British Aerospace Nimrod AEW3
Encyclopedia
The British Aerospace Nimrod AEW3 was a planned airborne early warning (AEW) aircraft intended as to provide airborne radar cover for the air defence of the United Kingdom
by the Royal Air Force
(RAF). The project was designed to use the existing Nimrod airframe, in use with the RAF as a maritime patrol aircraft, combined with a brand new radar system and avionics
package developed by Marconi Avionics.
The Nimrod AEW project proved to be hugely complex and expensive for the British government, as a result of the difficulties of producing brand new radar and computer systems and integrating them successfully into the Nimrod airframe. Despite close to a decade's work, the project was eventually cancelled, with the RAF instead purchasing new build Boeing E-3 Sentry aircraft to fulfil the AEW requirement.
for the United Kingdom
. At the time, the only recognised AEW aircraft in British service was the Fairey Gannet AEW3
aircraft used by the Fleet Air Arm
on board Royal Navy
aircraft carriers. these were fitted with the AN/APS-20 Radar, which had been developed during World War II and was rapidly becoming obsolete. To fulfill the planned requirements for a new AEW aircraft, the government had a number of factors to consider:
Engineers eventually decided that the new Hawker Siddeley Nimrod maritime patrol aircraft met these requirements
Eventually, a decision was taken to procure an aircraft fitted with a pulse-doppler radar
system, which then proceeded to a range of options:
While the fourth option was the most attractive as far as British industry was concerned, in that it would sustain thousands of British jobs, it was also far riskier than purchasing an "off the shelf
" product or spreading the risk across multiple partners. In 1977, the US had made an offer to NATO for purchasing several of the new Boeing E-3 Sentry aircraft, which were being delivered to the US Air Force; this was intended to provide airborne early warning cover for Europe's NATO nations without having torely on the US Air Force. However, the complex multi-lateral negotiations eventually led the United Kingdom to go it alone with the all-British development.
was modified for flight testing with the nose radome and conducted a series of trials, the results of which proved promising enough for an order for three prototype Nimrods to be built using redundant MR1 airframes. The first of these was rolled out in March 1980 and flew for the first time in July, and was intended to test the flight characteristics, with the second airframe planned to carry out trials on the Mission Systems Avionics (MSA) package. The MSA was based around a GEC 4080M
computer, which was required to process data from the two radar scanners, the ESM system, IFF
and inertial navigation systems. The integration of all of these systems into a single package proved too difficult for the underpowered computer, which had an ultimate data storage capacity of 2.4 MB
. Additionally, when operating at full power the radar scanners and on-board electronic systems generated a significant amount of heat. A system was developed to channel this via the fuel system, from where it could then dissipate, but which only worked when the fuel tanks were at least half full.
, receiving its first in 1984 to begin crew training. The problem was that, with an anticipated in-service date of mid 1982, No 8 Squadron had been reduced from 12 aircraft and crews to 6 as part of the 1981 Defence Review
. By the time of the Falklands War
, the Nimrod AEW had been originally scheduled to be in service; however the technical problems proved insurmountable to be deployed in the conflict. To provide some degree of airborne surveillance cover, several Nimrod MR.2 were quickly modified to serve in the AEW role for the task force however.
However, at the same time, the MoD
decided to conduct a complete review of the AEW programme. The result of this was the start of a bid process to supply AEW aircraft for the RAF that began in 1986. The primary bidders were GEC Marconi with the Nimrod, and Boeing
with its Sentry. In December 1986, the Sentry was finally chosen and the Nimrod AEW programme was cancelled.
The Nimrod programme had cost in the region of £
1 billion up to its cancellation, contrasting with manufacturer claims in 1977 that the total cost of the project would be between £200-300 million. The unused airframes were eventually stored and used as a source of spares for the Nimrod R1 and MR2 fleets, while the elderly Shackleton that had been commissioned in 1971 as a "stop-gap" measure for AEW cover until the planned entry of the Nimrod AEW were forced to soldier on until 1991 and the entry into RAF service of the Sentry. The scandal over the collapse of the Nimrod AEW project was a major factor in Prime Minister Margaret Thatcher
's stance to open up the UK defence market to competition.
aircraft that formed the basis of the E-3 Sentry, but was expected to accommodate sufficient crew and equipment to perform a similar function. The choice of computer to integrate the various sensor systems was wrong, as the GEC 4080M
was simply too slow and too underpowered to perform the tasks required of it, while using the FASS method to gain full 360° radar coverage proved problematic – the concept involved the scanner in the nose making a left to right sweep, with the signal then immediately passed to the scanner in the tail, which would sweep right to left. However, getting the two scanners to synchronise proved difficult, resulting in poor all-round surveillance capability.
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
by the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
(RAF). The project was designed to use the existing Nimrod airframe, in use with the RAF as a maritime patrol aircraft, combined with a brand new radar system and avionics
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...
package developed by Marconi Avionics.
The Nimrod AEW project proved to be hugely complex and expensive for the British government, as a result of the difficulties of producing brand new radar and computer systems and integrating them successfully into the Nimrod airframe. Despite close to a decade's work, the project was eventually cancelled, with the RAF instead purchasing new build Boeing E-3 Sentry aircraft to fulfil the AEW requirement.
Background
In the mid 1960s following the development of the Grumman E-2 Hawkeye carrier-borne AEW aircraft and its associated systems, the British government began looking around for a radar system that could be used to provide airborne early warningAirborne Early Warning
An airborne early warning and control system is an airborne radar system designed to detect aircraft at long ranges and control and command the battle space in an air engagement by directing fighter and attack plane strikes...
for the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
. At the time, the only recognised AEW aircraft in British service was the Fairey Gannet AEW3
Fairey Gannet
The Fairey Gannet was a British carrier-borne anti-submarine warfare and airborne early warning aircraft of the post-Second World War era developed for the Royal Navy's Fleet Air Arm by the Fairey Aviation Company...
aircraft used by the Fleet Air Arm
Fleet Air Arm
The Fleet Air Arm is the branch of the British Royal Navy responsible for the operation of naval aircraft. The Fleet Air Arm currently operates the AgustaWestland Merlin, Westland Sea King and Westland Lynx helicopters...
on board Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
aircraft carriers. these were fitted with the AN/APS-20 Radar, which had been developed during World War II and was rapidly becoming obsolete. To fulfill the planned requirements for a new AEW aircraft, the government had a number of factors to consider:
- British industry wanted to develop a type of radar that would not operate effectively near propellors, meaning a jet aircraft would be needed.
- The size of antennas needed for the required scanning range, together with the fairly large mission crew, meant that a large aircraft was required.
Engineers eventually decided that the new Hawker Siddeley Nimrod maritime patrol aircraft met these requirements
Eventually, a decision was taken to procure an aircraft fitted with a pulse-doppler radar
Pulse-doppler radar
Pulse-Doppler is a 4D radar system capable of detecting both target 3D location as well as measuring radial velocity . It uses the Doppler effect to avoid overloading computers and operators as well as to reduce power consumption...
system, which then proceeded to a range of options:
- Purchase the AN/APS-125 pulse-doppler radar system and its associated avionics, as fitted to the E-2 Hawkeye, and fit them into the Nimrod.
- Purchase the AN/APS-125 radar and combine it with a British avionics package.
- Purchase the radomeRadomeA radome is a structural, weatherproof enclosure that protects a microwave or radar antenna. The radome is constructed of material that minimally attenuates the electromagnetic signal transmitted or received by the antenna. In other words, the radome is transparent to radar or radio waves...
and antenna from the E-2 and combine with a British radar transmitter, receiver and avionics package. - Develop a wholly British radar system and avionics package using a Fore Aft Scanner System (FASS) rather than the E-2 radome.
While the fourth option was the most attractive as far as British industry was concerned, in that it would sustain thousands of British jobs, it was also far riskier than purchasing an "off the shelf
Off the shelf
Off the shelf may refer to:* Off-the-shelf component* Commercial off-the-shelf, a phrase in computing terminology* Ready-to-wear* Shelf corporation, a type of company...
" product or spreading the risk across multiple partners. In 1977, the US had made an offer to NATO for purchasing several of the new Boeing E-3 Sentry aircraft, which were being delivered to the US Air Force; this was intended to provide airborne early warning cover for Europe's NATO nations without having torely on the US Air Force. However, the complex multi-lateral negotiations eventually led the United Kingdom to go it alone with the all-British development.
Development issues
In 1977 an RAF Comet 4De Havilland Comet
The de Havilland DH 106 Comet was the world's first commercial jet airliner to reach production. Developed and manufactured by de Havilland at the Hatfield, Hertfordshire, United Kingdom headquarters, it first flew in 1949 and was a landmark in aeronautical design...
was modified for flight testing with the nose radome and conducted a series of trials, the results of which proved promising enough for an order for three prototype Nimrods to be built using redundant MR1 airframes. The first of these was rolled out in March 1980 and flew for the first time in July, and was intended to test the flight characteristics, with the second airframe planned to carry out trials on the Mission Systems Avionics (MSA) package. The MSA was based around a GEC 4080M
GEC 4000 series
The GEC 4000 was a series of 16/32-bit minicomputers produced by GEC Computers Ltd. of the UK during the 1970s, 1980s and early 1990s.- History :...
computer, which was required to process data from the two radar scanners, the ESM system, IFF
Identification friend or foe
In telecommunications, identification, friend or foe is an identification system designed for command and control. It is a system that enables military and national interrogation systems to identify aircraft, vehicles, or forces as friendly and to determine their bearing and range from the...
and inertial navigation systems. The integration of all of these systems into a single package proved too difficult for the underpowered computer, which had an ultimate data storage capacity of 2.4 MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...
. Additionally, when operating at full power the radar scanners and on-board electronic systems generated a significant amount of heat. A system was developed to channel this via the fuel system, from where it could then dissipate, but which only worked when the fuel tanks were at least half full.
Cancellation
Despite the problems, the Nimrod was persevered with, and 8 production aircraft were ordered (which would also come from spare MR1 airframes), with the first of these flying in March 1982. Even while the technical problems were being worked on, the aircraft was delivered to the RAF, with No 8 Squadron, the RAF's AEW squadron which at that time operated the Avro ShackletonAvro Shackleton
The Avro Shackleton was a British long-range maritime patrol aircraft for use by the Royal Air Force. It was developed by Avro from the Avro Lincoln bomber with a new fuselage...
, receiving its first in 1984 to begin crew training. The problem was that, with an anticipated in-service date of mid 1982, No 8 Squadron had been reduced from 12 aircraft and crews to 6 as part of the 1981 Defence Review
1981 Defence White Paper
The 1981 Defence White Paper was a major review of the United Kingdom's defence policy brought about by the Conservative government under the Prime Minister Margaret Thatcher. The main author was the then Secretary of State for Defence, John Nott...
. By the time of the Falklands War
Falklands War
The Falklands War , also called the Falklands Conflict or Falklands Crisis, was fought in 1982 between Argentina and the United Kingdom over the disputed Falkland Islands and South Georgia and the South Sandwich Islands...
, the Nimrod AEW had been originally scheduled to be in service; however the technical problems proved insurmountable to be deployed in the conflict. To provide some degree of airborne surveillance cover, several Nimrod MR.2 were quickly modified to serve in the AEW role for the task force however.
However, at the same time, the MoD
Ministry of Defence (United Kingdom)
The Ministry of Defence is the United Kingdom government department responsible for implementation of government defence policy and is the headquarters of the British Armed Forces....
decided to conduct a complete review of the AEW programme. The result of this was the start of a bid process to supply AEW aircraft for the RAF that began in 1986. The primary bidders were GEC Marconi with the Nimrod, and Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
with its Sentry. In December 1986, the Sentry was finally chosen and the Nimrod AEW programme was cancelled.
The Nimrod programme had cost in the region of £
Pound sterling
The pound sterling , commonly called the pound, is the official currency of the United Kingdom, its Crown Dependencies and the British Overseas Territories of South Georgia and the South Sandwich Islands, British Antarctic Territory and Tristan da Cunha. It is subdivided into 100 pence...
1 billion up to its cancellation, contrasting with manufacturer claims in 1977 that the total cost of the project would be between £200-300 million. The unused airframes were eventually stored and used as a source of spares for the Nimrod R1 and MR2 fleets, while the elderly Shackleton that had been commissioned in 1971 as a "stop-gap" measure for AEW cover until the planned entry of the Nimrod AEW were forced to soldier on until 1991 and the entry into RAF service of the Sentry. The scandal over the collapse of the Nimrod AEW project was a major factor in Prime Minister Margaret Thatcher
Margaret Thatcher
Margaret Hilda Thatcher, Baroness Thatcher, was Prime Minister of the United Kingdom from 1979 to 1990...
's stance to open up the UK defence market to competition.
Issues
The thinking behind the attempted development of the Nimrod AEW was to maintain Britain's position at the forefront of radar technology and development as part of defence. However, the complexity of the AEW requirement proved too much for British industry to overcome by itself. The choice of the Nimrod airframe proved to be the wrong one, as it was too small to accommodate the radar, electronics, power generation and cooling systems required for a system as complex as the one required – at just over 38.5 m (126.3 ft), the Nimrod was close to 8 m (26.2 ft) shorter than the Boeing 707Boeing 707
The Boeing 707 is a four-engine narrow-body commercial passenger jet airliner developed by Boeing in the early 1950s. Its name is most commonly pronounced as "Seven Oh Seven". The first airline to operate the 707 was Pan American World Airways, inaugurating the type's first commercial flight on...
aircraft that formed the basis of the E-3 Sentry, but was expected to accommodate sufficient crew and equipment to perform a similar function. The choice of computer to integrate the various sensor systems was wrong, as the GEC 4080M
GEC 4000 series
The GEC 4000 was a series of 16/32-bit minicomputers produced by GEC Computers Ltd. of the UK during the 1970s, 1980s and early 1990s.- History :...
was simply too slow and too underpowered to perform the tasks required of it, while using the FASS method to gain full 360° radar coverage proved problematic – the concept involved the scanner in the nose making a left to right sweep, with the signal then immediately passed to the scanner in the tail, which would sweep right to left. However, getting the two scanners to synchronise proved difficult, resulting in poor all-round surveillance capability.