Editing Fighter aircraft (section)

== Piston engine fighters ==

=== 1914–1918: World War I ===
{{Further|Aviation in World War I}}

[[File:SPAD S.A-2 named Ma Jeanne.jpg|thumb|left|[[SPAD S.VII|SPAD]] S.A.2, with gunner in "basket" up front]]

The word "fighter" was first used to describe a two-seat aircraft carrying a machine gun (mounted on a pedestal) and its operator as well as the [[Aviator|pilot]]. Although the term was coined in the United Kingdom, the first examples were the French Voisin pushers beginning in 1910, and a [[Voisin III]] would be the first to shoot down another aircraft, on 5 October 1914.<ref>{{cite book |last=Guttman |first=John |year=2009 |url=https://books.google.com/books?id=is-ij4XZRTIC&pg=PA9 |title=Pusher Aces of World War I |publisher=[[Osprey Publishing]] |page=9 |isbn= 978-1-84603417-6}}</ref>

However at the outbreak of [[World War I]], front-line aircraft were mostly unarmed and used almost exclusively for [[reconnaissance]]. On 15 August 1914, [[Miodrag Tomić]] encountered an enemy airplane while on a reconnaissance flight over Austria-Hungary which fired at his aircraft with a revolver,{{sfn|Glenny|2012|p=316}} so Tomić fired back.{{sfn|Blume|1968|p=291}}{{sfnm|1a1=Glenny|1y=2012|1p=316|2a1=Buttar|2y=2014|2p=298}} It was believed to be the first exchange of fire between aircraft.{{sfn|Buttar|2014|p=298}} Within weeks, all Serbian and Austro-Hungarian aircraft were armed.{{sfn|Glenny|2012|p=316}}

Another type of military aircraft formed the basis for an effective "fighter" in the modern sense of the word. It was based on small fast aircraft developed before the war for [[air racing]] such with the Gordon Bennett Cup and [[Schneider Trophy]]. The military [[Scout (aircraft)|scout]] airplane was not expected to carry serious armament, but rather to rely on speed to "scout" a location, and return quickly to report, making it a flying horse. British scout aircraft, in this sense, included the [[Sopwith Tabloid]] and [[Bristol Scout]]. The French and the Germans didn't have an equivalent as they used two seaters for reconnaissance, such as the [[Morane-Saulnier L]], but would later modify pre-war racing aircraft into armed single seaters. It was quickly found that these were of little use since the pilot couldn't record what he saw while also flying, while military leaders usually ignored what the pilots reported.

Attempts were made with handheld weapons such as pistols and rifles and even light machine guns, but these were ineffective and cumbersome.<ref name=woodman31>Woodman, 1989, p. 33</ref>{{full citation needed|date=September 2024}} The next advance came with the fixed forward-firing machine gun, so that the pilot pointed the entire aircraft at the target and fired the gun, instead of relying on a second gunner. [[Roland Garros (aviator)|Roland Garros]] bolted metal deflector plates to the propeller so that it would not shoot itself out of the sky and a number of [[Morane-Saulnier N]]s were modified. The technique proved effective, however the deflected bullets were still highly dangerous.<ref>{{cite book |last1=Angelucci |first1=A. |last2=Matricardi |first2=P. |title=World Aircraft: Origins – World War I |publisher=Sampson Low |date=1977 |page=110}}</ref>

Soon after the commencement of the war, pilots armed themselves with pistols, [[carbines]], [[grenade]]s, and an assortment of improvised weapons. Many of these proved ineffective as the pilot had to fly his airplane while attempting to aim a handheld weapon and make a difficult deflection shot. The first step in finding a real solution was to mount the weapon on the aircraft, but the propeller remained a problem since the best direction to shoot is straight ahead. Numerous solutions were tried. A second crew member behind the pilot could aim and fire a swivel-mounted machine gun at enemy airplanes; however, this limited the area of coverage chiefly to the rear hemisphere, and effective coordination of the pilot's maneuvering with the gunner's aiming was difficult. This option was chiefly employed as a defensive measure on two-seater reconnaissance aircraft from 1915 on. Both the [[SPAD S.A]] and the [[Royal Aircraft Factory B.E.9]] added a second crewman ahead of the engine in a pod but this was both hazardous to the second crewman and limited performance. The [[Sopwith L.R.T.Tr.]] similarly added a pod on the top wing with no better luck.
[[File:Jules Védrines in a Nieuport 16 fighter at Vadelaincourt airfield (cropped).jpg|thumb|[[Jules Védrines]] in his [[Nieuport 16]], armed with a [[Lewis gun|Lewis]], after clearing the front line of German observation balloons with the first rocket attack in history]]
An alternative was to build a [[Pusher configuration|"pusher"]] scout such as the [[Airco DH.2]], with the propeller mounted behind the pilot. The main drawback was that the high [[Drag (physics)|drag]] of a pusher type's tail structure made it slower than a similar [[Tractor configuration|"tractor"]] aircraft.
A better solution for a single seat scout was to mount the machine gun (rifles and pistols having been dispensed with) to fire forwards but outside the propeller arc. Wing guns were tried but the unreliable weapons available required frequent clearing of [[Firearm malfunction|jammed rounds and misfires]] and remained impractical until after the war. Mounting the machine gun over the top wing worked well and was used long after the ideal solution was found. The [[Nieuport 11]] of 1916 used this system with considerable success, however, this placement made aiming and reloading difficult but would continue to be used throughout the war as the weapons used were lighter and had a higher rate of fire than synchronized weapons. The British [[Foster mounting]] and several French mountings were specifically designed for this kind of application, fitted with either the [[Hotchkiss M1909 Benét–Mercié machine gun|Hotchkiss]] or [[Lewis Gun|Lewis Machine gun]], which due to their design were unsuitable for synchronizing. The need to arm a [[tractor scout]] with a forward-firing gun whose bullets passed through the propeller arc was evident even before the outbreak of war and inventors in both France and Germany devised [[Synchronization gear|mechanisms]] that could time the firing of the individual rounds to avoid hitting the propeller blades. [[Franz Schneider (engineer)|Franz Schneider]], a Swiss engineer, had patented such a device in Germany in 1913, but his original work was not followed up. French aircraft designer [[Raymond Saulnier (aircraft manufacturer)|Raymond Saulnier]] patented a practical device in April 1914, but trials were unsuccessful because of the propensity of the machine gun employed to [[hang fire]] due to unreliable ammunition. In December 1914, French aviator [[Roland Garros (aviator)|Roland Garros]] asked Saulnier to install his synchronization gear on Garros' [[Morane-Saulnier Type L]] [[parasol monoplane]]. Unfortunately the gas-operated [[Hotchkiss M1914 machine gun|Hotchkiss]] machine gun he was provided had an erratic rate of fire and it was impossible to synchronize it with the propeller. As an interim measure, the propeller blades were fitted with metal wedges to protect them from [[ricochet]]s. Garros' modified monoplane first flew in March 1915 and he began combat operations soon after. Garros scored three victories in three weeks before he himself was downed on 18 April and his airplane, along with its synchronization gear and propeller was captured by the Germans. Meanwhile, the synchronization gear (called the ''Stangensteuerung'' in German, for "pushrod control system") devised by the engineers of [[Anthony Fokker]]'s firm was the first system to enter service. It would usher in what the British called the "[[Fokker scourge]]" and a period of air superiority for the German forces, making the [[Fokker Eindecker|Fokker ''Eindecker'']] monoplane a feared name over the [[Western Front (World War I)|Western Front]], despite its being an adaptation of an obsolete pre-war French [[Morane-Saulnier]] racing airplane, with poor flight characteristics and a by now mediocre performance. The first ''Eindecker'' victory came on 1 July 1915, when ''Leutnant'' [[Kurt Wintgens]], of [[Feldflieger Abteilung]] 6 on the Western Front, downed a Morane-Saulnier Type L. His was one of five [[Fokker M.5]]K/MG prototypes for the ''Eindecker'', and was armed with a synchronized aviation version of the [[Parabellum MG14]] machine gun.{{sfn|Munson|1976|p=161}} The success of the ''Eindecker'' kicked off a competitive cycle of improvement among the combatants, both sides striving to build ever more capable single-seat fighters. The [[Albatros D.I]] and [[Sopwith Pup]] of 1916 set the classic pattern followed by fighters for about twenty years. Most were [[biplane]]s and only rarely monoplanes or [[triplane]]s. The strong box structure of the biplane provided a rigid wing that allowed the accurate control essential for [[dogfighting]]. They had a single operator, who flew the aircraft and also controlled its armament. They were armed with one or two [[Maxim gun|Maxim]] or [[Vickers]] machine guns, which were easier to synchronize than other types, firing through the propeller arc. Gun breeches were in front of the pilot, with obvious implications in case of accidents, but jams could be cleared in flight, while aiming was simplified.

[[File:Fokker DR1 at Airpower11 18.jpg|thumb|left|A replica German [[Fokker Dr.I]]]]
The use of metal aircraft structures was pioneered before World War I by Breguet but would find its biggest proponent in Anthony Fokker, who used chrome-molybdenum steel tubing for the fuselage structure of all his fighter designs, while the innovative German engineer [[Hugo Junkers]] developed two all-metal, single-seat fighter monoplane designs with [[cantilever]] wings: the strictly experimental [[Junkers J 2]] private-venture aircraft, made with steel, and some forty examples of the [[Junkers D.I]], made with corrugated [[duralumin]], all based on his experience in creating the pioneering [[Junkers J 1]] all-metal airframe technology demonstration aircraft of late 1915. While Fokker would pursue steel tube fuselages with wooden wings until the late 1930s, and Junkers would focus on corrugated sheet metal, Dornier was the first to build a fighter (the [[Dornier-Zeppelin D.I]]) made with pre-stressed sheet aluminum and having cantilevered wings, a form that would replace all others in the 1930s. As collective combat experience grew, the more successful pilots such as [[Oswald Boelcke]], [[Max Immelmann]], and [[Edward Mannock]] developed innovative tactical formations and maneuvers to enhance their air units' combat effectiveness.

Allied and&nbsp;– before 1918&nbsp;– German pilots of World War I were not equipped with [[parachute]]s, so in-flight fires or structural failures were often fatal. Parachutes were well-developed by 1918 having previously been used by balloonists, and were adopted by the German flying services during the course of that year. The well-known [[Manfred von Richthofen]], the "Red Baron", was wearing one when he was killed, but the allied command continued to oppose their use on various grounds.<ref>{{cite book |last=Lee |first=Arthur Gould |title=No Parachute |location=London |publisher=Jarrolds |date=1968 |isbn=0-09-086590-1}}</ref>{{page needed|date=September 2024}}

In April 1917, during a brief period of German aerial supremacy a British pilot's average life expectancy was calculated to average 93 flying hours, or about three weeks of active service.<ref>{{cite book |first1=Eric |last1=Lawson |first2=Jane |last2=Lawson |title=The First Air Campaign: August 1914–November 1918 |url=https://books.google.com/books?id=9PGHckhHiX0C&pg=PT123 |year=2007 |publisher=Da Capo Press |isbn=978-0-306-81668-0 |page=123}}{{Dead link|date=April 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{cite book |first=Harry |last=Furniss |title=Memoirs One: The Flying Game |url=https://books.google.com/books?id=NqlZ0cSkUWcC&pg=PT183 |year=2000 |publisher=Trafford |isbn=978-1-55212-513-7 |page=183}}</ref> More than 50,000 airmen from both sides died during the war.<ref>John Buckley (1998). "''[https://books.google.com/books?id=0_-DJcwmQ20C Air power in the age of total war]''", {{Webarchive|url= https://web.archive.org/web/20170329152848/https://books.google.com/books?id=0_-DJcwmQ20C |date=29 March 2017 }}. Taylor & Francis. p. 43. {{ISBN|1-85728-589-1}}</ref>

=== 1919–1938: Inter-war period ===
Fighter development stagnated between the wars, especially in the United States and the United Kingdom, where budgets were small. In France, Italy and Russia, where large budgets continued to allow major development, both monoplanes and all metal structures were common. By the end of the 1920s, however, those countries overspent themselves and were overtaken in the 1930s by those powers that hadn't been spending heavily, namely the British, the Americans, the Spanish (in the Spanish civil war) and the Germans.

Given limited budgets, air forces were conservative in aircraft design, and biplanes remained popular with pilots for their agility, and remained in service long after they ceased to be competitive. Designs such as the [[Gloster Gladiator]], [[Fiat CR.42 Falco]], and [[Polikarpov I-15]] were common even in the late 1930s, and many were still in service as late as 1942. Up until the mid-1930s, the majority of fighters in the US, the UK, Italy and Russia remained fabric-covered biplanes.

Fighter armament eventually began to be mounted inside the wings, outside the arc of the propeller, though most designs retained two synchronized machine guns directly ahead of the pilot, where they were more accurate (that being the strongest part of the structure, reducing the vibration to which the guns were subjected). Shooting with this traditional arrangement was also easier because the guns shot directly ahead in the direction of the aircraft's flight, up to the limit of the guns range; unlike wing-mounted guns which to be effective required to be [[Gun harmonisation|harmonised]], that is, preset to shoot at an angle by ground crews so that their bullets would converge on a target area a set distance ahead of the fighter. Rifle-caliber {{cvt|.30|and|.303|in|2}} calibre guns remained the norm, with larger weapons either being too heavy and cumbersome or deemed unnecessary against such lightly built aircraft. It was not considered unreasonable to use World War I-style armament to counter enemy fighters as there was insufficient air-to-air combat during most of the period to disprove this notion.

[[File:Nieuport-Delage NiD 52 L'Aéronautique June,1928.jpg|thumb|[[Nieuport-Delage NiD.52]], which in various forms would be used through the 20s and into the 1930s by various European air arms, including that of the French and Spanish.]] 
The [[rotary engine]], popular during World War I, quickly disappeared, its development having reached the point where rotational forces prevented more fuel and air from being delivered to the cylinders, which limited horsepower. They were replaced chiefly by the stationary [[radial engine]] though major advances led to inline engines gaining ground with several exceptional engines—including the {{cvt|1145|cuin}} V-12 [[Curtiss D-12]]. [[Aircraft engine]]s increased in power several-fold over the period, going from a typical {{cvt|180|hp}} in the {{cvt|900|kg}} [[Fokker D.VII]] of 1918 to {{cvt|900|hp}} in the {{cvt|2500|kg}} [[Curtiss P-36]] of 1936. The debate between the sleek [[Straight engine|in-line engines]] versus the more reliable radial models continued, with naval air forces preferring the radial engines, and land-based forces often choosing inlines. Radial designs did not require a separate (and vulnerable) radiator, but had increased drag. Inline engines often had a better [[power-to-weight ratio]].

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

The primary driver of fighter innovation, right up to the period of rapid re-armament in the late 1930s, were not military budgets, but civilian aircraft racing. Aircraft designed for these races introduced innovations like streamlining and more powerful engines that would find their way into the fighters of World War II. The most significant of these was the [[Schneider Trophy]] races, where competition grew so fierce, only national governments could afford to enter.

At the very end of the inter-war period in Europe came the [[Spanish Civil War]]. This was just the opportunity the German [[Luftwaffe]], Italian [[Regia Aeronautica]], and the Soviet Union's [[Soviet Air Forces|Voenno-Vozdushnye Sily]] needed to test their latest aircraft. Each party sent numerous aircraft types to support their sides in the conflict. In the [[dogfight]]s over Spain, the latest [[Messerschmitt Bf 109]] fighters did well, as did the Soviet [[Polikarpov I-16]]. The later German design was earlier in its design cycle, and had more room for development and the lessons learned led to greatly improved models in World War II. The Russians failed to keep up and despite newer models coming into service, I-16s remaining the most common Soviet front-line fighter into 1942 despite being outclassed by the improved Bf 109s in World War II. For their part, the Italians developed several monoplanes such as the [[Fiat G.50 Freccia]], but being short on funds, were forced to continue operating obsolete [[Fiat CR.42 Falco]] biplanes.

From the early 1930s the Japanese were at war against both the Chinese Nationalists and the Russians in China, and used the experience to improve both training and aircraft, replacing biplanes with modern cantilever monoplanes and creating a cadre of exceptional pilots. In the United Kingdom, at the behest of [[Neville Chamberlain]] (more famous for his 'peace in our time' speech), the entire British aviation industry was retooled, allowing it to change quickly from fabric covered metal framed biplanes to cantilever stressed skin monoplanes in time for the war with Germany, a process that France attempted to emulate, but too late to counter the German invasion. The period of improving the same biplane design over and over was now coming to an end, and the [[Hawker Hurricane]] and [[Supermarine Spitfire]] started to supplant the [[Gloster Gladiator]] and [[Hawker Fury]] biplanes but many biplanes remained in front-line service well past the start of World War II. While not a combatant in Spain, they too absorbed many of the lessons in time to use them.

The Spanish Civil War also provided an opportunity for updating fighter tactics. One of the innovations was the development of the "[[finger-four]]" formation by the German pilot [[Werner Mölders]]. Each fighter [[squadron (aviation)|squadron]] (German: ''Staffel'') was divided into several flights (''Schwärme'') of four aircraft. Each ''Schwarm'' was divided into two ''Rotten'', which was a pair of aircraft. Each ''Rotte'' was composed of a leader and a wingman. This flexible formation allowed the pilots to maintain greater situational awareness, and the two ''Rotten'' could split up at any time and attack on their own. The finger-four would be widely adopted as the fundamental tactical formation during World War Two, including by the British and later the Americans.{{Clarify|date=November 2011}}

=== 1939–1945: World War II ===
{{Further|Aviation in World War II}}
[[File:Messerschmitt Bf 109E at Thunder Over Michigan.jpg|thumb|left|A [[Messerschmitt Bf 109| Messerschmitt Bf 109E]] warbird demonstrator ]]
World War II featured fighter combat on a larger scale than any other conflict to date. German Field Marshal [[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..."<ref>{{cite book |last=Lewin |first=Ronald |author-link=Ronald Lewin |date=1968 |title=Rommel as Military Commander |publisher=Batsford |page=162}}</ref> Throughout the war, fighters performed their conventional role in establishing [[Air supremacy|air superiority]] through combat with other fighters and through bomber interception, and also often performed roles such as [[ground-attack aircraft|tactical air support]] and [[reconnaissance aircraft|reconnaissance]].

Fighter design varied widely among combatants. The Japanese and Italians favored lightly armed and armored but highly maneuverable designs such as the Japanese [[Nakajima Ki-27]], [[Nakajima Ki-43]] and [[Mitsubishi A6M Zero]] and the Italian [[Fiat G.50 Freccia]] and [[Macchi MC.200]]. In contrast, designers in the United Kingdom, Germany, the Soviet Union, and the United States believed that the increased speed of fighter aircraft would create [[g-force|''g''-forces]] unbearable to pilots who attempted maneuvering dogfights typical of the First World War, and their fighters were instead optimized for speed and firepower. In practice, while light, highly maneuverable aircraft did possess some advantages in fighter-versus-fighter combat, those could usually be overcome by sound tactical doctrine, and the design approach of the Italians and Japanese made their fighters ill-suited as interceptors or attack aircraft.

==== European theater ====
During the [[invasion of Poland]] and the [[Battle of France]], Luftwaffe fighters—primarily the [[Messerschmitt Bf 109]]—held air superiority, and the Luftwaffe played a major role in German victories in these campaigns. During the [[Battle of Britain]], however, British [[Hawker Hurricane|Hurricanes]] and [[Supermarine Spitfire|Spitfires]] proved roughly equal to Luftwaffe fighters. Additionally Britain's radar-based [[Dowding system]] directing fighters onto German attacks and the advantages of fighting above Britain's home territory allowed the RAF to deny Germany air superiority, saving the UK from possible German invasion and dealing the Axis a major defeat early in the Second World War. On the [[Eastern Front (World War II)|Eastern Front]], [[Soviet Air Force|Soviet fighter forces]] were overwhelmed during the opening phases of [[Operation Barbarossa]]. This was a result of the tactical surprise at the outset of the campaign, the leadership vacuum within the Soviet military left by the [[Great Purge]], and the general inferiority of Soviet designs at the time, such as the obsolescent [[Polikarpov I-15]] [[biplane]] and the [[Polikarpov I-16|I-16]]. More modern Soviet designs, including the [[Mikoyan-Gurevich MiG-3]], [[Lavochkin-Gorbunov-Gudkov LaGG-3|LaGG-3]] and [[Yakovlev Yak-1|Yakolev Yak-1]], had not yet arrived in numbers and in any case were still inferior to the [[Messerschmitt Bf 109]]. As a result, during the early months of these campaigns, [[Axis powers|Axis]] air forces destroyed large numbers of Red Air Force aircraft on the ground and in one-sided dogfights. In the later stages on the Eastern Front, Soviet training and leadership improved, as did their equipment. By 1942 Soviet designs such as the [[Yakovlev Yak-9]] and [[Lavochkin La-5]] had performance comparable to the German Bf 109 and [[Focke-Wulf Fw 190]]. Also, significant numbers of British, and later U.S., fighter aircraft were supplied to aid the Soviet war effort as part of [[Lend-Lease]], with the [[Bell P-39 Airacobra]] proving particularly effective in the lower-altitude combat typical of the Eastern Front. The Soviets were also helped indirectly by the American and British bombing campaigns, which forced the Luftwaffe to shift many of its fighters away from the Eastern Front in defense against these raids. The Soviets increasingly were able to challenge the Luftwaffe, and while the Luftwaffe maintained a qualitative edge over the Red Air Force for much of the war, the increasing numbers and efficacy of the Soviet Air Force were critical to the Red Army's efforts at turning back and eventually annihilating the [[Wehrmacht]].
[[File:Spitfire - Season Premiere Airshow 2018 (cropped).jpg|thumb| A [[Supermarine Spitfire]], typical World War II fighter optimized for high level speeds and good climb rates.]]
Meanwhile, air combat on the [[Western Front (World War II)|Western Front]] had a much different character. Much of this combat focused on the [[strategic bombing]] campaigns of the [[Royal Air Force|RAF]] and the [[United States Army Air Forces|USAAF]] against German industry intended to wear down the Luftwaffe. Axis fighter aircraft focused on [[Defence of the Reich|defending against Allied bombers]] while Allied fighters' main role was as bomber escorts. The RAF raided German cities at night, and both sides developed radar-equipped [[night fighter]]s for these battles. The Americans, in contrast, flew daylight bombing raids into Germany delivering the [[Combined Bomber Offensive]]. Unescorted [[Consolidated B-24 Liberator]]s and [[Boeing B-17 Flying Fortress]] bombers, however, proved unable to fend off German interceptors (primarily Bf 109s and Fw 190s). With the later arrival of long range fighters, particularly the [[North American P-51 Mustang]], American fighters were able to escort far into Germany on daylight raids and by ranging ahead [[Attrition warfare|attrited]] the Luftwaffe to establish control of the skies over Western Europe.

By the time of [[Operation Overlord]] in June 1944, the Allies had gained near complete air superiority over the Western Front. This cleared the way both for intensified strategic bombing of German cities and industries, and for the [[tactical bombing]] of battlefield targets. With the Luftwaffe largely cleared from the skies, Allied fighters increasingly served as ground attack aircraft.

Allied fighters, by gaining air superiority over the European battlefield, played a crucial role in the eventual defeat of the Axis, which ''Reichmarshal'' [[Hermann Göring]], commander of the German [[Luftwaffe]] summed up when he said: "When I saw [[North American P-51 Mustang|Mustangs]] over Berlin, I knew the jig was up."<ref>Sherman, Steven. [http://acepilots.com/usaaf_eto_aces.html "Aces of the Eighth Air Force in World War Two."] {{Webarchive|url=https://web.archive.org/web/20110808030112/http://acepilots.com/usaaf_eto_aces.html |date=8 August 2011 }} ''acepilots.com'', June 1999. Retrieved: 7 August 2011.</ref>

==== Pacific theater ====
Major air combat during the [[Pacific Ocean theater of World War II|war in the Pacific]] began with the entry of the Western Allies following Japan's [[Attack on Pearl Harbor|attack against Pearl Harbor]]. The [[Imperial Japanese Navy Air Service]] primarily operated the [[Mitsubishi A6M Zero]], and the [[Imperial Japanese Army Air Service]] flew the [[Nakajima Ki-27]] and the [[Nakajima Ki-43]], initially enjoying great success, as these fighters generally had better range, maneuverability, speed and climb rates than their Allied counterparts.{{sfn|Eden|2004|p=370}}{{sfn|Grove|Ireland|1997|p=182}} Additionally, Japanese pilots were well trained and many were combat veterans from [[Second Sino-Japanese War|Japan's campaigns in China]]. They quickly gained air superiority over the Allies, who at this stage of the war were often disorganized, under-trained and poorly equipped, and Japanese air power contributed significantly to their successes in [[Philippines campaign (1941–1942)|the Philippines]], [[Malayan Campaign|Malaysia and Singapore]], [[Dutch East Indies campaign|the Dutch East Indies]] and [[Burma Campaign 1942–1943|Burma]].

By mid-1942, the Allies began to regroup and while some Allied aircraft such as the [[Brewster Buffalo]] and the [[Bell P-39 Airacobra|P-39 Airacobra]] were hopelessly outclassed by fighters like Japan's [[Mitsubishi A6M Zero]], others such as the Army's [[Curtiss P-40 Warhawk]] and the Navy's [[Grumman F4F Wildcat]] possessed attributes such as superior firepower, ruggedness and dive speed, and the Allies soon developed tactics (such as the [[Thach Weave]]) to take advantage of these strengths. These changes soon paid dividends, as the Allied ability to deny Japan air superiority was critical to their victories at [[Battle of the Coral Sea|Coral Sea]], [[Battle of Midway|Midway]], [[Guadalcanal Campaign|Guadalcanal]] and [[New Guinea campaign|New Guinea]]. In China, the [[Flying Tigers]] also used the same tactics with some success, although they were unable to stem the tide of Japanese advances there.
By 1943, the Allies began to gain the upper hand in the Pacific Campaign's air campaigns. Several factors contributed to this shift. First, the [[Lockheed P-38 Lightning]] and second-generation Allied fighters such as the [[Grumman F6F Hellcat|Grumman F6 Hellcat]] and later the [[Vought F4U Corsair|Vought F4 Corsair]], the [[Republic P-47 Thunderbolt]] and the [[North American P-51 Mustang]], began arriving in numbers. These fighters outperformed Japanese fighters in all respects except maneuverability. Other problems with Japan's fighter aircraft also became apparent as the war progressed, such as their lack of armor and light armament, which had been typical of all pre-war fighters worldwide, but the problem was particularly difficult to rectify on the Japanese designs. This made them inadequate as either bomber-interceptors or ground-attack aircraft, roles Allied fighters were still able to fill. Most importantly, Japan's training program failed to provide enough well-trained pilots to replace losses. In contrast, the Allies improved both the quantity and quality of pilots graduating from their training programs. By mid-1944, Allied fighters had gained air superiority throughout the theater, which would not be contested again during the war. The extent of Allied quantitative and qualitative superiority by this point in the war was demonstrated during the [[Battle of the Philippine Sea]], a lopsided Allied victory in which Japanese fliers were shot down in such numbers and with such ease that American [[fighter pilot]]s likened it to a great 'turkey shoot'. Late in the war, Japan began to produce new fighters such as the [[Nakajima Ki-84]] and the [[Kawanishi N1K]] to replace the Zero, but only in small numbers, and by then Japan lacked the trained pilots or sufficient fuel to mount an effective challenge to Allied attacks. During the closing stages of the war, Japan's fighter arm could not seriously challenge raids over Japan by American [[Boeing B-29 Superfortress]]es, and was largely reduced to [[Kamikaze]] attacks.

==== Technological innovations ====
[[File:F4F-3 new pitot tube of later model.jpg|thumb|left|[[Grumman F4F Wildcat|Grumman F4F-3 Wildcat]], early 1942]]

Fighter technology advanced rapidly during the Second World War. [[Reciprocating engine|Piston-engine]]s, which powered the vast majority of World War II fighters, grew more powerful: at the beginning of the war fighters typically had engines producing between {{convert|1000|hp|kW|abbr=on}} and {{convert|1400|hp|kW|abbr=on}}, while by the end of the war many could produce over {{convert|2000|hp|kW|abbr=on}}. For example, the [[Supermarine Spitfire|Spitfire]], one of the few fighters in continuous production throughout the war, was in 1939 powered by a {{convert|1030|hp|kW|abbr=on}} [[Rolls-Royce Merlin|Merlin II]], while [[Supermarine Spitfire (late Merlin powered variants)|variants]] produced in 1945 were equipped with the {{convert|2035|hp|kW|abbr=on}} [[Rolls-Royce Griffon|Rolls-Royce Griffon 61]]. Nevertheless, these fighters could only achieve modest increases in top speed due to problems of [[compressibility]] created as aircraft and their propellers approached the [[sound barrier]], and it was apparent that propeller-driven aircraft were approaching the limits of their performance. German [[Fighter aircraft#Jet-powered fighters|jet]] and [[#Rocket-powered fighters|rocket]]-powered fighters entered combat in 1944, too late to impact the war's outcome. The same year the Allies' only operational jet fighter, the [[Gloster Meteor]], also entered service. World War II fighters also increasingly featured [[monocoque]] construction, which improved their aerodynamic efficiency while adding structural strength. [[Laminar flow]] wings, which improved high speed performance, also came into use on fighters such as the P-51 Mustang, while the [[Messerschmitt Me 262]] and the [[Messerschmitt Me 163]] featured [[swept wing]]s that dramatically reduced [[Wave drag|drag]] at high subsonic speeds. [[Armament]] also advanced during the war. The rifle-caliber machine guns that were common on prewar fighters could not easily down the more rugged warplanes of the era. Air forces began to replace or supplement them with cannons, which fired explosive shells that could blast a hole in an enemy aircraft&nbsp;– rather than relying on [[kinetic energy]] from a solid bullet striking a critical component of the aircraft, such as a fuel line or control cable, or the pilot. Cannons could bring down even [[heavy bomber]]s with just a few hits, but their slower rate of fire made it difficult to hit fast-moving fighters in a dogfight. Eventually, most fighters mounted cannons, sometimes in combination with machine guns. The British epitomized this shift. Their standard early war fighters mounted eight [[.303 British|{{convert|.303|in|abbr=on}} caliber]] machine guns, but by mid-war they often featured a combination of machine guns and [[Hispano-Suiza HS.404|{{cvt|20|mm}} cannons]], and late in the war often only cannons. The Americans, in contrast, had problems producing a cannon design, so instead placed multiple [[M2 Browning|{{cvt|.50|in|1}}]] [[heavy machine gun]]s on their fighters. Fighters were also increasingly fitted with bomb racks and [[Air-to-ground weaponry|air-to-surface ordnance]] such as bombs or rockets beneath their wings, and pressed into [[close air support]] roles as [[fighter-bomber]]s. Although they carried less ordnance than [[light bomber|light]] and [[medium bomber|medium]] bombers, and generally had a shorter range, they were cheaper to produce and maintain and their maneuverability made it easier for them to hit moving targets such as motorized vehicles. Moreover, if they encountered enemy fighters, their ordnance (which reduced [[Lift (force)|lift]] and increased [[Drag (physics)|drag]] and therefore decreased performance) could be jettisoned and they could engage enemy fighters, which eliminated the need for fighter escorts that bombers required.

Heavily armed fighters such as Germany's [[Focke-Wulf Fw 190]], Britain's [[Hawker Typhoon]] and [[Hawker Tempest]], and America's [[Curtiss P-40 Warhawk|Curtiss P-40]], F4U Corsair, P-47 Thunderbolt and P-38 Lightning all excelled as fighter-bombers, and since the Second World War ground attack has become an important secondary capability of many fighters.
World War II also saw the first use of airborne [[radar]] on fighters. The primary purpose of these radars was to help [[night fighter]]s locate enemy bombers and fighters. Because of the bulkiness of these radar sets, they could not be carried on conventional single-engined fighters and instead were typically retrofitted to larger [[heavy fighter]]s or [[light bomber]]s such as Germany's [[Messerschmitt Bf 110]] and [[Junkers Ju 88]], Britain's [[de Havilland Mosquito]] and [[Bristol Beaufighter]], and America's [[Douglas A-20 Havoc|Douglas A-20]], which then served as night fighters. The [[Northrop P-61 Black Widow]], a purpose-built night fighter, was the only fighter of the war that incorporated radar into its original design. Britain and America cooperated closely in the development of airborne radar, and Germany's radar technology generally lagged slightly behind Anglo-American efforts, while other combatants developed few radar-equipped fighters.

A concept originated from German engineer [[Bernhard J. Schrage]] in 1943 as a response to the increasing threat posed by Allied heavy bombers, particularly at night. The [[Schräge Musik|Schrage Musik]] system involved mounting upward-facing cannon turrets, typically twin 20mm or 30mm guns, in the belly of German night fighters such as the Messerschmitt [[Messerschmitt Bf 110|Bf 110]] and later versions of the Junkers [[Junkers Ju 88|Ju 88]]. These guns were angled upwards to target the vulnerable underside of enemy bombers.

=== 1946–present: Post–World War II period ===
[[File:P-51-361.jpg|thumb|North American P-51D Mustang during WWII]]
Several prototype fighter programs begun early in 1945 continued on after the war and led to advanced piston-engine fighters that entered production and operational service in 1946. A typical example is the [[Lavochkin La-9]] 'Fritz', which was an evolution of the successful wartime [[Lavochkin La-7]] 'Fin'. Working through a series of prototypes, the La-120, La-126 and La-130, the [[Lavochkin]] design bureau sought to replace the La-7's wooden airframe with a metal one, as well as fit a [[laminar flow]] wing to improve maneuver performance, and increased armament. The La-9 entered service in August 1946 and was produced until 1948; it also served as the basis for the development of a long-range escort fighter, the [[Lavochkin La-11|La-11]] 'Fang', of which nearly 1200 were produced 1947–51. Over the course of the Korean War, however, it became obvious that the day of the piston-engined fighter was coming to a close and that the future would lie with the jet fighter.

This period also witnessed experimentation with jet-assisted piston engine aircraft. La-9 derivatives included examples fitted with two underwing auxiliary [[Pulse jet engine|pulsejet engines]] (the La-9RD) and a similarly mounted pair of auxiliary [[ramjet|ramjet engines]] (the La-138); however, neither of these entered service. One that did enter service – with the U.S. Navy in March 1945 – was the [[Ryan FR-1 Fireball]]; production was halted with the war's end on [[Victory over Japan Day|VJ-Day]], with only 66 having been delivered, and the type was withdrawn from service in 1947. The USAAF had ordered its first 13 mixed turboprop-turbojet-powered pre-production prototypes of the [[Consolidated Vultee XP-81]] fighter, but this program was also canceled by VJ Day, with 80% of the engineering work completed.

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