Editing Night fighter (section)

===Second World War===
The war opened on 1 September 1939, and by this time, the RAF were well advanced with plans to build a radar – then called 'RDF' in Britain – equipped night-fighter fleet. The [[Aircraft interception radar|Aircraft Interception Mk. II]] radar (AI Mk. II) was being fitted experimentally to a small number of [[Bristol Blenheim]] aircraft, having been selected for this role as its fuselage was sufficiently roomy to accommodate the additional crew member and radar apparatus;<ref name = "moyes 6">Moyes 1966, p. 6.</ref> the first prototype system went into service in November 1939, long before the opening of major British operations. These early systems had significant practical problems, and while work was underway to correct these flaws, by the time [[the Blitz]] opened in August 1940, the night fighter fleet was still in its infancy.

Through this period, the RAF experimented with many other aircraft and interception methods in an effort to get a working night fighter force. One attempt to make up for the small number of working radars was to fit an AI to a [[Douglas A-20 Havoc|Douglas Havoc]] bomber which also carried a searchlight in its nose. These [[Turbinlite]] aircraft were intended to find the targets and illuminate them with the searchlight, allowing [[Hawker Hurricane|Hurricanes]] adapted for night flying to shoot them down visually.<ref>Cotton 1969, pp. 205–211.</ref><ref>Cotton, Frederick Sidney and William Helmore. "An improved method and means for intercepting night flying hostile aircraft." ''GB Patent 574970,'' 29 January 1946.</ref> This proved almost impossible to arrange in practice, and the Cat Eye fighters had little luck during the closing months of 1940. The Turbinlite squadrons were disbanded in early 1943.<ref>White, E. G. [http://www.nightfighternavigator.com/chapters/1459flightand538squadron.php "1459 Flight and 538 Squadron."] {{Webarchive|url=https://web.archive.org/web/20110709094854/http://www.nightfighternavigator.com/chapters/1459flightand538squadron.php |date=2011-07-09 }} ''Nightfighter navigator.'' Retrieved: 1 August 2011.</ref>

By early 1941, the first examples of a production-quality radar, AI Mk. IV, were beginning to arrive. This coincided with the arrival of the [[Bristol Beaufighter|Beaufighter]], which offered significantly higher performance than the pre-war Blenheims; it was the highest performance aircraft capable of carrying the bulky early aircraft interception radars used for night fighter operations, and quickly became invaluable as a night fighter.<ref name = "moyes 5">Moyes 1966, p. 5.</ref><ref name="Has240">Hastings 1979, p. 240.</ref> Over the next few months, more and more Beaufighters arrived and the success of the night fighters roughly doubled every month until May, when the ''Luftwaffe'' ended their bombing efforts. Although night bombing never ended, its intensity was greatly decreased, giving the RAF time to introduce the [[AI Mk. VIII radar]] working in the [[microwave]] band, and the [[de Havilland Mosquito]] to mount it.<ref>Thirsk 2006, pp. 124–127.</ref><ref name="Has240">Hastings 1979, p. 240.</ref>{{refn|The Mosquito increased German night-fighter losses to such an extent the Germans were said to have awarded two victories for shooting one down.<ref name="Has240"/>|group=N}} This combination remained the premier night fighter until the end of the war.

As the German effort wound down, the RAF's own bombing campaign was growing. The Mosquitos had little to do over the UK, so a number of squadrons were formed within [[No. 100 Group RAF]] and fitted with special systems, such as [[Perfectos]] and [[Serrate radar detector|Serrate]], for homing-in on German night fighters.<ref>Rawnsley and Wright 1998, p. 151.</ref> The British also experimented with mounting pilot-operated AI Mark 6 radar sets in single-seat fighters, and the Hurricane II C(NF), a dozen of which were produced in 1942, became the first radar-equipped, single-seat night fighter in the world. It served with 245 and 247 Squadrons briefly and unsuccessfully before being sent to India to 176 Squadron, with which it served until the end of 1943.<ref>Marchant 1996 {{page needed|date=August 2012}}</ref><ref>Thomas 1996 {{page needed|date=August 2012}}</ref> A similarly radar-equipped [[Hawker Typhoon]] was also developed, but no production followed.<ref>Sortehaug 1998, pp. 23, 30.</ref>

[[File:Bordpeilgerät Peil G 6.jpg|thumb|Luftwaffe [[instrument landing system]] indicator, built 1943]]
German aircraft interception radar efforts at this point were about two years behind the British. Unlike in Britain, where the major targets lay only a few minutes' flight time from the coast, targets in Germany after the occupation of France in 1940 were [[defense of the Reich|far from Allied airbases]], which gave German air defenses long times to deal with intruding bombers. Instead of airborne radar, they relied on ground-based systems; the targets would first be picked up by radar assigned to a "cell", the radar would then direct a [[searchlight]] to "paint" the target, allowing the fighters to attack them without on-board aids. The searchlights were later supplanted with short-range radars that tracked both the fighters and bombers, allowing ground operators to direct the fighters to their targets. By July 1940, this system was well developed as the [[Kammhuber Line]], and proved able to deal with the small raids by isolated bombers the RAF was carrying out at the time.<ref>Robinson 1988, p. 68.</ref>

At the urging of [[R.V. Jones]], the RAF changed their raid tactics to gather all of their bombers into a single "[[Bomber stream|stream]]". This meant that the ground-based portion of the system was [[Saturation attack|overwhelmed]]; with only one or two searchlights or radars available per "cell", the system was able to handle perhaps six interceptions per hour. By flying all of the bombers over a cell in a short period, the vast majority of the bombers flew right over them without ever having been plotted, let alone attacked. German success against the RAF plummeted, reaching a nadir on 30/31 May 1942, when the first [[Bombing of Cologne in World War II|1,000-bomber raid]] attacked [[Cologne]], losing only four aircraft to German night fighters.<ref>Jones 1978, pp. Preface, p. 500.</ref>

[[File:Junkers Ju 88 RAF Hendon.jpg|thumb|right|The Ju 88R-1 night fighter captured by the RAF in April 1943]]
[[File:ME-110G-2 at RAF Hendon.jpg|thumb|right|A restored Bf 110G night fighter with the VHF-band SN-2 radar antennae]]

In 1942, the Germans first started deploying the initial B/C low [[UHF]]-band version of the [[Lichtenstein radar]], and in extremely limited numbers, using a 32-[[dipole]] element ''Matratze'' (mattress) antenna array. This late date, and slow introduction, combined with the capture of a Ju 88R-1 night fighter equipped with it in April 1943 when flown to [[RAF Dyce]], Scotland, by a defecting Luftwaffe crew, allowed British radio engineers to develop jamming equipment to counter it. A race developed with the Germans attempting to introduce new sets and the British attempting to jam them. The early Lichtenstein B/C was replaced by the similar UHF-band Lichtenstein C-1, but when the German night fighter defected and landed in Scotland in April 1943, that radar was quickly jammed. The low [[VHF]]-band SN-2 unit that replaced the C-1 remained relatively secure until July 1944, but only at the cost of using huge, eight-dipole element ''Hirschgeweih'' (stag's antlers) antennae that slowed their fighters as much as 25&nbsp;mph, making them easy prey for British night fighters that had turned to the offensive role. The capture in July 1944 of a Ju 88G-1 night fighter of [[NJG 2]] equipped with an SN-2 Lichtenstein set, flown by mistake into [[RAF Woodbridge]], revealed the secrets of the later, longer-wavelength replacement for the earlier B/C and C-1 sets.<ref>Price 2006, p. 67.</ref>

The [[Luftwaffe]] also used single-engined aircraft in the night-fighter role, starting in 1939 with the [[Arado Ar 68]] and early [[Messerschmitt Bf 109]] models, which they later referred to as ''[[Wilde Sau]]'' (wild boar). In this case, the fighters, typically [[Focke-Wulf Fw 190]]s, were equipped only with a direction finder and landing lights to allow them to return to base at night. For the fighter to find their targets, other aircraft, which were guided from the ground, would drop strings of [[flare]]s in front of the bombers. In other cases, the burning cities below provided enough light to see their targets.<ref>Scutts and Weal 1998, pp. 46–47.</ref> [[Messerschmitt Bf 109|Messerschmitt Bf 109G variants]] had G6N and similar models fitted with FuG 350 ''[[Naxos radar detector|Naxos]]'' "Z" radar receivers for homing in on the 3-gigahertz band [[H2S radar|H2S]] emissions of RAF bombers – the April 1944 combat debut of the American-designed [[H2X]] bomb-aiming radar, operating at a higher 10&nbsp;GHz frequency for both RAF Pathfinder Mosquitos and USAAF B-24 Liberators that premiered their use over Europe, deployed a bombing radar that could not be detected by the German ''Naxos'' equipment. The Bf 109G series aircraft fitted with the ''Naxos'' radar detectors also were fitted with the low- to mid-VHF band FuG 217/218 ''[[Neptun radar|Neptun]]'' active search radars, as were Focke-Wulf Fw 190 A-6/R11 aircraft: these served as radar-equipped night-fighters with [[NJGr 10]] and [[NJG 11]]. A sole Fw 190 A-6 Wk.Nr.550214 fitted with FuG 217 is a rare survivor.<ref>Ledwoch and Skupiewski 1994 {{page needed|date=August 2012}}</ref>

The effective ''[[Schräge Musik]]'' {{#tag:ref|''Schräge Musik'' was derived from the German [[colloquialism]] for "[[Jazz]] Music" (the German word "''schräg''" literally means "slanted" or "oblique"; it also has a secondary meaning of "weird", "strange", "off-key", or "abnormal" as in the English "[[queer]]")|group=N}} offensive armament fitment was the German name given to installations of upward-firing [[autocannon]] mounted in [[Heavy fighter|large, twin-engined night fighters]] by the Luftwaffe and both the [[Imperial Japanese Navy Air Service]] and [[Imperial Japanese Army Air Service]] during World War II, with the first victories for the Luftwaffe and IJNAS each occurring in May 1943. This innovation allowed the night fighters to approach and attack [[bomber]]s from below, where they were outside the bomber crew's field of view. Few bombers of that era carried defensive guns in the ventral position. An attack by a ''Schräge Musik''-equipped fighter was typically a complete surprise to the bomber crew, who would only realise that a fighter was close by when they came under fire. Particularly in the initial stage of operational use until early 1944, the sudden fire from below was often attributed to ground fire rather than a fighter.<ref>Wilson 2008, p. 3.</ref>

[[File:419th Night Fighter Squadron P-61A-1-NO Black Widow - 42-5508.png|thumb|left|A wartime P-61A in flight]]
Rather than nighttime raids, the [[US Army Air Forces]] were dedicated to daytime bombing over Germany and Axis allies, that statistically were much more effective.<ref>Currie 1999, p. 11.</ref> The British night-bombing raids showed a success rate of only one out of 100 targets successfully hit.<ref>Heaton and Lewis 2008 {{page needed|date=August 2012}}</ref>{{Page needed|date=April 2011}} At the urging of the British, who were looking to purchase US-made aircraft, US day fighters were initially adapted to a night role, including the Douglas [[Douglas A-20#P-70|P-70]] and later [[Lockheed P-38 Lightning|Lockheed P-38M "Night Lightning"]]. The only purpose-built night fighter design deployed during the war, the American [[Northrop P-61 Black Widow]] was introduced first in [[European Theater|Europe]] and then saw action in the [[Asiatic-Pacific Theater|Pacific]], but it was given such a low priority that the British had ample supplies of their own designs by the time it was ready for production. The first USAAF unit using the P-61 did not move to Britain until February 1944; operational use did not start until the summer, and was limited throughout the war. Colonel Winston Kratz, director of night-fighter training in the USAAF, considered the P-61 as adequate in its role, "It was a good night fighter. It did not have enough speed".<ref name="Pape">Pape 1992, p. 208.</ref>

The [[United States Navy]] (USN) Project Affirm was established at [[Naval Air Station Quonset Point]] on 18 April 1942 to develop night fighting equipment and tactics. Aircraft selection was limited to single-engine, single-seat planes by the requirement to be capable of operating from [[aircraft carrier]]s.<ref name=wco>{{cite journal |last=Odell |first=William C. |date=Winter 1989 |title=The Development of Night Fighters in World War II |journal=Naval History |volume=3 |issue=1 |pages=33–35 |publisher=[[United States Naval Institute]] }}</ref> Urgency for the night-fighting role increased when Japanese aircraft successfully harassed naval forces on night raids in the [[Solomon Islands]]. The Japanese Navy had long screened new recruits for exceptional night vision, using the best on their ships and aircraft instead of developing new equipment for this role.<ref name=Gunston>Gunston 1976, pp. 112, 183–184.</ref> VF(N)-75 was established as the first USN night fighter squadron on 10 April 1943. Six pilots with six aircraft were sent to the South Pacific on 1 August 1943. A Night Fighter Training Unit (NFTU) was established at [[Charlestown, Rhode Island]], on 25 August 1943 using radar-equipped [[Douglas SBD Dauntless]] training aircraft to allow instructors to accompany student pilots. USN carrier-launched fighter combat missions began in January 1944 with six-plane detachments of single-engined [[Grumman F6F Hellcat]]{{#tag:ref|The Hellcat proved to be the best single-engined night fighter deployed in World War II.<ref>Gunston 1976, p. 184.</ref>|group=N}} and [[Vought F4U Corsair]] fighters fitted with compact, microwave-band radar sets in wing-mounted pods. The specially trained night fighter and torpedo planes of Night Air Group 41 (NAG-41) began flying from {{USS|Independence|CVL-22}} in August 1944. NAG-41 achieved full night status on 1 October 1944 in time to participate in the [[Battle of Leyte Gulf]]. Night fighter patrols effectively countered ''[[kamikaze]]'' attacks timed to arrive during [[twilight]] conditions at [[dawn]] or [[dusk]].<ref name=wco/> In several cases these USN aircraft were used on raids of their own.<ref name=Gunston/>