion and high lift-to-drag ratio design are adopted in the structure, artificial intelligence technology is a typical and iconic technology of the sixth-generation fighter jets. Artificial intelligence technology is integrated into the basic electronic information systems such as avionics and flight control of the sixth-generation fighter jets. Technologies such as big data and intelligent algorithms based on large models are widely used in signal intelligence comprehensive processing, auxiliary decision-making, automatic control and other links, as well as the entire process of observation, judgment, decision-making and action (OODA). Another innovation is the tactical feature of manned and unmanned coordination. The Air Force has always been a high-tech military branch. At present, drones have not yet been involved in air combat with the Air Force as the protagonist (rather than a simple drone battle). However, unmanned tankers and drones as "loyal wingmen" have appeared and gradually matured. After unmanned tankers, "loyal wingmen" and other drones join the air combat, coordination between manned and unmanned aircraft will become the basic tactical feature of air combat. Main combat aircraft are the main force for gaining air superiority and are also the most important weapon of the country. In modern wars where air superiority is becoming more and more important and the competition for air superiority is becoming more and more fierce, the importance of the new generation of main combat aircraft is self-evident. For the upcoming sixth-generation fighter, the future development will have the following three trends. First, the sixth-generation fighter aircraft itself will become a powerful combat platform with comprehensive functions. The initial combat functions of fighter aircraft were mainly close-range combat and bomb dropping. With the improvement of fighter aircraft's own performance and the diversification of bombs, it began to have air-launched missiles, electronic warfare and other functions. By the fifth generation of fighter aircraft, stealth performance and networking capabilities have been greatly improved. The sixth-generation fighter will make a qualitative leap in situational awareness, electronic warfare, cyber warfare and stealth capabilities. In terms of situational awareness, the sixth-generation fighter is not only equipped with a high-level electronically scanned phased array radar, but also able to integrate sensor data from networked combat platforms, and has super situational awareness and information fusion capabilities. In terms of electronic warfare and cyber warfare, the sixth-generation fighter uses artificial intelligence technology and cognitive electronic warfare technology to accurately detect sudden electromagnetic radiation sources, and accurately locate and analyze their parameters, so as to carry out electromagnetic attacks and electromagnetic cover. Through the integration of cyber warfare and electronic warfare, network-electronic integrated warfare can be achieved. In addition, the sixth-generation fighter adopts radar avoidance design and a new generation of stealth coatings, and its stealth capability will be further improved. In terms of airborne ammunition, the sixth-generation fighters will generally have the ability to launch and intercept hypersonic missiles. This makes the sixth-generation aircraft not only part of an integrated network combat system, but also an air combat platform with super comprehensive combat capabilities. Second, the sixth-generation fighter must have the ability to fight in conjunction with drones. Intelligent technology is the iconic technology of the sixth-generation fighter. While improving the functions of the sixth-generation fighter, it also gave rise to a large number of various drones to join the battle, which objectively promoted the formation of an ecosystem where manned and drones coexist and coexist in the air battlefield. Unmanned intelligent "loyal wingman" can perform difficult and dangerous tasks, such as forward reconnaissance missions when the enemy's air defense system is still capable of combat, identifying and destroying the enemy's air defense system, or engaging enemy fighters in highly confrontational and dangerous airspace. In view of the unique advantages of "loyal wingman", countries around the world are developing "loyal wingman". For example, "Air Wolf", XQ-58A "Valkyrie" and UTAP-22 "Mako" developed by Kratos Defense and Security Solutions in the United States, "Ghost Bat" developed by Boeing, "Warrior" developed by Hindustan Aeronautics Limited, "Ray-X" developed by Korean Air's Aerospace Division, and S-70 "Hunter-B" developed by Sukhoi and Russian Aircraft Corporation of Russia. Each generation of fighter jets has a carrier-based version, such as the F-18 in the fourth generation and the F-35B in the fifth generation. The sixth generation fighter jet will inevitably have its carrier-based version. The U.S. Navy has successfully developed the MQ-25A "Stingray" carrier-based unmanned tanker and formed the 59th Task Force to conduct manned and unmanned collaborative experiments. In other words, the carrier-based version of the sixth generation fighter jet must also have the ability to cooperate with unmanned tankers. The third is to promote the evolution of air combat towards manned and unmanned coordinated operations. Since the birth of aircraft and the emergence of air combat, it has basically been a contest between manned combat aircraft of the participating parties. In recent years, although drone combat has developed rapidly and played an important role in actual combat, it is basically a confrontation between drones and unmanned clusters of two or more parties. The main role of drones is to undertake battlefield reconnaissance, ammunition delivery and other tasks. Although unmanned tankers and "loyal wingmen" have appeared, they are still in the test and improvement stage. In other words, the coordinated and joint operations between manned and unmanned aircraft have not yet appeared in actual combat. However, as "loyal wingmen" and unmanned tankers, as well as other unmanned aircraft that emerge in the future, mature, unmanned aircraft will inevitably join actual combat and cooperate and fight together with manned aircraft. The coordination and cooperation between manned aircraft and unmanned aircraft includes the coordination and cooperation between manned aircraft and manned aircraft, between manned aircraft and unmanned aircraft, and between unmanned aircraft and unmanned aircraft. This will make the coordination and cooperation of air combat more complicated, and must rely on the assistance of intelligent command, management, and control systems, which will also have a profound impact on the appearance of future air combat.
- Fully Autonomous Operation: While 6th generation fighters might feature semi-autonomous capabilities, 7th generation fighters could be fully autonomous, capable of conducting missions without any human intervention, thanks to advanced AI.
- Swarm Coordination: Ability to control and coordinate large swarms of drones or unmanned aerial systems (UAS), effectively turning the fighter into a command and control hub for a network of autonomous assets.
- Enhanced Stealth and Cloaking Technologies: Advancements in materials science might lead to new forms of stealth, potentially including active camouflage systems that make the aircraft invisible not just to radar but also to the human eye.
A number of other fetures are amazing, but unlikely to enter service:
- Quantum Computing: Integration of quantum computing for real-time processing of vast amounts of data, significantly enhancing decision-making and operational effectiveness.
- Hypersonic Speeds: While 6th generation fighters may achieve higher speeds than their predecessors, 7th generation fighters could potentially reach hypersonic speeds (Mach 5 and above), drastically reducing reaction times and increasing survivability.
- Energy Weapons: Beyond directed energy weapons, 7th generation fighters could feature more advanced, compact, and powerful energy weapons capable of neutralizing threats at unprecedented ranges and with extreme precision.
- Self-Healing Materials: Use of advanced materials that can automatically repair damage sustained in flight, increasing the aircraft's durability and mission readiness.
- Advanced Propulsion Systems: Utilization of revolutionary propulsion technologies such as scramjets or hybrid propulsion systems, enabling efficient operation across a wide range of speeds and altitudes.
- Multi-Domain Integration: Seamless integration across all domains of warfare (air, land, sea, space, and cyber), allowing the fighter to coordinate with a diverse set of assets and provide a comprehensive battlefield picture.
- Environmental Adaptability: Ability to operate in a variety of environments, including space, potentially bridging the gap between atmospheric and exoatmospheric combat capabilities.
The development of such advanced fighters would require significant breakthroughs in multiple fields of science and technology, as well as substantial investments in research and development. Given the pace of current technological advancements, the timeline for the conceptualization and realization of a 7th generation fighter is uncertain, and it may be several decades before such aircraft become a reality. However, the pursuit of these capabilities will likely drive innovation and set new standards for future military aviation.
Sixth-Generation Combat Aircraft
Sixth-generation aircraft, still in their early phase of development, are expected to have advanced digital features like artificial intelligence (AI) integration and data fusion, as well as other enhanced command, control, and communication (C3) capabilities. The aircraft would be similar to fifth-generation combat aircraft—designed for greater air-to-air capability, battlefield survivability in anti-access/area denial environments, and ground support—but with greater focus on enhanced integration of AI systems and less focus on close-in dogfighting, which is a less common feature of current and future war scenarios. As one of the world's military powers, Russia is not far behind in the development of the sixth-generation fighter. According to a report by the Russian Satellite News Agency on July 16, 2020, the Russian MiG Aircraft Group and Sukhoi Company will jointly develop the sixth-generation combat aviation system. The performance indicators of the sixth-generation fighter announced by Russia include super stealth and electronic warfare capabilities, and can intercept and launch hypersonic missiles. Russia has revealed little information on the development of the sixth-generation fighter, and there are many influencing factors, so there is still uncertainty in future development. Russia hopes to have a sixth-generation combat aircraft prototype by 2050, according to the excerpted analysis of a report written by Evgeny Fedosov of the Russian Academy of Sciences published by state news agency TASS 25 February 2024. “Currently, we are thinking about the concept of a sixth-generation aircraft, conducting search research, exchanging views with military specialists. Such an aircraft should appear sometime by 2050, but already now it is necessary to understand what the armed conflicts of the future will be like.” – Evgeny Fedosov, Scientific Director of the State Research Institute of Aviation Systems (GosNIIAS). Touching upon the design of future aircraft, Fedosov suggested that “to go further according to the logic of complication is a vicious practice.” He also pointed out that combat aircraft are becoming more complex from generation to generation and, as a result, becoming heavier. “And the larger and heavier the plane, the more expensive it is,” the academician concluded. GosNIIAS is a leading center in the development of on-board aviation systems and equipment. The founder of modeling methods for designing automatic systems of any degree of complexity. The Institute participates in the creation of aircraft at all stages: from the development of the concept of aircraft creation to modernization during operation. He also added that the sixth-generation combat aviation group will include both manned aircraft and unmanned vehicles. “There is an opinion that the air group should be mixed and consist of drones and manned aircraft. Such a mixed park, in principle, can exist,” Fedosov remarked. He said that the size and speed of the drones would enable them to function as wingmen within a group. Building upon the success of fifth-generation platforms, sixth-generation fighters would be designed to adapt to evolving trends in aerial warfare, where traditional dogfighting scenarios are giving way to long-range engagements utilizing beyond-visual-range air-to-air missile capabilities. This is not the first time that the Russians have announced plans to develop a sixth-generation combat aircraft. TASS first reported these developments in 2017 and the article touts Russia’s Su-57 [RG1] Felon as “almost” possessing capabilities or easy upgradable features to become a sixth-generation aircraft. These capabilities include supercruise (i.e. sustained supersonic flight without use of an afterburner) and advanced avionics (i.e. an aircraft’s communications, navigation, and flight control systems). The second excerpted article from the The EurAsian Times is a commentary on Fedosov’s report. It notes that AI technology will provide the aircraft with advanced digital and C3 capabilities, as well as data fusion and remote or autonomous piloting. Fedosov expects the pilot to be integrated into the airframe, with cockpits and helmet-mounted displays allowing for 360-degree vision similar to the F-35 [RG2] . Stealth, as before, will continue to play a huge role in sixth-generation aircraft capabilities. Several other nations have announced plans to develop sixth-generation combat aircraft to include Turkey as well as the UK, Italy, and Japan, which announced a joint plan to develop a similarly advanced fighter. The Russian military’s development of advanced combat aircraft has been notorious for delays, cost overruns, and faulty features evident in the deployment of its fifth-generation Su-57 aircraft. Discussing the aircraft, Fedosov acknowledged the complication of designing future combat aircraft as they become larger, heavier, and costlier to make. The TASS article suggests that the U.S. Air Force’s Next Generation Air Dominance plan to roll out a sixth-generation combat aircraft to replace its F-22 Raptor fighters by 2030 is unlikely to be eclipsed by the Russians anytime soon. The report further highlights divisions among the engineers, strategists, and aviators of Russia’s ministry of defense, over which capabilities to emphasize. The main divide is whether to focus on producing fighters designed for beyond visual range engagement or models (not unlike its previous Sukhoi or Mikoyan versions) capable of close-range dogfights, but there is also major disagreement over whether future models should be manned or unmanned. Retired Indian Air Force Lieutenant General Chopra wrote a long article expounding on the current development trends of the air forces of various countries in the world, and pointed out that China was already developing the next generation of fighter jets. In this regard, he said in the article that "it is time for India to develop the sixth-generation aircraft." However, Chopra did not explain where the technology of the sixth-generation aircraft came from and how to deal with the basic research and development industrial problems. Analysts said that India is the only country in the world that leads the fifth-generation and sixth-generation aircraft development plans without even having complete research and development and production capabilities for third-generation aircraft. In theory, even for third-generation aircraft like the MiG-21/J-7, India does not have the ability to imitate, because India did not announce until 2022 that it had digested some of the MiG-21UPG's technology to a limited extent, which shows how poor India's aviation industry is. The LCA fighter is not an equipment independently developed and produced by India. The aerodynamic design of the LCA fighter was completed by France, because India does not have a group of wind tunnels and cannot complete the aerodynamic experiments required in the design process. For this reason, the LCA fighter looks "French", similar to the Mirage fighter. The LCA's fly-by-wire flight control was first completed by France and the United States, as well as the onboard avionics. However, due to India's nuclear tests in 1998, the United States withdrew from the LCA project and initiated sanctions against India, which delayed the project for a long time. Even the F-404 engine scheduled to be used lost its source due to US sanctions and had to be delayed. Although the United States later lifted sanctions on India and provided more advanced F-414 engines, the "imported products" all over the LCA can hardly be called a "domestic" fighter. In the field of fourth-generation aircraft, India first purchased more than 200 Su-30MKI heavy fighters from Russia, and then purchased 36 Rafale F3s from France, forming the most preliminary fourth-generation aircraft combat system in this century, but in the field of domestic fighters, it is still poor. With the gradual strengthening of China's national strength, the Sino-Indian border issue has been planned near the actual control line. A large number of high-quality troops of the People's Liberation Army have begun to move forward. How to deal with the pressure from the People's Liberation Army has become a major problem for India. The original plan was to rely on 36 Rafale F3 fighters to reverse the situation and carry out the fifth-generation aircraft planning, but because the T50 project is too pit, Russia's backward technology is too backward to make India dissatisfied, and there is no news about the fifth-generation aircraft project in Europe, so the Indian government is currently in the country. The shocking remarks that "Rafale is stronger than J-20" are fooling the people, but the gap still allows India to see the reality. Many people think that India's fifth-generation and sixth-generation aircraft can rely on Europe and the United States to "lie flat", but it is actually very difficult. No matter how the outside world evaluates the J-20, and no matter how they define China's sixth-generation aircraft, it is undeniable that fighter jets have reached the "watershed" of technology and industry since the "fourth and a half generations". Countries that can develop fourth-generation aircraft may not be able to develop a qualified fourth-generation and a half, and countries that can develop fourth-generation and a half may not be able to develop fifth-generation aircraft. Taking Russia as an example, the Su-27 and Su-30 are indeed fourth-generation aircraft, but the Su-35S and Su-30SM can hardly be called qualified "fourth and a half generations". With the Su-35S and Su-30SM, Russia's Su-57 can hardly be called a fifth-generation aircraft. The reason is that simple. If India wants to lie flat, Europe and the United States will have difficulty. The term "Generation 4.5 fighter" refers to a class of fighter aircraft that are an evolutionary step between fourth-generation and fifth-generation fighters. These aircraft incorporate advanced technologies and capabilities that bring them closer to the performance and capabilities of fifth-generation fighters, without fully meeting all the criteria. Key Characteristics of Generation 4.5 Fighters Advanced Avionics and Sensors: Upgraded radar systems, often Active Electronically Scanned Array (AESA) radars. Enhanced electronic warfare (EW) capabilities and sensor fusion. Improved Stealth Features: Incorporation of some stealth technologies, such as reduced radar cross-section (RCS) and advanced materials, although not to the extent of full fifth-generation fighters. Enhanced Maneuverability: Use of thrust vectoring engines and improved aerodynamics for superior agility and performance in air combat. Network-Centric Warfare: Advanced communication systems and data links that enable better interoperability with other military assets and platforms. Multirole Capabilities: Versatility to perform a variety of missions, including air-to-air combat, ground attack, and reconnaissance. Upgraded Weapons Systems: Integration of advanced missile systems, precision-guided munitions, and other modern weaponry. Examples of Generation 4.5 Fighters Eurofighter Typhoon: A multirole fighter with advanced avionics, AESA radar, and thrust vectoring. Dassault Rafale: A French multirole fighter with sophisticated sensors, reduced RCS, and highly capable EW systems. Saab JAS 39 Gripen E/F: A Swedish multirole fighter known for its advanced avionics, AESA radar, and cost-effectiveness. Boeing F/A-18E/F Super Hornet: An American carrier-capable fighter with significant upgrades over earlier models, including AESA radar and improved sensors. Sukhoi Su-35: A Russian multirole fighter with thrust vectoring engines, advanced radar, and electronic warfare capabilities. Comparison with Fourth and Fifth Generation Fighters Fourth-Generation Fighters: Typically designed in the 1970s-1980s, characterized by advanced aerodynamics, digital avionics, and multirole capabilities. Examples include the F-16 Fighting Falcon, MiG-29, and Mirage 2000. Fifth-Generation Fighters: Designed in the 1990s and beyond, these aircraft feature all-aspect stealth, advanced sensor fusion, and network-centric warfare capabilities. Examples include the F-22 Raptor and F-35 Lightning II. Generation 4.5 fighters serve as a bridge between these generations, incorporating many advanced features of fifth-generation fighters while being based on the airframes and designs of fourth-generation fighters. This makes them highly capable in modern air combat scenarios and a more affordable option for many air forces looking to upgrade their capabilities without investing in the more expensive and complex fifth-generation fighters. In February 2021, the Chief of Staff of the US Air Force, CQ Brown, said that the United States would develop a "fourth-generation and a half/fifth-generation minus" fighter to replace the F-16. From the literal meaning, its stealth performance does not reach the level of a standard fifth-generation aircraft. The main difference between 4.5 generation fighters and 5th generation fighters is stealth. Stealth is the ability to avoid or reduce detection by enemy sensors. Stealth is achieved by using advanced materials, design, and technology to reduce the aircraft's radar, heat, and noise signatures. Stealth gives an aircraft an advantage in combat because it can surprise, evade, or engage the enemy without being detected. Fifth generation fighters are designed with stealth as a key feature. They have internal weapons bays, low observable signatures, supersonic cruise engines, and advanced avionics that enhance their situational awareness and communications capabilities. Some examples of fifth generation fighters include the US F-22 and F-35, Russia’s Su-57, China’s J-20 and J-31, and India’s HAL AMCA. Fourth generation fighters were not designed with stealth as a key feature. They have external weapons pylons, less low observable features, less powerful engines, and less advanced avionics. However, some fourth generation fighters have been improved to incorporate some features of fifth generation fighters. These are sometimes called 4.5 generation fighters. They have better stealth, maneuverability, and electronics, but not as good as fifth generation fighters. Some examples of 4.5 generation fighters include the US F-15E and F/A-18E/F, the Russian Su-34 and Su-35, the European Eurofighter Typhoon and Dassault Rafale, and the Chinese J-10 and J-163. n classification. The origin of fighter generation The origin of fighter jet generation classification is the communication problem between Western aviation experts and politicians and parliamentarians. It has always been extremely difficult to explain the advanced nature of new fighter jets to politicians who hold financial power. Usually, most Western politicians and parliamentarians know nothing about aviation technology, but at budget review hearings, they have to decide whether the country supports the development of a certain aviation technology and approve funding for it. This gave rise to a method of briefly describing complex technical equipment, which is the origin of fighter jet generation classification. The method of using generation classification to summarize the complex performance of fighter jets quickly became popular in the West in the 1970s and was widely accepted and cited by the general public. Walter Boyne's method of classifying jet fighter generations In the past, the United States has always regarded the F-22 and other aircraft as fourth-generation aircraft. Around 2006, the US military and Lockheed Martin began to call the F-22 a fifth-generation aircraft. Lockheed Martin also invited Mr. Walter Boyne, who was once the director of the National Air and Space Museum, to write an article entitled "Generation Gap". The article provides a method for classifying fighter jets (see the table below). Generational division method of the US Air Force magazine in 2008 The ninth issue of the U.S. Air Force magazine in 2008 published an article titled “Fighter Generations”. In the article, the author described the fighter generation (six generations) as follows: The first generation of fighters includes the earliest jet fighters, such as the German Me262, the British Meteor ("Shooting Star") and the American F-80, which are characterized by a revolutionary increase in speed over previous piston engine aircraft. The second generation. The most famous second generation fighters are the F-86 of the US Air Force and the MiG-15 of the former Soviet Union. The "fusels of this generation of aircraft are designed and manufactured according to the potential of the jet engine in order to give full play to the performance of the fighter", for example, the use of large swept wings. 3rd Generation. The third generation of fighters appeared in the late 1950s and early 1960s, including the U.S. Air Force's "Centennial Series" fighters - F-100, F-101, F-102, F-104, F-105, F-106, and the former Soviet MiG-17 and MiG-21. These aircraft are characterized by advanced missiles, supersonic speeds, and more sophisticated engines. The F-4 Phantom belongs to the late third generation of fighters and may be regarded as the model of this generation. 4th generation. This generation began to appear in the mid-1970s and is still the top fighter in most countries in the world, including the US Air Force's F-15 and F-16, and Russia's Su-27 and MiG-29 and their derivatives, whose advanced weapon systems, engines and avionics make earlier aircraft look pale in comparison. After more than 30 years of technological improvements, some fighters have been pushed into the "4.5 generation" category, including the latest export models of the F-15 and F-16, as well as the MiG-35, Su-30 and the European fighter "Typhoon". 5th generation. This generation of fighters is defined as aircraft with all-round stealth, internal ammunition bays with precision-guided weapons, active phased array radars (AESA), and plug-and-play electronics. Currently, only the F-22 can be classified as this generation, and the F-35 Lightning II can also be classified as this generation after it becomes combat-ready. The sixth generation of fighter jets, which are currently in the design stage but are unlikely to appear for decades, will feature hypersonic speeds, dual-mode engines and adaptive shapes. Generational division method of the US Air Force magazine in 2009 The article "Sixth Generation Fighter" published in the 10th issue of the US Air Force magazine in 2009 mainly discussed some issues about the sixth generation aircraft. The article mentioned that the definition of fighter generation has been debated for a long time, and most people agree on the following generation: 1st generation: jet propulsion, including F-80 and German Me262. Second generation: swept wings, ranging radar, infrared missiles, including F-86 and MiG-15. The third generation: supersonic speed, pulse radar, beyond-visual-range attack, including the "Centenary Series" fighters such as the F-105, F-4, MiG-17, and MiG-21. 4th generation: pulse Doppler radar, high maneuverability, look-down and shoot-down missiles, including F-15, F-16, Mirage 2000, and MiG-29. Generation 4+: High agility, sensor fusion, low signature, including Typhoon, Su-30, new variants of F-16 and F/A-18, Rafale. 4++ generation: active phased array radar, with lower signal characteristics or active (waveform cancellation) stealth, some of which have supersonic cruise capability, including Su-35 and F-15SE. 5th generation: internally buried weapons, all-round stealth, ultra-high agility, full sensor fusion, integrated avionics system, partial or full supersonic cruise capability, including F-22 and F-35. 6th generation: Super stealth capability, effective in all flight ranges (from subsonic to high Mach), possible "morphing" capability, smart skin, highly networked, ultra-sensitive sensors, optionally manned, directed energy weapons. A brief discussion on the generation method of American fighter jets From the three generation classification methods introduced in this article, the ideas of these three methods are generally the same, but the classification of some specific fighter models is not exactly the same. Since the latter two methods were introduced by the US Air Force magazine, it should be said that this fighter generation classification method, that is, calling the F-22 a fifth-generation aircraft instead of the so-called fourth-generation aircraft in the past, represents the mainstream of the US military, and this generation classification method has gradually been accepted by the outside world. For example: In August 2010, the Japanese Ministry of Defense issued a document entitled "Prospects for Future Fighter Research and Development Trends", and the generation classification method basically refers to the current US generation classification method. Russia's generation classification method (see Ren Yuanbo's article "Fighter Generation Classification" in China Aviation News on September 13) has a different starting point from the current U.S. generation classification method. In addition, Russia counts variable-sweep wings as a generation, while the U.S. does not, so Russia and the U.S. generation classification methods are not exactly the same, but both methods consider the F-22 as a fifth-generation fighter, which can only be seen as a coincidence. It should be pointed out that the current method introduced by the US Air Force magazine is not completely appropriate and comprehensive, and there are some problems. For example, in the US Air Force's fighter generation classification method in 2008, the Su-27 is a fourth-generation aircraft, but in the US Air Force's fighter generation classification method in 2009, the Su-27 is not listed among the fourth-generation aircraft, and only the MiG-29 is listed, which is obviously unreasonable. In addition, the US Navy's classic F-14 did not appear in the US Air Force's fighter generation classification method in 2008 and 2009. Conclusion In fact, the various fighter generation classification methods used by different countries and at different times all have their own reasons, which are understandable and not absolutely right or wrong, and their acceptance depends entirely on the audience's own point of view. It should be pointed out here that the various fighter generation classification methods are actually like coordinate systems. The same aircraft may belong to different generations under different classification methods. Therefore, when commenting on whether a certain fighter belongs to a certain generation, it is necessary to state which classification method is used to avoid misunderstanding. ?Print? ?Close? Back to top Related Links:Chinese Governm Why is the Su-27 a fourth-generation aircraft in Russia, but a third-generation aircraft in China? Is the F-22 the fourth or fifth generation? Why is there a "fourth and a half generation" between the fourth and fifth generations, and what is the difference between it and the fourth generation? This type of question often confuses rookie military fans who have not been "in the pit" for a long time, and even many veteran military fans can't explain it clearly. However, whether it is a novice or an old bird, perhaps those who talk about concepts such as "third-generation aircraft" and "fourth-generation aircraft" all day long have not discovered that the fighter generation standards circulating in China may be rumors! What, what is going on, and what is the "correct" fighter generation standard? Today we will talk about this issue seriously. Figure: F-22 fifth-generation stealth fighter Surprise: The "American Standard" and "Russian Standard" cannot be verified Among Chinses military observers, there had long been an unverified legend: the Soviet Union and the United States originally agreed on the standards for fighter generation classification. The first generation of fighters were all supersonic fighters, and the second generation fighters were fighters with the ability to fly at twice the speed of sound. When it came to the third generation of fighters, differences began to emerge. The Soviet Union believed that variable-sweep wing fighters were the generation standard for third-generation fighters, but the United States disagreed. It was not until the emergence of high-maneuverability fighters that a separate generation was divided. Therefore, the problem of "American standard third generation" = "Soviet standard fourth generation" emerged. This statement has been widely circulated and is still heard today, and many people believe that the fighter generation standard used in China is the "old American standard." The fact is that this standard cannot be verified at all. There is a saying that in order to win funding from congressmen who hold financial power in Congress, the U.S. military simplified the complex technical and tactical characteristics of fighter jets into generational replacement, and used the new combat capabilities brought by the new generation of fighter jets as an inducement to win support from congressmen, but there is no strong evidence for this statement so far. The so-called "old American standard" can be traced back to the 1980s. At that time, the aviation industry had the saying of "four major next-generation fighter jets", namely F-22, "Rafale", "Typhoon" and JAS-39 (of course, now it seems that F-22 and the other three are completely different). Since there is a new generation, the previous generations should also be divided out. Therefore, the four-generation division method of fighter jets from the early models entering the supersonic era according to the flight speed of Mach 1, the flight speed of Mach 2 and radar and air-to-air missiles, the flight speed of Mach 2 and high agility and advanced avionics systems, and the next-generation fighter jets has spread like wildfire. But in fact, the U.S. Air Force has never issued similar standards for fighter generation classification, and this generation classification method is not an American patent, but is used by countries around the world, so it is inappropriate to call this generation classification method the "American standard." As for the Soviets' classification of variable-sweep wings as a separate generation, this may be because the Soviet Union lagged behind the United States in the development of second-generation fighters (the MiG-23 did not make its first test flight until 1967, six years later than the F-4 with the same performance, and at this time the United States had already begun to develop a newer generation of F-14 and F-15). In order to ensure "face", the variable-sweep wing was simply made the generation standard for third-generation fighters, making the MiG-23 nominally the "third generation" on par with the F-15, and the high agility and advanced avionics systems also made the MiG-29 and Su-27 the fourth generation, "a generation ahead" of the new US fighters. However, the Soviets certainly could not have imagined at the time that this "oolong" caused by this "oolong" would have a profound impact on the formulation of fighter generation standards in the future Historically, the United States did have a relatively detailed fighter generation standard, but this generation standard is completely different from the "old American standard" rumored in China. In 1990, American aviation historian Richard P. Hallion first proposed a complete fighter generation concept in the world. According to Hallion's generation classification method, the fighter generation standard up to that time was as follows: The first generation of fighters are subsonic fighters, characterized by aerodynamic design that is not much different from the late piston fighters, single or twin engines, optical sights, straight wing design, mechanical transmission system, the most basic avionics design, and a flight speed of 0.75 to 0.58 Mach. Typical models include Me262, F-80, MiG-9, etc. The second generation of fighters are transonic fighters, characterized by second generation jet engines, radar sights, swept wings, early hydraulic control systems for adjustable stabilizers, and a flight speed of 0.9 to 1.05 Mach. Typical models include F-86, MiG-15, "God of War", etc. The third generation fighters are early supersonic fighters, characterized by swept wings, full-moving tail, radar sights, early air-to-air missiles, fourth-generation jet engines, early stabilization technology, and some models have both air combat and attack capabilities. Typical models are F-100, MiG-19, and "super mysterious"; the fourth generation fighters are supersonic fighters with limited mission capabilities, characterized by aerodynamic design suitable for supersonic flight, fourth-generation jet engines, radar and fire control systems, excessive reliance on beyond-visual-range air-to-air missiles in combat, and a flight speed of Mach 2. Typical models are F-104, MiG-19, and "super mysterious". 21. "Lightning", "Mirage" 3; The fifth-generation fighter is a multi-purpose supersonic fighter, characterized by more precise supersonic aerodynamic design, diversified wing design, fourth to fifth generation jet engine, stability enhancement design, weapon system with both machine gun and air-to-air missile, equipped with terrain tracking radar suitable for low-altitude and high-speed flight, equipped with radar and infrared sensors and fire control system, with head-up display, can be mounted with laser navigation and targeting pods, can use a variety of different types of air and surface weapons, flight speed 1.4 to 2.5 Mach, typical models F-105, F-4, MiG-23 /27, Su-24, "Jaguar", "Mirage" F.1; The sixth-generation fighter is a multi-purpose, highly maneuverable supersonic fighter, characterized by improved aerodynamic design, radar, and perception capabilities based on the fifth-generation fighter, and a highly flexible fly-by-wire control system, high maneuverability, and the ability to perform various types of air and surface missions, high thrust-to-weight ratio and meet the flight capability of an angle of attack of more than 70°, and a flight speed of 1.8 to 2.5 Mach. Typical models are F-14, F-15, F-16, F/A-18, "Mirage" 2000, "Tornado", MiG-29, Su-27. As for more advanced models, he didn't even mention them. It is not difficult to see that Hallion's generation standard is completely different from the rumored "old American standard" and the current American fighter generation standard, and the two generation classification methods do not match at all. So, what about the "fourth and a half generations" and "fifth generation aircraft" in the current American fighter generation classification? In 2008, the U.S. Air Force's official publication "Air Force" magazine published an article entitled "Generation Gap" written by Walter Boyne, director of the National Air and Space Museum. The article first proposed the five-generation classification of American fighter jets: the first generation is the transition period from straight wings to swept wings, and from centrifugal jet engines to axial-flow jet engines, with typical models such as He280, Me262, and "Meteor"; the second generation is swept wings, and the engine performance is maximized, with typical models such as F-86 and MiG-15/17; the third generation is capable of launching air-to-air missiles and has more complete The fourth generation is the models with advanced weapons systems, engines and avionics systems, such as the F-15, F-16, F/A-18, Su-27, MiG-29, Mirage 2000 and Typhoon; the fifth generation is the models with comprehensive stealth design, weapons mounted inside the fuselage, active phased array radar and modular electronic equipment, such as the F-22 and F-35; the sixth generation is the models equipped with variable cycle engines, capable of hypersonic flight and adaptive shape. At this time, the current generation standards for American fighter jets have taken shape, but are still not perfect. By 2009, in an article titled "The Sixth Generation of Fighter Planes" published in the Air Force magazine, the standards for fighter generation classification were revised: the first generation refers to early jet fighters, with typical models being the F-80 and Me262; the second generation refers to models with swept wings, radar rangefinders, and the ability to launch short-range air-to-air missiles, with typical models being the F-86 and MiG-15; the third generation refers to models with supersonic flight capabilities, equipped with pulse radars, and capable of beyond-visual-range air combat capabilities, with typical models being the "Century Series", F-4, MiG-17, and MiG-21; the fourth generation refers to models equipped with pulse Doppler radars, highly maneuverable, and able to launch upward/downward air-to-air missiles, with typical models being the F-15 , F-16, Mirage 2000, MiG-29; Fourth generation + refers to models with high maneuverability, integrated sensor design, and partial reduction of radar reflection area, typical models are "Typhoon", Su-30 series, F/A-18E, "Rafale"; fourth generation ++ refers to models equipped with active phased array radar, further reducing radar reflection area or using active jamming technology, and some models can cruise at supersonic speed, typical models are Su-35 and F-15SE; fifth generation fighters are models that fully adopt radar stealth design and built-in weapon design, and have high sensitivity and omnidirectional perception capabilities, integrated avionics systems, and full or partial supersonic cruise capabilities, typical models are F-22 and F-35. So far, the standard for the generation of American fighters has been fully established, and the so-called "fifth generation" and "fourth and a half generations" are divided according to this standard. The specific models of each generation of this "new American standard" are definitely different from some people's concepts. China originally did not have the so-called "fighter generation classification". However, in recent years, with the popularity of military media programs and the Internet providing a communication medium, military fans have accidentally agreed on a "Chinese fighter generation standard" over time, in which the first and second generations are the same as the "Soviet standard", and the third and fourth generations continue to use the "old American standard". With the expansion of the influence of the "new American standard", the "new national standard" has now appeared, with the first two generations using the "old American standard" and the last three generations using the "new American standard". Regardless of whether this classification method is scientific, it is at least scientific in terms of the current popularity. However, since the generation standards of the American and Russian standards are different from the "Chinese standard", is there no country that uses a fighter generation classification method that is close to the "Chinese standard"? In 2012, the Australian Air Force Air Power Development Center released a new fighter generation standard: the first generation fighter is subsonic, has neither radar nor self-defense system, can only use unguided bombs or rockets when attacking, and is equipped with an engine without afterburner. Typical models are F-86 and MiG-15/17; the second generation fighter is equipped with air-to-air radar, can launch semi-active radar-guided or infrared-guided air-to-air missiles, is equipped with radar warning devices, and can fly at supersonic speeds. Typical models are F-104, F-5, MiG-19, MiG-21; the third generation fighter is equipped with multi-tasking capabilities, can launch look-down and shoot-down air-to-air missiles, and can launch beyond-visual-range semi-active radar-guided air-to-air missiles. Typical models are MiG-23, F-4, "Mirage" 3. The fourth generation fighter is a multi-purpose model equipped with a head-up display and a fly-by-wire control system, typical models are MiG-29, Su-27, "Mirage" 2000, F-15, F-16; the fourth and a half generation fighter is a multi-purpose model that uses stealth technology and radar absorbing materials, has a vector nozzle, is equipped with an active phased array radar and has networked combat capabilities, typical models are F/A-18E, F-15SG, "Typhoon", "Rafale", JAS-39; the fifth generation fighter is a model that adopts a stealth design, has multiple perception capabilities, and can realize networked combat, typical models are F-22, F-35, Su-57, J-20. It can be seen that although there are differences in the generation of the first generation of fighters, this division standard is still very close to the "new national standard", so it cannot be said that the conventional "national standard" fighter generation division method is unscientific. In addition to the "mainstream", there is also the "non-mainstream". In 2004, the Aerospaceweb website proposed a rather crude generation standard. It is crude because this generation method is almost entirely based on the service years of the models, and very few technical commonalities are considered, so that the Harrier and MiG-25, two models with completely different technical characteristics, can be classified as the third generation, and the IDF and Su-33 can also share the title of the fourth generation fighter. Because this generation standard is too general and lacks scientificity, and Aerospaceweb is not an authoritative organization, this generation standard is rarely used internationally. In addition, American aviation scientist Jim Winchester also has his own fighter generation method. He also divides fighters into five generations, and the model classification of each generation is basically the same as the "New American Standard", but uses different technical feature judgment methods. These "non-mainstream" fighter generation classifications are just statements made by some researchers for the convenience of research and are not universally applicable. To be honest, it doesn’t really matter whether a fighter is classified as the fourth generation or the fifth generation according to different standards, because no matter how it is classified, the expected use environment and technical requirements of a fighter determine its technical and tactical characteristics. On the other hand, even if it is classified into different generations, due to the overlap of service time, the main opponents of a fighter in a certain period are basically determined. Therefore, it is useless to overemphasize the generation issue when comparing the combat capabilities of different types of fighters. After all, the performance of fighters is a hard indicator and is not determined by the generation. If we must classify the fighters in our military’s history and in use according to the "new American standard" that is currently popular internationally, the division should be like this: First generation: MiG-9, Uyak-17 Second generation: MiG-15, MiG-15bis Third generation: J-5, J-6, J-7, J-8 Fourth generation: J-10/J-10A, Su-27SK, Su-27UBK, J-11A/B Fourth generation +: Su-30MKK/MK2, J-10B Fourth generation++: Su-35SK, J-16 Fifth generation: J-20 However, even so, from the perspective of tactical and combat research, it is still necessary to establish a truly scientific fighter generation standard for our army. The current "new national standard" can basically meet this requirement, and the generation classification of fourth-generation, fourth-generation and a half and fifth-generation aircraft is also in line with international standards, which can avoid propaganda confusion and improper research caused by different generation classification methods. However, it is still necessary to conduct specific technical feature determination similar to the "new American standard", which will have a positive impact on the research of air force equipment and air combat tactics.0th Generation
The transition from reciprocating engines to gas turbine engines for military aircraft propulsion began in the years following 1946. Jet propulsion is a means of moving an aircraft forward by sending rearward at high velocity a stream of flowing gases, like sending a balloon across the room by letting go of its neck. In 1923 Edgar Buckingham of the US Bureau of Standards declared that jet propulsion for aircraft was practically impossible. From his analysis of the thrust produced by an exhaust of burning compressed air in a combustion chamber, Buckingham determined that there was "no prospect whatsoever that jet propulsion . . . will ever be of practical value, even for military purposes." Even at the highest flying speed anyone then had in view~250 miles per hour~a jet-propelled aircraft could not come close to matching the efficiency of an airplane equipped with a piston engine and propeller. The jet's fuel consumption would be far too excessive, he argued, largely because the weight of the compressor machinery would have to be so great. Buckingham calculated that the fuel consumption of a jet would be four times that of a conventional engine producing equivalent thrust. He assumed that aircraft turbines would have to be huge and heavy, similar to industrial turbines then being used in blast furnaces and boilers, to withstand the high temperatures and attendant high pressures. Buckingham's error was in this and other assumptions, not in his subsequent analysis. Because he failed to consider the possibility that aircraft might someday be able to fly at speeds well in excess of 250 mph, he failed to consider the possibility that fuel efficiency might significantly improve at higher speeds. Like his counterparts elsewhere, he also assumed that compressors would necessarily have to be huge and heavy devices similar to those then used for industrial purposes. In 1928, twenty-one-year-old Royal Air Force flight cadet Frank Whittle speculated that it would be possible to attain very high speeds-speeds in excess of 500 mph - if one could achieve stratospheric flight. He also perceived that the piston-engined, propeller-driven airplane would never do the job. To achieve the speed and altitude he envisioned, some alternative form of pro- pulsion system uniquely suited to those conditions was essential.v After less than two years of self-directed study and speculation, he had deduced that, for very high speeds and altitudes, employing a gas turbine to produce jet propulsion was the most feasible and, ultimately, obvious answer, as originally conceived in his patent application of 1930. One early system was developed by Italian engineer Secondo Campini in the 1930s and applied in the early 1940s to a Caproni airplane, based on the principle of the ducted fan. In 1927, the Italian Air Ministry built and tested a plane driven by a form of mechanical jet propulsion. The fuselage of this plane was shaped like a tube, with flaring ends. A conveutional propeller was mounted in the throat of the tube, forming a "ducted propeller" installation. This craft had good maneuverability and good stability, but in other respects its performance was poor. In 1932, Campini, an Italian, designed and later flew the first plane powered by a thermal jet; it differed from modern jets in using a piston engine, rather than a turbine, as a compressor. After Campini's successful flight, development of improved jet engines was undertaken in several countries. Frank Whittle, a British pilot, who designed and patented the first turbo jet engine in 1930. The Whittle engine first flew successfully in May, 1941. This engine featured a multistage compressor, and a combustion chamber, a single stage turbine and a nozzle. General Electric built the first American jet engine for the US Army Air Force jet plane . It was the XP-59A experimental aircraft that first flew in October 1942. At the same time that Whittle was working in England, Hans von Ohain was working on a similar design in Germany. The first airplane to successfully use a gas turbine engine was the German Heinkel He 178, in August, 1939. It was the world's first turbojet powered flight. During an early 1941 visit to England, -Maj. Gen. Harold H. Arnold, acting deputy chief of staff for the Army Air Corps, became interested in the jet propulsion engine under development by the British. At the time, the British were ahead of the United States in this technology. The engine was developed by Air Commodore Frank Whittle of the Royal Air Force and was known as the Whittle Engine. Arnold witnessed the pure jet Whittle engine in operation on an airplane and was absolutely stunned by how far the British had advanced. By October 1941, a Whittle Engine arrived at Wright Field, Ohio. On Jan. 8, 1944, at Muroc Army Airfield (later Edwards Air Force Base), Lockheed’s chief engineering test pilot, Milo Garrett Burcham, conducted the maiden flight of the prototype Model L-140, the Army Air Forces XP-80 (serial number 44-83020). This aircraft used a General Electric variant of the Whittle Engine. J-33 engines of various variants continued to be used in F-80s during the Korean War and later around the world. The American aviation industry helped win World War II largely through mass production of prodigious quantities of a few outstanding but relatively conventional prop fighter designs that were continually improved incrementally. America's rela- tively slow entry into the jet age resulted in part from this mass-production strategy and the failure of some firms to transition successfully to the radical new technology. The Army Air Corps did, however, take an early interest in jet fighters even before U.S. entry into the war and continued to push forward jet-fighter development as the war progressed. The US Navy remained more skeptical about jet fighters than the Air Force and was thus slower to initiate jet-fighter development. The relatively short takeoff space available on carrier decks, combined with the low thrust ratings of first-generation jet engines, caused most of the Navy doubts about jet fighters. As a result, the Navy tended to turn to its "second-string" companies with less experience in Navy fighter R&D to initiate the process. This was also because the Navy's leading contractor, Grumman, was overwhelmed with war work, and because the Navy believed that newer companies, or those less well established in Navy fighter R&D, might be more innovative in dealing with the new technologies and designs. Though overshadowed by German development of jet aircraft during World War II, the U.S. Navy initiated work on its first jet fighter as early as 1942. Chosen to build the aircraft was McDonnell Aircraft Corporation, whose initial design featured three 300 lb. static thrust jet engines on each wing. After settling on a two-engine configuration for the new fighter, McDonnell began construction of two prototypes in January 1944, with the airplane's first flight occurring a year later. Delivered to the Navy for evaluation under the designation XFD-1, the Phantom made history on 21 July 1946 when Lieutenant Commander Jim Davidson caught an arresting wire on board the aircraft carrier USS Franklin D. Roosevelt (CVB-42). This was the first landing of a pure jet fighter on an American aircraft carrier The complexity of weapon system mission requirements began to increase during this transition period. In combination, these factors placed new and greater demands on propulsion system performance and operational suitability. Thrust, specific fuel consumption, weight, and external dimensions, long used as engine performance parameters, were being forced to the limits of the existing state of the art. Correspondingly, engine operating characteristics under environmental conditions and life functions, such as durability, reliability, and maintainability, commonly used as measures of operational suitability, were being pushed to new levels. But the most significant aspect of this transition period was that a major change emerged in the evaluation of operational suitability; along with life functions, propulsion system stability became an important system criterion. Stability of turbine engines was defined in ensuing years as the ability of an engine to produce continuous thrust outputs proportional to power lever settings. Correspondingly, engine-airframe compatibility came to include the capability of a propulsion system to perform during the required mission flight maneuvers and engine power modulations with "stable" propulsive -output. History shows that over the years stability problems continually plagued propulsion system development and operation. In the most significant cases, serious system instabilities were not discovered until after the first flights of the associated aircraft. Development and operational problems with stability have been traced to several causes: (1) inadequate definition of the causes of instability, (2) inappropriate test techniques and test sequencing, (3) insufficient coordination between engine and airframe developers, and (4) utilization of inadequate descriptors of turbine engine stability and system compatibility. History also shows that improved approaches to development evolved, and whcn considering all previous experience, recommendations can be made for more appropriate development techniques and programming for future systems, In the early years of jet-propelled military aircraft developments, a number of stability related factors arose in integrating engines and airframes. Early systems encountered various inlet-engine interfacerelated phenomena such as engine surge, flameout during armament firing, and inlet duct rumble. While these problems appeared in various aircraft during 1946-1955, indications were that they were viewed as "normal development problems" in what might be described as first generation military jet aircraft. In due time, these difficulties appear to .have been resolved with relatively minor systems impact as compared with later systems in which the situation was to change significantly.1st Generation
First-generation fighter jets refer to the earliest jet-powered aircraft developed during and immediately after World War II, roughly from the mid-1940s to the early 1950s. These jets represented the transition from propeller-driven aircraft to jet propulsion but were relatively simple compared to later generations. Key Features of First-Generation Fighter Jets: The period from the mid-1940s through the early 1950s was a time of particularly rapid and dramatic technological advancement and change, as developers exploited the enormous increases in potential per- formance made possible by the jet engine. In this era, innovation, new ideas, and experimentation predominated, particularly in the immediate postwar years—when relatively new firms and established industry leaders had to struggle and fiercely compete to survive in a peacetime world in which the gigantic production orders of World War II no longer existed. While important changes in industry leadership took place during this period, the industry lead- ers in fighter R&D that had emerged during World War II continued to remain prominent. At the same time, relatively new entrants were able to take advan- tage of rapidly advancing technology also to rise to leadership positions. With straight wings, the aerodynamics were similar to propeller aircraft, limiting top speeds. Speeds were typically capped below the speed of sound (~600–700 mph). Early Turbojet engines offered basic jet propulsion, often with limited reliability and efficiency. Engines lacked the afterburners seen in later generations. Guns (typically machine guns or cannons) were the primary weaponry; early unguided rockets were sometimes used. The planed had minimal avionics, with little to no electronics for navigation or targeting. Examples of First-Generation Fighter Jets: Messerschmitt Me 262 (Germany): The world's first operational jet fighter, Messerschmitt's Me 262 started as Projekt 1065 in 1939. Competing with Ernst Heinkel's experimental He-280, the Me 262 was selected because it was designed for the Junkers Jumo 003 axial-flow engine. Nicknamed Schwalbe (Swallow), the Me 262 first took to the air in April 1941, powered by a piston engine. At the time, the German view held that the war could be won using conventional, piston-powered aircraft. Thus, what could have placed Germany in a position of advantage in the air war was squandered as the program languished until July 1942, when the first "jet" flight was made. Jumo 004-powered Me 262s appeared in 1943, and were in production by April 1944. Despite its short time in combat, the Me 262 had proven superior to all Allied fighters, accounting for 542 Allied aircraft destroyed while losing 100. Gloster Meteor (UK): The Allies' first operational jet fighter, used primarily for intercepting German V-1 flying bombs. Lockheed P-80 Shooting Star (USA): One of the first operational jet fighters for the U.S. Air Force. Mikoyan-Gurevich MiG-9 (Soviet Union): Early Soviet jet, quickly succeeded by more advanced designs. de Havilland Vampire (UK): A British jet fighter used extensively in the early post-war years. Limitations: Engines were prone to breakdowns and inefficiencies, with short operational lifespans. Speed and maneuverability were often outclassed by high-performance propeller-driven aircraft like the P-51 Mustang or Spitfire in specific situations. Aircraft designs were experimental, with lessons learned feeding directly into second-generation developments. These jets marked a critical point in aviation history, demonstrating the potential of jet technology and paving the way for faster, more capable aircraft. The Korean War served as the arena for history's first air-to-air combat by jet-propelled aircraft. U.S. Air Force pilots did not start scoring heavily against Russian-made MiG-15 jets until the swept-wing F-86A Sabre arrived in Korea in late 1950. Then the victories began to mount, and by the end of hostilities in July 1953, 38 USAF pilots had become aces by shooting down five or more enemy aircraft (nearly all of which were MiG-15s). The first jet-to-jet victory took place on Nov. 8, 1950, when Lt. Russell J. Brown, flying an F-80C, shot down a much faster MiG-15 over North Korea.2nd Generation
Second-generation fighter jets refer to a class of military aircraft developed during the late 1940s through the 1950s. These jets introduced significant advancements over first-generation fighters, which were mainly subsonic and based on early jet engine technology from World War II. Swept Wings provided improved aerodynamics for higher speed and better maneuverability. Afterburners enabled short bursts of speed, often allowing for supersonic flight. Basic onboard radar was used for targeting and navigation. Early Air-to-Air Missiles were introduced, though often unreliable compared to later generations. More powerful and efficient jet engines compared to first-generation fighters. Early versions of electronic systems to assist in navigation and targeting, though relatively primitive. The Mikoyan-Gurevich MiG-15 (Soviet Union) was a notable early swept-wing design, particularly effective during the Korean War. Mikoyan-Gurevich MiG-17 (Soviet Union) was an evolution of the MiG-15 with enhanced performance. North American F-86 Sabre (USA) was widely used by the U.S. and its allies, also famous for its role in the Korean War. Dassault Mystère IV (France) was one of France's significant entries in second-generation jet technology. Hawker Hunter (UK) was a British fighter jet known for its reliability and export success. These fighters laid the groundwork for subsequent generations, focusing on supersonic speeds, enhanced weapons systems, and increasingly sophisticated avionics. In the late 1940's, a new generation of weapon system requirements, and hence military aircraft, was evolving. While this has been described in various literature as the trend toward "bigger-faster-higher" systems, some of the important requirements in terms of propulsion systems were increased range, speed, altitude, and maneuvering envelopes. These increased requirements for range, maneuvering envelopes, and subsonic and supersonic operation were to significantly affect the sensitivity and complexity of propulsion system matching of inlet-engine and aircraft. In general, there were limited numbers of engine altitude test facilities available through about 1951, in which turbojet engines could be tested under simulated altitude environment. In addition to limited testing experience in terms of procedures, techniques, and instrumentation, engine altitude testing to define inlet-engine interface factors (distortion) had not been pursued prior to about 1951-1952. large propulsion wind tunnels capable of performing free jet inlet-engine testing under simulated altitude conditions were not available until after 1955. The inlet-engine interface evolved into a major problem in the early 1950's, with the advent of the ' compressor stall problem" on several advanced Air Force weapon systems. The reason the problem became major was basically that the "compressor stall problem" was not revealed until late in development (i. e., flight test), and flight test schedules consequently became disrupted because of flight restrictions to avoid compressor stall. In some cases, systems were so restricted that required flight and maneuvering conditions could not be achieved. At the onset of these problems (1952- 1954), the Air Force and affected system contractors became increasingly concerned over the seriousness and implication of unstable engine operations in flight. During that time period, meetings were convened between those system contractors to determine the causes of engine compressor stall and remedies for its elimination. In 1954 was a typical example of such meetings and was significant as it was one of the earlier meetings convened expressly to examine "mutual inlet-engine problems" existing at that time for several advanced weapon systems. It is interesting from the standpoint of interface, that this meeting sought to determine whether inlet ducts or engine characteristics were the prime causes of "compressor stalls in aircraft operations. Compressor stalls in aircraft operations had occurred across a wide spectrum of flight conditions which differed according to aircraft flight and maneuvering requirements. A number of "fixes" to inlet and/or engine had been undertaken in flight testing with varying degrees of success in attempts to achieve stable engine operation. A "fix" for one system would not necessarily achieve the same result for another installation or aircraft. The "stability" or inlet-engine compatibility had become a major problem apparently as a result of improper development planning. Stringent requirements had arisen in range, Mach number, and weapons delivery capabilities. At that point, these requirements had been recognized to sonte degree as factors contributing to the complexities of propulsion system integration and inlet-engine matching. Efforts then to achieve the necessary development planning factors led to many important coordinations in the following months between propulsion research and development agencies. These all sought to better identify the problem as well as steps to achieve the solution. Delaying interface and propulsion stability considerations until first flight did little to ensure the compatibility of integrated systems for flight. Secondly, a lack of baseline stability data on propulsion subsystems led to multiple or trial and error testing approaches with excessive time and resources expenditures ensuing. Additionally, the pressing need for "early" resolution of flight problems and eventual stability results did not appear to significantly contribute to the understanding of causes, effects, and solutions of stability problems and translate into needed engineering approaches for propulsion system development procedures prior to flight. Typically, multiple fixes were tried until some combination is sufficiently successful. Thereafter, the airframe personnel recall that the problem was solved by changes in the engine geometry, control schedule, and/or operating procedures. Similarly, the engine personnel clearly remember that the problem disappeared when changes were made in the inlet geometry, control schedules and/or aircraft operating procedures.3rd Generation
A turn of historical events would deter or cut short programming directed toward these engineering goals. In the years following 1955, the advent of the ballistic missile family of strategic and tactical weapon systems was to divert significant levels of funding and effort from aircraft and propulsion developments. Aircraft developers found mission requirements more demanding, development costs spiraling upwards, and fewer funds available for advanced aircraft programs. During this period, many aerospace contractors diverted their efforts and technical resources away from aircraft and propulsion toward the field of missiles and rockets. In addition, government research, such as that at NASA (formerly NACA), in the area of aeronautics and propulsion was reoriented to support the space and missile programs. Thus, in aircraft and engine developments alike after the mid-1950's, fewer developments were initiated and major reductions occurred in exploratory and advanced development programming. As a result, early plans to define inletengine development programming factors and definition of the inlet-engine interface failed to culminate as technology sources, funding, and engineering efforts dwindled, But propulsion test facilities came into operation in the later 1950's, thus making available a number of engine altitude test cells, large scale propulsion wind tunnels, and other wind tunnels for airframe-propulsion subsystems testing for usage in later advanced military aircraft developments.18 Air Force weapon systems operational concepts continued to grow in scope in the later 1950's and influenced advanced propulsion system concepts and designs through their particular mission needs. Two types of such advanced weapon system concepts evolving in this time span included the long-range, sustained supersonic cruise vehicles and the mixed mission weapon systems possessing several mission range, Mach number, and high maneuverability requirements. Each type of weapon system requirement posed challenging engineering tasks contrasted to those of earlier systems. In the case of supersonic cruise vehicle types, the propulsion subsystems were moderate pressure ratio afterburning turbojet engines combined with variable-area, mixed-compression inlet systems. These types of weapon system propulsion systems would be required to accelerate an aircraft through takeoff and climb to cruise conditions. Upon reaching cruise altitudes and Mach numbers, efficient propulsion system cruise operations would be required for primary mission operations, which did not include requirements for wide ranges of transient maneuvers, Mach numbers, altitudes, or abrtupt engine power modulations. On the other hand, the multimission type of weapon system posed needs for efficient propulsion systems operations along several required mission trajectcries varying widely in speed, altitude, and range.. In addition to this desired mission flexibility, extensive aircraft maneuvering and transient capabilities were also required. These combinations of mission operations and aircraft range requirements led to propulsion subsystems consisting of supei'sonic, variable-area, mixed-compression inlet systems combined with high pressure ratio augmented turbofan engines. The significance of the increased scope of these Air Force required weapons delivery capabilities became apparent in the configurational and matching complexities of resulting propulsion systems requirements and configurations. Those arising complexities became even more significant considering the status of available propulsion engineering development criteria and approaches evolving from the late 1950's, particularly those relating to integrating inlet and engine functional operations in system devclopment. One of the principal effects of inlet distortion on engine operation was the increased tendency of the engine compressor to stall. Levels of inlet distortion as well as geometric distribution had been found to affect engine compressor stall characteristLcs. Compressor stall or engine flameout could be caused by high distortions resulting from poor inlet designs, pressure fluctuations during flight maneuvers (inlet unstart, buzz, flow separations, etc.), and the ingestion of armament firing gases. Compressor stall characteristics had been found to be affected by stage loading, stages and/or spool matching, control response (accel-decel), control operation, and Reynolds number. Supersonically, shock-boundary layer interactions had been found to result in higher inlet flow distortions at the compressor face. Inlet-engine compatibility problems on military aircraft had resulted in considerable difficulties and solutions had usually been found by "modifying engines." Full-scale inlet-engine compatibility testing was recommended in systems programs where compatibility remained questionable in design and development (prior to flight). Further, it was felt necessary to require engine contractors to develop and furnish more meaningful estimates of allowable inlet distortion limits. It was suggested that these estimates should contain the combined effects of pattern shapes as well ad disturbance levels, and should provide estimates of the engine's response, even if allowable distortion limits were exceeded. In the case of one US fighter system, early flight tests revealed another major problem in the inlet-engine area. It will be recalled from Figure IV- I that this system became defined with a highly loaded engine cycle in terms of compression system pumping and was to be matched for a broad spectrum of mission operations with an advanced and complex air induction system-. In terms of matching sensitivity or complexity, this system marked a major advance compared with earlier Air Force weapon systems. Flight testing into 1965 revealed unexpected and serious discrepancies in systems' stability (and performance). By mid-1965, propulsion system problems such as various modes of "compressor stall and flameout had limited the flight envelope and aircraft maneuvering capability to the extent that significant delays in the flight test schedule and program were evident. Air Force task force groups convened, such as shown in Reference 23, and after some examination, stated that the system could be made to work over some of the important parts of the wide mission spectrum required, but at the expense of overall program schedule. Perhaps more importantly, considering the complexity of the overall propulsion system and the wide spectrum of systems operating requirements, it was not felt possible at that time to fully define the problems; therefore, additional diagnostic investigations, studies, and tests were recommended for identifying and understanding the operating characteristics of the inlet and engine. Serious problems in flight testing continued and an accelerated program of flight and ground testing was implemented. With the influx of those tests and the incorporation of extensive diagnostic instrumentation t (including high response pressure measuring devices), another problem surfaced. Systems for handling, reducing, transmitting, and interpreting data from tests rapidly reached an unworkable point.4th Generation
In 1970, the US Navy upgraded from the successful F-4 Phantom II to the variablegeometry, carrier-capable Grumman F-14 Tomcat, ushering in a new generation of multipurpose fighter and attack jet aircraft. In 1979, the McDonnell Douglas F-15 Eagle and the General Dynamics/Lockheed Martin F-16 Fighting Falcon joined the USAF as the next generation of fighter aircraft.|
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