A glimpse of the defining characteristics of the Fifth Generation fighters can be had by studying the F-22 Raptor, which sets the benchmark for this category of fighter aircraft

The First Generation (1945-1955) belonged to subsonic jet fighters, prior to the arrival of Airborne Interception (AI) radars or smart munitions. Typical examples of this age were the Korean War MiG-15 and F-86 Sabre. Refinement of airframe design coupled with more powerful jet engines, rudimentary AI radars and first guided air-to-air missiles (AAMs) characterised the Second Generation—coinciding with the period from 1955 to 1960. American century series fighters and Russian MiG-21 belonged to this stable. Third Generation fighters (1960-1970) were the first to be designed as multi-purpose war machines. American F-4 Phantom and MiG-23 could be cited as the typical examples of this generation.

Fourth Generation (1970-1990) carried forward the trend of multi-role fighters equipped with increasingly sophisticated avionics and weapon systems. Enabled by advances in computers and system integration techniques, several new innovations, like Fly-by-Wire, Pulse-Doppler Fire Control Radars (affording a look-down shoot-down capability), hands on throttle and stick, Multifunction Displays, Infra Red Search and Track sensors, and so on, became signature features of this generation of aircraft. ‘All aspect’ infrared AAMs, which permitted engagement of enemy aircraft from any quarter, became the standard air superiority weapon. The F-15, F-16, Mirage 2000 and MiG-29 typically belong to this era.

Barring an odd branch of technology, since the end of World War II, the US has remained a clear leader in military aviation, while Europe and Russia (or erstwhile Soviet Union) has been trying to play catch up. The technology gap between the Americans and the rest was such that by the time Europe and Russia were ready to roll out their Fourth Generation fighters, Americans were already deep into the F-22 Raptor and Joint Strike Fighter (JSF) Lightning programmes. At the time, the Russians announced that their response fighter to the JSF would belong to the Fifth Generation—thus ushering the idea of generations in aviation lexicon.

Enhancing Capabilities

By early to mid 1990s the exponential growth in the capacity of microchips and Very High Speed Integrated Circuits were leading to revolutionary increase in computational capacity. Applications emerging out of technologies based on the enormous and expanding power of computers were to set the tone for evolution of the fighters of the future.

While the Europeans and Russians tried to work these cutting edge electronic technologies in fighters then on the drawing board or in early production phases, Americans used them to upgrade their legacy fighters, that is, the F-15, F-16 and F-18. With much enhanced capabilities, these new and upgraded fighters (and the process is continuing) have become the so called bridge between the Fourth and the Fifth Generation and a new category 4.5 has come into vogue. With advanced aerodynamic designs, up rated powerful engines, advanced digital flight control systems and thrust vectoring in some cases, manoeuvre capability is much enhanced. The new designs also deliver a degree of stealth. On the air borne radar front, new technology Active Electronically Scanned Array radars have arrived on the scene, becoming in fact a sine qua non for all 4.5 designs.

Many of the concepts and capabilities seen in the ‘Bridge Generation’ fighters are sought to be further refined and enhanced by a degree of magnitude in the Fifth Generation fighters. The F-22 Raptor is currently the only fighter operational in this class. The F-35 Lightning II JSF, the other claimant to the Fifth Generation stable, is likely to be inducted in operational service in the next couple of years. Therefore, a glimpse of the defining characteristics of the Fifth Generation fighters can be had by studying the F-22 Raptor, which sets the benchmark for this category of fighter aircraft.

Major Characteristics

Very Low Observability (Stealth): Several 4.5 Generation fighters have achieved a degree of stealth with aerodynamic refinement, radar absorbing materials and shaping intake ducts to prevent radar echoes from the highly reflective compressor and turbine faces. However, the Raptor takes stealth several notches higher by building low observance characteristics against the entire spectrum of sensors, including radar, infrared, acoustic and even visual. The remarkable feature of Raptor stealth is that, unlike the F-117 A, Raptor suffers from none of the performance penalties imposed by stealth dictated design. In fact, in manoeuvre performance, F-22 in dry power matches or exceeds F-15C in afterburner regime.

The exact radar cross section of the F-22 remains classified. However, in early 2009, Lockheed Martin revealed that from certain critical angles, Raptors signature was the equivalent of a ‘steel marble’.

Super-cruise: Equipped with two F-119-PW-100 engines, each delivering about 35,000 lb of afterburning thrust, the F22-A is capable of sustaining speeds in excess of Mach 1.5 at altitude in dry power. As a performance comparison, F-119 in dry power is comparable to the afterburning thrust envelope of F-100-PW-100 series fitted on the F-15C/E and many F-16 copies. To deliver high thrust ratings in dry power at high altitudes, a turbofan has to withstand much higher turbine inlet temperature, made possible by development of new heat resistant materials and advanced techniques of turbine cooling.

Supercruise gives the Raptor unique advantages. Entering an engagement at supersonic speed against a subsonic opponent gives it reserve of kinematic energy which allows it to dominate the terms of engagement. Sustained supersonic speed also presents severe problems of intercept geometry to an opposing conventional fighter. All AAMs, including Beyond Visual Range missiles, have kinematic limitations. To achieve a kill, a fighter must position itself in time and space such that the target falls within the ‘no escape zone’ of the AAM intended to be used. In the event of this condition being unfulfilled, the missile would run out of energy before reaching the target.

In engagements involving opponents with similar kinematic performance, balance of advantage lies with the one with a more capable missile and/or relative degrees of situational awareness of the pilot. However, when one of the opponents has sustained supersonic capability, the effect of imbalances in missile performance and networking would be reduced drastically. For example, by resorting to even a modest change in heading, a supersonic opponent can neutralise the interception geometry of the adversary fighter/missile combination.