Nimrod – Replacement or reincarnation?

John Chevedden looks at the options for the RAF’s Nimrod replacement, all of which have a high US content.

THE REQUEST FOR Tender for the Nimrod replacement was issued on January 10, 1995. The final selection is expected in the late summer of 1996 with a 2002 in-service date. The contract could be worth nearly £2 billion (S3.1 billion), including training and logistics support — twice the value of the hotly-contested contract recently awarded to Lockheed Corporation for 25 new C-130J Hercules 2 military transport aircraft.

The Ministry of Defence Staff Requirement Air (SRA) 420 requires a demanding performance for the aircraft, the mission system avionics and integrated logistics support, A 15-hour unrefuelled endurance and high-speed transit to and from the area of operations are two of the major performance requirements.

An MoD spokesman emphasised that the requirement is not just for the aircraft. It also includes equipment, spares, training, manuals and post design service, including modifications. Life-cycle costs are important. It requires the maximum use of existing design and could involve different quantities of aircraft, depending on the design selected.

The four competing prime contractors invited by the MoD are: BAe teaming with Boeing to upgrade existing Nimrod aircraft with new avionics, improved cockpit instrumentation and strengthening the airframe in certain areas.

A potential partnership between UK-based GEC-Marconi and other UK companies is offering an upgraded version of the Lockheed P-3C Orion 2. Besides the GEC-Marconi mission systems avionics, Lockheed is expected to take advantage of the UK partnerships it has established with the C-130J to offer new aircraft that would have more than 50% British content.

Dassault is offering the Atlantique 3, a re-engined version of the Atlantique 2 with Allison AE 2100 turboprops. The RAF has traditionally favoured a four-engined aircraft for maritime reconnaissance, but the increased reliability of twin-engined aircraft could alter the equation.

Loral ASIC, teamed with E-Systems, is proposing to recondition and re-equip used P-3A and B model Orions, which like the British Aerospace plan, would reduce the initial airframe cost.

Competitive factors

Key competitive factors are: offsets, the use of existing technology and airframes, the practicality of refurbishing aircraft with many flight hours and the progress and direction of other related aircraft programmes, such as the Future Large Aircraft (FLA).

A ‘clean sheet of paper’ is not the prime objective for this competition — ‘evolution’ is, making use of existing technology from current or related aircraft. The Nimrod would have the greatest advantage in using current logistics and cost less for training crews.

Whichever contractor is chosen by the MoD’s Acquisitions Committee, the MoD is believed to be insisting on 100% returns from offset contracts, involving large-scale participation in the programme by the British aerospace industry. Rolls-Royce’s pending purchase of Allison could improve the prospect of selling the Allison AE 2100-powered P-3 and C-130J to the RAF.

The true cost of refurbishing Nimrods or P-3s may be greater than expected. A mid-1980s Lockheed publication said, «Airframe components can be replaced. Avionics systems can be replaced in many cases, but Secretary of Defense Weinberger stated the problem in his Annual Report to Congress for Fiscal Year 1984: ‘Recent Navy assessments have reconfirmed that the cost of converting our older force of P-3A and lightweight P-3B aircraft to a modern configuration and extending their useful service life would approach 80-85% of the cost of producing new P-3C aircraft’.»

The availability of good quality P-3s to refurbish may be limited. Although there are approximately 80 P-3As and P-3Bs currently in storage, some are finding other uses. For instance, Australia will use P-3 bone-yard aircraft for flight crew training to save its newer operational aircraft.

The RAF is the launch customer for the Lockheed C-130J Hercules ‘2’, ordering 25 aircraft in December 1994, Defence Secretary Malcolm Rifkind concluded that refurbishment of existing RAF C-130s would provide «poor value for money» and this will be a theory to test on whether it applies to maritime reconnaissance aircraft.

To purchase and/or refurbish used aircraft, like the Nimrod, would reduce airframe costs now, giving the option to buy new generation aircraft sooner. This could help spread out the development costs of the FLA over more airframes and result in a maritime patrol version possibly as early as 2008-2010.

However, such a cargo-optimised aircraft would probably be more expensive to operate than airliner-derived patrol aircraft. This could be one of the reasons airlines have never purchased dedicated cargo aircraft in any significant numbers.

On the other hand, buying new P-3s would give the RAF an aircraft that could theoretically serve until 2040, since P-3 fatigue and corrosion life can be extended to 38 years. This would be an accomplishment for an aircraft that first flew in 1957 as the Electro.

The P-3 has the advantage of borrowing new engine and cockpit technology from Lockheed’s own C-l30J. The P-3 has already borrowed from the S-3B Viking. For instance, the P-3 uses a new surface search radar from Texas Instruments, a development of the radar on the smaller Lockheed carrier-based S-3B Viking.

By teaming with Boeing, the BAe proposal could have less UK content than expected. Lockheed could obtain a large UK content on the latest version of the proven P-3 aircraft that has great potential for future sales to other countries including the United States.


The Nimrod upgrade will include drag-reducing aerodynamic refinements — including flap fairing, wingtip end-plates or winqlets, fairing in the upper fuselage air refuelling probe, and rectifying airframe salt air corrosion. Boeing would focus on mission system sensors and avionics, adding stores management and defensive aid sub-systems as well as revising flight deck instrumentation with six liquid crystal displays.

The Nimrod played a major role in the Falklands and Gulf War and has recently commemorated its 25th anniversary of RAF service. On its anniversary BAe said that «Having earned Silver, Nimrod’s now going for Gold.» For Desert Storm, BAe helped to quickly modify the Nimrod with infra-red flares and additional missiles making it «the largest fighter in the world.»

A Boeing spokesperson said that Boeing would draw on its past experience as a supplier of avionics and system integrator.

The phased upgrade of the Nimrod could give an average operational life until approximately 2015, if the FLA is not ready by 2008-2010.


The P-3 has the advantage of borrowing new engine and cockpit technology from Lockheed’s own C-130J. It will use the Allison AE 2100 and glass cockpit technology from the advanced C-130J. The Allison AE 2100 was derived from the T406 for the tilt-rotor V-22 Osprey. The T406 in turn, was developed from the P-3’s T56.

The C-130J engine is matched to a Dowty R391 six-bladed propeller, rated at 6,000shp with specific fuel consumption of 0.41 lb/h/shp. For the P-3C Orion 2 a slightly different prop will be used.

The P-3C Update 3 aircraft now being built for the South Korean Navy feature an advanced avionics architecture based on the Unisys AN/ASQ-212 central processing computer. The system also includes a new AN/APS-137 surface search radar from Texas Instruments, a development of the radar on the smaller Lockheed carrier-based S-3B Viking.

In Desert Shield/Desert Storm P-3Cs flew 1,326 sorties, logging 11,877 hours. They evaluated 6,300 ships and provided primary targeting in the destruction of 53 Iraqi vessels. Also, special mission P-3s flew 791 sorties and 3,790 hours. Since 1991, P-3s have flown over 719 sorties and 5,478 hours in support of Operation Desert Calm. ASW operations of the Navy’s P-3 fleet now account for only 25% of their Cold War tasking.

Adm David Miller told the Senate Armed Services Committee that there is still a need to monitor movements of submarines of the former Soviet Union. He said the increasing numbers of Third World diesel submarines in littoral areas are driving a requirement to develop enhanced and improved capabilities for Maritime Patrol Aircraft (MPA) platforms to meet future missions.

Due to wide use of P-3s, operators are — Australia, Canada, Chile, Iran, Japan, NetheHands, New Zealand, Norway, Portugal, South Korea, Spain and Thailand, spares and support logistics are no problem.

Wlliam Bernstein, Lockheed P-3C programme manager, said the company is working with other potential customers in the Middle East, as well as the United Kingdom.


Dassault Aviation is proposing the upgraded Dassault/Breguet Atlantique 3 to succeed the Nimrod. This aircraft will be equipped with an in-flight refuelling system, new sensors and communications systems and enhanced ECM. The Atlantique 3 retains the original airframe, but incorporates a new avionics suite and weapons system. It also embodies improved manufacture and corrosion protection practices.

Dassault will replace the Rolls-Royce Tyne turboprops with new and more efficient Allison AE 2100s and incorporate air refuelling and advanced mission systems equipment supplied by Ferranti-Thomson Sonar Systems and Thomson-Sintro ASM.

The Atlantique is the only candidate developed from the start as a dedicated maritime reconnaissance aircraft. Despite the RAF favouring a four-engined aircraft, Dassault has dropped plans first revealed in 1991 to develop a four-engined Atlantique. It was to have two Garrett TFE 731 podded turbofans underwing, in addition to the two turboprops, a concept similar to the 1953 Lockheed Neptune P2V-5F. High costs halted development.

From a structural standpoint, the Atlantic 2 and its engines are practically identical to their predecessor, with some improvements taking into account wide operational experience gained through 25 years with the Atlantique 1. The airframe is produced by a European consortium of Dornier and MBB in Germany, Dassault and Aerospatiale in France, Alenia in Italy, and SABCA-Sonaca in Belgium. As a result there are many partners for relatively few aircraft over a stretched out production run. Atlantique operators are: France, Germany, Italy and Pakistan.

P-3 upgrade

Loral is proposing to become the prime contractor for updating used P-3s, following its similar contract for the Royal Navy’s EH 101 Medin ASW helicopter programme. Loral would team with E-Systems and provide mission systems. E-Systems would provide the airframe upgrades and refurbishment.

E-Systems of Dallas, Texas recently won the contract for the P-3C Sustained Readiness Program (SRP). The SRP is the US Navy’s effort to address high-corrosion areas of its current fleet of P-3C Orions, thus extending corrosion service life from 28 years to 38 years, to match the P-3’s 38-year fatigue life. It aims to replace, upgrade or recondition damaged and corroded components as well as replace obsolete or degraded systems.

E-Systems signed an A$600 million contract with Australia in late January 1995 to upgrade 18 Lockheed P-3C Orions, which could extend their operational life to 2015. The Australian Defence Department said major flight instruments, radar, acoustics, data management, navigation and communications systems will all be upgraded, and as prime contractor, E-Systems will design and integrate the system.

When evaluating the proven airframe technology of the P-3C Orion 2, Atlantique 3 and Nimrod, it is informative to look back on an earlier proposal that offered advanced technology which held development promise.


The McDonnell Douglas P-9D was a maritime reconnaissance version of the MD-87. It planned to introduce propfan engines to offer the speed and altitude of a modern jet transport with the fuel efficiency of a turboprop. P-9D Program Manager Bill Zakowicz said that when the price of fuel moderated, propfan development was deferred. Propfan research and development cost was forecasted at $2 billion.

The V2500 engine was substituted at the last minute in the competition that was eventually won by the Lockheed P-7 version of the P-3. However, it did not offer the specific fuel consumption necessary for the long-range and loiter requirement. In the end the P-7 was cancelled due to cost overruns.

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