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Fighter aircraft

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A fighter aircraft is a military aircraft designed primarily for attacking other aircraft, as opposed to a bomber, which is designed to attack ground targets, primarily by dropping bombs. Fighters are comparatively small, fast, and maneuverable. Fighter aircraft are the primary means by which armed forces gain air superiority. At least since World War II, air superiority has been a crucial component of victory in most modern warfare, particularly "conventional" warfare between regular armies(as opposed to guerrilla warfare), and their acquisition and maintenance represent a very substantial proportion of military budgets in militaries that maintain modern fighter forces.

Introduction

The word "fighter" did not become the official British term for a single seat fighter until after the First World War. In the RFC/RAF such aircraft continued to be called "scouts" into the early nineteen twenties. In the French, Italian, German and Portuguese languages the term used (and still in use) literally means "hunter", while in Russian the fighter is called "истребитель" (pronounced "istrebitel") which is literally "exterminator". The U.S. Army labeled their fighters as "pursuit" aircraft until the late nineteen forties.

Fighters were developed in response to the fledgling use of aircraft and dirigibles in World War I for reconnaissance and ground attack roles.

As aerial warfare became increasingly important, so did control of the airspace. By World War II, fighters were predominantly all-metal monoplanes with wing-mounted batteries of cannons or heavy machine guns. By the end of the war, turbojets were already beginning to replace piston engines as the means of propulsion, and missiles to augment or replace guns.

For historical purposes, jet fighters are sometimes classified by generation. The generation terminology was initiated by Russian defense parlance in referring to the F-35 Lightning II as a "fifth-generation" plane.

Modern jet fighters are predominantly powered by one or two turbofan engines, armed primarily with missiles (from as few as two on some lightweight day fighters to as many as eight to ten on air superiority fighters like the Su-37 Flanker or F-15 Eagle), with a cannon as backup armament (typically between 20 and 30mm in calibre), and equipped with a radar as the primary method of target acquisition.

Piston engine fighters

World War I

The word “fighter” was first used to describe a two seater aircraft, with sufficient lift to carry a machine gun and its operator as well as the pilot. The first such “fighters” belonged to the “gunbus” series of experimental gun carriers of the British Vickers company which culminated in the Vickers F.B.5 Gunbus of 1914. The main drawback of this type of aircraft was its lack of speed. It was quickly realised that an aircraft intended to destroy its kind in the air needed at least to be fast enough to catch its quarry.

Fortunately another type of military aircraft already existed, which was to form the basis for an effective "fighter" in the modern sense of the word. It was based on the small fast aircraft developed before the war for such air races as the Gordon Bennett and Schneider trophies. The military scout aeroplane was not initially expected to be able to carry serious armament, but to rely on its speed to be able to reach the location it was required to “scout” or reconnoitre and return quickly to report – all the time making a difficult target for AA artillery or enemy gun-carrying aircraft. British “scout” aircraft in this sense included the Sopwith Tabloid and Bristol Scout – French equivalents included the light, fast Morane-Saulnier N.

In practice, after the actual commencement of the war the pilots of small scout aircraft armed themselves with pistols, carbines and an assortment of improvised weapons with which to attack enemy aircraft – proving to be as successful in their efforts as specifically designed “fighter” aircraft. It was inevitable that sooner or later means of effectively arming “scouts” would be devised. One method was to build a “pusher” scout such as the Airco DH.2, with the propeller behind the pilot. The main drawback was that the high drag of a pusher type's tail structure meant that it was bound to be slower than an otherwise similar tractor aircraft. The other was to mount the machine gun armament outside the arc of the propeller. Given the tendency of early machine guns to jam (and hence the need for the pilot to have access to the gun’s breech) as well as determining the aiming point, this was a stopgap solution at best. Despite this mounting a machine gun to fire over the propeller arc was to remain in service from 1915 on the Nieuport 11 until 1918 on the Royal Aircraft Factory S.E.5 with its purpose built Foster mounting.

So clear was the need to arm a tractor scout with a forward firing gun whose bullets actually passed through the propeller arc that inventors were busy trying various methods in both France and Germany. Hanz Schneider had patented a device before the war to interrupt the machine gun's stream of bullets (by preventing it from firing when the propellor's blade was in the way) before the war and Anthony Fokker developed this into the Interrupter gear that would make the Fokker Eindecker such a feared name over the Western Front despite it being an adaptation of an obsolete pre-war French Morane-Saulnier racing monoplane. Simultaneously, Roland Garros (the first French 'Flying ace') was also working on a Interrupter gear, which attempted to time the firing of the individual rounds similarly when the propellor wasn't in the way. Unfortunately his choice of machine gun was poor - the gas operated Hotchkiss wasn't predictable enough to be able to time the firing and as a desperation measure he fitted metal wedges to protect the propellor's blades. At the same time the RNAS was taping up the blades on its scouts so that any rounds that damaged the prop wouldn't cause it to fail before the aircraft could be landed, with the fabric from the tape hopefully holding the blade together.

The success of the Eindecker started a cycle of improvement among the combatants, building ever more efficient single seat fighters. The Albatros D.I of late 1916 set the classic pattern followed by almost all such aircraft for about twenty years. Like the D.I, they were biplanes (only very occasionally monoplanes, or triplanes). The strong box structure of the biplane wing allowed for a rigid wing that afforded accurate lateral control, essential for fighter-type maneuvers. They had a single crew member, who flew the aircraft and also operated its armament. They were armed with two synchronised Maxim-type machine guns, which were much easier to synchronise than other types – firing through the propeller arc. The gun breeches were typically right in front of the pilot’s face. This had obvious implications in case of accidents, but enabled jams (to which Maxim-type machine guns always remained liable) to be cleared in flight and made aiming them much easier.

Notable aircraft: (with year of introduction)

1919-1938

Fighter development slowed between the wars, the most significant change coming late in the period, when the classic WWI type machines started to give way to metal monocoque or semi-monocoque monoplanes, with cantilever wing structures. Given limited defense budgets, air forces tended to be conservative in their aircraft purchases, and biplanes remained popular. Designs such as the Gloster Gladiator, Fiat CR.42, and Polikarpov I-15 were common even in the late 1930s. Up until the mid-1930s, the vast majority of fighter aircraft remained fabric- (or partially fabric-) covered biplanes.

Fighter armament eventually began to be mounted in the wings, outside the arc of the propeller, though most designs retained two synchronized machine-guns above the engine (which were considered more accurate). Rifle-caliber guns were the norm, with .50 caliber (12.7mm) MGs and 20mm cannons deemed "overkill." Considering that many aircraft were constructed similarly to WWI designs (albeit with aluminum frames), it was not considered unreasonable to use WWI-style armament to counter them. There was insufficient aerial combat during most of the period to disprove this notion.

The Rotary engine quickly disappeared, replaced by the stationary Radial engine. Aircraft engines increased in power several-fold over the period, going from a typical 180 HP in the 1918 Fokker D.VII to 900 HP in the 1938 Curtiss P-36. The debate between the sleek in-line engines versus the more reliable radial models continued, with Naval air forces preferring the radial engines, and land-based forces often choosing in-line units. Radial designs did not require a separate (vulnerable) cooling system, but had increased drag.

Some air forces dabbled with "heavy fighters" (called "destroyers" by the Germans). These were larger aircraft, sometimes adaptations of light or medium bomber types, and usually with two engines. Such designs typically had greater internal fuel capacity (thus, longer range) and heavier armament than their single-engine counterparts. In combat, they proved ungainly and vulnerable to more nimble single-engine fighters.

The primary driver of fighter innovation, right up to the period of rapid rearmament in the late thirties, were not military budgets, but civilian aircraft races. Aircraft designed for these races pioneered innovations like streamlining and more powerful engines that would find their way into the fighters of World War II.

At the very end of the inter-war period came the Spanish Civil War. This was just the opportunity the German Luftwaffe, Italian Regia Aeronautica, and Soviet Red Air Force needed to test their latest aircraft designs. Each party sent several aircraft to back their side in the conflict. In the dogfights over Spain, the latest Messerschmitt fighters (Bf-109) did well, as did the Soviet Polikarpov I-16. The German design had considerable room for development, however, and the lessons learned in Spain led to greatly improved models used in World War II. The Russians, whose side lost in the conflict, nonetheless determined that their planes were sufficient for their immediate needs. I-16s were later slaughtered en masse by improved German models in Operation Barbarossa. For their part, the Italians were satisfied with the performance of their Fiat CR.42 biplanes, and being short on funds, continued with this design even though it was borderline obsolete.

Notable aircraft:

World War II

Aerial combat formed an important part of World War II military doctrine. The ability of aircraft to locate, harass, and interdict ground forces was an instrumental part of the German combined-arms doctrine, and their inability to seize air superiority over Britain rendered an invasion infeasible. Erwin Rommel noted the effect of airpower: "Anyone who has to fight, even with the most modern weapons, against an enemy in complete command of the air, fights like a savage against modern European troops, under the same handicaps and with the same chances of success."

This was the era of the fast, monoplane interceptor. The older biplanes, some of which (see Fiat CR.42) were quite maneuverable, were also too slow to compete and were phased out. Initial battles in 1939, such as the Soviet-Japanese Battle of Khalkhyn Gol (technically not part of WWII, but still of strategic importance to the conflict) and the German invasion of Poland were too brief to provide much feedback to the participants. The Battle of France gave the Germans ample opportunity to encounter British and French aircraft in combat, which overall went very well for the Luftwaffe. The Soviets got their noses bloodied by the outnumbered Finns (see Finnish Air Force) in the Winter War, with poor doctrine and training hampering the large Soviet formations.

The Battle of Britain pitted a very capable Royal Air Force against the veteran Luftwaffe pilots, some of whom had combat experience in Spain. The result was a victory for the British, with lessons learned on both sides. British fighters tore apart the lightly-armed German bombers (especially the Stuka dive-bombers), while the Messerschmitt Bf-110 was finally revealed as a failed concept and relegated to night-fighter and fighter-bomber roles.

Operation Barbarossa showed that strategic surprise made Soviet preparations woefully inadequate, and Red Air Force command had rendered any lessons learned from previous experience in Spain and Finland virtually useless. The Axis were able to destroy large numbers of the Red Air Force aircraft on the ground, and in one-sided dogfights in the first few days. However, by winter 1941 the Red Air Force was able to put together a cohesive air defence of Moscow, successfully interdict attacks on Leningrad and begin production of new aircraft types in the relocated semi-built factories in the Urals, Siberia, Central Asia and the Caucasus to replace the aging designs with advanced monoplane fighters such as the Yak-1, Yak-3, LaGG-3, and Mig-3) to wrest air superiority from the Luftwaffe. From 1942 significant numbers of British, and later US, fighter aircraft were also sent to aid the Soviet war effort, with the P-39 proving particularly effective in the lower altitude combat typical of the Eastern Front. From 1942 the Eastern Front became the largest area of fighter aircraft use in the World, used in all the roles typical of the period, including close air support, interdiction, escort and interception roles. Some aircraft were armed with weapons as large as 45mm cannon, and the Germans began installing additional smaller cannon in under-wing pods to assist with ground-attack missions.

Eventually, the Allies developed advanced piston-engined fighters such as the P-47, P-51 and improved Spitfires that simply overwhelmed their German opposition. Despite having jets and even a rocket-powered interceptor (see Me-163), the Germans were swamped by superior numbers.

In the Pacific Theater, the experienced Japanese used their latest A6M Zero to clear the skies of all opposition. Caught off-guard, the Allied air forces (often flying obsolete aircraft, as the Japanese were not deemed as dangerous as the Germans) were driven back until the Japanese became overextended. Newer Allied fighter models were faster and better-armed than the Japanese fighters, and improved tactics (see Thach Weave) helped counter the nimble Zero. Japanese industry was not up to the task of creating fighter designs equal to the latest Western models, and they were largely driven from the skies by mid-1944.

Piston-engine power increased considerably during the war. The Curtiss P-36 "Hawk" had a 900 HP Radial engine but was soon redesigned as the P-40 "Warhawk" with an 1100 HP in-line engine. By 1943, the latest P-40N had a 1300 HP Allison engine. At war's end, the Ta 152 German interceptor could achieve over 2000 HP with MW-50 (Methanol-Water injection) and American P-51s had a similar amount of power.

The first jet-powered designs became operational in 1944, and clearly outperformed their piston-engined counterparts. New designs such as the Messerschmitt Me 262 and Gloster Meteor demonstrated the effectiveness of the new propulsion system. Many of these fighters could do over 400 mph (600 km/h) in level flight, and were fast enough in a dive that they started encountering the transonic buffeting experienced near the speed of sound, occasionally breaking up in flight due to the heavy load placed on an aircraft near the so-called "sound barrier". Dive brakes were developed late in World War II to minimise these problems and restore control to pilots.

Armament became a priority once it became apparent that newer stressed-skin monoplane fighters could not be easily shot down with rifle-caliber machine guns. The Germans, with experience from the Spanish Civil War put 20mm cannon on their Bf-109 and Bf-110 models. The British soon followed suit, putting cannons in the wings of Hawker Hurricanes and Supermarine Spitfires. The Americans, lacking a native cannon design, instead chose to place multiple .50 caliber (12.7mm) MGs on their fighters. Armaments continued to increase, with the German ME-262 jet having four 30mm cannons in the nose. Cannon fired explosive shells, and could blast a hole in an enemy aircraft rather than relying on kinetic energy from a solid bullet striking a critical subsystem (fuel line, hydraulics, control cable, pilot, etc.). A debate existed over the merits of high rate-of-fire machine guns versus slower-firing, but more devastating, cannon.

As the war progressed, use of drop tanks became common. This made the heavy twin-engine fighter designs redundant, as single-engine fighters could now cover a similar distance. Extra fuel was carried in lightweight aluminum tanks below the aircraft, and the tanks were discarded when empty. Such innovations allowed American fighter cover to range over Germany and Japan by 1944.

With the increasing need for Close air support on the battlefield, fighters were increasingly fitted with bomb racks and used as fighter-bombers. Some designs, such as the German FW-190, proved extraordinarily capable in this role -- though the designer (Kurt Tank) had designed it as a pure interceptor. Because an aircraft's lift is derived from the upper surface of the wing, the lower surface can easily be festooned with a variety of rockets, bombs, and other ordnance. This increases drag, and thus the performance of the fighter is lessened, but once the ordnance is delivered (or jettisoned), the aircraft is again a fully capable fighter aircraft. Command staff had the freedom to designate a particular air group as air superiority or ground-attack as need occasioned in many cases.

Radar, invented shortly prior to World War II, was fitted to some fighters, such as the Messerschmitt Bf 110, F6F Hellcat and Northrop P-61 Black Widow to enable them to locate targets at night. The Germans developed several night-fighter types as they were under constant night bombardment by British Bomber Command. The British, in turn, refined their own designs to counter the Germans. Since the radar of the era was fairly primitive and difficult to use properly, larger 2-3 seat aircraft were commonly adapted to this role (with dedicated Radar Operator).

Notable aircraft:

    • Jet-powered fighters

    First-generation jet fighters (1944-1953)

    The first generation represents the first attempts at using turbojets for propulsion, providing greatly increased speed (the efficiency of piston-driven propellers drops off considerably at transsonic speeds). Many of these early jets resembled their piston-driven counterparts in several ways. Many were straight-winged aircraft armed primarily with heavy machine-guns; radar was not yet in common usage except on specialized night fighters.

    The first jets were developed during World War II and saw combat in its last year. Messerschmitt developed the first operational jet fighter, the Me 262. It was considerably faster than piston-driven aircraft, and in the hands of a competent pilot, was quite difficult for Allied pilots to defeat. The design was never deployed in numbers sufficient to stop the Allied air campaign, and a combination of fuel shortages and technical difficulties with the engines kept the number of sorties low. Nevertheless the plane indicated the obsolescence of piston-driven aircraft. Spurred by reports of the German jets, Britain's Gloster Meteor entered production soon after and the two entered service around the same time in 1944. Meteors were commonly used to intercept the V-1 "buzz bomb", as they were faster than piston-engined contemporaries. By the end of the war almost all work on piston powered fighters had ended. Mixed-propulsion designs such as the Ryan FR Fireball saw brief use, but by the end of the 1940s virtually all new combat aircraft were jet-powered.

    Despite the advantages, the early jet fighters were far from perfect, particularly in the opening years of the generation. Their operational lifespans could be measured primarily in hours; the engines themselves were fragile and bulky, and power could be adjusted only slowly. Many squadrons of piston-engined fighters were retained until the early-to-mid 1950s, even in the US and Soviet Air Forces (though the types retained were the best of the WW2 designs -- such as the P-51). Innovations such as swept wings, ejector seats, and all-moving tailplanes were introduced in this period.

    The Americans were one of the first to begin using jet fighters post-war. The P-80 (soon re-designated F-80) was less elegant than the swept-wing Messerschimitt, but had a cruise speed (410 mph / 660 km) as high as the combat maximum of many piston-engined fighters. The British designed several new jets, including the iconic de Havilland Vampire which was sold to the air forces of many nations. Ironically, the English transferred Rolls-Royce jet engine technology to the Soviets, who soon put it to use in their advanced MiG-15 fighters. These proved quite a shock to the American F-80 pilots who encountered them over Korea. Where the American jets were armed with a "traditional" load of six .50 cal (12.7mm) heavy machine-guns, the MiGs used two 23mm cannons and a single 37mm cannon (good against bombers). A few hits from the MiG could knock an American fighter out of the sky.

    The response to this was to rush F-86 squadrons to battle against the MiGs. While carrying the same armament as the F-80, the F-86 was a true swept-wing transonic fighter, as was the MiG-15. The two aircraft had different strengths, but were similar enough that only the superior skills of the veteran United States Air Force pilots allowed them to prevail.

    The world's navies also went for jets during this period, despite the need for catapult-launching of the new aircraft. The F9F Panther was adopted by the US Navy as their primary jet fighter in the Korean War period. The Vampire was commonly used in this role for the Royal Navy.

    Notable aircraft:

    Second generation (1953-1960)

    The second generation describes the integration of many new technologies to greatly improve the fighting capability of the jet fighter. The introduction of guided missiles such as the AIM-9 Sidewinder and AIM-7 Sparrow moved combat to beyond visual range (though it often devolved into dogfights in visual range), necessitating the standardization of radar to acquire targets. Designers experimented with a variety of aeronautical innovations, such as the swept wing, delta wing, variable-geometry wings, and area ruled fuselages. With the aid of swept wing, these were the first production aircraft to break the sound barrier.

    The primary specializations of this era were the fighter-bomber (such as the F-105 and the Sukhoi Su-7), and the interceptor (English Electric Lightning and F-104 Starfighter). The interceptor was an outgrowth of the vision that guided missiles would completely replace guns and combat would take place at beyond visual range. As a result, interceptors were designed with a large missile payload and a powerful radar, sacrificing agility in favor of speed and rate of climb.

    Notable aircraft:

    • Third generation (1960-1970)

    The third generation is marked by maturity in the innovations introduced in the first generation. As this aeronautical development approached maturity, growth in combat capability grew via the introduction of improved missiles, radar, and other avionics. Most significantly, as a result of combat experience with guided missiles, designers conceded that combat could and would degenerate into close dogfights. New automatic-fire weapons, primarily gatling cannon, allowed a single multi-barrel weapon to be carried -- with a greater rate-of-fire and accuracy. Third generation designs also brought a new emphasis on maneuverability for many aircraft, though this was never a strength of the delta-winged fighters.

    These innovations, while greatly improving the capabilities of fighters (the F-4 could carry a payload greater than the B-24 Liberator, a World War II heavy bomber), also came at a considerable increase at cost. Whereas militaries had previously specialized fighters for specific roles, such as night fighter, heavy fighter and strike fighter, in order to counter the growing cost of fighters, militaries began to consolidate missions. The McDonnell F-4 Phantom II was designed as a pure interceptor for the United States Navy, but became a highly successful multi-role aircraft for the Air Force, Navy and Marine Corps as well as many other nations. It is the only combat aircraft to be simultaneously flown by all three American service branches.

    Notable aircraft:

    Fourth generation (1970-1990)

    In reaction to the continually rising cost of fighters and the demonstrated success of the F-4 Phantom II, multirole fighters became popular during this period, and even aircraft designed for a specific role (as the F-4 had) acquired multi-role capability. Fighters such as the MiG-23 and Panavia Tornado have versions specially suited for various roles, while true multirole warplanes include the F/A-18 Hornet and Dassault Mirage 2000. This was facilitated by avionics which could switch seamlessly between air and ground modes. As development costs increased, economics further pushed the development for multirole aircraft.

    Unlike interceptors of the previous era, most modern air-superiority fighters have been designed to be agile dog-fighters. Fly-by-wire controls and relaxed stability are common among modern fighters. Aircraft here make up most of the "fourth generations" of fighter jets.

    Notable aircraft:

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  • Republic of China (Taiwan)

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    • Generation 4.5 (1990-2000)

    This half-generation has been coined to describe an interim period of aircraft design marked by a relative stagnation of aerodynamic technologies compared to third and fourth generation advances, but with tremendous achievements made in the field of avionics and other flight electronics. This was largely due to advances made in microchip and semiconductor technology in the 1980s and 1990s. This combination led designers to produce "upgraded" fourth-generation designs, with airframes either based on existing airframes or on similar design theory as previous iterations, but implementing the avionics and radar advances developed in the interim as well as some of the lessons learned in fourth-generation stealth designs, which would later be fully envisaged in fifth-generation fighters. A prime example of this generation is the F/A-18E/F Super Hornet, based on the 1970s F/A-18 Hornet design. While the external profile remains largely the same, the Super Hornet features improved avionics in the form of a glass cockpit, a solid-state AESA fixed-array radar, new engines, the structural use of composite materials to reduce weight, and a slightly modified shape to minimize its radar signature. Another is the F-15E Strike Eagle, a ground-attack variant of the Cold War-era F-15 Eagle fighter with an strengthened airframe and upgraded engines, glass cockpit displays, and the very latest terrain-following navigation and targeting systems. Of the 4.5 generation designs, only the Super Hornet, Strike Eagle, and the Rafale have seen combat action.

    Notable aircraft:

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    • Fifth generation (2000-Present)

    The current cutting edge of fighter design combines previous emphasis on versatility with new developments such as thrust vectoring, short takeoff/landing, composite materials, supercruise, stealth technology, advanced radar and sensors, and integrated avionics designed to reduce the pilot's workload while vastly improving situational awareness. The avionics technologies such as glass cockpits and helmet-mounted display and targeting that were developed during Generation 4.5 have been further advanced and integrated into totally new aircraft designs, which draw on lessons learned from fourth-generation stealth, VTOL and composite aircraft like the F-117, B-2 and AV-8 Harrier.

    Of these, only the American F-22 Raptor, put into production in 2004, is operational, and is often regarded as the first of a new generation of fighters, termed the "fifth-generation". Design elements of the F-35 Lightning II (formerly Joint Strike Fighter) currently in pre-production, and the F-22 Raptor have influenced continued development of fourth-generation designs, and the shape of design work for the Russian PAK FA and other countries' long-term fighter development projects (for instance, the rumoured Chinese Shenyang J-XX project, Indian Medium Combat Aircraft and South Korean KFX). Later cancelled technology demonstrators of fifth-generation fighter aircraft include the United States YF-23 Black Widow II (which lost the Advanced Tactical Fighter competition to what is now the F-22), Boeing X-32 (which lost the Joint Strike Fighter competition to the YF-35) and McDonnell Douglas X-36, and the Soviet Union Project 1.42, later upgraded by Russia to version 1.44.

    In Service

    In Development

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    • 5th Generation Fighter Project (based on Sukhoi PAK FA, maiden flight expected 2012)
    • KFX

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    • Technology Demonstrators

    See also

    References

    External links



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