Jet fighters can be classified in five generations. The first consisted
of subsonic aircraft developed early in World War II through the Korean War (German ME–262 Schwalbe, American F–86 Sabre). The second generation incorporated lessons from air combat and ground support during the Korean War and exploited technological advances, especially in materials and electronics (F–8 Crusader, F–104 Starfighter) and was capable of supersonic flight. Third-generation
fighters were largely shaped by Cold War competition with the Soviet Union and combat experience in the Vietnam War; these included increasing use of air-to-air missiles and defense against surface-to-air missiles, both of which put a premium on advanced avionics (F–4 Phantom, F–111).
The first three generations of jet fighters lasted about a decade each. The fourth generation began around 1970 and continues to constitute most fighters in service, although recent versions of some fighters are so improved that they sometimes are called generation 4.5 (F–15 Eagle, F–16 Falcon). Fifth-generation fighters are air superiority
and multimission aircraft that achieve increased performance through numerous advances in airframe and propulsion and increasingly
sophisticated avionics, including flight control systems.
Fifth-generation fighters are distinguished from generations 4 and 4.5 mainly by their inherent stealth and compatibility with a network-
centric or distributed concept of operations, although they are much more capable in many respects. Computing capacity, sensors, and communications systems enable them to gather, exploit, and disseminate
information to an extent that can multiply the effectiveness
of military forces throughout a theater of operations. To date, only the Air Force F–22 and F–35 qualify as fifth-generation fighters, although several nations are developing comparable fighters.
Non-experts tend to think the shift from legacy aircraft to fifth-generation aircraft is largely about the airframe or stealthiness.
Stealth is important, but it is the conjunction of stealth and other capabilities that creates a different capability for a flying force:
■ Stealth allows the aircraft to operate over enemy positions, and onboard sensors enable it to target mobile as well as fixed weapons
systems. Indeed, the increasing capability of mobile air defenses is a major threat to air superiority in the 21st century. Legacy aircraft rely on target data from other platforms to launch strikes and may not be able to identify and target mobile systems. Incorporation of stealth and sensors in one aircraft puts mobile targets within the scope of effective strike actions.
■ Command, control, communications, computers, and intelligence,
surveillance, and reconnaissance capabilities are built into the aircraft itself. Integration allows the aircraft to process data and to make informed decisions much more rapidly than fourth-generation
aircraft, which need Airborne Warning and Control Systems, electronic attack aircraft, and a variety of accompanying specialized assets to operate effectively in a 21st-century threat environment.
■ An easily upgradeable, distributed computer system provides processing power that facilitates a greatly improved man-machine relationship. The aircraft can process data and assist pilot decisionmaking.
Indeed, many decisions can be made without intervention by the pilot, which makes the aircraft particularly useful in 21st-century air operations. The man-machine relationship of fifth-generation aircraft
enables integration of airborne robotic systems in 21st-century air operations as well. Indeed, as the new aircraft are deployed, a new generation of unmanned systems will develop as well.http://www.ndu.edu/ctnsp/defense_horizons/DH_66.pdf