Country of origin | USA |
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Type | air-to-ground radar system [1] |
H2X, officially known as the AN/APS-15, [2] was an American ground scanning radar system used for blind bombing during World War II. It was a development of the British H2S radar, the first ground mapping radar to be used in combat. [3] It was also known as the "Mickey set" [4] and "BTO" for "bombing through the overcast" radar. [5]
H2X differed from the original H2S primarily in its X band 10 GHz operating frequency rather than H2S' S band 3 GHz emissions. This gave H2X higher resolution than H2S, allowing it to provide usable images over large cities which appeared as a single blob on the H2S display. The Royal Air Force (RAF) initially considered using H2X as well, but would instead develop their own X band system, the H2S Mk. III. The RAF system entered service in late 1943, before the first use of H2X in early 1944.
The desire for even higher resolution, enough to image individual docks and bridges, led to a number of variations on the H2X system, as well as the more advanced AN/APQ-7 "Eagle" system. All of these were replaced in the post-war era with systems customized for the jet powered strategic bombers that entered service.
H2X was used by the USAAF during World War II as a navigation system for daylight overcast and nighttime operations. It was introduced as an improvement of the earlier H2S set, which had been supplied to the US to aid in the war effort. While the RAF Bomber Command utilized ground mapping radar as an aid to night area bombing, the primary use by the USAAF was as a fallback, to allow cities to be bombed even when hidden by cloud cover, an issue that had dogged their policy of precision daylight bombing since the start of the war, especially in cloud-prone Europe. With H2X, a city could be located and a general area targeted, night or day, cloud cover or no, with equal accuracy. H2X used a shorter 3 cm "centimetric" wavelength (10 GHz frequency) than the H2S, giving a higher angular resolution and thus a sharper picture, which allowed much finer details to be discerned, aiding in target identification. [6] H2S subsequently also adopted 3 cm in the Mark III version entering operational service on 18 November 1943, for "Battle of Berlin").
H2X is not known to have ever been spotted by the German FuG 350 Naxos radar detector, due to that receiving device's specific purpose being to spot the original British H2S equipment's lower frequency, 3 GHz emissions.
The first H2X-equipped B-17's arrived in England in early October 1943, and were first used in combat on 3 November 1943 when the USAAF VIII Bomber Command attacked the port of Wilhelmshaven. Those missions where bombing was done by H2X were called "Pathfinder missions" and the crews were called "Pathfinder crews", after the RAF practice of using highly trained Pathfinder crews to go in before the main bomber stream and identify and mark the target with flares.
American practice used their Pathfinder crews as lead bombers, with radar equipped aircraft being followed by formations of radar-less bombers, which would all drop their loads when the lead bomber did. The ventral hemispherical radome for the H2X's rotating dish antenna replaced the ball turret on B-17 Flying Fortress Pathfinders, with the electronics cabinets for the "Mickey set" being installed in the radio room just aft of the bomb bay. The system was used extensively by The 91st Bomb Group in 1945 with occasional excellent but generally inconsistent results. [7]
The H2X on later B-24 Liberators also replaced the ball turret, being made retractable as the ball turret was for landing on the Liberator. The operators panel was installed on the flight deck behind the co-pilot (where the radio operator's normal position was). In combat areas the Mickey operator directed the pilot on headings to be taken, and on the bomb run directed the airplane in coordination with the bombardier. The first use of Mickey was against Ploiești on 5 April 1944. [8]
Due to the absence of radar maps, in late April 1944 six PR Mk.XVI de Havilland Mosquito aircraft in the 482nd Bomb Group were equipped with H2X equipment. The idea was to produce photographs of the radar screen during flights over Germany allowing easy interpretation of these radar images in later bombing runs. Three aircraft were subsequently lost in training, and the project was discontinued. A further twelve PR Mk.XVI Mosquitos of the 25th Bomb Group (Reconnaissance) of the Eighth Air Force were fitted with H2X and beginning in May 1944 flew radar mapping night missions until February 1945.
The sets tended to overload the Mosquito's electrical system and occasionally exploded. Mickey-equipped Mosquitos had the highest loss, abort, and mission failure rates of any version of the otherwise successful Mosquito reconnaissance aircraft, and were severely curtailed after 19 February 1945. Three were lost to enemy action and one was shot down by friendly fire from a Ninth Air Force P-47. In Europe several P-38 fighters were also converted to carrying H2X radar in the nose, along with an operator/navigator in a cramped compartment in the nose behind the radar dish, provided with small side windows and an access/exit hatch in the floor (much like the earlier P-38 "Droop Snoot" bomber-leader variants, but with a radome instead of a glazed nose). These missions were to obtain radar maps of German targets but plans to produce the variant in quantity never materialized.
In the Pacific theater, B-29’s were equipped with the improved H2X radar called the AN/APQ-13, a ground scanning radar developed by Bell, Western Electric, and MIT. The radome was carried on the aircraft belly between the bomb bays and was partially retractable. The radar operated at a frequency of 9,375 ± 45 megahertz and used a superheterodyne receiver. The radar was used for high altitude area bombing, search and navigation. Computation for bombing could be performed by an impact predictor. A range unit permitted a high degree of accuracy in locating beacons.
Post-war, the AN/APQ-13 became the first military radar converted to a domestic peacetime application as a storm warning radar. About thirty systems were converted and installed on military bases. It was replaced by the AN/CPS-9 system in 1949.
The Avro Lancaster, commonly known as the Lancaster Bomber, is a British Second World War heavy bomber. It was designed and manufactured by Avro as a contemporary of the Handley Page Halifax, both bombers having been developed to the same specification, as well as the Short Stirling, all three aircraft being four-engined heavy bombers adopted by the Royal Air Force (RAF) during the same era.
A night fighter is a largely historical term for a fighter or interceptor aircraft adapted or designed for effective use at night, during periods of adverse meteorological conditions, or in otherwise poor visibility. Such designs were in direct contrast to day fighters: fighters and interceptors designed primarily for use during the day or during good weather. The concept of the night fighter was developed and experimented with during the First World War but would not see widespread use until WWII. The term would be supplanted by “all-weather fighter/interceptor” post-WWII, with advancements in various technologies permitting the use of such aircraft in virtually all conditions.
The Consolidated B-24 Liberator is an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and some initial production aircraft were laid down as export models designated as various LB-30s, in the Land Bomber design category.
The Pathfinders were target-marking squadrons in RAF Bomber Command during World War II. They located and marked targets with flares, at which a main bomber force could aim, increasing the accuracy of their bombing. The Pathfinders were normally the first to receive new blind-bombing aids such as Gee, Oboe and the H2S radar.
H2S was the first airborne, ground scanning radar system. It was developed for the Royal Air Force's Bomber Command during World War II to identify targets on the ground for night and all-weather bombing. This allowed attacks outside the range of the various radio navigation aids like Gee or Oboe, which were limited to about 350 kilometres (220 mi) of range from various base stations. It was also widely used as a general navigation system, allowing landmarks to be identified at long range.
The Naxos radar warning receiver was a World War II German countermeasure to S band microwave radar produced by a cavity magnetron. Introduced in September 1943, it replaced Metox, which was incapable of detecting centimetric radar. Two versions were widely used, the FuG 350 Naxos Z that allowed night fighters to home in on H2S radars carried by RAF Bomber Command aircraft, and the FuMB 7 Naxos U for U-boats, offering early warning of the approach of RAF Coastal Command patrol aircraft equipped with ASV Mark III radar. A later model, Naxos ZR, provided warning of the approach of RAF night fighters equipped with AI Mk. VIII radar.
Oboe was a British bomb aiming system developed to allow their aircraft to bomb targets accurately in any type of weather, day or night. Oboe coupled radar tracking with radio transponder technology. The guidance system used two well-separated radar stations to track the aircraft. Two circles were created before the mission, one around each station, such that they intersected at the bomb drop point. The operators used the radars, aided by transponders on the aircraft, to guide the bomber along one of the two circles and drop the bombs when they reached the intersection.
The Telecommunications Research Establishment (TRE) was the main United Kingdom research and development organisation for radio navigation, radar, infra-red detection for heat seeking missiles, and related work for the Royal Air Force (RAF) during World War II and the years that followed. It was regarded as "the most brilliant and successful of the English wartime research establishments" under "Rowe, who saw more of the English scientific choices between 1935 and 1945 than any single man."
Serrate was a World War II Allied radar detection and homing device that was used by night fighters to track Luftwaffe night fighters equipped with the earlier UHF-band BC and C-1 versions of the Lichtenstein radar. It allowed RAF night fighters to attack their German counterparts, disrupting their attempts to attack the RAF's bomber force.
Royal Air Force Chelveston or more simply RAF Chelveston is a former Royal Air Force station located on the south side of the B645, 5 miles (8.0 km) east of Wellingborough, near the village of Chelveston in Northamptonshire, England. During the Second World War the airfield was occupied by both the Royal Air Force and the United States Army Air Forces. It was given the USAAF designation Station 105.
The Battle of Berlin was a bombing campaign against Berlin by RAF Bomber Command along with raids on other German cities to keep German defences dispersed. Air Chief Marshal Sir Arthur Harris, Air Officer Commanding-in-Chief (AOC-in-C) Bomber Command, believed that "We can wreck Berlin from end to end if the USAAF come in with us. It will cost us between 400 and 500 aircraft. It will cost Germany the war".
The AN/APQ-13 radar was an American ground scanning radar developed by Bell Laboratories, Western Electric, and MIT as an improved model of the airborne H2X radar, itself developed from the first ground scanning radar, the British H2S radar. It was used on B-29s during World War II in the Pacific theater for high altitude area bombing, search and navigation. Computation for bombing could be performed by an impact predictor. A range unit permitted a high degree of accuracy in locating beacons. The radome was carried on the aircraft belly between the bomb bays and was partially retractable on early models. The radar operated at a frequency of 9375 ± 45 megahertz and used a superheterodyne receiver.
The Defence of the Reich is the name given to the strategic defensive aerial campaign fought by the Luftwaffe of Nazi Germany over German-occupied Europe and Germany during World War II against the Allied strategic bombing campaign. Its aim was to prevent the destruction of German civilians, military and civil industries by the Western Allies. The day and night air battles over Germany during the war involved thousands of aircraft, units and aerial engagements to counter the Allies bombing campaigns. The campaign was one of the longest in the history of aerial warfare and with the Battle of the Atlantic and the Allied naval blockade of Germany was the longest of the war. The Luftwaffe fighter force defended the airspace of German-occupied Europe against attack, first by RAF Bomber Command and then against the RAF and United States Army Air Forces (USAAF) in the Combined Bomber Offensive.
The Mid-Atlantic gap is a geographical term applied to an undefended area of the Atlantic Ocean during the Battle of the Atlantic in the Second World War. The region was beyond the reach of land-based RAF Coastal Command antisubmarine (A/S) aircraft. This resulted in heavy merchant shipping losses to U-boats.It is frequently known as The Black Pit, as well as the Atlantic Gap, Air Gap, Greenland Gap, or just "the Gap". The gap was eventually closed in May 1943, as growing numbers of VLR Liberators and escort carriers became available, and as basing problems were addressed.
The 482d Operations Group is a United States Air Force Reserve unit assigned to the 482d Fighter Wing. It is stationed at Homestead Air Reserve Base, Florida.
The de Havilland Mosquito was a British light bomber that served in many roles during and after the Second World War. Mosquito-equipped squadrons performed medium bomber, reconnaissance, tactical strike, anti-submarine warfare and shipping attack and night fighter duties, both defensive and offensive. Mosquitos were widely used by the RAF Pathfinder Force, which marked targets for night-time strategic bombing. Despite an initially high loss rate due to low-level daylight attack operations, the Mosquito ended the war with the lowest losses of any of the aircraft types in RAF Bomber Command service.
The FuG 240 "Berlin" was an airborne interception radar system operating at the "lowest end" of the SHF radio band, which the German Luftwaffe introduced at the very end of World War II. It was the first German radar to be based on the cavity magnetron, which eliminated the need for the large multiple dipole-based antenna arrays seen on earlier radars, thereby greatly increasing the performance of the night fighters. Introduced by Telefunken in April 1945, only about 25 units saw service.
The AN/APQ-7, or Eagle, was a radar bombsight system developed by the US Army Air Force. Early studies started in late 1941 under the direction of Luis Alvarez at the MIT Radiation Laboratory, but full-scale development did not begin until April 1943. By this time US-built, higher frequency systems promising better performance over the existing British H2S radar were entering production. Eagle's even higher resolution was considered important to Air Force planners who preferred precision bombing but were failing to deliver it, and high hopes were put on the system's abilities to directly attack small targets like docks and bridges.
Radar, Air to Surface Vessel, or ASV radar for short, is a classification used by the Royal Air Force (RAF) to refer to a series of aircraft-mounted radar systems used to scan the surface of the ocean to locate ships and surfaced submarines. The first examples were developed just before the opening of World War II and they have remained a major instrument on patrol aircraft since that time. It is part of the wider surface-search radar classification, which includes similar radars in ground and ship mountings.