Jet fighter generations

Various features in jet fighters are described in terms of "generations", whereby a typical jet fighter of a given generation tends to have a certain class of engines, avionics, etc., and a typical jet fighter of the succeeding generation tends to have a different (and superior) set of engines, avionics, etc.

The terminology is unofficial and the current system of generations differs from the original set proposed by Richard P. Hallion. There is no central registry of features that qualify for each generation, and categorization is imprecise; there are occasionally disagreements as to how a fighter should be categorized.

First generation (1945-1955)
This generation encompasses all early jet fighters up to and including those used in the Korean War. The early models are similar in construction to their propellor driven predecessors with 1st and 2nd generation turbojets for power. The first operational fighters were the German Messerschmitt Me 262 and British Gloster Meteor during World War II. During the Korean War, the first air combat between jet fighters took place when MiG 15 and F-86 Sabre met.

Second generation (1950-1965)
These jet fighters started to regularly use onboard radar and passive-homing infrared-guided (IR) missiles. Early IR missile sensors had poor sensitivity and a very narrow field of view (typically no more than 30°)

Third generation (1965-1975)
The archetype of this generation is the McDonnell Douglas F-4 Phantom II, the US jet fighter model with the highest production number to date.
 * improved air-to-air missiles
 * improved radar systems
 * other avionics
 * guns remained standard equipment
 * air-to-air missiles became the primary weapons for air superiority fighters, which employed more sophisticated radars and medium-range RF AAMs to achieve greater "stand-off" ranges,
 * guided ground-attack missiles
 * first truly effective avionics for enhanced ground attack
 * terrain-avoidance systems.
 * Air-to-surface missiles (ASM) equipped with electro-optical (E-O) contrast seekers – such as the initial model of the widely used AGM-65 Maverick – became standard weapons
 * laser-guided bombs (LGBs) became widespread

Fourth generation (1970-2010)
Fourth-generation designs are heavily influenced by lessons learned from the previous generation of combat aircraft. They include the Teen Series (F-14, F-15, F-16 and F-18) group of jet fighters.


 * much higher maneuverability due to low static stability, made possible by fly-by-wire flight control system
 * advances in digital computers and system integration techniques
 * system upgrades such as AESA, digital avionics buses and IRST

4.5 generation
The United States Government defines 4.5 generation fighter aircraft as fourth generation jet fighters that have been upgraded with AESA radar, high capacity data-link, enhanced avionics, and "the ability to deploy current and reasonably foreseeable advanced armaments."

Fifth generation (1995 - 2025)

 * General design concern about radar cross-section (RCS), in particular:
 * chines instead of standard leading edge extensions or canards
 * internal weapon bays instead of outboard weapon pylons
 * a high percentage of composite materials (also to reduce weight)
 * commercial off-the-shelf main processors to directly control all sensors to form a consolidated view of the battlespace that is then shared via low observable data links.
 * newest generation of high performance jet engines

Sixth generation (proposed)
A sixth generation jet fighter is a conceptual airplane expected to enter service in the United States Air Force and United States Navy in 2025–30 timeframe.