Fighter Aircraft Generations: A Reference...
1st GENERATION: 1945-1955
The generational system for figher aircraft seems to start with post-WWII fighters.
These are typically subsonic jet aircraft with similar abilities to their piston engined counterparts, they also had similar limitations, such as a lack of radar, and WWII vintage weaponry such as **** bombs and belt-fed machine guns.
Aircraft seen in dogfights over the skies of the Korean War typify this generation. Aircraft such as the MiG-15, MiG-17, F-86 Sabre, as well as the de Havilland Vampire, Supermarine Attacker, Saab Lansen and Dasault Ouragan.
(aircraft links go to pictures)
2nd GENERATION: 1955-1960
According to the Rand Corporation the 2nd generation of fighter aircraft had performance goals in such categories as supersonic speed, ceiling and rate of climb. In addition the technology driving the second generation centered around aerodynamics, propulsion and building materials. New technology advances also enabled this generation to incorporate radar and missiles into their list of assets.
Aircraft typical of this generation are the F-104 Starfighter, F-105 Thunderchief, F-106 Delta Dart, Dassault Mirage III, Saab Draken, MiG-19 & the MiG-21.
3rd GENERATION: 1960-1970
The 3rd generation is marked by technological refinements with a push toward improved maneuverability, multi-role capabilities (carrying out both air to air and ground attack).
Continued improvements in propulsion such as more reliable jet engines with increased thrust and the beginnings of large advances in avionics and weapons systems.
Fighter aircraft that flew in the Vietnam War are included in this group - the 3rd generation includes the F-4 Phantom, Northrop F-5, MiG-23, MiG-25, Sukhoi Su-15, Dassault Mirage F1 and the Dassault Super Etendard.
4th GENERATION: 1970-1990
The 4th generation includes notably more sophisticated avionics and weaponry brought on by advances in computers and system integration. Increased agility and flexibility in mission roles is also a typical attribute of the 4th gen. Examples of the 4th generation are the F-14, F-15, F-16, F-18, AV8 Harrier, MiG-29, MiG-31, Sukhoi Su-27, Panavia Tornado, Dassault Mirage 2000 and the Saab Viggen.
4.5 GENERATION: 1990-2000
The 4.5 generation is typified by many of the same attributes as the 4th generation aircraft except that they incorporate advanced technology that could be interpreted as that for the 5th generation. Dominant performance and technology goals for 4.5 is reduced radar cross section through advanced airframe shaping and radar absorbant materials being used in the construction. Highly advanced avionics are also a prerequisite for this category. The 4.5 generation includes F-18 Super Hornet, Sukhoi Su-33, Sukhoi Su-35, Eurofighter Typhoon, Saab Grippen and the Dassault Raphale. (it bears acknowledgement that Aerospaceweb says that the Typhoon and the Raphale are arguably somewhere between 4.5 and 5th generation.)
5th GENERATION: 2000-
The attributes that characterize the 5th generation of fighter aircraft include highly advanced avionics and stealthy sensory suites giving the pilot a comprehensive view of the entire battlespace. Also characterizing 5th gen is a combination of stealthy design and efficient supersonic speeds.
Aircraft that stand as examples of 5th generation fighters are the F-22 Raptor, the not yet operational F-35, and possibly the MiG MFI and Sukhoi Su-47, should either of them ever see production.
Sources:
Aerospaceweb.Org
Rand Corporation
"Jet Fighter Development", Hallion (1990)