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Home , Battle of the Ruhr, Bomber (novel), Bomber stream, Chaff (countermeasure), Dehousing, Freya radar

Manus från föredraget i historiegruppen av Keevin Siegel 20161122

The British bombing of in WW2 development of tactics and technologies from both sides

 Background o Theory predominance . Gurenica . Italy Ethopia . Bomber get trough theory . Cheap way winning . Disrupt moral . Impact on Flygvapnet

 British early war experience o ½ shot down o Pushed off the continent o Circuses, limited to fighter range o Only way to fight back o Night bombing only possibility

Freya

 Freya was first successfully used on December 18, 1939 when two stations detected an approaching daytime raid on Wilhelmshaven by 22 RAF Vickers Wellingtonbombers at a range of 113 km and guided fighter planes toward them via .[1]Only half of the Wellingtons returned to Britain undamaged, but the German fighters only reached the bomber after they had made their bombing run on ships in harbor. The performance of Freya left the so impressed that by the Spring of 1940, eleven Freya stations were installed to guard Germany's western border

After the of Britain, RAF began night attacks against German cities. Although Bomber Command had reported good results from the raids, the of 18 August 1941  showed only one in ten hit the target,  half the fell on open country  and in some cases the bombing was seen to fall as far as 50 kilometres (31 mi) from the target.  which demonstrated only 5% of the bombs sent out on a mission landed within 5 mi (8.0 km) of their target.  With these sorts of statistics, any sort of strategic campaign based on attacks against factories and similar targets was hopeless. This led to Frederick Lindemann's notorious "" paper, which called for the bomber efforts to be used against the houses of the German citizens in order to break their ability to work and will to resist. This became official policy of the RAF in 1942.

Kammhuber Line

 The first version of the Line consisted of a series of stations with overlapping coverage, layered three deep from Denmark to the middle of France, each covering a zone about 32 km long (north-south) and 20 km wide (east-west).  The consisted of three layers of zones of about 32 km long (north–south) and 20 km wide (east–west). In each zone there were two German aircraft receiving ground-directed guidance from their own Himmelbettcontroller within each zone. While the Himmelbett control center could only handle two fighters, this was adequate for dealing with the RAF Bomber Command tactic of sending its night time individually, with each bomber plotting its own route to the target, to avoid flak concentrations.

 Each control centre was known as a Himmelbett (canopy bed) zone, consisting of a with a range of about 100 km, a "master " directed by the radar, and a number of manually directed spread through the cell. Each cell was also assigned one primary and one backup night fighter.

 Later versions of the Himmelbett added two Würzburg , with a range of about 30 km. Unlike the early-warning Freya, Würzburgs were accurate (and complex) tracking radars. One was locked onto the night fighter as soon as it entered the cell and as soon as the Freya picked up a target the second Würzburg locked onto it. All position reports were sent to the Himmelbett control centre thereby allowing controllers in the Himmelbett centre to get continual readings of the positions of both planes.

 Freya devices turned out to be vulnerable to , along with other countermeasures, which meant they could still be used for early warning but no longer for guiding fighter planes. British bombing raids could also be organized such that the Kammhuber Line could be overwhelmed in massed raids. 30/31 May 1942 when the first 1,000 bomber raidattacked , losing only four aircraft to German night fighters.

 To counter Freya, the British used equipment called 'Moonshine'. Carried by aircraft of the Special Duties Flight (later No. 515 Squadron RAF), a single set retransmitted a portion of the Freya signal amplifying the apparent return. Eight planes with 'Moonshine' could mimic a force of 100 bombers.[3] A second countermeasures system, "Mandrel" was a noise jammer carried by aircraft of No. 100 Group RAF which overwhelmed the signals from Freya. Individual aircraft were sent to orbit fixed positions 50 miles (80 km) off the enemy coast. By using nine airplanes, a 200-mile (320 km) gap could be knocked into the German's radar coverage, while further jammers were carried in the to counter the inlandFreya network.[4]

Bomber Stream  A typical bomber stream of 600 to 700 aircraft was on average 8 or 10 miles broad, and 4,000 to 6,000 feet deep.  The earlier RAF tactic of sending bombers on individual routes meant that it could take four hours before all its planes would have passed over their target; the bomber stream reduced this window to 90 minutes  first use of the bomber stream was the first 1,000 bomber raid against Cologne on the night of 30–31 May 1942.

Luftwaffe Nightfighters

Lichtenstein radar  It was available in at least four major revisions, designated o FuG 202 Lichtenstein B/C, o FuG 212 Lichtenstein C-1, o FuG 220 Lichtenstein SN-2 o the very rarely used FuG 228 Lichtenstein SN-3. o (FuG is short for Funk-Gerät, German "radio set").

Matratze aerial Hirschgeweih (stag's antlers) antennas FuG 202 Lichtenstein B/C  It was not until 1942 that the Germans first started deploying the initial B/C low UHF-band version of the Lichtenstein radar, and at that time in extremely limited numbers, using a Matratze (mattress) antenna array, consisting of thirty-two dipole elements, mounted in four groups of eight, each at the forward end of one of four forward-projecting masts..

 A race developed with the Germans attempting to introduce new sets and the British attempting to jam them, with the British holding the upper hand throughout. FuG 212 Lichtenstein C-1  During 1943 the Lichtenstein B/C was improved as the FuG 212 Lichtenstein C-1, with longer range and wider angle of view, still operating at UHF Frequencies between 420 and 480 MHz and still using the complex Matratze aerial set. By this point in the war, the British had become experts on jamming German radars.  The Luftwaffe flightcrew of a B/C-equippedJu 88 R-1 night fighter, Werknummer 360 043, defected in April 1943 and landed in , presenting a working example of the German radar for the first time, with the aircraft itself, still in existence as of the 21st century, currently a museum exhibit in the UK.  The subsequent refinement of 'Window' (known as Düppel by the Luftwaffe, from the Berlin suburb it was first found near) rendered Lichtenstein B/C almost useless for several crucial weeks. FuG 220 Lichtenstein SN-2 o 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) antennas that slowed their fighters as much as 25 mph, making them easy prey for British night fighters who had turned to the 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.[21]

Serrate radar detector

 Serrate was an Allied radar detection and homing device, used in Allied nightfighters to track German night fightersequipped with the earlier UHF- band BC and C-1 versions of the Lichtenstein radar  commenced operations over Germany in support of the Bomber Offensive from 14 June to 7 September 1943  The technique developed was for the RAF nightfighters to fly slowly off the bomber stream, mimicking the characteristics of a , until the rearward- facing Serrate() detector picked up the emissions from a Luftwaffe night fighter approaching.

Schräge Musik

 Schräge Musik (or Schrägwaffen, as it was also called) was first used operationally during (the first instance of the Allied bombing of Peenemünde) on the night of 17/18 August 1943.  Adoption of Schräge Musik began in late 1943 and by 1944, a third of all German night fighters carried upward-firing guns.

Wilde Sau  (German for wild boar) was the term given by the Luftwaffe to the tactic used from 1943 to 1944 during II by which British night bombers were engaged by single-seat day- flying in the . It was adopted when the Allies had the advantage over German radar controlled interception. The fighters had to engage the British bombers freely as they were illuminated by searchlight batteries while also avoiding their own anti-aircraft fire. After some initial successes, rising losses and deteriorating weather conditions led to the abandonment of the tactic.

o On the night of 3/4 July 1943, 653 Bomber Command aircraft attacked Cologne and the Wilde Sau squadrons took part in the defense of the city. The Luftwaffe shot down thirty British aircraft, of which twelve were shot down by Wilde Sau units

British capture of a R-1 night fighter (Werknummer 360043) when its crew defected and flew to Scotland.[3] The aircraft carried the initial B/C form of the UHF- band Lichtenstein radar, so its existence was revealed to the Allies; subsequently, RAF Bomber Command began to use a new form of "Window" (or chaff): aluminium strips sized to jam the Lichtenstein B/C radar when dropped. This brought about the need to deploy new night-fighting methods that no longer relied solely on AI radar until the longer wavelength, VHF-band Lichtenstein SN-2 radar could be produced for use in German night fighters. By mid-1943 it became clear that the past approach was not working and a change in the general aerial defensive doctrine was needed.

The week-long Battle of in July 1943 proved disastrous for the Luftwaffe, when the first use of Window by Bomber Command knocked out the Himmelbett radar defence system. Window jammed the GCI system, airborne radar sets, gun-laying radar and searchlight controls and British losses to Flak and night-fighters declined.

Monica

 Monica was a range-only for bombers, introduced by the RAF in June 1942.  Unfortunately for the RAF, the Germans developed a passive radar receiver, Flensburg (FuG 227), which was used byLuftwaffe nightfighters from spring 1944 onward to home in on bombers using Monica.[  After examining the Flensburg equipment, the RAF ordered Monica withdrawn from all Bomber Command aircraft

RAF Navigation

Gee  , sometimes written ,[a] was a system used by the during World War II. It measured the time delay between two radio signals to produce a fix, with accuracy on the order of a few hundred meters at ranges up to about 350 miles (560 km).  Gee offered enough accuracy to be used as an aiming reference without the need to use a or other external reference. Jamming reduced its usefulness as a bombing aid, but it remained in use as a navigational aid in the UK area throughout the war.  The first operational mission using Gee took place on the night of 8/9 March 1942 when a force of about 200 aircraft attacked .

Oboe (navigation)

was a British aerial blind bombing targeting system in World War II, based on radio transponder technology.[1] The system consisted of a pair of radio on the ground, which sent signals which were received and retransmitted by a transponder in the aircraft. By comparing the time each signal took to reach the aircraft, the distance between the aircraft and the station could be determined.  The system was first used in December 1941 in short range attacks over France where the necessary line of sight could be maintained.  Oboe was most used during the Battle of the in 1943, after which Bomber Command began moving its attention further eastward, out of Oboe range. For these raids new systems were used, notably increasingly accurate versions of .  Oboe's limitation of guiding a single aircraft at a time led to the Gee-H system that placed the transponder on the ground and the readouts in the aircraft, allowing around 80 aircraft to use the service at once. Neither offered the accuracy of Oboe, however, which demonstrated the highest average bombing accuracy of any system in the war.  But the Mosquitoes were also the only aircraft that had the performance to fly at altitudes that made Oboe clearly visible over Germany. At a meeting in the summer of 1942, it was agreed that the Mosquitoes would be equipped with Oboe. Having faced opposition before, the addition of Oboe upset the argument against the specialist role, and what would become Pathfinder Force began forming over the ongoing objections

H2S

On its second operational mission on 2/3 February 1943, an H2S was captured almost intact by German forces. Combined with intelligence gathered from the surviving crew, they learned it was a mapping system and were able to determine its method of operation. This led to the introduction of the FuG 350 Naxos radar detector, which enabled Luftwaffe night fighters to home on the transmissions of H2S.

Cavity magnetron  The high power of pulses from their device made centimeter-band radar practical for the Allies of World War II, with shorter wavelength radars allowing detection of smaller objects from smaller antennas. The compact tube drastically reduced the size of radar sets[4] so that they could be more easily installed in night-fighter aircraft, anti-submarine aircraft[5] and escort ships  Prior to the introduction of the cavity magnetron, radar systems used traditional vacuum tube electronics and were limited to about 1.5 m wavelength in UK use, and as low as 50 cm in German systems.

Naxos  The Naxos was a World War II German countermeasure to X band radar produced by a cavity magnetron. Introduced in September 1943,  The first operational use was in a Junkers Ju 88 on 2 September 1943.  When it was clear that the magnetron was known to the Germans, the RAF released its night fighter version, AI Mk. VIII radar, for use over Europe. This radar provided a significant advantage to the RAF over the older systems used by the Germans, and for the first time the RAF was able to seriously disrupt German night fighter operations by attacking them directly. Aircraft that did survive reported that there was no warning of the attack, and it was quickly surmised that the RAF had introduced a new microwave AI radar. This led to the rapid introduction of the Naxos ZR, tuned to the Mk. VIII's frequency and equipped with rearward facing antennas.

1,000 bomber raid  The first ever 1,000 bomber raid by the RAF was conducted on Cologne on the night of 30/31 May 1942. Codenamed Operation Millennium.  At this stage of the war Bomber Command only had a regular front line strength of around 400 aircraft, and were in the process of transitioning from the twin enginedmedium bombers of the pre-war years to the newer more effective four- enginedheavy bombers

Pathfinders  The Pathfinders were target-marking squadrons in RAF Bomber Command during World War II. They located and marked targets with flares, which a main bomber force could aim at, increasing the accuracy of their bombing. The Pathfinders were normally the first to receive new blind bombing aids like Gee, Oboe and the H2S radar.  The early Pathfinder Force (PFF) squadrons was expanded to become a group, No. 8 (Pathfinder Force) Group in January 1943. The initial Pathfinder Force was five squadrons, while No. 8 Group ultimately grew to a strength of 19 squadrons.  2nd and 3rd tours for aircrews  Disliked by Harris  The proportion of Pathfinder aircraft to Main Force bombers could vary according to the difficulty and location of the target; 1 to 15 was common, though it could be as low as 1 to 3.  By the start of 1944, the bulk of Bomber Command was bombing within 3 miles of the PFF indicators, an appreciable improvement in accuracy since 1942. The success or failure of a raid now largely depended on the Pathfinder's marker placement and the success of further correction marking.  Master bomber, master of ceremonies o target indicators (TIs) o Markers"; would then drop incendiaries onto the TIs just prior to the Main Force arrival o Further "Markers" called "Backers-Up" or "Supporters" would be distributed at points within the main bomber stream to remark or reinforce the original TIs as required.  Creepback

Light Night Striking Force[  The Light Night Striking Force (LNSF) was an outgrowth of the Pathfinder Force use of the fast and long-ranged Mosquito bomber, which could carry a sizeable bombload.