Small Note for Concept of 6th Generation Fighters : And Future Aerial-Warfare

* Related my previous articles for 6th Gen. Fighters (Also for Hypersonic MIRV Air-to-Air Missile)

   -> History of Air-warfare Part 2 (2017.04.21)
   -> French-German's proposal for replacement of Tornado jet (2018.01.28)
   -> USAF-2030 Commercial (2018.03.27)
   -> High AoA capability become useless in future air-warfare? (laser, stealth, hypersonic, etc) (2018.05.04)
   -> Current Technical Difficulties in Hypersonic MIRV Air to Air Missile (2018.05.10)
   -> Small-note-for-SRAAM and Their Futures (2018.05.23)
   -> French-German's proposal for replacement of Tornado jet (2) (2018.07.06)
   -> New-fighter-jet-for-UK:Tempest (2018.07.16)
   -> Example-of-booster-with-SRAAM : New Solution of Long-Range Air-to-Air Missile? (2018.07.20)
   -> More Information for UK's Tempest (2018.08.04)

  * Related my previous articles for Stealth Tankers (USN's MQ-25 and USAF's Stealth Tanker project)
   -> Boeing's-mq-25-candidate is revealed (2018.03.08)
   -> Lockheed's-mq-25-candidate is-revealed (2018.03.26)
   -> General Atomics'-mq-25-candidate is-revealed (2018.04.02)
   -> Additional-image-is-revealed-for MQ-25 of Boeing (2018.04.07)
   -> Additional-image-is-released-for MQ-25 of Lockheed (2018.04.09)
   -> Stealth-tanker-model-from-AFRL and Lockheed (2018.06.30)
   -> Boeing's design is Now MQ-25 (2018.08.31)
   -> Boeing MQ-25 - Additional Images (2018.08.31) 

1. Background of 6^th Generation fighter

1.1. Big ice age for jet fighters: Collapse of Soviet Union and War on Terror

 As described in the previous articles or numerous phenomenon in aerospace industry, after collapse of Soviet Union in 1990’s, development of a new air-warfare weapon became sluggish or even cancelled like A-12 of USN or RAH-66 of Army as shown in Fig. 1.1. This event made USN, USAF and air-borne of US army concentrate exhausted CAS missions; fancy maneuverability or acceleration/speed was no longer required for Afghanistan or Iraq. Russia, descendant of Soviet, lost their willing for new fighters because of their economic chaos; only demonstrators like MiG-1.44, Su-37, or 47 were in show-window.

 Frankly, about for 25 years after the collapse, there was no equivalent rival for F-15 with AIM-120C, and this had been proved by record; most of the Su-27 series were limited in usage of R-27. War on Terror and sub-prime mortgage consumed certain part of the defense budget, and there was no room for ‘already-the-best-area-of-USAF’; amount of production for F-22 was also reduced. USN should adopt F/A-18E/F as replacement of glory F-14 and A-6 for cost reason; Congress did not allow expensive stealth jet for ‘GBU-truck’ missions.

 F-22 and F-35 was the latest jet fighters developed by US just before end of the Cold War; F-22 pursued for countering-all-imaginable-threat while F-35 tried to make entire air-fleet as sum of F-16 and F-117 with reasonable(?) cost. This kind of approach still showed glimpse of Cold-War age idea which try to overwhelm rival Russia in every aspect. Naturally, these had been criticized by internal enemies arguing their cost. It looked reasonable that special ability for day-1 strike was no-longer represented in Pax-Americana, and all-stealth of entire air-fleet is still argued topic for constitute of high air-command. So, it is not surprising that proliferation of unmanned concept for reducing ‘human-exhaust or risk’ and cost was fancy at that time. Mission of ISR or police type patrol could be replaced by relatively simple platforms, and few of them bear fruit like MQ-1, 9 or Global Hawk.

Fig. 1.1. Two typical example of “Cancelled as Collapse of Soviet Union”, A-12 and RAH-66; Cost is not only problem for these, also ‘too-strong-or-expensive’ for War-on-Terror. They lost their primary adversary at early 90’s.

Fig. 1.2. The two latest jet fighter projects of US, F-22 and 35, were criticized for its in-effectiveness in cost for Ice-age, however is it right again for new Cold-War age?

1.2. Advent of T-50 and J-20

As the US have struggled in desert, global power of Russia was partially restored, and Chinese pursued regional power in western Pacific. Aspiration of the two countries was proved by prototype of T-50 and J-20 as shown in Fig. 1.3, challenging air-superiority of US. Two aircraft is similar or larger than F-22; clearly they pursue super-cruise, stealth, and high maneuverability performance like that of F-22. Still, exact performance of the two are in fog via unfinished development of them, however it clearly showed long-lived high teen series will face end of their prime time. If we changed our focus from ‘common between F-22 and its rivals’ to ‘differentiation’, physical size of the two fighters are noticeable. They prepare long range missions to cover their deep territory or have intention to penetrate air-space.

Penetration of air-space with long range is essential for 1^st class of air-superiority fighters requiring sniping of prime assets guarded by their own escort fighters like AWACS, Tankers, and Bombers. That kinds of mission profiles were limitedly supported by Su-27 class fighters in Cold-War age with specially designed air-to-air missiles, Kh-31A/P or KS-172. Proof of the intention is clearly shown for these fighters; both fighters have deep internal weapon bays for long range missiles like new R-37M class as shown in Fig. 1.3. With combination of enhanced long range missiles and stealth performance of them, threat for US air-superiority is not only for front-line fighters also for the prime assets.

Contrary to Chinese and Russian, European did not show any noticeable movement related to development of fighters like F-22, J-20, or T-50. They have struggled much time for Eurofighter and Rafale, and satisfied a few number of F-35 during the Ice Age of jet fighters. They have concentrated development of cruise missiles and UCAV projects for Day-1 Strike missions.

Fig. 1.3. J-20 (Top) and T-50 (Middle) are result of two countries challenging air-superiority of USAF and USN. Bottom view of T-50 (Bottom) shows R-37M class long range missiles (blue) could be carried internal bay of the T-50.

1.3. Current Limit of 5^th Generation fighters: Range/Loitering of Current Platform

USAF and USN are the most sensitive forces in the world for the range and payload of their platform because they always did offensive role in the air-warfare. So it is not strange that size of US jet fighters is mostly bigger than their counter part except few bizarre Soviet interceptors, Yak-128, MiG-25 and 31. As shown in the Fig. 1.4, F-22 and F-35 invest much of their internal space for fuel, however, basically, stealth performance requires limitation of external fuel tank and consume internal space as weapon bay, then, leads to short range.

Advent of enemy’s advance air-defense system including fighters (J-20, T-50, and J-31) and SAMs (S-300, 400, and 500) aggravate the situation worse as it limits ‘safe-range’ from enemy territory for aerial refueling or external fuel tank. Also it is bonus that Russia and China has very deep offensive depth via size of their land. For F-22, 1^st capable super cruiser, problem is not negligible; advantage of super-cruise is unavoidably consuming a lot of fuel.

Fig. 1.4. Internal fuel tank layout or cutaway of F-22 (Top), F-35 (Middle), and T-50 (Bottom). As attachment of external fuel tank is limited by stealth, space for internal tank become more important.

2. Concepts of 6^th Generation fighters

After advent of J-20 and T-50 for 10 years, whether western countries developed 5^th generation fighters or not, western counter parts showed their plan for the jet fighters breaking the ice age. Fortunately, their plan is well summarized in Fig. 2.1 with uncertainties; political, technical, or budget issues always changed what they planned. Among the planned fighters, T-50 and J-20 are the initial triggers for the other jet fighters; from the plan, absolute advantage of US’ F-22 and F-35 will be challenged by Russian and Chinese at 2020, and US’ answer will be prepared at 2030.

Plan for other fighters like India, Korea, Turkey, Japan is uncertain to ‘overwhelm’ the Chinese and Russian due to lack of experience for leading air-warfare technologies. Even in the Korean case, target of the jet fighter performance is limited in 4.5^th generation fighter for Block I; full performance of Block III is expected to be slightly worse than 5^th generation fighters. Project of India always suffers long delay as shown in the project of Tejas. Turkish has lack of experience in full-scale jet fighters like Korean while Japanese has possibilities of conducting better fighter than others. However, willing to develop Japanese fighter is still uncertain.

Indeed, this article focuses on 6^th generation fighter projects related to US, French-German, and UK having possibility to overwhelm J-20 and T-50.

Fig. 2.1. Plan/situation of jet fighter development; about 2030, picture of air-warfare will be changed.

2.1. Common Goals presented in Concepts

Few pictures of known projects, F/A-XX, F-X, FCAS, and Tempest are shown in below from Fig. 2.2 to Fig. 2.5; all of these are still in CG concept level. We could speculate some common characteristics from these eye candies. All of them targeted extremely large platform size as fighter. Although few of them has same physical size of conventional fighters for length and span, expected payload and internal volume is much bigger than current 4^th and 5^th generation fighters; huge delta wing with or without tails committed it. That kind of external configuration of the jets means more loitering time/range/payload is emphasized rather than conventional dog-fighting or maneuvering. Actually, that kinds of tendency for maneuver in transonic region was already in the road of decline as R-73 emerged. Advanced SRAAMs including MICA-IR, ASRAAM, IRIS-T, R-74, Python-5, and AIM-9X already overwhelmed maneuverability of human-driven jet vehicle limited by physical condition of human (http://jaesan-aero.blogspot.com/2018/05/small-note-for-short-range-air-to-air.html).

Fig. 2.2. Few concept CG related to 6^th Generation fighters for F-X of USAF from Northrop (Top), Lockheed (Middle), Boeing (Bottom)

Fig. 2.3. Few concept CG related to 6^th Generation fighters for F/A-XX of USN from Boeing

Fig. 2.4. Few concept CG related to 6^th Generation fighters for France-German (FCAS)

Fig. 2.5. Few concept CG related to 6^th Generation fighters for UK Tempest

Indeed, all of the published concepts seems to focus wide range of weapons including DEW to cover short range engagement; combination of short range missiles and DEW act like RAM and CIWS of modern destroyers. It means new generation of fighters did not act like individual vehicle also take role of modern ship having complex layer of defense and offensive payloads. In order to keep the jet flyable status with various payloads, advanced engine is also proposed by GE and Rolls Royce which uses adaptive variable cycle engine as shown in Fig. 2.6. It is not certain that other aircraft like FCAS will carry the variable cycle engine however, similar technology should be attained to FCAS as one of competitive contender. Concept of the engine is basically controlling the bypass ratio of the jet to maximize its fuel economy; saving power is directly connected to magazine of the DEW.

Not only for its self-defense, also weapon for offensive punch already start its race as shown in Fig. 2.7. Recent race for hypersonic weapon is not irrelevant to this trend because ace in the hole for the 6^th generation fighter would become hypersonic missile or glider to penetrate enemy air-defense. Miniature version of ‘Kinzhal’ missile will be popular and large volume of internal bay should be prepared for that kinds missiles. Although performance of stealth, sensors, or network capabilities are not represented in fancy art or OML shape, to maximize effectiveness of payloads or hardware of the jets, numerous videos already emphasized wide range of stealth, fused-sensors, and network capabilities with UCAVs. Commercial of USAF (http://jaesan-aero.blogspot.com/2018/03/usaf-2030-commercial.html) or replacement of tornado jet fighter by Airbus as shown in Fig 2.8 and 2.9.

Conventional jet fighter will RTB when they use all of their payload however, 6^th generation fighters loiters air-space to control or provide precise ISR information to friendly air-asset. It maximized not only performance of own, also of friendly forces; it represented reality that even major countries could not replace all of their jets using 6^th generation fighters. Co-operating with previous generation jet fighter or UCAV essential.

Certainly Common things in Concepts

l  Large platform for payload/endurance

l  Highly Stealth

l  ISR performance with network capabilities

Fig. 2.6. Concept of variable cycle engine by GE; it is not surprise that YF-120 had proposed similar configuration.

Fig. 2.7. One of ‘Silver Bullet’ type weapon developed for F-35 or 6^th generation fighters; highly stealth or hypersonic weapon will be carried inside of the jets for day-1 strike mission.

Fig. 2.8. Network capabilities with friendly asset is continuously shown in commercial of 6^th generation fighters (Airbus)

Fig. 2.9. Network capabilities with friendly asset is continuously shown in commercial of 6^th generation fighters (USAF 2030)

2.2. Discrimination between Concepts

Table 1 Summary table for common and different things of 6^th generation fighters’ concepts

Previous paragraph described common goals and concepts of the jets however, even in the CGs, there are some differences as shown in Table 1. First of all, we selection of seat # for each concept; most of concepts choose single seat while FCAS and F/A-XX for two seat (even F/A-XX could be unmanned). FCAS emphasized endurance on the enemy air-space and ISR role, and naturally leads to additional crew. Requirement for F/A-XX might be similar if F/A-XX replace EA-18G and F/A-18E/F series. Other jets like F-X or Tempest also emphasize that way however they show no sign of additional crew behind the pilot. We could assume that USAF has enough resources to cover needs of additional crew for the fighter, however, USN or French-German’s should cover various role in limited number of sorties.

As described in the figures and descriptions, all of the 6^th generation fighter jet has large planform of the wing however, in the configuration of the tails, there is some differences. While others deleted HT as pitch control, tail surface of Lockheed still remained. Actually, Northrop’s one seems like big warship than conventional fighters, so it is the most radical approach among 6^th generation fighters. Also, it is the only Northrop that air-inlet is installed upper surface of the jet and deleted TVC; upper inlet and deletion of TVC shows worst performance in conventional maneuver in air combat. Approaches of F/A-XX from Boeing, FCAS and Tempest is between Lockheed and Northrop; LEVCON of FCAS, TVC of Tempest and F/A-XX compromise between conventional maneuverability and warship like concepts.

As a payload of 6^th Generation fighters, DEW is the most controversial thing; degree of maturity of DEW and other RAM style weapons, SACM and MDSM, determine dependence of conventional maneuverability. As the Northrop one more depend on technological maturity of such things, their jet become warship like bigger one. 6^th generation fighters of US and UK definitely showed concept of usage of DEW while French-German one is in uncertainty. UK Tempest, revealed at most recently, showed concept of carriage of UCAV inside of IWB; in US commercial, transports or bombers will be specialized for this duty. Or maybe in USN, unmanned module is installed in F/A-XX to cooperate manned version.

2.3. Advent of Stealth Tankers

Stealth tanker proposal is another issue for USAF and USN; both are planning to develop own stealth tankers. If the tactical aircraft is non-stealth, stealth tanker itself is not pursued. And also, every tanker could not be stealth because of cost. Indeed, we could speculate stealth tanker will be member of team which consists of stealth tanker + 6^th generation fighter + 5^th generation fighter + UCAV + swarm of drones. That kinds of package replace conventional strike package which is armada of air fleet before stealth technology was emerged. As shown in Fig. 2.10 and 11, USN and USAF currently develop stealth tanker while USN proceed further; they already receive competition of three companies, Boeing, General Atomics, and Lockheed.

Advent of stealth tanker and long range/endurance of 6^th generation fighter is not irrelevant. As the threat from J-20 and Pak-Fa become invisible and their military depth of air-defense is deeper, whole components of the strike package is under the threat. Cost of 5^th and 6^th generation fighter is rising; they should cover longer time of campaign with limited number of jets. It means whole strike package require large amount of fuel in one sortie, however, no tactical level jet could carry massive internal fuel for that requirement. MQ-25 of USN and Stealth tanker of USAF will never refuel for their aircraft in the enemy air-space, however, their stealth performance significantly reduces the distance from enemy air-defense system where refuel is managed. So, adaptive-variable cycle engine, large platform, and stealth tanker make synergy for perfect overwhelming of enemy air-space in spatially and temporally.

Fig. 2.10. MQ-25 : USN’s new stealth tanker

Fig. 2.11. One model of USAF’s Stealth tanker is shown.

3. Conclusion and future of further

Author had written short review for 6^th generation fighters with limited information; most of them could be changed as concept is matured. Actually, need for 6^th generation fighter was sluggish until threat of J-20 and Pak-Fa was realized. As they challenged technological superiority of old-western world, current edge of US Aerospace technology, F-22 and F-35 expose their weakness, high cost, short range for long depth, and small-payload.

Revealed 6^th generation fighters commonly emphasize large platform for flexibility/range/payload/enhanced capability of ISR with stealth performance. Another aspect of the concept is co-work with previous generation fighter, UCAV, and stealth tankers. Advertisement of previous generation fighters always emphasized simple-overwhelming of pre-previous ones, and recommend air-forces to replace all of their jets. However, as cost of jet fighter rises sky-rocketing, number of 6^th generation fighter is under the pressure. So the concepts have studied more about co-operation capability with other assets of forces, and try to maximize overall effectiveness of sorties. Unlike 5^th generation fighters, 6^th generation fighter does not pursue winning every aspect of previous generation fighters; the new planned fighter will take the leading role of the fighting group, containing 6^th and 5^th generation fighters, UCAV, and even with stealth tanker.

As they limited their role in aerial warfare, it is hard to imagine the new fighter perform fancy maneuver; DEW and small munitions guard the fighter or other friendly jet like Aegis warships. Fight of aerial fleet having multi-layered weapon and vehicle become more systematic than fight in the past. Even the new weapon emerges like hypersonic MIRV air-to-air missile (https://jaesan-aero.blogspot.com/2017/04/1-high-aoa-aerodynamics-for-combat_21.html), the fleet just need absorb the new weapon as one of their spear. It is interesting to see how evolve these concepts until 2030s.