Hawker Siddeley Nimrod

From Wikipedia, the free encyclopedia

Nimrod

RAF Nimrod MR2 taxis for takeoff
Type	Maritime patrol aircraft
Manufacturer	Hawker Siddeley
Maiden flight	May 1967
Status	Active
Primary user	Royal Air Force

The Nimrod is a maritime patrol aircraft developed in the United Kingdom. It is a conversion of the de Havilland Comet, the world's first jet airliner. It was originally designed by de Havilland's successor, Hawker Siddeley, but today BAE Systems is the prime contractor.

It has been the Royal Air Force's primary maritime patrol bomber since the early 1970s, when it replaced the Avro Shackleton. The RAF uses two variants: the R1 variant in a reconnaissance and electronic intelligence gathering capacity (ELINT), and the MR2 variant in the Maritime Reconnaissance role.

The Nimrod was the first jet-powered patrol aircraft. Earlier designs used piston or turboprop engines to improve fuel economy and allow for lengthy patrols. Jet engines are thirstiest at low altitudes — but the Nimrod's huge fuel capacity compensated for this. The aircraft can shut down two outboard engines at low altitude to extend endurance. It can also dash to its targets at a speed unmatched by propeller aircraft. Since the UK introduction of the Nimrod, most other new patrol designs have been jet powered, including the US Navy's S-3 Viking and future P-8.

1 Development
- 1.1 MR1
- 1.2 R1
- 1.3 MR2
- 1.4 AEW3
- 1.5 MRA4
2 Operators
3 Accidents and incidents
4 Specifications (MR2/R1)
5 Specifications (MRA4)
6 Units using the Nimrod
- 6.1 Royal Air Force
- 6.2 Former RAF units
7 References
8 Related content

[edit] Development

[edit] MR1

Nimrod MR1

Nimrod development began in 1964 as a project to replace the elderly Avro Shackleton. Like many other successful maritime patrol aircraft, it was based on a civil airliner which had reached the end of its market life — in this case, the Comet 4. The first two RAF aircraft were unfinished Comet 4 airliners. The Comet's turbojet engines were replaced with 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 magnetic anomaly detector (MAD) boom. After a first flight in May 1967 the RAF ordered 46 Nimrod MR1s. The first example entered service in October 1969. Five squadrons were eventually equipped with the MR1.

[edit] R1

Hawker Siddeley (now BAE Systems) Nimrod R1

Three Nimrod aircraft were adapted to the SIGINT role, replacing the Comet C2s and Canberras of No. 51 Squadron in May 1974. The R1 is distinguished from the MR2 by the lack of a MAD boom. Only since the end of the Cold War has the role of the aircraft been officially acknowledged. Officially these were once described as "radar calibration aircraft". The R1s have not suffered the same rate of fatigue and corrosion of the MR2s and will continue in service long after the MR2 is replaced by the MRA4. New Bombardier Sentinel R1 (ASTOR) aircraft due for delivery from mid 2004 may take on some duties performed by the R1.

The Nimrod R1 is based at RAF Waddington in Lincolnshire, England and flown by 51 Sqn.

[edit] MR2

Starting in 1975, 32 aircraft were upgraded to MR2 standard, including modernisation of the electronic suite and (as the MR2P) provision for inflight refueling and additional ESM pods on the wingtips. The inflight refueling capability was introduced during the Falklands War, as well as hardpoints to allow the Nimrod to carry the AIM-9 Sidewinder missile (giving rise to the aircraft being called "the largest fighter in the world"). Eventually all MR2s gained refueling probes and the "P" designation was dropped.

The Nimrod MR2 carries out three main roles. Anti-Submarine Warfare (ASW), Anti-Surface Unit Warfare (ASUW) and Search and Rescue (SAR). Its extended range enables 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 is greatly extended. The MR2 is 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 can be mounted in the starboard wing pod for Search and rescue (SAR) operations.

The crew is comprised 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 will be used as observers positioned at the port and starboard beam lookout windows when flying in dense air traffic. The MR2 has the longest bomb bay of any NATO aircraft.

On the 17 November, 1980, a Nimrod MR2 crashed near RAF Kinloss after three engines failed following multiple birdstrikes, killing both pilots. The remaining crew survived.^[1]

On the 2 September 1995, a Nimrod MR2 crashed into Lake Ontario while participating in the Canadian International Air Show, killing the 7 crew members.^[2]^[3]

On the 2 September, 2006, a Nimrod MR2 crashed near Kandahar, Afghanistan, killing 12 airmen, one marine and one soldier — the largest single day loss of UK personnel since the Falklands War.^[4]. On 23 February 2007, the Ministry of Defence took the decision to ground all MR2 aircraft while investigations were carried out on fuel pumps. The MoD were quick to stress that this was not necessarily related to the crash in Afghanistan.^[5]

The Nimrod MR2 is based at RAF Kinloss in Scotland and flown by 201, 120 and 42(R) Squadrons. First maintenance of the MR2 is carried out by the Nimrod Line Sqn. Software Support for the MR2 is carried out by the Nimrod Software Team also based at RAF Kinloss.

[edit] AEW3

Nimrod AEW3

In the mid-1970s the Nimrod's duties were expanded to include AEW — again as a replacement for the Lancaster-derived, piston-engined Shackleton which was still in service in that role. The aircraft were modified by BAe at the former Avro plant at Woodford, Greater Manchester to house the GEC Marconi radars in a bulbous nose and tail (see picture). From the start of the first flight trials in 1982 the Nimrod AEW3 project was plagued by cost over-runs and electronic difficulties. Eventually, the MoD realised 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 Sentries (AWACS) instead, with proven radar performance, and electronic enhancements to the original USAF systems to address UK-specific requirements. Of the 11 RAF Nimrods that were selected for conversion to AEW3 standard, none returned to the maritime reconnaissance role: all were eventually reduced for spares to support the maritime Nimrod fleet.

[edit] MRA4

Nimrod MRA4

In 1992 the RAF started a Replacement Maritime Patrol Aircraft (RMPA) procurement programme to replace the Nimrod MR2 aircraft. To meet the requirement BAe proposed rebuilding each Nimrod MR2 with new engines and electronics which it called Nimrod 2000. The RAF considered bids from Lockheed with its P-3 Orion, Loral Corp. with rebuilt ex-US Navy Orions, and Dassault with the Atlantique 3, but in December 1996 awarded the contract to BAe for the Nimrod 2000 as the Nimrod MRA4.

The MRA4 is essentially a new aircraft, with current-generation Rolls-Royce BR710 turbofan engines, a new larger wing, and fully refurbished fuselage. Much larger air intakes are required because the airflow of the BR710 engine is significantly higher than that of the original Spey 250. The rebuilt aircraft borrows heavily from Airbus technology; the wings are designed and manufactured by BAE Systems (a former Airbus partner) and the glass cockpit is derived from that of the Airbus A340.

Development has taken longer than anticipated and the first of 12 MRA4s have not yet entered service. The contract was initially for the supply of 21 rebuilt Nimrods, but due to technical problems the project was halted. Early in the contract BAE discovered that none of the Nimrod airframes supplied by the RAF for refurbishing were to a common standard. This considerably complicated the refurbishment process.

The British House of Commons Defence Committee, in July 2004, reported a forecast cost of £3.5 billion compared to £2.8 billion approved at Main Gate ^[6]. They noted that the in-service date had slipped to 2009, compared to the date of 2003 approved at "Main Gate".

Following public recriminations between the Ministry of Defence and BAE the development contract was renegotiated for the revised number of 18 aircraft. Officially this is attributed to increased capability and availability MRA4 will provide, but it has been suggested that this is in effect compensation to BAE, who had to absorb the cost increases. Announcing plans for the future of the British military on 21 July 2004, the Defence Secretary Geoff Hoon detailed plans to reduce the upgrade programme to cover only 16 aircraft and suggested that an eventual fleet of twelve might suffice. On 18 July 2006 BAE received a production contract worth £1.1 billion for 12 MRA4s. This involves the completion of 3 development aircraft and conversion of 9 more. In response to the news of the production contract, Mike Turner, Chief Executive of BAE Systems, said: "The new NIMROD MRA4 is a world leader in terms of maritime patrol platforms and it will give the UK at least 30 years of adaptable capability in maritime reconnaissance and attack operations." The NIMROD MRA4 mission systems enable the crews to gather, process and display up to 20 times more technical and strategic data than in the current aircraft, the MR2. The SEARCHWATER 2000 RADAR is capable over land as well as water: it can sweep the area the size of the UK every 10 seconds. Delivery of the first production order aircraft to the RAF is planned for 2009 ^[7]

[edit] Operators

United Kingdom
- Royal Air Force

As of late 2006, 15 Nimrods remain in operation ^[8].

[edit] Accidents and incidents

Five Nimrods have been lost in accidents ^[9]:

Date	Type	Serial Number	Operator	Fat.	Location	Category	Notes
17 November 1980	Nimrod	XV256	RAF	2	near Forres, Kinloss	A1	Bird strike on takeoff
3 June 1984	Nimrod	XV257	RAF	0	near Land's End	A1
16 May 1995	Nimrod	XW666	RAF	0	near Lossiemouth	A1
2 September 1995	Nimrod	XV239	RAF	7	near Toronto	A1	Air Display
2 September 2006	Nimrod	XV230	RAF	14	near Kandahar	A1