Sixth Gen Fighter Aircraft (SiGFA) -Part 1

This is the era of 5th gen fighters, as of now only US is managed to induct a 5th gen fighter. Other countries like Russia & China is conducting testing of their respective 5th gen fighters. But still there are rumors of developing 6th gen fighters. Countries like Japan & India also developing 5th gen fighters probably they are 5+ gen fighters because they are incorporating some 6th gen technologies like GaN based radar, fly by light, self healing/ self repairing and improved cockpits. 
 
Sixth Generation Fighter aircraft (SiGFA) is a fighter being designed on concepts akin to concepts of spacecraft depicted in star wars trilogy. The aircraft, equipped with new concept weapon systems, is expected to become operational by 2030-2050. What will 6th generation fighter aircraft be like and what will be the capabilities of SiGFA? Researches are going on the following areas

a) Air Vehicle
b) Vehicle/Sensor Protection
c) Propulsion
d) Warning and Situational Awareness
e) Sensors
f) Data Fusion
g) Offensive/Defensive Systems
h) Automatic Target Recognition (Ground and Air)
i) Communications, Networks, and Data Links
j) Kinetic Weapons
k) Non-kinetic Weapons
l) Electronic Warfare and Information Operations
m) Secondary Power Generation, Storage and Management
n) Thermal Management and Heat Rejection
o) Human System Integration (HSI)
p) Remotely Piloted Aircraft (RPA) and Optionally Manned Systems

NEED FOR A 6th GENERATION OF COMBAT AIRCRAFT
 
For any modern air force, achieving air superiority remains the primary mission. Air superiority can be understood as that degree of air dominance which allows air, land, and sea forces to operate free from interference by an opponent’s air forces, while at the same time denying the opponent such dominance. To achieve air superiority, it is not enough to simply defeat an opponent’s air forces, but it is also necessary to sufficiently degrade, disrupt, or deny air defenses and air bases. With air superiority assured, ground forces can then move into areas without fear of attacks from the skies; aircraft can observe and strike the opponent without obstruction; navies can position themselves freely and support ground operations; for example. In operations over the last two decades or so, Allied states had air superiority from the beginning or achieved it very quickly. It is therefore easy to forget that such absolute freedom of action in the air should not be taken for granted in the future. If a country want to possess the best air forces in the world, their fighter jets need to remain at the global technological vanguard.
Naturally, at such an early stage of thinking about a 6th-generation combat aircraft, the precise capabilities and requirements of such an aircraft are still very much subject to debate. Indeed, the next few years’ work on a future fighter jet will be devoted to exploring possibilities and clarifying what such a jet should be able to accomplish. Still, most experts converge around a few general features.
 
-     extreme stealth, e.g. the jets should be stealthy across a greater range of spectrums
-     engine efficiency at all flight speeds, from subsonic to multi-Mach speeds
-     advanced exterior skin constructed with nano-technology and meta-material, i.e.
      material engineered to exhibit properties not found in nature
-     exceptionally powerful computer networking and communication capabilities
-     extremely sensitive sensors
-     the option of unmanned flight
-     advanced weapon systems, possibly lasers and other directed energy weapons
-     Morphing capability (the ability of an aircraft to change its shape while in flight)

PROPULSION SYSTEMS

​                Jet fighter engines are evolving gradually in comparison to the exponential advances in aerospace technologies like radar, software, sensors, stealth, and weapons. A fundamental factor is that aircraft engines are bound by the physics of jet propulsion systems and the limits of an airplane’s aerodynamics, size, and weight.
 
                Still, current engine development efforts are set to advance jet engine technology substantially over the next few years. SiGFA Adaptive-Cycle Engines/variable cycle engines. Such engines are different from previous models because they possess an additional third manageable air stream. This dramatically improves the aircraft’s reach, fuel efficiency (enabling supercruise at more fuel efficient rates), and speed. The third stream of air in the variable cycle engine can be controlled by the pilot. By opening or closing the third air stream, the pilot can adjust the fuel intake of the jet engine and optimise its performance (the pilot has the option to exit cruise mode and significantly increases thrust as needed). This enables smooth transition from strike aircraft speeds (supersonic) to cruising (subsonic). The engine will also include light‑weight ceramic‑matrix composite materials that will allow the engine to operate above the melting point of steel.
 
Adaptive-cycle engine has an adaptive fan, which allows the engine to vary its bypass ratio depending on its altitude and speed due to a third stream of air. Air flows through the third stream as needed to increase or decrease the bypass ratio of the engine—or alternatively use the extra airflow for cooling. We can effectively vary the performance of the engine across the flight envelope. At high-supersonic speed, the third stream can reduce spill drag by letting the excess air flow through the engine— however performance above about Mach 2.2 is still limited by the physics of air inlet geometry. The third stream does help supersonically very much and this third stream of air provides additional heat sink capacity that both reduces the aircraft's infrared signature and enables the aircraft to accommodate directed energy weapons.
 
General Electric made substantial progress in adaptive cycle or variable cycle engines as a result of the US Air Force's Adaptive Versatile Engine Technology (ADVENT) program. The aim of the ADVENT programme is to develop a variable cycle engine that provides for 5 to 10% more thrust and a 25% reduction in fuel consumption compared to the jet engines in current F-35s.
 
                A 6th-generation combat aircraft would need to travel substantially faster and with less fuel intake than current 4.5th- and 5th-generation jets. After a plane achieves Mach 1 without afterburners, i.e. in supercruise mode, it can achieve faster speeds with relatively less energy. The variable cycle engine will possibly advance propulsion to speeds that are three to four times the speed of sound. At present, flying at these speeds has been achieved for only short periods of time. An engine that can sustain Mach 3 to 4 and maintain fuel efficiency would be a dramatic technological development. Some posit that a 6th-generation jet may be able to achieve hypersonic travel (five times the speed of sound or more), although most industry insiders doubt this would be possible by 2030, barring a revolution in engine technology. But hypersonic fight entails a whole new range of materials development, for sensors, fuzes, apertures, etc to ensure which must operate in that intense heat environment at ... Mach 5-plus
 
Use of electric propulsion for SiGFA is an another possibility. A prototype of the first Japan-made stealth fighter X-2 Shinshin, formerly called ATD-X may be equipped with powerful batteries and electric motors. Such a hybrid would take advantage of a jet engine's speed and use electric generators so as to give power to directed-energy weapons, including lasers. It would also fly at low speeds.

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