First-generation jet fighter

Aircraft classified as first generation jet fighters are the first attempts at creation of military aircraft using jet engines. A few were developed during the closing days of World War II but saw very limited combat operations. The generation can be split into two broad groups: World War II era fighters such as the Me 262 and the Meteor and mature first generation fighters such as the F-86 used in the Korean War.

The "generations" of fighter aircraft are a relatively modern concept based on claims for "Fifth Generation". They are rough categories based on similar designs and do not correspond to a rigid definition.
The first operational turbojet aircraft, the He 178, was a German design that first flew in 1939. It was used as the basis of the later He 280, a design passed over for the Me 262. A similar British design, the Gloster E.28/39 had provisions for some armament, but the guns were not fitted on either prototype.
The plans for the first operational jet fighter, the Messerschmitt Me 262 Schwalbe were drawn up in 1939, and the airplane first flew under jet power in 1942. The Me 262 was not operational until 1944, and its effectiveness was crippled by the deteriorating infrastructure of Nazi Germany; the advanced materials needed for its engines were in short supply. World War II ended before jet fighters were common. The United States and the United Kingdom also had jet fighters operational before the end of the war. The British Gloster Meteor twin-engined high speed fighter was used to intercept Germany's V-1 flying bombs missiles over the British Isles and not deployed for combat over Europe until 1945 but still kept away from occupied territory to prevent the technology being picked up by the Germans or Soviets. By 1946 16 RAF squadrons were equipped with Meteors. The American Lockheed P-80 entered service in the closing phases of the war and was deployed to Europe but arrived too late to see any combat.
Early jet engines had poor acceleration, and the FR Fireball was a mixed-propulsion aircraft with a propeller in front and a jet engine in the back designed for use on an aircraft carrier. The Russian Mikoyan-Gurevich I-250 and Sukhoi Su-5 were similar concepts but used a motorjet instead of a turbojet and were not designed for carrier use.

Further experiments after the war with mixed propulsion involving at least one turboprop powerplant included the XF2R Dark Shark and the XF-84H Thunderscreech, one of the loudest aircraft ever flown. The Thunderscreech, however, was a much later design, being a contemporary of the clearly second generation F-104 Starfighter. None of these hybrid-propulsion planes saw combat or major use, though the Fireball was used operationally for two years.