Hawker Siddeley Nimrod

The Hawker Siddeley Nimrod was a maritime patrol aircraft developed and operated by the United Kingdom. It was an extensive modification of the de Havilland Comet, the world's first operational jet airliner. It was originally designed by de Havilland's successor firm, Hawker Siddeley; further development and maintenance work was undertaken by Hawker Siddeley's own successor companies, British Aerospace and BAE Systems, respectively.

Designed in response to a requirement issued by the Royal Air Force (RAF) to replace its fleet of ageing Avro Shackletons, the Nimrod MR1/MR2s were primarily fixed-wing aerial platforms for anti-submarine warfare (ASW) operations; secondary roles included maritime surveillance and anti-surface warfare. It served from the early 1970s until March 2010. The intended replacement was to be extensively rebuilt Nimrod MR2s, designated Nimrod MRA4; however due to considerable delays, repeated cost overruns, and financial cutbacks, the development of the MRA4 was abandoned in 2010.

In addition to the three Maritime Reconnaissance variants, two further Nimrod types were developed. The RAF operated a small number of the Nimrod R1, an electronic intelligence gathering (ELINT) variant. A dedicated airborne early warning platform, the Nimrod AEW3 was in development from late 1970s to the mid-1980s; however, much like the MRA4, considerable problems were encountered in development and thus the project was cancelled in 1986 in favour of an off-the-shelf solution in the Boeing E-3 Sentry. All Nimrod variants had been retired by mid-2011.

Hawker Siddeley Nimrod
Class Aircraft
Type Utility
Manufacturer Hawker Siddeley
Origin United Kingdom - UK (Great Britain)
Country Name Origin Year
United Kingdom - UK (Great Britain) 1967
Country Name Operational Year Retirement Year
United Kingdom - UK (Great Britain) 1969 2011 View
ManufacturerName Production From Production To Quantity
Hawker Siddeley 51 View

The Hawker Siddeley Nimrod is a maritime patrol aircraft developed in the United Kingdom. It is an extensive modification of the de Havilland Comet. It was originally designed by Hawker Siddeley, now part of BAE Systems. A major modification was the fit of a large weapon bay under the fuselage that can carry and drop torpedoes, mines, bombs and other stores. Sonobuoys for tracking submarines are dropped from special launchers in the rear of the fuselage. 

The Nimrod is also capable of carrying American-made Harpoon anti-ship missiles, and Sidewinder air-to-air missiles for self-defense. 

The Nimrod has been the primary Maritime Patrol Aircraft (MPA) of the Royal Air Force since the early 1970s, when it replaced the piston-engined Avro Shackleton. The RAF uses two Nimrod variants: the MR2 variant in the Maritime and Reconnaissance role; the R1 variant in a reconnaissance and electronic intelligence gathering capacity (ELINT).

The Nimrod was the first jet-powered maritime patrol aircraft (MPA) to enter service, being powered by the Rolls-Royce Spey turbofan engine. Aircraft in this role have been commonly propelled by piston or turboprop powerplants instead to maximise fuel economy and enable maximum patrol time on station; advantages of the Nimrod's turbofan engines included greater speed and altitude capabilities, it was also more capable of evading detection methods by submarines, whereas propeller-driven aircraft are more detectable underwater to standard acoustic sensors. Inflight, the Nimrods had a flight endurance of ten hours without aerial refuelling; the MR2s were later fitted to receive mid-air refuelling in response to demands in the Falklands War.

At the start of a patrol mission all four engines would normally be running, but as the aircraft's weight was reduced by the consumption of onboard fuel up to two engines could be intentionally shut down, allowing the remaining engines to be operated in a more efficient manner. Instead of relying on ram air to restart an inactive engine, compressor air could be crossfed from a live engine to a starter turbine; the crossfeed duct was later discovered to be a potential fire hazard. Similarly, the two hydraulic systems onboard were designed to be powered by the two inner engines that would always be running. Electrical generation was designed to far exceed the consumption of existing equipment to accommodate additional systems installed over the Nimrod's operational service.

The standard Nimrod fleet carried out three basic operational roles during their RAF service: Anti-Submarine Warfare duties typically involved surveillance over an allocated area of the North Atlantic to detect the presence of Soviet submarines in that area and to track their movements. In the event of war, reconnaissance information gathered during these patrols would be shared with other allied aircraft to enable coordinated strikes at both submarines and surface targets. Search and rescue (SAR) missions were another important duty of the RAF's Nimrod fleet, operating under the Air Rescue Coordination Centre at RAF Kinloss, and were a common sight in both military and civil maritime incidents. Throughout the Nimrod's operational life, a minimum of one aircraft was being held in a state of readiness to respond to SAR demands at all times.


Introduction to service

The Nimrod first entered squadron service with the RAF at RAF St Mawgan in October 1969. These initial aircraft, designated as Nimrod MR1, were intended as a stop-gap measure, and thus were initially equipped with many of the same sensors and equipment as the Shackletons they were supplementing. While some improvements were implemented on the MR1 fleet to enhance their detection capabilities, the improved Nimrod MR2 variant entered service in August 1979 following a lengthy development process. The majority of the Nimrod fleet operated from RAF Kinloss.

Operationally, each active Nimrod would form a single piece of a complex submarine detection and monitoring mission. An emphasis on real-time intelligence sharing was paramount to these operations; upon detecting a submarine, Nimrod aircrews would inform Royal Navy frigates and other NATO-aligned vessels to pursuit in an effort to continuously monitor Soviet submarines. The safeguarding of the Royal Navy's Resolution-class ballistic missile submarines, which were the launch platform for Britain's nuclear deterrent, was viewed as being of the utmost priority.

Falklands War

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. As the Task Force neared what would become the combat theatre and the threat from Argentine submarines rose, the more capable Nimrod MR2s took on operations initially performed by older Nimrod MR1s. Aviation author Chris Chant has claimed that the Nimrod R1 also conducted electronic intelligence missions operating from Punta Arenas in neutral Chile.

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. The use of air-to-air refuelling allowed extremely long reconnaissance missions to be mounted, one example being a 19-hour 15-minute patrol conducted on 15 May 1982, which passed within 60 miles (97 km) of the Argentine coast to confirm that Argentine surface vessels were not at sea. Another long-range flight was carried out by an MR2 on the night of 20/21 May, covering 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.

Gulf 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. Due to the level of threats present in the Gulf theatre, operational Nimrods were quickly retrofitted with a Marconi-towed active decoy. 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.

Nimrods were often deployed to the Middle East

After the ground offensive against Iraqi forces had ended, Britain elected to maintain an RAF presence in the region through assets such as the Nimrod and other aircraft. Nimrod R1s operated from August 1990 to March 1991 from Cyprus, providing almost continuous flying operations from the start of the ground offensive. Each R1 was retrofitted with the same Marconi towed active decoy as well as under wing chaff/flare dispensers, reportedly sourced from the Tornado fleet.

Afghanistan and Iraq War

Nimrods were again deployed to the Middle East as part of the British contribution to the US-led invasion of Afghanistan; missions in this theatre involved the Nimrods performing lengthy overland flights for intelligence-gathering purposes. On 2 September 2006, 12 RAF personnel were killed when a Nimrod MR2 was destroyed in a midair explosion following an onboard fire over Afghanistan, it was the single greatest loss of British life since the Falklands War. 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 to direct attacks by friendly coalition forces.

Search and rescue

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.

The Nimrod was most often featured in the media in relation to its search-and-rescue role, such as in the reporting of major rescue incidents.In August 1979, several Nimrods were involved in locating yachting competitors during the disaster-stricken 1979 Fastnet race and coordinated with helicopters in searches for survivors from lost vessels. In March 1980, the Alexander L. Kielland was a Norwegian semi-submersible drilling rig that capsized whilst working in the Ekofisk oil field killing 123 people; six different Nimrods searched for survivors and took turns to provide rescue co-ordination, involving the control of 80 surface ships and 20 British and Norwegian helicopters. 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.

Operation Tapestry

The Nimrods were often used to enforce Operation Tapestry. 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 given the task of 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 routinely patrolled; in addition to surveillance, the aircraft would communicate with all oil and gas platforms. In 1978, an airborne Nimrod arrested an illegal fishing vessel 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 fleet closely cooperated with Royal Navy surface vessels to protect British civilian fishing ships.

Role Maritime patrol, ELINT
Manufacturer Hawker Siddeley
BAE Systems
First flight 23 May 1967
Introduction 2 October 1969
Retired 28 June 2011
Status MR1 inactive
R1 inactive
MR2 inactive
Primary user Royal Air Force
Number built 49 (+2 prototypes)
Developed from de Havilland Comet
Variants Nimrod AEW.3
Nimrod MRA.4


General characteristics

  • Crew: 12
  • Capacity: 24 POB (Persons On Board)
  • Length: 38.63 m (126 ft 9 in)
  • Wingspan: 35.00 m (114 ft 10 in)
  • Height: 9.45 m (31 ft)
  • Wing area: 197.05 m (2,121 sq ft)
  • Empty weight: 39,009 kg (86,000 lb)
  • Max takeoff weight: 87,090 kg (192,000 lb)
  • Powerplant: 4 x Rolls-Royce Spey turbofans, 54.09 kN (12,160 lbf) each

Performance

  • Maximum speed: 923 km/h (575 mph)
  • Cruise speed: 787 km/h (490 mph)
  • Range: 8,340-9,265 km (5,180-5,755 mi)
  • Service ceiling 13411 m (44,000 ft)

Armament

  • R1: none
  • MR2: AIM-9 Sidewinder, AGM-84 Harpoon, Sting Ray torpedo, depth charges, nuclear depth bombs (until 1992)

End notes