Indian Defence Review

Lockheed Martin F-35

Classification of fighter aircraft into ‘generations’ dates back to the 1990s and there are several diverse classification criteria applied by air historians, the National Aeronautics and Space Administration (NASA) of the United States (US), leading Original Equipment Manufacturers (OEMs) and some prominent militaries. While there is no universal agreement on airtight definitions of generations, a coarse grouping started with the appearance of jet fighters at the end of World War II i.e. in the mid-1940s, that are referred to as the first generation, while improvements in design and speeds led to the second generation being pronounced. These were the fighter aircraft operating during the Korean War, many of which had swept wing designs. Supersonic speeds and advanced engines characterised the third generation through the 1950s and 1960s.

The fourth generation appeared on the scene during the 1970s and was differentiated by significant improvement in avionics and automation, Fly By Wire (FBW) and Full Authority Digital Engine Controls (FADEC) debuted in this generation. Prominent current day fighter aircraft are essentially fourth generation although they are being constantly retrofitted with features to enhance their original capabilities. The defining characteristic of the fifth generation is significant amount of stealth, some other features being Active Electronically Scanned Array (AESA) radars, super cruise capability, plug-and-play electronics and automation permitting fair amount of autonomy in some areas of operations. Lockheed Martin F-22 Raptor was the first fifth generation fighter to enter service in 2005, followed by Lockheed Martin F-35 Lightning in 2015, Chinese Chengdu J-20 in 2017 and Russian Sukhoi Su-57 in 2020. Some analysts are of the view that the Su-57 falls short of fifth generation criteria and the under-development Su-75 would be a true fifth generation aircraft ; its first fight is expected to be in 2023. High costs have limited fifth generation types and numbers although several nations including India have ambitions and ongoing programmes to produce these platforms.

The sixth generation is evolving and holds the interest of every Air Force in the world. Artificial Intelligence (AI) is the defining but not the only technological incorporation into this generation. This article looks at what a sixth generation fighter could mature into and its prospects as an aerial platform.

What a Sixth Generation Fighter Could Be

Although a US prototype sixth generation fighter is claimed to have been flown already, the first induction into service is expected only in the 2030s. Ongoing programmes are discussed later. The distinctive feature of this generation is the use of advanced digital technologies of which AI is the most prominent. Needless to say, the capabilities of fifth generation fighters will be improved upon in terms of aerial engagements, ground support, cyber warfare and battlefield survivability. Their envelope may be distended into space too, since space is a weaponised and militarised part of battle space now.

Stealth with possibly a tailless delta wing airframe would be carried beyond fifth generation levels of low Radar Cross Section (RCS) and radar absorbent materials despite the speculation that advanced sensor technology would reduce the effectiveness of stealthy airframes. As an extension of this logic, on board weapons would need to have much longer ranges, air-to-air missiles would have to enhance their Beyond Visual Range (BVR) reaches while air-to-surface ones would have to cater to air defence weapons of the S-400/S-500/S-550 variety. As aerial combat within visual range is almost extinct, design may trade in manoeuverability in favour of greater payload, larger internal fuel capacity and heavier but more sophisticated power plants. The adaptive cycle engine is being designed to operate equally efficiently under mixed flight conditions such as subsonic, transonic and supersonic. 3-D vectoring and high levels of thrust would be its essential attributes.

The abundance of AI-enabled avionics and neural networks would permit fighters to perform more and more vital combat functions at speeds far exceeding the mental abilities of human pilots. Helmet-mounted displays would become standard equipment and may even displace cockpit instrumentation while voice activated commands could interface with avionics. While some fourth generation fighters carried a Weapon System Operator (WSO) to help the pilot, fifth generation fighters are all single-seaters with AI sharing the pilot’s workload. In the sixth generation, AI is expected to move from sharing the cockpit with a human pilot to manning it independently. An “optionally manned cockpit” design is thus slated to be a key attribute of the sixth generation fighter. Another spin-off of this feature is the AI-driven capability of manned fighters to team up with Unmanned Aerial Vehicles (UAVs) and Unmanned Combat Aerial Vehicles (UCAVs) for undertaking a variety of offensive and defensive roles. There are already programmes which have demonstrated and are constantly refining this Manned-Unmanned Team (MUM-T) concept. AI and machine learning are enabling the concept of one manned aircraft leading a team of unmanned aircraft capable of autonomous operations.

The sixth generation fighter’s payload would include directed energy weapons such as lasers or microwaves and hypersonic/ramjet-powered missiles such as the Meteor. Electronic Warfare (EW) suites can be expected to be superior to the fifth generation ones. While stealth or airframe shapes are not clearly defined, superior radar evading capabilities are expected to be essential features. Onboard radio electronic equipment could be a combination of communication, EW and radars. The design would have a common multi-tasking hardware that works with adaptable software capable of switching tasks instantaneously. On board mission computers would develop into data collection and processing centres with huge, high performance computing capability to help decision making. Needless to say, AI would empower this aspect by turning data into real time information.

In avionics, emerging higher levels of modularity, integration and unification would simplify maintenance processes and reduce down time. As far as sensors are concerned, plug-and-play capabilities could be refined further to permit task-related swaps between missions right on the flight line. Sensor fusion with friendly forces in the air and on the surface of the Earth, is another projection for the sixth generation design. This envisages collection of huge amounts of sensor data and sharing it via data links to friendly forces to create and composite picture of the operational area. For maritime operations, self-landing on carrier decks is a feature sought for the sixth-generation fighter. Indeed, Chinese writings suggest the possibility of an electromagnetic launch system even for land operations which would cater for runway damage contingencies.

Sixth Generation Programmes

The US undoubtedly leads the world in fighter aircraft technology. After producing two fifth generation fighters, the F-22 and the F-35, it is now engaged in two sixth generation programmes. China and Russia too have fifth generation fighters to their credit namely the J-20 and the Su-57 respectively. Both have sixth generation programmes although details of these are not as openly available as for those being developed by the US. All other nations or nation groups that are pursuing sixth generation programmes, have skipped fifth generation and have gone from fourth to sixth directly.

The US has two programmes underway. The first is the F-X, also known as Next Generation Air Dominance (NGAD) or Penetrating Counter Air (PCA) for the US Air Force (USAF) and the second is the F/A-XX which the US Navy also calls NGAD, related to a replacement for US Navy’s F/A-18E/F. In September 2020, the USAF issued a statement that a prototype of the NGAD had performed its first flight, thus stealing a march over rival programmes.

The USAF sees its NGAD programme as a successor to the successful F-22 Raptor air superiority fighter with possible role of a long range stealth fighter escort for stealth bombers and capable of penetrating counter-air platforms with multi-domain situational awareness, agile resilient communication and an integrated family of capabilities as advertised.

The US Navy’s NGAD programme on the other hand, relates to carrier and land operations. The fighter is expected to team with attritable unmanned aircraft which would act as the manned airplane’s eyes and ears, detecting threats on the ground, over the sea and in the air, relaying information back to the pilot and entering contested airspace in the F/A-XX’s stead. Boeing, Lockheed-Martin and Northrop-Grumman have already unveiled sixth-generation concepts. The aircraft has never been seen in public although in November last year, Northrop Grumman released a 15-second advertisement using the slogan “Defining Possible In Aerospace” and featuring a five second glimpse of a hangar with possibly a sixth generation aircraft, leaving the viewer to draw his own conclusions. A 60-second follow up of that video also did not show a clear picture of the NGAD, just some low resolution 3D animation. The projected date of induction for both NGAD is 2030.

 Europe has a good aerospace manufacturing record and has two sixth generation programmes afoot. The first is the Tempest being developed by the UK, Sweden and Italy, none of which have a fifth generation programme. Japan has been partnering on some parts of the Tempest programme since 2020 and in December last year, it was announced that the UK and Japan are jointly going to produce an engine for the Tempest. Japan’s OEM Mitsubishi Heavy Industries (MHI) and the IHI consortium will work with Rolls-Royce and BAE Systems for developing the engine. UK’s BAE systems is the design lead, Saab, Leonardo, Rolls-Royce, MBDA and about 200 other entities being other team partners. Besides the stealth and data fusion features of fifth generation, the Tempest is expected to have significant AI to assist the pilot and for management of unmanned platforms. One of the promises by Leonardo, one of the OEMs in the programme, is that of a new Multi Function Radar Frequency System expected to have massive amounts of computing power to collect and process ten thousand times the data managed by existing radar systems. The Tempest is expected to carry hypersonic weapons and lasers. According to the UK Ministry of Defence (MoD), it is expected to enter service in mid-2030s.

The other European sixth generation programme is the Future Combat Air System (FCAS) being developed by a consortium of nations comprising France, Germany and Spain. It aims at producing a Next Generation Fighter (NGF) which will connect through the cloud to a variety of UAVs for offensive and surveillance roles. This programme is slated to undertake its first test flight in 2027 and be operational by 2045. Noises are being made in Europe about FCAS and the Tempest programme being combined to make one programme for the sixth generation fighter as the two programmes have a fair amount of similarity. Such a merger would definitely make economic sense and possibly speed up the emergence of a sixth generation fighter in Europe. However, this could also pose problems due to the large number of stakeholders and OEMs involved. There are also other problems such as UK’s Brexit from the European Union with implications for its commercial ties with Europe and the cancellation of a French deal to supply Australia with submarines after the AUKUS. The security pact between Australia, UK and US announced that the US and the UK would help Australia acquire nuclear powered submarines.

Russia is working on MiG-41, a long range sixth generation interceptor optimised for air-to-air combat, with a projected first flight in mid-2020s and entry into service after 2030. Very few details have been officially revealed about the MiG-41, but it is expected to be hypersonic and capable of operating in near space in the satellite hunter role. Air-to-air missiles are projected to have 600km range and it is expected to have a powerful, networked radar. Informed conjecture has it that an unmanned variant may also emerge from the programme.

General Mark D Kelly, Commander of US Air Combat Command, reportedly last year warned that China could field a sixth generation fighter before the US. In December 2021, a model of this Chinese fighter was exhibited in Shanghai at the First Science and Technology Conference of the airborne Cockpit System Division. A cockpit simulator was also on display. Earlier, in June 2018, a Chinese model called ‘Dark Sword’ was unveiled as the future and world’s first sixth generation fighter. However, that appeared to be an unmanned platform and could have been a hyped up high performance UAV/UCAV. There is no official information on this project, but China has already proved its capability to produce a sixth generation fighter by fielding the J-20. The new fighter could have hypersonic air-to-air missiles, impressive AI and a new generation of engines improving upon the indigenous WS-15 installed on J-20s.

The Challenge

Many of the design features of sixth generation fighters continue to be work in progress. There is optimism about ongoing development coming to fruition in close conformity to expectations. However, there could be challenges. In tandem with sixth generation technologies, sensor technology could attain competency to overwhelm known levels of stealth design and radar absorbent material. For the “penetrating counter air” concept to work, the fighters would have to overwhelm area denial wherewithal of the enemy. Whether or not stealth related technologies would outrace detection capabilities, is a moot point. Thus, the deficit between stealth and sensor technologies would have to be met by brawnier EW capability on the fighter.

AI technology would have to rise to the challenge of exercising control over unmanned platforms operating in tandem with the manned fighter. Given the cost and the small numbers that these fighters may be produced in, it would not be desirable to have them operate near their targets or enemy fighters and so their missiles would have to get enhanced ranges and possibly have hypersonic speeds. Even if the missiles could be given long range, that would mean making them larger and heavier, in turn urging the fighter towards bigger airframe, more powerful power plant and reliance for survival on unmanned team members. Given the earliest projected induction date of the known sixth generation programmes as 2030s and the increasing use of digital engineering for design and manufacture, there is enough time, almost a decade, to address these challenges. While individual technological problems appear to be surmountable, integrating them all into a single airframe could still prove to be a vexing conundrum. All this could add up to a much more daunting problem – the high cost of the new fighter.

The F-22, which despite being regarded as the best air superiority fighter in the world, was considered too expensive. Its production was stopped in 2012 after only 187 had been produced against the original fleet projection of 750 fighters. A subsequent proposal in 2017 to restart the F-22 production line was rejected as the cost was again found unacceptably high. Although it is too early to predict the exact R&D and production costs for sixth generation aircraft, one thing is sure that it will cost more than the F-22. And that is a problem that will increasingly raise its head in the coming years, threatening to squelch these programmes.

Concluding Remarks

Expectedly, there is a current impetus to reconsider fifth and sixth generation programmes in favour of rejuvenating fourth generation ones with some additional features of later generations. Obviously, these initiatives are limited to what can be retro-fitted without major design changes. Thus, there is a shift towards 4.5^th generation varyingly called 4+ and 4++, which achieves a compromise between cost which would be far less than a fifth/ sixth generation aircraft and capability which is undoubtedly better than fourth generation.

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This trend might put a damper on sixth generation programmes. However, it is unlikely that these will be shelved in toto. Technology may also enable mobility of fifth generation fighters to sixth. While fourth generation improvement programmes would thrive, the race to produce sixth generation is likely to continue unabated. China’s appetite for expenditure on its programmes and US compulsions not to be seen as lagging behind China or any other nation, will keep the chase going.

As far as India is concerned, the fact that China already has a fifth generation J-20 in service and is working on a sixth generation fighter, should be a dire warning. As an aside, even a late starter like Turkey has announced that its fifth generation fighter will fly in 2025 and its unmanned fighter as early as 2023. The velocity exhibited by Indian R&D with the fourth generation Tejas, is a sobering factor to consider when looking at future fighter ambitions. A fifth generation fighter, the Advanced Medium Combat Aircraft (AMCA), may take ages to materialise and be out of sync with air power doctrine by the time it becomes a reality. India could think of following Europe’s lead, skip the fifth generation step altogether and leapfrog to sixth generation fighter. Of course, this would be possible only if we can coax or entice a sixth generation capable nation to partner with us. The lure of low cost of production in India might just work as leverage. However, the bigger impediment to the consummation of such a project is the current political mood in the country in favour of Atmanirbhar which appears to favour self-reliance over quality and capability, even in critical areas such as aerospace and defence.