Bids to replace the US Navy's ageing P-3C aircraft are in. Now the stage is set for the service to choose between a jet and a turboprop

The US Navy will soon award a $2.25 billion contract to develop its Multi-mission Maritime Aircraft (MMA), the long-awaited replacement for the submarine-hunting Lockheed Martin P-3C Orion. With an unlikely face-off between Lockheed Martin's Orion 21 turboprop and Boeing's 737-based jet, the selection could depend as much on the service's operational philosophy as on pricing and technical details.

It took 10 years to secure the blessing of navy leadership for a P-3C replacement, and the MMA programme has adopted a low-risk development strategy that is designed to avoid straining that support.

But there is little margin for delay during the development phase and the winning team has less than six years to begin flying the new aircraft, and less than nine years to deliver enough of them for the navy's initial operational capability in 2012. The first aircraft will arrive as most P-3Cs are scheduled to be phased out of service.

Key operating criteria outlined in the MMA solicitation ask for relatively marginal improvements over the Lockheed Electra-based P-3C in speed, altitude and range. The desired 90% reliability rate, while higher than the 58% availability rate of the ageing P-3Cs, seems modest compared with commercial standards.

Baseline system

The MMA's mission systems is not required to improve on the reconnaissance capability of the current fleet, although the baseline architecture must allow easy insertion of new technology and hardware. The MMA's sensor suite must include an electro-optical/infrared (EO/IR) imager, a synthetic aperture radar, acoustic processor and an electronic threat warning system.

The rival teams led by Boeing and Lockheed Martin have proposed widely different solutions, although the navy has drawn up performance requirements that accommodate both bids.

Boeing's proposal is based on a militarised derivative of its 737-800, which borrows the wing from the larger 737-900, and introduces a weapons bay in the aft cargo hold and wing-mounted weapons stations. The airliner's jet performance would offer a 20% faster dash speed and 31% higher transit speed compared with a turboprop, plus an ability to climb to 41,000ft (12,500m) says Boeing. These advantages aim to offset the higher fuel burn of a turbofan at low altitude.

Notionally, the aircraft would be assembled and receive fuselage modifications in Renton, Washington before completing preparation in Wichita, Kansas. Raytheon would supply the APS-137 maritime surveillance radar, Northrop Grumman the datalinks and EO/IR sensor, and Smiths Aerospace would provide flight management and stores management systems.

Having once considered a bid based on the Airbus A320 family, Lockheed Martin has instead settled on an improved version of the P-3 called the Orion 21. Upgrades include a 60% increase in thrust (provided by the new integration of Pratt & Whitney Canada PW150 7,000shp-class (5,200kW) turboprop engines with eight-bladed Hamilton Sundstrand NP2000 propellers, plus strengthened wing, glass cockpit and auto throttle. Powerplant improvements raised the Orion 21's maximum ceiling by about 7,000ft to 35,000ft.

Orion 21 production would involve several Lockheed Martin units. Programme management would be based in Marietta, Georgia and assembly in Palmdale, California. Mission systems would be delivered by Lockheed Martin in Owego, New York, and training systems supplied from Orlando, Florida. UK-based GKN Aerospace has also signed on as a significant partner in the programme.

The competing proposals have a clash of operational styles. The jet offers advantages in dash speed and altitude performance, while the turboprop offers an efficient long-endurance loitering capability, even at low altitudes. Navy Cdr Mark Hewitt, the MMA requirements officer, acknowledges a capability gap between "dash speed and range on one side, and endurance on the other".

The winner, expected to be chosen in late May or early June, would gain billions of dollars in follow-on production orders and a strong foothold in the international market for next-generation maritime patrol aircraft. Including the US purchase, Boeing estimates a market for 300 aircraft for the MMA worldwide, with India, Pakistan and Taiwan considered the prime candidates for MMA orders.

Perhaps mindful of the navy's first priority of minimising development challenges, both competitors are quick to say their bid offers the low-risk solution.

Lockheed Martin boasts of its 40-years association with the P-3 airframe, the anti-submarine warfare (ASW) community and ties to an established support infrastructure. Despite the need to restart the P-3 production line, the company says the basic design elements of the Orion 21 are ready for maritime operations and to carry weapons. The company says it considered a commercial jet platform, but rejected it after a risk analysis raised concerns about design tweaks needed to carry more fuel, weapons and sonobuoys.

Boeing's team claims it has reduced risk by basing its proposal on an aircraft with an active production line. Boeing also notes it is using digital design tools to produce the militarised version, and has funded windtunnel tests to check its data.

Aware that the 737 has never been tested in the ASW role, Boeing has arranged demonstration flights for the media and P-3C pilots. The ASW mission is characterised by frequent diving to identify potential threats and long loitering periods at low altitude for radar sweeps. In a series of flights last year, Boeing pilots demonstrated that the 737 is capable of climbing to altitude on one engine. From 41,000ft, the aircraft can descend rapidly at 10,000ft/min (50m/s) to level off at 1,000ft. The aircraft can then continue at a shallower angle to 200ft, where it can perform 60¼ bank turns with its wingtips barely 100ft above the wavetops.

Hewitt says the service is comfortable with its options so far. "Both companies know how to build aircraft," he says. "We're not worried about that."

Low-risk approach

As part of the low-risk development approach, the navy intends to steadily upgrade the capability of mission systems and avionics aboard the aircraft. As a result, the navy's requirements demand a design flexible enough to add significant changes.

Both aircraft will be equipped with five mission system workstations, but each has room to grow to eight consoles if the navy elects to use the aircraft in an electronic intelligence (ELINT) role, foregoing a plan to replacing the ageing EP-3 ELINT fleet with a naval version of the army's Aerial Common Sensor (ACS) programme.

Hewitt however insists that the navy is committed to ACS, he says, and is following guidance from the Office of the Secretary of Defense to find common solutions among the mix of manned intelligence platforms currently moving forward, including the MMA, ACS and the US Air Force's E-10A Multi-sensor Command & Control Aircraft (MC2A). One initial proposal was to streamline to one or two shared platforms, says Hewitt, but a detailed analysis found that the only feasible option was a joint ACS programme.

Meanwhile, the navy expects that the MMA's capabilities will be expanded in the years after the rush to field the first replacements for the geriatric P-3C fleet. The service is mandating an open architecture, non-proprietary mission system solution that would allow for significant growth in capabilities, says Hewitt.

When the navy released its final version of the MMA solicitation in mid-March, Boeing programme officials said they were surprised by the requested level of sophistication for the open architecture. But Hewitt says there really should be no surprise, as the service had consistently listed its requirements for several months.

As well as the emphasis on a low-risk solution, Hewitt says altitude is a critical feature for the MMA programme. The navy no longer wishes to fly ASW missions at 200ft, skimming wavetops to search for submarine periscopes and snorkels. Flying low is no longer deemed safe in the current threat environment and also is a major cause of airframe fatigue, says Hewitt.

Critical delivery

Speed of delivery for the MMA has also emerged as a critical factor in the navy's decision-making. An analysis last year revealed the P-3 fleet was in crisis, deteriorating at a much faster rate than the navy had imagined. Nearly 80 P-3s will have to be retired over the next two years, leaving a critical shortfall of patrol aircraft until the MMA fleet begins to enter service in 2010. Critics note that the sudden discovery has conveniently bolstered the navy's case for funding the MMA programme, and the findings helped to sway navy leaders to finally approve the programme's go-ahead in June 2003. That urgency is also helping to drive the navy's demand for a low-risk development and integration path.

Over three decades, the P-3's original mission to hunt for submarines and surface vessels has expanded into a variety of tasks, such as overland strike. P-3Cs are now operating over certain parts of Afghanistan and Iraq, as well as performing counter-narcotics reconnaissance in Colombia. In the campaign against Yugoslavia in 1999, P-3Cs were used to launch air strikes using Boeing AGM-84H SLAM-ER missiles against Serbian targets.

But navy officials believe a maritime aircraft is ill-equipped for most such roles, and is turning many of these missions over to the planned Broad Area Maritime Surveillance (BAMS) unmanned air vehicle and more manoeuvrable strike aircraft. The service plans to devote the MMA force to anti-submarine and anti-surface warfare and, for now, intends to push back against proposals to broaden its operational profile.

Navy officials project a need for 108-112 MMAs, or less than half of the existing P-3 Orion fleet. After 24 aircraft were retired last year, due to growing aircraft fatigue issues, the navy is operating 227 P-3s, some of which have surpassed 20,000 flight hours - twice their projected lifespan.

But the numbers gap does not perturb the navy. It believes that switching to a modern, reliable airframe will eliminate the need for about one-third of the P-3 fleet. The P-3's notoriously low reliability has forced the service to operate 80 redundant airframes to sustain sortie generation rates, and the navy now is striking the excess margin from the MMA order. Projecting a roughly 40% improvement in fleet reliability, the service plans to downsize squadrons from nine aircraft to eight, or seven, and to eliminate two special mission squadrons.

Mission control

Training will be affected by the cutbacks. About half of the 25-aircraft Fleet Reserve Squadron, used primarily for training flights, is expected to be cut. The navy has determined that training cycles were a primary cause in the P-3 fleet's deterioration and it wants to avoid making the same mistake with MMA. The next generation of pilots will instead spend more time in the simulator, and a robust training package is considered a key part of the programme.

Improved reliability metrics alone, however, does not make up for the number of P-3s lost after the conversion to the smaller MMA fleet. The navy maintains a requirement for 150 patrol aircraft, which will probably be filled by about 50 UAVs to be purchased under the still-undefined BAMS programme, which is focused on littoral and overland patrol missions.

Rejecting a sole-source order for the Northrop Grumman RQ-4 Global Hawk, the navy is to open a competitive procurement for BAMS in June that is expected to include the Global Hawk and a modified Predator B, the Mariner, jointly offered by General Atomics and Lockheed Martin.







Source: Flight International