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|Hawker Siddeley (now BAE Systems) Nimrod R1|
|Role||Maritime patrol, ELINT|
|First flight||May 1967|
|Retired||28 June 2011|
|Primary user||Royal Air Force|
|Number built||49 (+2 prototypes)|
|Developed from||de Havilland Comet|
|Variants||British Aerospace Nimrod AEW3
BAE Systems Nimrod MRA4
The Hawker Siddeley Nimrod was a military aircraft developed and built in the United Kingdom. It is an extensive modification of the de Havilland Comet, the world's first jet airliner. It was originally designed by de Havilland's successor, Hawker Siddeley, now part of BAE Systems.
It was designed as a Royal Air Force maritime patrol aircraft, the Nimrod MR1/MR2, its major role being anti-submarine warfare (ASW), although it also had secondary roles in maritime surveillance and anti-surface warfare. It served from the early 1970s until March 2010. The current Nimrod series was due to be replaced by the now cancelled Nimrod MRA4.
In addition to the three Maritime Reconnaissance variants, two further Nimrod types were developed. The RAF also used the Nimrod R1 variant in an electronic intelligence gathering (ELINT) role, while the Nimrod AEW3 was intended as a dedicated airborne early warning platform in the early-to-mid 1980s; this was unsuccessful and was cancelled in 1986 in favour of the Boeing E-3 Sentry.
|Circa 1967, Nimrod XV242 taxiing at RAF Changi during the type's test and evaluation phase in the Far East|
The development of the Nimrod patrol aircraft began in 1964 as a project to replace the Avro Shackleton. The Nimrod design was based on that of the Comet 4 civil airliner which had reached the end of its commercial life (the first two RAF aircraft were unfinished Comets). The Comet's turbojet engines were replaced by Rolls-Royce Spey turbofans for better fuel efficiency, particularly at the low altitudes required for maritime patrol. Major fuselage changes were made, including an internal weapons bay, an extended nose for radar, a new tail with electronic warfare (ESM) sensors mounted in a bulky fairing, and a MAD (Magnetic anomaly detector) boom. After the first flight in May 1967, the RAF ordered 46 Nimrod MR1s. The first example (XV230) entered service in October 1969. Five squadrons were eventually equipped with the MR1.
Three Nimrod aircraft were adapted for the signals intelligence role, replacing the Comet C2s and Canberras of No. 51 Squadron in May 1974. The R1 was visually distinguished from the MR2 by the lack of a MAD boom. It was fitted with an array of rotating dish aerials in the aircraft's bomb-bay, with further dish aerials in the tail cone and at the front of the wing-mounted fuel tanks. It had a flight crew of five (two pilots, a flight engineer and two navigators) and up to 23 crew operating the SIGINT equipment.
Only since the end of the Cold War has the role of the aircraft been officially acknowledged; they were once described as "radar calibration aircraft". The R1s have not suffered the same rate of fatigue and corrosion as the MR2s. One R1 was lost in a flying accident since the type's introduction; this occurred in May 1995 during a flight test after major servicing, at RAF Kinloss. To replace this aircraft an MR2 was selected for extensive conversion, undertaken by BAE Systems at the Woodford factory, to R1 standard, and entered service in December 1996.
The Nimrod R1 was based at RAF Waddington in Lincolnshire, England, and flown by 51 Sqn. The two remaining Nimrod R1s were originally planned to be retired at the end of March 2011, but operational requirements forced the RAF to deploy one to RAF Akrotiri, Cyprus on 16 March in support of Operation Ellamy. The last flight of the type was on 28 June 2011 from RAF Waddington, in the presence of the Chief of the Air Staff, ACM Sir Stephen Dalton. Aircraft XW664 was transferred to East Midlands Aeropark on 12 July 2011 and will go on public display once classified systems have been removed.
The R1 is to be replaced by ex-USAF Boeing RC-135W Rivet Joint aircraft, which will be known as the Air Seeker in RAF service. The three Air Seekers will be delivered between 2014 and 2018.
Starting in 1975, 35 aircraft were upgraded to MR2 standard, being re-delivered from August 1979. The upgrade included extensive modernisation of the aircraft's electronic suite. Changes included the replacement of the obsolete ASV Mk 21 radar used by the Shackleton and Nimrod MR1 with the new EMI Searchwater radar, a new acoustic processor capable of handling more modern sonobouys and additional ESM pods on the wingtips. Provision for in-flight refuelling was introduced during the Falklands War (as the MR2P), as well as hardpoints to allow the Nimrod to carry the AIM-9 Sidewinder missile for use against Argentine Air Force Boeing 707 which were configured for maritime patrol/surveillance duties shadowing the British naval task force. Eventually all MR2s gained refuelling probes and the "P" designation was dropped.
Further modifications were introduced during the 1991 Gulf War, with a small number of MR2s being fitted with improved Link 11 datalinks, improved defensive electronic countermeasures including the first operational use of a towed radar decoy, and a Forward looking infrared turret under the starboard wing, with the modified aircraft being known as MR2P(GM) (Gulf Mod).
The Nimrod MR2 carried out three main roles – Anti-Submarine Warfare (ASW), Anti-Surface Unit Warfare (ASUW) and Search and Rescue (SAR). Its extended range enabled the crew to monitor maritime areas far to the north of Iceland and up to 4,000 km out into the Western Atlantic. With Air-to-Air Refuelling (AAR), range and endurance was greatly extended. The MR2 was a submarine killer carrying up to date sensors and data processing equipment linked to the weapon systems. In addition to weapons and sonobuoys, a searchlight was mounted in the starboard wing pod for Search and Rescue (SAR) operations.
The crew consisted of two pilots and one flight engineer, two navigators (one tactical navigator and a routine navigator), one Air Electronics Officer (AEO), the sonobuoy sensor team of two Weapon System Operators (WSOp ACO) and four Weapon System Operators (WSOp EW) to manage passive and active electronic warfare systems. Two of the WSOps were used as observers positioned at the port and starboard beam lookout windows when flying in dense air traffic. The MR2 had the longest bomb bay of any NATO aircraft.
The Nimrod MR2 was based at RAF Kinloss in Scotland and flown by 201, 120 and 42(R) Squadrons. First maintenance of the MR2 was carried out by the Nimrod Line Sqn. Software support for the MR2 was carried out by the Nimrod Software Team also based at RAF Kinloss. The Nimrod MR2 aircraft was withdrawn on 31 March 2010, a year earlier than planned, for financial reasons. The last official flight of the MR2 Nimrod took place on 26 May 2010, with XV229 flying from RAF Kinloss to Kent International Airport, Manston in Kent, where it will be used by the nearby MOD Defence Fire Training and Development Centre as an evacuation training airframe.
In the mid-1970s a modified Nimrod was proposed for the Airborne Early Warning (AEW) mission – again as a replacement for the Lancaster-derived, piston-engined Shackleton AEW.2. Eleven existing Nimrod airframes were to be converted by British Aerospace at the former Avro plant at Woodford to house the GEC Marconi radars in a bulbous nose and tail. The Nimrod AEW3 project was plagued by cost over-runs and problems with the GEC 4080M computer used. Eventually, the MoD recognised that the cost of developing the radar system to achieve the required level of performance was prohibitive and the probability of success very uncertain, and in December 1986 the project was cancelled. The RAF eventually received seven Boeing E-3 Sentry aircraft instead.
The Nimrod MRA4 was intended to replace the capability provided by the MR2. It was essentially a new aircraft, with current-generation Rolls-Royce BR710 turbofan engines, a new larger wing, and fully refurbished fuselage. However the project was subject to delays, cost over-runs, and contract re-negotiations. It was cancelled in 2010 as a result of the Strategic Defence and Security Review at which point it was £789 million over-budget and nine years late. The prototype aircraft, produced at a cost of over £1bn each, have been scrapped.
The Nimrod is the first jet-powered Maritime Patrol Aircraft (MPA). Earlier MPA designs used piston engines or turboprop engines to improve fuel economy and to allow for lengthy patrols at low altitudes, as with the Lockheed P-3 Orion. Jet engines are most economical at high altitudes and less economical at low altitudes; the aircraft can travel to the operational area at high altitude which is economical on fuel and fast compared to earlier piston aircraft. On reaching the patrol area the Nimrod descends to its working altitude.
On patrol at high weight all four engines are used, but as fuel is consumed and weight is reduced first one and then a second engine is shut down, allowing the remaining engines to be run at an efficient RPM rather than running all engines at less efficient RPM. A "rapid start" system is fitted should the closed-down engines need to be restarted quickly; instead of relying only on ram air for restarting an engine, compressor air from a live engine is used in a starter turbine which rapidly accelerates the engine being started. All engines are used for travel back to base at high altitude.
At first the crews, who were transferred to the Nimrod from the piston-engine Avro Shackletons, were not enthusiastic with the craft, mainly because its sensor suite was only marginally superior to the Shackleton's. In fact most sensors were the same, although the aircraft had a new digital data fusion computer. The Nimrod gave sterling service during the "Cod Wars" between Iceland and the UK over fishing rights. During the Falklands war (Operation Corporate), several Nimrods combed the sea for enemy submarines. The Nimrods took part in Operation Granby (the Gulf War 1990/1991), the NATO operations against Serbia in 1999, Operation Telic (the Iraq war in 2003 and beyond), the campaign in Afghanistan, and over Libya in 2011. They also were a routine component of British search and rescue (SAR) operations in the North Sea.
Nimrods were first deployed to Wideawake airfield on Ascension Island on 5 April 1982, the type at first being used to fly local patrols around Ascension to guard against potential Argentine attacks, and to escort the British Task Force as it sailed south towards the Falkands, with Nimrods also being used to provide search and rescue as well as communications relay support of the Operation Black Buck bombing raids by Avro Vulcans.
The addition of air-to-air refuelling probes allowed operations to be carried out in the vicinity of the Falklands, while the aircraft's armament was supplemented by the addition of 1,000 lb (450 kg) general purpose bombs, BL755 cluster bombs and AIM-9 Sidewinder air-to-air missiles. Plans to add Harpoon anti-ship missiles did not come to fruition until after the end of the war. The use of air-to-air refuelling allowed extremely long reconnaissance missions to be mounted, with a 19 hour 15 minute patrol on 15 May 1982 passing within 60 miles (97 km) of the Argentine coast to confirm that Argentine surface vessels were not at sea. Another long-range flight on the night of 20/21 May covered a total of 8,453 miles (13,609 km), the longest distance flight carried out during the Falklands War. In all, Nimrods flew 111 missions from Ascension in support of British operations during the Falklands War.
A detachment of three Nimrod MR2s was deployed to Seeb in Oman in August 1990 as a result of the Iraqi invasion of Kuwait, carrying out patrols over the Gulf of Oman and Persian Gulf. Once hostilities commenced, the Nimrod detachment, by now increased to five aircraft, concentrated on night patrols, with daylight patrols carried out by US Navy Lockheed P-3 Orions. Nimrods were used to guide Westland Lynx helicopters and Grumman A-6 Intruder attack aircraft against Iraqi patrol vessels, being credited with assisting in sinking or damaging 16 Iraqi vessels. 51 Squadron R1's were detached to RAF Akrotiri immediately following the Iraqi invasion and operated continuously from August 1990 to March 1991. Defensive system modifications added at this time were Chaff & Flare pods and a Towed Radar Decoy.
Nimrods were again deployed to the Middle East as part of the British participation in the US led invasion of Afghanistan, with long overland reconnaissance missions being added to the Nimrod's normal maritime patrol missions. The outbreak of the Iraq War in March 2003 saw the RAF's Nimrods being used for operations over Iraq, using the aircraft's sensors to detect hostile forces, and directing attacks by coalition air forces.
While the Nimrod MR1/MR2 was in service, one aircraft from each of the squadrons on rotation was available for search and rescue operations at one-hour standby. The standby aircraft carried two sets of Lindholme Gear in the weapons bay. Usually one other Nimrod airborne on a training mission would also carry a set of Lindholme Gear. As well as using the aircraft sensors to find aircraft or ships in trouble, it was used to find survivors in the water, with a capability to search areas of up to 20,000 square miles (52,000 km2). The main role would normally be to act as on-scene rescue coordinator to control ships, fixed-wing aircraft, and helicopters in the search area.
Because of the search and rescue role, Nimrod aircraft often appeared in the media in connection with major rescue incidents. In August 1979 a number of Nimrods were involved in finding competitors in distress in the disaster-stricken 1979 Fastnet race, and directing helicopters to the scene. The Alexander L. Kielland was a Norwegian semi-submersible drilling rig that capsized whilst working in the Ekofisk oil field in March 1980 killing 123 people. Six different Nimrods searched for survivors and took it in turn to provide a rescue co-ordination role, involving the control of 80 surface ships and 20 British and Norwegian helicopters; control became particularly important as the visibility deteriorated. In an example of the search capabilities, in September 1977 when an attempted crossing of the North Atlantic in a Zodiac inflatable dinghy went wrong, a Nimrod found the collapsed dinghy and directed a ship to it.
Tapestry is a codeword for the activities by ships and aircraft that protect the United Kingdom's Sovereign Sea Areas, including the protection of fishing rights and oil and gas extraction. Following the establishment of a 200 nautical miles (370 km) Exclusive Economic Zone (EEZ) at the beginning of 1977 the Nimrod fleet was tasked with patrolling the 270,000 square miles (700,000 km2) area. The aircraft would locate, identify, and photograph vessels operating in the EEZ. The whole area was normally covered every week, with each vessel being photographed. The aircraft would also check and communicate with all oil and gas platforms. In 1978 a Nimrod arrested an illegal fishing vessel from the air in the Western Approaches and made the vessel proceed to Milford Haven for further investigation. During the Icelandic Cod Wars of 1972 and 1975–1976 the Nimrod aircraft operated with Royal Navy surface vessels protecting British fishing fleets.
|42 Squadron||1971–1984||Nimrod MR1||RAF St Mawgan|
|1983–2010||Nimrod MR2||RAF St Mawgan, RAF Kinloss|
|51 Squadron||1971–2011||Nimrod R1||RAF Wyton, RAF Waddington|
|120 Squadron||1970–1982||Nimrod MR1||RAF Kinloss|
|1981–2010||Nimrod MR2||RAF Kinloss|
|201 Squadron||1970–1983||Nimrod MR1||RAF Kinloss|
|1982–2010||Nimrod MR2||RAF Kinloss|
|203 Squadron||1971–1977||Nimrod MR1||RAF Luqa|
|206 Squadron||1970–1981||Nimrod MR1||RAF Kinloss|
|1980–2005||Nimrod MR2||RAF Kinloss|
|236 OCU||1970–1992||Nimrod MR1 and MR2||RAF St Mawgan|
|Nimrod MR1 cutaway and weapon loadout|
|1970s cutaway of Nimrod MR1 XV230 retouched by Flight Global in 2006.|
Data from Wilson
|Wikimedia Commons has media related to: Hawker Siddeley Nimrod|