131-469: 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
262-675: A Companion of the Order of the Bath (CB) but the head of the Civil Service Sir Horace Wilson threatened to resign as Jones was only a lowly Scientific Officer, and the CBE was a compromise. ) He was subsequently appointed CB in 1946; and Companion of Honour (CH) in the 1994 Queen's Birthday Honours . He was elected Fellow of the Royal Society in 1965, and received an honorary DSc from
393-722: A V-2 rocket expert on the Cabinet Defence Committee (Operations) and headed a German long range weapons targeting deception under the Double-Cross System . In 1946 Jones was appointed to the Chair of Natural Philosophy at the University of Aberdeen , which he held until his retirement in 1981. He did not want to stay in Intelligence under the proposed postwar reorganisation. During his time at Aberdeen, much of his attention
524-610: A Würzburg radar that had been photographed near the French coast. This led to concerns that the Germans might launch a similar raid on British installations. When reports were received that "seventeen train loads" of paratroopers had been stationed near Cherbourg, directly across the English Channel from Christchurch , near panic broke out in the Air Ministry, and yet another emergency move
655-651: A 360 degree coverage, the radar antenna of the Chinese AWACS does not rotate. Instead, three PAR antenna modules are placed in a triangular configuration inside the round radome to provide a 360 degree coverage. The installation of equipment at the Il-76 began in late 2002 aircraft by Xian aircraft industries (Xian Aircraft Industry Co.). The first flight of an airplane KJ-2000 made in November 2003. All four machines will be equipped with this type. The last to be introduced into service
786-482: A Russian-made Ilyushin-76 cargo plane [also incorrectly reported as a Beriev A-50 Mainstay] with advanced Elta electronic, computer, radar and communications systems. Beijing was expected to acquire several Phalcon AEW systems, and reportedly could buy at least three more [and possibly up to eight] of these systems, the prototype of which was planned for testing beginning in 2000. In July 2000, the US pressured Israel to back out of
917-460: A backbone of Bomber Command. With the target marked by Pathfinders using H2S, RAF bombers hit the city with high explosive and incendiary bombs. They returned on 25 and 27 July, with the USAAF performing two daylight attacks in between the three RAF raids. Large parts of the city were burned to the ground by a firestorm . About 45,000 people, mostly civilians, were killed. The Mk. II was soon upgraded to
1048-428: A benchtop set on 7 March 1943, and then quickly fit it to Stirling N3724 to make its first flight on 11 March. Testing showed the unit had very short range, and could not be used effectively over 10,000 feet (3,000 m) altitude. Further work was delayed by the need to fit the existing 10 cm sets to operational aircraft. Airborne radar system An airborne early warning and control ( AEW&C ) system
1179-471: A bombing aid but also as a navigation aid. In early operations, H2S had proved able to detect coastlines at such a great distance that it could be used as a long-range navigation system, allowing the aircraft to fly in all weather. To aid the navigator, the bomb aimer had the task of operating the H2S during these periods. To further improve operations, on 12 March it was decided that Bomber Command would receive more of
1310-432: A book in 1989 entitled Reflections on Intelligence . In this book, he mused: "I for one would have little objection to any authority having any information it wished about my actions - or even my thoughts - provided that I could be sure that it would not misinterpret the information to come to false conclusions about me." Jones married Vera Cain in 1940; they had two daughters and a son. He died on 17 December 1997. He
1441-503: A different installation was used to direct Bristol Beaufighters toward Heinkel He 111s , which were air-launching V-1 flying bombs . In February 1944, the US Navy ordered the development of a radar system that could be carried aloft in an aircraft under Project Cadillac. A prototype system was built and flown in August on a modified TBM Avenger torpedo bomber . Tests were successful, with
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#17332023125101572-618: A disused hangar with no heating, and work became almost impossible as the weather turned cold. The main research teams remained in Dundee during this period. The ongoing search for a more suitable location for all the teams led to the selection of Swanage on the southern coast of the UK. The rest of the original radar group moved there in May 1940, the AI group arriving the day before them. The AI group, located in shacks on
1703-445: A ground map exactly as before. The first experimental system flew on 27 May with a Mosquito providing a target. The Mosquito clearly appeared on the display, and photographs of the display caused much excitement. When the photos reached the desk of Bomber Command's Deputy Commander-in-Chief Robert Saundby , he immediately sent a message to the Air Ministry demanding that they be installed with all possible speed. The new display, given
1834-426: A length appropriate to the radar's wavelength, and dropped in bundles from aircraft, which then appeared on enemy radar screens as "false bombers". This technology is now known as chaff and contrary to the popular belief, was also known to the Germans at the time. Both parties were reluctant to use it out of fear that their enemy would do the same. This delayed its deployment for almost two years. Jones also served as
1965-420: A magnetron was recovered by the Germans, they would immediately understand its operation. Since the magnetron was also being designed for use in night fighters and Coastal Command , the loss of the secret would not only provide the Germans with the information to build radar detectors on this new frequency, but also allow them to develop their own effective airborne radars. The H2S design team did not believe
2096-474: A major advance in capability, being the first AEW to use a pulse-Doppler radar , which allowed it to track targets normally lost in ground clutter. Previously, low-flying aircraft could only be readily tracked over water. The AWACS features a three-dimensional radar that measures azimuth, range, and elevation simultaneously; the unit installed upon the E-767 has superior surveillance capability over water compared to
2227-487: A major asset in an AEW aircraft. Following a crash, the US Navy opted to discontinue lighter than air operations in 1962. In 1958, the Soviet Tupolev Design Bureau was ordered to design an AEW aircraft. After determining that the projected radar instrumentation would not fit in a Tupolev Tu-95 or a Tupolev Tu-116 , the decision was made to use the more capacious Tupolev Tu-114 instead. This solved
2358-592: A maximum range of over 850 km at 9,000 metres (30,000 ft) altitude. The Swedish Air Force uses the S 100D Argus ASC890 as its AEW platform. The S 100D Argus is based on the Saab 340 with an Ericsson Erieye PS-890 radar. Saab also offers the Bombardier Global 6000 -based GlobalEye . In early 2006, the Pakistan Air Force ordered six Erieye AEW equipped Saab 2000s from Sweden. In December 2006,
2489-480: A new time base generator that also output a hyperbolic signal, fixing this problem. This was called the "scan corrected indicator", or display Type 184. All of these concepts were being worked on largely in parallel, and at a meeting in March 1944, it was learned that only low rates of production could be expected through the end of the year. By that time the new 3 cm sets were being introduced as well, and this led to
2620-506: A new team was set up to combine the magnetron with a new scanning antenna and plan position indicator display. The prototype's first use in April confirmed that a map of the area below the aircraft could be produced using radar. The first systems went into service in early 1943 as the H2S Mk. I and H2S Mk. II , as well as ASV Mark III . On its second operational mission on 2/3 February 1943, an H2S
2751-452: A number of problems greatly delayed their entry. Added as they became available, this produced a profusion of different Marks, detailed below. Late in April 1942, during a test flight of V9977 , the prototype unit was shown to Flight Lieutenant E. Dickie, a navigator. Dickie pointed out that navigational charts were always produced with north at the top, while the PPI display of H2S had the top of
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#17332023125102882-532: A number of tough scientific and technical intelligence problems during World War II and is generally known today as the "father of S&T Intelligence". He was briefly based at Bletchley Park in September 1939, but returned to London (Broadway) in November, leaving behind a small specialized team in Hut 3 , who reported any decrypts of scientific or technological nature to "ADI Science". F. W. Winterbotham passed Jones
3013-473: A profusion of various Marks featuring one or more of these additional corrections. These delays had not been expected, and Lovell later noted: We were aghast at these delayed dates, but worse was to follow in the months ahead – we had overloaded the firms, people's brains and probably ourselves. The delays were appalling – it seemed that the whole country had stopped working... Matters steadily got worse and worse. Radar operates by sending out very short pulses of
3144-476: A pseudorandom set of frequencies and also have very short scanning rates, which makes them difficult to detect and jam. Up to 1000 targets can be tracked simultaneously to a range of 243 mi (450 km), while at the same time, multitudes of air-to-air interceptions or air-to-surface (including maritime) attacks can be guided simultaneously. The radar equipment of the Israeli AEW&;C consists of each L-band radar on
3275-429: A radio signal from a transmitter, then turning the transmitter off and listening for echoes in a receiver. The output of the receiver is sent to an oscilloscope's brightness input, so strong echoes cause a spot on the screen to light up. To make the spots correspond to locations in space, the oscilloscope quickly scans from the centre to the outside of the display; echoes that return later in time are produced further out on
3406-442: A second known as " Oboe ". Both were based on transmitter stations in the UK which sent out synchronized signals. In the case of Gee, an oscilloscope in the aircraft measured the time difference between two signals to determine location. Oboe used a transponder in the aircraft to reflect the signals back to the UK where operators carried out the same measurements on much larger displays to produce more accurate values. In both cases,
3537-588: A substantial AEW capability, initially with American Douglas AD-4W Skyraiders , designated Skyraider AEW.1, which in turn were replaced by the Fairey Gannet AEW.3 , using the same AN/APS-20 radar. With the retirement of conventional aircraft carriers, the Gannet was withdrawn and the Royal Air Force (RAF) installed the radars from the Gannets on Avro Shackleton MR.2 airframes, redesignated Shackleton AEW.2. To replace
3668-461: A total of 584 aircraft to the defences. Although this represented only 4% of the sorties, this was nevertheless worrying because the increasing daylight length during the summer meant that the defences would inevitably be more effective. Several systems were already under development to help the bombers defend themselves, including the Monica radar (a simple adaptation of the original AI Mk. IV radar from
3799-512: Is an airborne radar early warning system designed to detect aircraft , ships , vehicles , missiles and other incoming projectiles at long ranges, as well as performing command and control of the battlespace in aerial engagements by informing and directing friendly fighter and attack aircraft . AEW&C units are also used to carry out aerial surveillance over ground and maritime targets , and frequently perform battle management command and control (BMC2). When used at altitude,
3930-473: Is considered to be both more capable and less expensive to operate than the older Boeing 707-based Phalcon fleet. In 2017, India announced plans to purchase six airborne early warning and control (AEW&C) ("AWACS") aircraft that can also perform aerial refuelling, with the first two AEW&C aircraft awaiting approval by Cabinet in 2020. However, in September 2021, it was decided to use six Airbus A321s acquired from Air India instead. On 3 June 1957,
4061-483: Is currently in service with Israel, Italy, and Singapore. Instead of using a rotodome, a moving radar was found on some AEW&C aircraft, and the EL/W-2085 used an active electronically scanned array (AESA) – an active phased array radar. This radar consists of an array of transmit/receive (T/R) modules that allow a beam to be electronically steered, making a physically rotating rotodome unnecessary. AESA radars operate on
H2S (radar) - Misplaced Pages Continue
4192-546: The "Pathfinder" force used H2S to drop incendiaries or flares on a target in Hamburg . One hundred Lancasters following the Pathfinders used the flares as the target for their bombsights. The results were considered "satisfactory". Similar raids were carried out against Turin the next night, and Cologne on the night of 2/3 February. On 21 February, the decision was made to equip all Bomber Command aircraft with H2S, not only as
4323-650: The Clarendon Laboratory , completed his DPhil in 1934. Subsequently, he took up a Skynner Senior Studentship in Astronomy at Balliol College , Oxford. In 1936 Jones took up the post at the Royal Aircraft Establishment , Farnborough , a part of the Air Ministry . Here he worked on the problems associated with defending Britain from an air attack, and later in support of the liberation of Europe from
4454-667: The H2S Mk. III . Almost simultaneously, its American equivalent was introduced as the H2X in October of that year. A wide variety of slightly different Mk. III's were produced before the Mk. IIIG was selected as the late-war standard. Development continued through the late-war Mk. IV to the 1950s era Mk. IX that equipped the V bomber fleet and the English Electric Canberra . In the V-force, Mk. IXA
4585-741: The Indian Air Force (IAF) and Defence Research and Development Organisation (DRDO) began a study of requirements for developing an Airborne Early Warning and Control (AWAC) system. In 2015, DRDO delivered 3 AWACs, called Netra , to the IAF with an advanced Indian AESA radar system fitted on the Brazilian Embraer EMB-145 air frame. Netra gives a 240-degree coverage of airspace. The Emb-145 also has air-to-air refuelling capability for longer surveillance time. The IAF also operates three Israeli EL/W-2090 systems, mounted on Ilyushin Il-76 airframes,
4716-637: The Italian Navy is operated from the aircraft carriers Cavour and Giuseppe Garibaldi . During the 2010s, the Royal Navy opted to replace its Sea Kings with a modular "Crowsnest" system that can be fitted to any of their Merlin HM2 fleet. The Crowsnest system was partially based upon the Sea King ASaC7's equipment; an unsuccessful bid by Lockheed Martin had proposed using a new multi-functional sensor for either
4847-578: The Oslo Report , received in 1939 from an anti-Nazi German scientist, and Jones decided that it was genuine and largely reliable, though the three service ministries regarded it as a "plant" and discarded their copies: "... in the few dull moments of the War, I used to look up the Oslo report to see what should be coming along next." Jones's first job was to study "new German weapons", real or potential. The first of these
4978-518: The Pakistan Navy requested three excess P-3 Orion aircraft to be equipped with Hawkeye 2000 AEW systems. China and Pakistan also signed a memorandum of understanding (MoU) for the joint development of AEW&C systems. The Hellenic Air Force , Brazilian Air Force and Mexican Air Force use the Embraer R-99 with an Ericsson Erieye PS-890 radar, as on the S 100D. Israel has developed
5109-675: The Thorn-EMI ARI 5980/3 Searchwater LAST radar attached to the fuselage on a swivel arm and protected by an inflatable dome. The improved Sea King ASaC7 featured the Searchwater 2000AEW radar, which was capable of simultaneously tracking up to 400 targets, instead of an earlier limit of 250 targets. The Spanish Navy fields the SH-3 Sea King in the same role, operated from the LPH Juan Carlos I . The AgustaWestland EH-101A AEW of
5240-479: The Turkish Air Force are deploying Boeing 737 AEW&C aircraft. The Boeing 737 AEW&C has a fixed, active electronically scanned array radar antenna instead of a mechanically-rotating one, and is capable of simultaneous air and sea search, fighter control and area search, with a maximum range of over 600 km (look-up mode). In addition, the radar antenna array is also doubled as an ELINT array, with
5371-562: The United States Navy , the Northrop Grumman E-2 Hawkeye AEW&;C aircraft is assigned to its supercarriers to protect them and augment their onboard command information centers (CICs). The designation "airborne early warning" (AEW) was used for earlier similar aircraft used in the less-demanding radar picket role, such as the Fairey Gannet AEW.3 and Lockheed EC-121 Warning Star , and continues to be used by
H2S (radar) - Misplaced Pages Continue
5502-408: The radar equation . This made the area directly under the bomber much brighter than the surroundings if the signal was not adjusted to account for this. The solution was to adjust the broadcast power according to the cosecant-squared rule , so-called after the mathematical function that defined the effective change in gain. The change was originally produced by fixing an angled metal plate on part of
5633-508: The $ 1 billion agreement to sell China four Phalcon phased-array radar systems. Following the cancelled A-50I/Phalcon deal, China turned to indigenous solutions. The Phalcon radar and other electronic systems were taken off from the unfinished Il-76, and the airframe was handed to China via Russia in 2002. The Chinese AWACS has a unique phased array radar (PAR) carried in a round radome. Unlike the US AWACS aircraft, which rotate their rotodomes to give
5764-602: The 1930s, the British developed a radar set that could be carried on an aircraft for what they termed "Air Controlled Interception". The intention was to cover the North West approaches where German long range Focke-Wulf Fw 200 Condor aircraft were threatening shipping. A Vickers Wellington bomber (serial R1629) was fitted with a rotating antenna array. It was tested for use against aerial targets and then for possible use against German E boats . Another radar equipped Wellington with
5895-721: The AEW role. The "Mainstay" is based on the Ilyushin Il-76 airframe, with a large non-rotating disk radome on the rear fuselage. These replaced the 12 Tupolev Tu-126 that filled the role previously. The A-50 and A-50U will eventually be replaced by the Beriev A-100 , which features an AESA array in the radome and is based on the updated Il-476. In May 1997, Russia and Israel agreed to jointly fulfill an order from China to develop and deliver an early warning system. China reportedly ordered one Phalcon for $ 250 million, which entailed retrofitting
6026-498: The AN/APY-1 system on the earlier E-3 models. The E-2 Hawkeye was a specially designed AEW aircraft. Upon its entry to service in 1965, it was initially plagued by technical issues, causing a (later reversed) cancellation. Procurement resumed after efforts to improve reliability, such as replacement of the original rotary drum computer used for processing radar information by a Litton L-304 digital computer. In addition to purchases by
6157-853: The AW101 or another aircraft. The Russian-built Kamov Ka-31 is deployed by the Indian Navy on the aircraft carriers INS Vikramaditya and INS Vikrant and also on Talwar -class frigates . The Russian Navy has two Ka-31R variants, at least one of which was deployed on their aircraft carrier Admiral Kuznetsov in 2016. It is fitted with E-801M Oko (Eye) airborne electronic warfare radar that can track 20 targets simultaneously, detecting aircraft up to 150 km (90 mi) away, and surface warships up to 200 km (120 mi) distant. Reginald Victor Jones Reginald Victor Jones CH , CB , CBE , FRS , FRSE , LLD (29 September 1911 – 17 December 1997)
6288-539: The British decided to assign a scientist to the Intelligence section of the Air Ministry. No scientist had previously worked for an intelligence service. Jones quickly rose to become Assistant Director of Intelligence (Science) there. During the course of the Second World War he was closely involved with the scientific assessment of enemy technology, and the development of offensive and counter-measures technology. He solved
6419-541: The British were able to build jammers whose effect was to "bend" the Knickebein beams so that German bombers spent months scattering their bomb loads over the British countryside. Thus began the " Battle of the Beams " which lasted throughout much of World War II, with the Germans developing new radio navigation systems and the British developing countermeasures to them. Jones frequently had to battle against entrenched interests in
6550-581: The Canadian Defence Research Board to test US models of AI radar, and since then had been widely used in the development of several versions of AI, ASV and H2S. George Beeching had been assigned the task of fitting H2S to the Stirling, and in early 1943 he managed to obtain a single 3 cm magnetron from Herbert Skinner 's AI group working on the Boeing. He had it working in the H2S electronics in
6681-505: The Chinese Air Force until the end of 2007. China is also developing a carrier-based AEW&C, Xian KJ-600 via Y-7 derived Xian JZY-01 testbed. The EL/W-2085 is an airborne early warning and control (AEW&C) multi-band radar system developed by Israel Aerospace Industries (IAI) and its subsidiary Elta Systems of Israel. Its primary objective is to provide intelligence to maintain air superiority and conduct surveillance. The system
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#17332023125106812-503: The Germans two years to develop a centimetric radar once the cavity magnetron fell into their hands and that there was no reason to believe they were not working on the technology already. The first concern would prove correct; although a magnetron was captured in early 1943, the war ended before German examples were in production. In the midst of the debate, Isidor Isaac Rabi of the American Radiation Laboratory visited
6943-555: The IAI/Elta EL/M-2075 Phalcon system, which uses an AESA ( active electronically scanned array ) in lieu of a rotodome antenna. The system was the first such system to enter service. The original Phalcon was mounted on a Boeing 707 and developed for the Israeli Defense Force and for export. Israel uses IAI EL/W-2085 airborne early warning and control multi-band radar system on Gulfstream G550 ; this platform
7074-469: The Mk. II, which would go on to be the most numerous version built. This was largely identical to the Mk. I's with the exception of various packaging and electronics details intended to make them easier to build. Bomber Command started general use of H2S in summer 1943. On the night of 24 July, the RAF began Operation Gomorrah , a large attack on Hamburg. By that time, H2S had been fitted to Lancasters, which became
7205-494: The Mk. IIA version, which differed from the Mk. II only in the detail of the scanner antenna; IIA replaced the original dipole antenna at the scanner's focal point with a feed horn that sent the signal back to the receiver in a waveguide , eliminating the lossy coaxial cable of the earlier model. It was noted on even the earliest flights of V9977 that a number of basic features of the H2S made it difficult to use. Attempts to fix these began even before H2S entered service, but
7336-448: The Nazis. More generally, he was fond of practical jokes and describes in his book Most Secret War how he used that skill to deceive the Germans during World War II. His extensive use of deception to deceive the Germans is consistent with the term disinformation , which is defined as deliberate planting of false information and physical evidence to lead an opponent astray. In September 1939,
7467-492: The RAF Bomber Command where the night targeting issue was discussed. Dee mentioned the recent discoveries using AIS. On 1 November, Dee performed an experiment in which he used an AIS radar mounted on a Blenheim to scan the ground. Using this display he was able to pick up the outline of a town 35 miles (56 km) away while flying at 8,000 feet (2,400 m) altitude. The commanders were impressed and, on 1 January 1942,
7598-777: The RAF for its Sentry AEW1 , while AEW&C (airborne early warning and control) emphasizes the command and control capabilities that may not be present on smaller or simpler radar picket aircraft. AWACS (Airborne Warning and Control System) is the name of the specific system installed in the E-3 and Japanese Boeing E-767 AEW&C airframes, but is often used as a general synonym for AEW&C. Modern AEW&C systems can detect aircraft from up to 400 km (220 nmi) away, well out of range of most surface-to-air missiles. One AEW&C aircraft flying at 9,000 m (30,000 ft) can cover an area of 312,000 km (120,000 sq mi). Three such aircraft in overlapping orbits can cover
7729-591: The RAF's own night fighters) and the Automatic Gun-Laying Turret (AGLT), which was intended to automate defensive fire. However, the former proved almost useless in practice, and it was already clear the latter would not be available at least until 1944. Dudley Saward, the Bomber Command liaison with the radar teams, visited the Malvern site on 18 April to view progress on the microwave radars and mentioned
7860-444: The S-bands. Historically, UHF radars had resolution and detection issues that made them ineffective for accurate targeting and fire control; Northrop Grumman and Lockheed claim that the APY-9 has solved these shortcomings in the APY-9 using advanced electronic scanning and high digital computing power via space/time adaptive processing. The Russian Aerospace Forces are currently using approximately 3-5 Beriev A-50 and A-50U "Shmel" in
7991-424: The Second World War that I have ever read" and, more generally, it has acquired almost classic status. In 1981, Jones became a founding member of the World Cultural Council . The same year he delivered the Royal Institution Christmas Lectures on From Magna Carta to Microchip . In 1993 he was the first recipient of the R. V. Jones Intelligence Award , which the CIA created in his honour. Jones published
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#17332023125108122-452: The Shackleton AEW.2, an AEW variant of the Hawker Siddeley Nimrod , known as the Nimrod AEW3 , was ordered in 1974. After a protracted and problematic development, this was cancelled in 1986, and seven E-3Ds, designated Sentry AEW.1 in RAF service, were purchased instead. Many countries have developed their own AEW&C systems, although the Boeing E-3 Sentry , E-7A and Northrop Grumman E-2 Hawkeye and Gulfstream/IAI EL/W-2085 are
8253-442: The TRE offices on 5 and 6 July 1942. According to Lovell, Rabi stated that the H2S device provided to them during the Tizard Mission was "unscientific and unworkable" and expressed his feelings that the only use of it would be to hand the magnetron to the Germans. Years later, Lovell attempted to discover the reasons for this negative report, but he found that no one recalled Rabi being so negative. The only explanation that anyone had
8384-440: The TRE set up a team under Bernard Lovell to develop an S-band airborne targeting radar based on AIS. An initial order for 1,500 sets was placed. It was clear even at this point that a plan position indicator (PPI) display would be desirable, but this would require a complex scanning parabolic antenna , compared to the very simple set of fixed antennas used in the A-scope system. It was decided to test both systems. In March, it
8515-409: The US Navy, the E-2 Hawkeye has been sold to the armed forces of Egypt , France , Israel , Japan , Singapore and Taiwan . The latest E-2 version is the E-2D Advanced Hawkeye , which features the new AN/APY-9 radar. The APY-9 radar has been speculated to be capable of detecting fighter-sized stealth aircraft, which are typically optimized against high frequencies like Ka, Ku, X, C and parts of
8646-416: The University of Aberdeen in 1996. In 1969 he delivered the Wilkins Lecture . Jones was principal interviewee of the BBC One TV documentary series " The Secret War " , first aired on 5 January 1977 and narrated by William Woollard . His 1978 published autobiography Most Secret War: British Scientific Intelligence 1939–1945 was described by historian A. J. P. Taylor as "the most fascinating book on
8777-407: The aircraft instruments, this left only the selection of the elevation of the target over sea level to be set manually, which could be done before the mission. The other problem was that when the aircraft rolled, the signal hit the ground only on the lower side of the aircraft, filling one side of the display with a solid signal while the other side was blank. This was particularly annoying because it
8908-412: The aircraft, the time needed to travel to the ground and back at the aircraft's current altitude, the H2S display naturally had an empty area around the centre of the display, with its radius representing the altitude of the aircraft. This was known as the centre-zero . Normally the operator used a dial that delayed the start of the sweep in order to reduce the size of this centre-zero, and thereby increase
9039-475: The amount of the screen used for the ground display. When the centre-zero was not entirely dialled out, operators noticed that fleeting echoes were visible within this circle, and quickly concluded these were from other aircraft. This presented a simple way to see enemy night fighters as long as they were below the bomber and not far enough away that they would be hidden in the ground return. German night fighters normally approached from below as it helped silhouette
9170-448: The armed forces, but, in addition to enjoying Churchill's confidence, had strong support from, among others, Churchill's scientific advisor F. A. Lindemann and the Chief of the Air Staff Sir Charles Portal . As early as 1937, Jones had suggested that a piece of metal foil falling through the air might create radar echoes. He, together with Joan Curran , was later instrumental in the deployment of " Window ": strips of metal foil, cut to
9301-412: The available spares, as it was believed that they would need to make up for higher casualty rates. Previously, every equipped squadron was required to hold 100% spares for all parts, and there simply were not enough to go around. The original H2S sets were essentially prototype units that were hand-built to equip the Pathfinders with all possible speed. Among the many problems with the rushed service entry
9432-479: The bomb aimer, and from then the navigator could see any residual drift on his display and call out corrections to the pilot, and to the bomb aimer who would update his settings in the bombsight. This basic idea was later expanded to allow the navigator's measurements to be automatically sent back to the bombsight, meaning the bomb aimer no longer had to do this during the approach. Since the other settings, like altitude and airspeed, were already automatically fed in from
9563-432: The consequence of lessons learnt by the Royal Navy during the 1982 Falklands War when the lack of AEW coverage for the task force was a major tactical handicap, and rendered them vulnerable to low-level attack. The Sea King was determined to be both more practical and responsive than the proposed alternative of relying on the RAF's land-based Shackleton AEW.2 fleet. The first examples were a pair of Sea King HAS2s that had
9694-447: The crash site "it is, perhaps, hardly surprising that I believed this to be the end of the H 2 S project". Also killed in the crash were Blumlein's colleagues Cecil Oswald Browne and Frank Blythen; a TRE scientist Geoffrey S. Hensby, and seven RAF personnel. As development continued, a great debate broke out in the Air Ministry and RAF about the relative merits of the H2S system. While the ability to bomb in all weather at great distances
9825-401: The delay timer that reduced the size of the centre-zero as a switch; the existing display would receive returns exactly as it had before, with everything before that timer being suppressed, while a new display would receive everything before that time, and could be adjusted so the centre-zero filled the display. This would result in one display showing everything in the air, and a second providing
9956-420: The display representing whatever direction the aircraft was flying. He suggested that this would cause significant problems during navigation. This had not been considered before because H2S had been developed as a bombing aid. Now that it was also used as an important navigation aid, this was a major issue. This led to a crash program at EMI to modify the prototype sets with a system to correct this problem. This
10087-445: The display, indicating a further distance from the aircraft. The times are synchronized by using the transmission pulse to trigger the scan. In the case of H2S, the echoes are returned from the ground and objects on it. That means the very first signal that would normally be received would be from the ground directly beneath the aircraft, as this is the closest to the aircraft. Since the echo from this location took some time to return to
10218-456: The display. To address this, a further addition produced a bright line on the display indicating the direction of travel. A later modification allowed the heading indicator line to be manually controlled by the operator. This was used in concert with the Mark XIV bomb sight to accurately correct for any wind blowing the aircraft off the bomb line. The indicator was set to an initial angle provided by
10349-573: The first of 2 HR2S-1W, a derivative of the Sikorsky CH-37 Mojave , was delivered to the US Navy, it used the AN/APS-32 but proved unreliable due to vibration. The British Sea King ASaC7 naval helicopter was operated from both the Invincible -class aircraft carriers and later the helicopter carrier HMS Ocean . The creation of Sea King ASaC7, and earlier AEW.2 and AEW.5 models, came as
10480-708: The first of which first arrived on 25 May 2009. The DRDO proposed a more advanced AWACS with a longer range and with a 360-degree coverage akin to the Phalcon system, based on the Airbus A330 airframe, but given the costs involved there is also the possibility of converting used A320 airliners as well. IAF has plans to develop 6 more Netra AEW&CS based on Embraer EMB-145 platform and another 6 based on Airbus A321 platform. These systems are expected to have an enhanced performance including range and azimuth The Royal Australian Air Force , Republic of Korea Air Force and
10611-426: The ground below us, and it was a pity it couldn't give us a good picture of the aeroplanes around us. Lovell was aware that this was indeed possible. The team promised they could build a sample of a special display that was effectively the opposite of the main mapping display; instead of adjusting the display so the centre-zero was eliminated and thus provide maximum screen space to the map, this new display would adjust
10742-467: The ground-based portion of the system limited range to a line-of-sight , about 350 kilometres (220 mi) for aircraft flying at typical mission altitudes. This was useful against targets in the Ruhr , but not the heart of Germany. Taffy Bowen had noticed during his early 1.5 m wavelength AI radar experiments before the war that the radar returns from fields, cities and other areas were different. This
10873-437: The klystron could do the job, and tests of an H2S built with klystrons showed a drop in output power by a factor of 20 to 30. At the same altitude, the klystron powered versions were able to detect a town at 10 miles (16 km) while the magnetron version was capable of 35 miles (56 km). There appeared to be no way to improve this, so it would have to be the magnetron or nothing. The H2S team also protested that it would take
11004-480: The left and right sides of the fuselage and each S-band antenna in the nose and tail. The phased array allows aircraft positions on operator screens to be updated every 2–4 seconds rather than every 10 seconds, as is the case on the rotodome AWACS. ELTA was the first company to introduce an Active Electronically Scanned Array Airborne (AESA) Early Warning Aircraft and implement advanced mission aircraft using efficient, high-performance business jet platforms. In 2003,
11135-516: The magnetron for use by Bomber Command. During this same period, it had been noticed that German submarines had been fitted with a radar detector, later known to be the FuMB 1 Metox 600A , which allowed them to detect Coastal Command's ASV sets operating on the older 1.5 m band. In September the decision was made to prioritize construction for the ASV Mk. III, which the Germans would not be able to detect. It
11266-463: The matter had been forgotten. In 1940, John Randall and Harry Boot , PhD students at the University of Birmingham , devised a new microwave -frequency vacuum tube known as the cavity magnetron that output thousands of watts of radio signal at 9 cm wavelength. At this wavelength, the antennas were only a few centimeters long, making radar much easier to fit into an aircraft. The mapping idea resurfaced in March 1941 when Philip Dee 's group
11397-586: The most common systems worldwide. Boeing produces a specific system with a " rotodome " rotating radome that incorporates Westinghouse (now Northrop Grumman ) radar. It is mounted on either the E-3 Sentry aircraft ( Boeing 707 ) or more recently the Boeing E-767 ( Boeing 767 ), the latter only being used by the Japan Air Self-Defense Force . When AWACS first entered service it represented
11528-445: The official title Type 182 and nicknamed "Mousetrap", was on the assembly line by August 1943. At this point, the team received a message demanding they immediately stop using the name Mousetrap as that was the name of an upcoming secret mission. They were officially allocated the new name "Fishpond", a choice that was made official by a telegram from Churchill on 9 July. The first operational units went into service in October 1943, and by
11659-431: The original developers and Frederick Lindemann ( ennobled as Lord Cherwell in 1941), science advisor to Winston Churchill , development of the technology was delayed as the engineers thought that Lord Cherwell did not like the idea. Later, when Cherwell asked how the project was progressing, he was most upset to hear that it had been put on hold and repeatedly declared about the delay that "it stinks". The engineers called
11790-481: The parabolic reflector of the aerial, as may be seen in the picture of the aerial on a Halifax bomber. Later reflectors were actually shaped with a cosecant-squared curvature, no longer a perfect parabolic section. On 7 June 1942, the Halifax performing H2S tests crashed , killing everyone on board and destroying the prototype H2S. One of the dead was Alan Blumlein , the chief designer. Lovell recalled that after inspecting
11921-447: The problem to Lovell. He was particularly frustrated by a raid carried out the night before on 16/17 April on the Škoda Works , where 11.3% of the attacking force was lost due to enemy action and all other issues. Mentioning the problems with Monica and especially the AGLT, Saward told Lovell: What on earth are we going to do for a stop-gap? [Then I added that...] H2S gave us a good picture of
12052-629: The problems with cooling and operator space that existed with the narrower Tu-95 and Tu-116 fuselage. To meet range requirements, production examples were fitted with an air-to-air refueling probe. The resulting system, the Tupolev Tu-126 , entered service in 1965 with the Soviet Air Forces and remained in service until replaced by the Beriev A-50 in 1984. During the Cold war, United Kingdom deployed
12183-404: The radar downward instead of towards the sky, he would have a new use for radar, ground tracking instead of for identifying air targets and that it was simply "rotten" that he had not thought of it sooner. The "rotten" connection, with a twist, is propounded by R. V. Jones , director of the Air Ministry 's scientific intelligence unit. He relates the tale that, owing to a misunderstanding between
12314-540: The radar system on AEW&C aircraft allows the operators to detect, track and prioritize targets and identify friendly aircraft from hostile ones in real-time and from much farther away than ground-based radars. Like ground-based radars, AEW&C systems can be detected and targeted by opposing forces, but due to aircraft mobility and extended sensor range, they are much less vulnerable to counter-attacks than ground systems. AEW&C aircraft are used for both defensive and offensive air operations, and serve air forces in
12445-432: The radio operator's station, not the navigator's. This reduced the navigator's workload while also simplifying communications when a target was seen; the radio operator could easily communicate with the crew or send messages to other aircraft. Normally a number of blips would be seen, as other aircraft in the bomber stream made excellent returns. These remained largely stationary on the display as they were all flying roughly
12576-549: The raids, the Butt Report showed only one bomb in twenty landed within 5 miles (8.0 km) of the target, half the bombs fell on open country, and in some cases, the bombing was seen to fall as far as 50 kilometres (31 mi) from the target. Radio electronics promised some improvement and the Telecommunications Research Establishment (TRE) developed a radio navigation system called " Gee " and then
12707-481: The resumed project "H2S" and later, when Cherwell inquired what H2S stood for, no one dared tell him that it was named after his phrase. Instead, they pretended, on the spot, that it meant "Home Sweet Home", which was the meaning that Cherwell related to others (including Jones). After the Battle of Britain , RAF Bomber Command began night attacks against German cities. Although Bomber Command had reported good results from
12838-461: The same antenna. When priority was given to Bomber Command, Coastal Command responded by producing specifications for a far more advanced ASV system operating at 1.25 cm, but this was not completed by the end of the war. Work on 3 cm magnetrons had been ongoing for some time, and an AIS unit with such a device had been fitted to the nose of RAF Defford 's Boeing 247 -D, DZ203 as early as 1942. This aircraft had originally been supplied by
12969-404: The same path, so enemy fighters were easy to see as dots moving around within the pattern of returns. If it was suspected a blip was approaching the bomber, they would change their heading and see if the blip followed; if it did, immediate defensive manoeuvring started. The resolution of any radar is a function of the wavelength used and the size of the antenna. In the case of H2S, the antenna size
13100-553: The same radar. The Lockheed WV and EC-121 Warning Star , which first flew in 1949, served widely with US Air Force and US Navy. It provided the main AEW coverage for US forces during the Vietnam war. It remained operational until replaced with the E-3 AWACS. Developed roughly in parallel, N-class blimps were also used as AEW aircraft, filling gaps in radar coverage for the continental US, their tremendous endurance of over 200 hours being
13231-410: The same role as what the combat information center is to naval warships , in addition to being a highly mobile and powerful radar platform. So useful and advantageous is it to have such aircraft operating at a high altitude, that some navies also operate AEW&C aircraft for their warships at sea, either coastal- or carrier-based and on both fixed-wing and rotary-wing platforms. In the case of
13362-552: The shoreline near Worth Matravers , was particularly exposed and only a short distance from German-occupied Cherbourg . While the move was taking place, A.P. Rowe took the opportunity to set up a second airborne group working with magnetrons, sidelining Bowen's group. Bowen was soon forced out of the TRE and sent on the Tizard Mission that summer. On 25 May 1942, Combined Operations Headquarters carried out Operation Biting to capture
13493-457: The signal to return did not increase linearly, but hyperbolically. As a result, returns close to the aircraft were fairly similar to what would be seen on a map, but those further from the aircraft were increasingly compressed in range. At the shortest range setting, 10 miles (16 km), this was not a serious problem, but at the longest, 100 miles (160 km), this made the display very difficult to understand. This led F. C. Williams to develop
13624-460: The size of the centre-zero until it filled the display, thus making the returns from other aircraft easier to see. They only asked that the "whole affair was to be kept quiet to avoid difficulties". Saward supplied an electronics technician, Sergeant Walker, and two mechanics, all of whom arrived the next day and immediately set about building a display in Halifax BB360 . The basic idea was to use
13755-469: The spring of 1944, most of Bomber Command's aircraft carried it. Two hundred examples of the prototype model were produced before a slightly modified version was introduced, the Type 182A. This version had the range fixed at 26,000 feet (7,900 m), with the side-effect that if the aircraft flew below this altitude the ground appeared as a ring of noise on the display. The Type 182 display was normally located at
13886-650: The system being able to detect low flying formations at a range greater than 100 miles (160 km). US Navy then ordered production of the TBM-3W, the first production AEW aircraft to enter service. TBM-3Ws fitted with the AN/APS-20 radar entered service in March 1945, with 27 eventually constructed. It was also recognised that a larger land-based aircraft would be attractive, thus, under the Cadillac II program, multiple Boeing B-17G Flying Fortress bombers were also outfitted with
14017-489: The target aircraft against the Moon, and the lack of a gun position in that location made it safe to approach from that direction. This left them ideally positioned for detection by H2S. However, the display was very small, and this blank area on the screen only a small portion of that, so seeing these returns was difficult. In early 1943 German night fighter operations were improving. Between January and April 1943 Bomber Command lost
14148-425: The transmissions of H2S. The British learned of Naxos and a great debate ensued over the use of H2S. Later calculations showed that losses after the introduction of Naxos were actually less than before it, and use continued. After it was found the resolution of the early sets was too low to be useful over large cities like Berlin, in 1943 work started on a version operating in the X band at 3 cm (10 GHz),
14279-564: The whole of Central Europe . AEW&C system indicates close and far proximity range on threats and targets, help extend the range of their sensors, and make offensive aircraft harder to track by avoiding the need for them to keep their own radar active, which the enemy can detect. Systems also communicate with friendly aircraft, vectoring fighters towards hostile aircraft or any unidentified flying object. After having developed Chain Home —the first ground-based early-warning radar detection system—in
14410-653: Was a British physicist and scientific military intelligence expert who played an important role in the defence of Britain in World War II by solving scientific and technical problems, and by the extensive use of deception throughout the war to confuse the Germans. Reginald Jones was born in Herne Hill , South London, on 29 September 1911. He was educated at Alleyn's School , Dulwich , and Wadham College , Oxford , where he studied Natural Sciences. In 1932 he graduated with First Class honours in physics and then, working in
14541-439: Was a function of the bomber's turret opening, and when combined with the 10 cm wavelength, this led to a resolution of 8 degrees in arc. This was much coarser than desired, both for mapping purposes and for Coastal Command's desires to easily detect submarine conning towers . On 6 February 1943, work began on an X band version of the electronics, operating at 3 cm. This would improve resolution to 3 degrees when used with
14672-511: Was a radio navigation system which the Germans called Knickebein . This, as Jones soon determined, was a development of the Lorenz blind landing system and enabled an aircraft to fly along a chosen heading with useful accuracy. At Jones's urging, Winston Churchill ordered up an RAF search aircraft on the night of 21 June 1940, and the aircraft found the Knickebein radio signals in the frequency range which Jones had predicted. With this knowledge,
14803-417: Was already being used by the aircraft interception radar team as a deliberately confusing abbreviation for its operating wavelength in the "sentimetric [ sic ]" range, which ultimately gave name to the S band . It is widely reported that it was named after hydrogen sulphide (chemical formula H 2 S, in connection with its rotten smell), because the inventor realized that had he simply pointed
14934-420: Was also widely used as a general navigation system, allowing landmarks to be identified at long range. In March 1941, experiments with an early aircraft interception radar based on the 9.1 cm wavelength , (3 GHz) cavity magnetron revealed that different objects have very different radar signatures ; water, open land and built-up areas of cities and towns all produced distinct returns. In January 1942,
15065-576: Was captured almost intact by German forces, and a second unit a week later. Combined with intelligence gathered from the surviving crew, they learned it was a mapping system and were able to determine its method of operation. When they pieced one together from parts and saw the display of Berlin , near panic broke out in the Luftwaffe . This led to the introduction of the FuG 350 Naxos radar detector in late 1943, which enabled Luftwaffe night fighters to home on
15196-447: Was decided that both H2S and a new centimetric air-to-surface-vessel (ASV) radar , ASV Mk. III , would be built using the same components, simplifying production. In early tests in April, the superiority of the scanning PPI system was evident, and all work on the older A-scope version ended. H2S performed its first experimental flight on 23 April 1942, with the radar mounted in a Handley Page Halifax bomber, V9977 . The scanning unit
15327-408: Was developing a new AI radar, christened "AIS" in reference to its "sentimetric" wavelength. During tests in a Blenheim , the team noticed the same sort of effects Bowen had earlier. The set's wavelength, over ten times shorter than the original 1.5 m AI sets, provided much greater resolution and allowed them to pick out individual objects on the ground. In October 1941, Dee attended a meeting of
15458-564: Was devoted to improving the sensitivity of scientific instruments such as seismometers , capacitance micrometers, microbarographs and optical levers. His book Instruments and Experiences details much of his later work in some depth and can act as a reference work on fine mechanism design. Jones was appointed Commander of the Order of the British Empire (CBE) in 1942, for the planning of a raid on Bruneval to capture German radar equipment (Churchill had proposed that Jones should be appointed
15589-416: Was due to geometry; objects with vertical sides, like buildings or ships, produced much stronger returns than flat objects like the ground or sea. During early tests of the AI system, the operator would often see coastlines at very long distances, and the development team used this as an ad hoc navigation system on several occasions. Bowen had suggested developing a targeting radar based on this principle, but
15720-418: Was during the last minute of the approach to the target that the navigator would be giving course corrections to the pilot, rendering the display unusable every time the pilot responded. This problem was solved through the introduction of a mechanical stabilizer that kept the scanning system level with respect to the ground. A preliminary version was ready by September 1943, but several problems were noted, and it
15851-421: Was felt the chance that a magnetron falling into German hands from a patrol aircraft was vanishingly small. The Air Ministry radar groups had originally formed up at Bawdsey Manor on the eastern coast of England. When the war began in 1939, this location was considered too exposed to a potential German attack, and a pre-arranged move to the University of Dundee was carried out almost overnight. On arrival, it
15982-626: Was found nothing was prepared and there was little room for the teams to work in. Worse, the team working on airborne radars ended up at a tiny private airstrip in Perth, Scotland that was entirely unsuitable for development. It took some time before the nature of the problem was finally accepted by management and a search began for a new location. In late 1939, the Airborne team moved to RAF St Athan , about 15 miles (24 km) from Cardiff . Although this location should have been ideal, they found themselves in
16113-409: Was installed in the aircraft's belly using the position previously occupied by the mid-under turret, which was by that time seldom installed. The rotating scanner mounting was designed and manufactured by Nash & Thompson . The scanning aerial was covered by a distinctive streamlined radome . One problem was that the returns from closer objects were much stronger than more distant objects, due to
16244-458: Was made. The team ended up at Malvern College about 160 kilometres (99 mi) to the north. This provided ample office space but little in the way of housing and introduced yet more delays in the development program. Despite all the problems, on 3 July 1942 Churchill held a meeting with his military commanders and the H2S group, where he surprised the radar designers by demanding the delivery of 200 H2S sets by 15 October 1942. The H2S design team
16375-413: Was not until 5 November that the decision was made to move it into production. By this time development of the 3 cm version of H2S was underway, and Nash & Thompson promised to have versions of the stabilizer for both 10 and 3 cm units available by 15 December 1943. A final problem related to the geometry of the signals returned by the radar. As the scanning angle increased, the time taken for
16506-488: Was obviously useful to Bomber Command, the loss of an H2S aircraft would potentially reveal the secret of the magnetron to the Germans. Churchill's science advisor, Lord Cherwell, wanted the design team to build H2S around the klystron rather than the magnetron . Unlike a klystron, which is made mostly of glass and fragile metal parts, the magnetron was built out of a single block of copper that would be extremely difficult to destroy with any reasonable demolition charge . If
16637-401: Was solved with the introduction of a selsyn (or "servo") connected to the aircraft's gyrocompass , whose output modified the scan rotation. Testing of this modification immediately revealed another problem. With the display always showing north-up, it was no longer obvious whether the aircraft was flying towards its target, which previously was easy to see as the target would be at the top of
16768-457: Was that problems getting the sets working were taken out of context. Taffy Bowen had noted that he had significant trouble getting the sets to do anything in the US; in testing against Springfield, Hartford and Boston, the display simply did not show anything. By September, a prototype version suitable for operational use was ready. While debate on the issue of losing a magnetron to the Germans continued, on 15 September Churchill personally released
16899-413: Was that the developers were forced to use existing plug-and-socket designs to connect the various units of the complete set together. There were no bulkhead mounting male connectors available at this time, and consequently many of the male free connectors at the ends of cable runs carried exposed lethal voltages. While installations of the prototypes progressed, work was underway on a true production version,
17030-752: Was tied into both the bombsight and navigation system to provide a complete long-range Navigation and Bombing System (NBS). In this form, H2S was last used operationally during the Falklands War in 1982 on the Avro Vulcan . Some H2S Mk. IX units remained in service on the Handley Page Victor aircraft until 1993, providing fifty years of service. The radar was originally called "BN" (Blind Navigation), but it quickly became "H2S". The genesis of this remains somewhat contentious, with different sources claiming it meant "Height to Slope"; or "Home Sweet Home". The "S"
17161-410: Was under great pressure, but they were given priority on resources. The pressure also gave them an excellent argument to convince Lord Cherwell that the klystron-based H2S program finally be dropped. TRE failed to meet the 15 October deadline; by 1 January 1943, only twelve Stirling and twelve Halifax bombers had been fitted with H2S. On the night of 30 January 1943, thirteen Stirlings and Halifaxes of
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