Nimrod is a British military aircraft with several variants, flown by the
RAF. In sum, it is a long-range/high-endurance reconnaissance and search platform, with some variants capable of marine attack roles as well.
The aircraft is based quite closely on an airliner, the de Havilland Comet 4-engine jet. The Comet suffered (famously) from lethal metal fatigue problems, and was retired from service with civil airways after a fairly short life; however, since de Havilland had already done the engineering work to fix said problems, the British military decided that it was an acceptable platform to build their long-range search/surveillance aircraft on. The lack of confidence in the civil aviation world resulting from highly-publicized crashes of earlier Comets made the new model unattractive as a civil product, and de Havilland (by then Hawker Siddeley, I believe) eagerly accepted the opportunity to sell to the RAF.
The original role of the Nimrod (which means 'Hunter', as other writeups note, quite proper for a search/surveillance/attack aircraft) was twofold. The MR.1 model would be the Maritime Reconnaissance version; the R.1 would be used for electronic and photographic surveillance. Between 1968 and 1978, forty-nine aircraft were produced at the Hawker Siddeley / BAe plant at Woodford. Of these, forty-five were MR.1, three were R.1 variants and one was the newer MR.2. The remainder of the MR.2 line, and the new MR.4 versions, were produced by upgrading or remanufacturing original airframes.
Thirty-four aircraft were upgraded to the MR.2 in late 1979 through the early 1980s through the addition of a new radar system (Searchwater) and massive computer system upgrades. The new MRA.4 variant (A for attack), an extension of the Nimrod 2000 upgrade, involves more extensive remanufacturing of the airplane which will result in the lengthening of the fuselage as well as complete ‘zero-lifing’ on all components. New wings will be fitted, which exposed problems in the original manufacture – after building the first wing set prototype, British Aerospace discovered that the original aircraft varied from the blueprints by as much as four inches around the wing measurements; as a result, the wing upgrades had to be manufactured as ‘one-offs’ – adding greatly to the cost. Other structural changes include a changeover to modern turbofan engines for increased efficiency and reliability, as well as completely new control surfaces, external pods, cockpits and more. Boeing and BAe are sharing this contract.
The MR.2 variant sports four Rolls-Royce Spey RB168-20/250 engines. These turbofan plants generate 12,150 lbs. of thrust apiece, or around 55 kilonewtons (kN). The MRA.4 will carry four Rolls-Royce/BMW BR710 engines, generating 66.3 kN each (~15,000 lb).
Systems
MR.2
- Radar: EMI Searchwater
- Computer: Ferranti 1600D
- Sonar Search: two Marconi Avionics acoustic processors and disposable sonobuoys (each processor can handle multiple live buoys)
- Magnetic Anomaly Detector
- U.S. AN/UYS-503 data processor
- Missile Alert warning and IR detection system, with chaff/flare dispensers
- Link 11 Datalink
MRA.4
The MRA.4’s systems are a bit vaguer; all-glass cockpits, Racal computers, new nav systems, surveillance systems, etc. etc. – essentially, it’s an entirely new airplane as far as avionics and combat systems go. Although the RAF won’t tell us what it carries, the (A) in its new title indicates an attack capability, and the odds are that it will carry ASMs similar to its U.S. cousins the P-3 Orion, which means AGM-84 Harpoons or perhaps Exocet versions…but I can’t see the British buying French arms, can you?
Sources:
- RAF Kinloss web pages
- Boeing project web pages
- David Hastings' Comet enthusiast pages
- Jane's Combat Fleets 1993