1. Background of 6th
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 1st
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 5th
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, 1st 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 6th
Generation fighters
After advent of J-20 and T-50 for 10 years, whether western countries
developed 5th 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 4.5th generation fighter for Block I; full
performance of Block III is expected to be slightly worse than 5th
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 6th 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 4th and 5th
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 6th Generation fighters
for F-X of USAF from Northrop (Top), Lockheed (Middle), Boeing (Bottom)
Fig. 2.3. Few concept CG related to 6th Generation fighters
for F/A-XX of USN from Boeing
Fig. 2.4. Few concept CG related to 6th Generation fighters
for France-German (FCAS)
Fig. 2.5. Few concept CG related to 6th 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 6th
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, 6th 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 6th
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 6th
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 6th generation fighters (Airbus)
Fig. 2.9. Network capabilities with friendly asset is continuously
shown in commercial of 6th generation fighters (USAF 2030)
2.2. Discrimination between
Concepts
Table 1 Summary table for common and different things of 6th
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 6th
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 6th 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 6th 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. 6th 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 + 6th generation
fighter + 5th 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 6th
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 5th and 6th
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 6th generation fighters
with limited information; most of them could be changed as concept is matured. Actually,
need for 6th 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 6th 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 6th 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 5th generation fighters, 6th
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 6th and 5th 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.
