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Wednesday, September 1, 2004

B737 Joins the Navy

The U.S. Navy calls its Multimission Maritime Aircraft a 'low-risk truck.' True, the B737 airframe is well proven. But it houses an advanced mission system you won't find in any truck.

James W. Ramsey

The U.S. Navy's new Multimission Maritime Aircraft (MMA), a modified Boeing 737-800, is touted as a significantly enhanced mission platform, compared with the venerable P-3C it will replace. Prime contractor Boeing and the Navy assert that the commercially proven twin-engine jet offers greater speed, agility and endurance, and can better accommodate the P-3C's primary anti-submarine and anti-surface warfare missions, as well as a limited intelligence, surveillance and reconnaissance (ISR) role.

"We look at the Boeing solution as providing a low-risk `truck'--a very highly proven, reliable airframe--to go with an open missions systems architecture, providing a very flexible platform that will easily accommodate future upgrades," says James Lackey, the Navy's deputy program manager for MMA.

"As soon as the first 737 MMA aircraft is delivered to the Navy, our nation's naval forces will have a dramatic increase in capability and reliability," claims Jim Albaugh, president and chief executive officer of Boeing's St. Louis-based Integrated Defense Systems unit. MMA is expected to provide 1,600 Boeing jobs in St. Louis, Seattle and Patuxent River, Md., home of Naval Air Systems Command.

The Navy awarded the Boeing-led industry team--which includes CFM International, Northrop Grumman, Raytheon and Smiths Aerospace--a $3.9-billion contract in June for the program's system development and demonstration (SDD) phase. It includes production of three flyable aircraft by 2010, two mission demonstrators and one aircraft to test flying characteristics. Four more aircraft not included in the SDD award are to be built for testing and evaluation purposes. Plans call for 108 production aircraft (which may be called the P-8 or PC-40) to replace the Navy's aging fleet of 191 P-3C aircraft. (The original P-3A Orion began flying in 1959, and the upgraded P-3C joined the fleet in 1969.) Total acquisition value to the Boeing team is estimated at $20 billion, and far more if it wins a 20-year support contract. The schedule calls for low-rate initial production of 34 operational aircraft to be built from 2010 to 2012. Full-rate production is to begin in 2013 and initial operational capability (IOC) is slated to take place the same year.

The reason for the P-3 replacement? "The major need comes from the P-3s' having reached their service life--the metal in the aircraft is reaching its fatigue life," explains Tim Norgart, director of business development for Boeing's MMA program. "So if they were retained, they would basically have to be rebuilt."

"Right now [the P-3s] are being retired at a pretty significant rate," he adds. "Their processing systems and sensors also are in dire need of upgrades." Norgart, a former P-3C wing commander, says the Navy found it would be difficult to upgrade older aircraft with newer systems because of their older architecture. He believes the Navy has "a quantifiable need for [the B737] platform for its `assured access' mission." A long-range patrol aircraft capable of doing anti-submarine warfare (ASW) is a major requirement in the Navy's Seapower 21 war fighting doctrine, which outlines how the Navy will fight for the next 20 years.

"If you can't get into a body of water to operate an aircraft carrier, then you can't get a whole lot of Hornets [F/A-18s] across the beach," says Norgart. "So the MMA will be out there in front of the fleet, clearing the way and making sure the water is safe for them to go through."

Boeing Selected

Aside from producing the Navy's F/A-18, Boeing brings to the table considerable maritime experience in ASW, anti-surface warfare (ASuW) and reconnaissance operations. The company integrates the tactical command system--the core of the mission system--for the UK's Nimrod (maritime reconnaissance aircraft) MRA-4, an upgraded version of the MRA-2 ASW surveillance aircraft. From its Anaheim, Calif., division Boeing also provides part of the acoustic processing system for the P-3C--as a subcontractor to Lockheed Martin. And Boeing integrates the Nimrod's acoustic processing system, which processes information received from the sonabuoys and displays it to onboard analysts for interpretation. Boeing will build the MMA's acoustic processing system.

In the cockpit Smiths Aerospace provides the flight management system (FMS)--similar to that provided for the commercial B737-300/400/500 and NG, but with added functionality. "We're taking our civil FMS [software] and adding the tactical functions we provided for Nimrod, with a few changes as we go along," says Jim Smith, military air transport marketing manager for Smiths Aerospace's Grand Rapids, Mich., business unit.

A unique FMS feature on Nimrod "is the ability for multiple climb, cruise and descent profiles, allowing [the flight crew] to plan for different tactical situations," Smith says. He adds that the commercial 737 FMS computer will be replaced on the MMA by a newly designed one that is being developed for the Boeing 767 tanker program. Smiths' FMS provides an integrated open architecture that is compliant with communication, navigation, surveillance/air traffic management (CNS/ATM) standards and provides an inherent growth path for upgrades, the company maintains.

The FMS will use ARINC 653 partitioned operating environment software, which allows multiple applications on the same processor. "Because the aircraft is going to have so many more functions in the cockpit and in the back, the AFMC [avionics flight management computer] is going to be asked to do much more than just [manage] the FMS," Smith says. The AFMC will interface with a mission computer in the back of the aircraft, which controls the sonabuoys dropped into the water.

The Flight Dynamics unit of Rockwell Collins will supply the MMA's HGS 4000 head-up guidance system; however, the Navy has not yet decided whether the cockpit will be equipped with two systems or a single system for the captain. The MMA HUD incorporates mission modifications that include display of tactical symbology and enhanced vision system (EVS) video, in addition to normal primary flight guidance symbology. The HGS 4000 "enables MMA pilots to keep eyes out of the cockpit during the low-altitude maneuvering often required over water," says John Thomas, Flight Dynamics' principal marketing manager.

The MMA's HUD system is comparable to ones offered as options for the B737. The HGS Model 2300 is installed on earlier 737-300/400/500 aircraft, and the later model HGS 4000 series is on the next generation (NG) 737-600-900 series. Flight Dynamics has delivered more than 900 systems for various B737 models, which include the Navy and Air Force C-40 fleets and the Australian Wedgetail 737 airborne early warning and control (AEW&C) aircraft.

Cockpit Displays

The MMA cockpit is expected to feature the same basic avionics systems as the B737NG. The commercial aircraft employs five 8-by-8-inch displays across the cockpit, with a sixth display just above the center pedestal. The tactical situation normally will be shown on the pedestal display, but will be "rotatable" to the inboard pilot and copilot displays on the forward panel at the flight crew's discretion. The cockpit display, a smaller version of the tactical display in the back of the airplane, will include situational awareness information such as radar contacts and sonabuoy symbols. The B737NG cockpit displays are interchangeable. If one fails, the screen next to it automatically shifts to a split screen and displays the information from the failed screen.

The B737NG features, as standard, Honeywell flat panel displays, or multifunction display units (MFDUs), as well as the air data inertial reference system (ADIRS) and enhanced ground proximity warning system (EGPWS). Optional, customer-selected Honeywell equipment on the commercial aircraft includes GPS navigation, radios, weather radar, traffic alert collision avoidance system (TCAS), communications management, and a cockpit voice recorder.

A Honeywell spokeswoman emphasizes that the Navy has not yet announced its selection of cockpit instrumentation for the MMA. But Boeing's philosophy is "that they are going to use as much off-the-shelf commercial aircraft equipment as possible," says Smith. "Changes will be made only where mission requirements dictate."

Northrop Grumman's Baltimore-based Electronic System sector will provide the MMA's electro-optical/infrared (EO/IR) sensor, the early warning self-protection suite, and electronic support measures (ESM). It also will integrate the aircraft's self-protection suite with the ESM suite.

The MMA's EO/IR sensor will be a new system called Night Hunter II. It builds on the company's Litening targeting pod, which is installed on the Air Force's F-16, F-15 and A-10 aircraft. The new system, used to identify targets, will be fitted to a stabilized, retractable turret.

Northrop Grumman's directed infrared countermeasures (DIRCM) system, which also is on the C-130, provides the MMA's IR countermeasures capability as part of the self-protection suite. Northrop Grumman also will provide a new radio frequency (RF) countermeasures system, developed at the company's Baltimore and Rolling Meadows, Ill., facilities, says Kent Murray, the company's program manager.

The MMA's self-protection suite will include Raytheon's towed decoy. The ESM system, used for electronic surveillance, will be an enhanced all-digital receiver system located in the aircraft's nose. It is based on the LR-100 currently flown on the Air Force's Global Hawk unmanned air vehicle. Murray believes "the ability to integrate sensor suites, such as self-protection and ESM, means lower costs and higher reliability due to [the installation of] fewer electronic boxes. It also streamlines information flow," he adds.

Raytheon will equip the MMA with an upgraded APS-137 maritime surveillance radar. It will have the same capabilities as its APS-137D(V)5 radar in production for the Navy's P-3 ASuW improvement program. Sixty-eight upgraded P-3Cs currently fly with the system. This radar system provides maritime surveillance modes, as well as high-resolution, inverse synthetic aperture radar (ISAR) and synthetic aperture radar (SAR). ISAR is used "for imaging and classifying small, fast-moving vessels that operate close to shore, and SAR is for overland imaging, target identification, battle damage assessment, and precision geo-location of land targets," says Brad Hopper, business development manager for Raytheon's Precision Attack and Surveillance Systems, in McKinney, Texas.

Key improvements over earlier radar systems to be offered for the MMA include an upgraded color weather mode, full integration with the Boeing MMA mission system, and joint technical architecture (JTA) compliance. That means the radar is part of the MMA network backbone and supports network centric operations.

Raytheon also is offering a GPS with anti-jam capability, identification friend or foe (IFF), a broadcast information system (BIS) and secure UHF satcom capability. These products can provide MMA with network centric connectivity.

Looking like a stinger sticking out of the MMA's tail will be a magnetic anomaly detector (MAD) provided by CAE, says Norgart. It is designed to detect submarines by measuring disturbances of the Earth's magnetic field caused by large metal objects under water.

Weapons Control

Boeing has yet to select the provider of the mission computing and display system (MCDS). However, it chose Smiths Aerospace to provide the system that controls all weapons on the aircraft. A central stores management processor takes input from the mission computer and then sends messages out to station control units (SCUs) at each of the MMA's pylons. The MMA will have two pylons on each wing, two centerline weapons stations and a weapons bay with two SCUs--one for the sonabuoys. "The SCUs send signals to the individual weapons," Smith explains. "If you have smart weapons that need data, they will be responsible for loading that data, as well."

The aircraft will carry 12,500 pounds (680 kg) of weapons, including missiles, torpedoes, depth bombs, mines and sonabuoys in a weapons bay and on wing and fuselage pylons. Three sonabuoy automated rotary launchers--located behind the wing, inside the weapons bay--are pressurized and can be loaded before takeoff or in flight. Harpoon and Slam-ER antiship missiles would be launched from the wing pylons.

Five mission tactical workstations will be located over the MMA's wing. Each one will feature two wide-screen multifunction displays. Both screens will be touch-sensitive, so targets or tracks can be designated either by touch or by a track ball. "You can look at sensor data overlaid on top of other sensor data and still maintain your main screen for a full tactical plot," says Boeing's Norgart. "Or you can split the screen."

The same software used in the tactical displays will run on a desktop or laptop computer, as well as in the MMA weapons system and in the tactical support centers. "The software is completely portable and reconfigurable," Norgart adds. "You can even reconfigure it on a desktop in your office before you go flying, then plug your memory stick into the USB port on the front of the display and dump all your preferences right into the system."

The tactical display system is configured to be faster and require "a lot less operator entry [than the P-3C's tactical display]. It gives the operator more time to evaluate tactics and return to the days of being a tactician and analyst rather than a system operator," Norgart maintains. The MMA's GPS navigation system also will be the reference for the tactical system used in the back of the aircraft.

The MMA's communications suite and data link package will include the ability to move pictures, video and data between the aircraft and other units. Radios, line of sight data links and satellite communications, including an Inmarsat system, will be used to move large amounts of data long distances. Initial data link speed is expected to be slightly higher than Inmarsat's Swift 64 service used on some business jets. Swift64 provides 64 kilobits/s (Kbits/s), up to 128 Kbits/s if systems are combined. The satcom antenna will be mounted on top of the MMA's tail. Although Boeing has demonstrated the Connexion by Boeing high-speed broadband communications system, it is not part of MMA at this time.

Communications Links

The Navy plans to have Link 11 and Link 16 data distribution on the MMA. Using Link 11, surveillance data can be sent or received through two HF channels, a single UHF channel or via UHF satcom. "Link 11 interfaces with the communications set on the airplane and the mission computer via the 5053 avionics bus," says the Navy's Lackey. "It is embedded within the mission computer processor, and we provide encryption through a subset."

Link 16 is a stand-alone box with a transmitter/receiver, power supply and its own encryption/decryption. With this data distribution system "MMA will be able to get com, nav and ID capabilities for airborne tactical operation," Lackey says. It also has an embedded Tacan functionality, providing distance and bearing. "But the main purpose of Link 16 is to allow the MMA to post info onto a net and then pull info from the net in a network centric environment, allowing the mission operation to take place."

Open System

Link 16 offers a machine-to-machine interface for the exchange of targeting data. It also facilitates communications between MMA and an aircraft carrier or home base. "All the systems required to make the data link secure and support those communications will be on board, allowing you to talk to a commercial merchant ship, an aircraft carrier, or exchange data with an AWACS [airborne warning and control system] aircraft," Norgart says.

Boeing plans to use "industry standard interfaces and protocols in developing the MMA's mission system, so it can be grown easily and affordably. "Using standard programming languages like C++ and Java, we're able to put in the hooks, as we call them, for the next set of sensors and tools that will be used by this system," Norgart explains.

For example, he cites the new JTRS (Joint Tactical Radio System), planned to be operational by 2008. With MMA, the old radios can be taken out and JTRS plugged in. And when the next generation data link becomes available, "you'll be able to just load it as an application rather than completely rewrite the software,"he says.

By building the architecture this way, with no proprietary software code, the Navy will not have to come back to Boeing to upgrade its software. Norgart claims, "that really has never been done before for DoD [Department of Defense]."

Why a Jet?

Skeptics may question the U.S. Navy's selection of a commercial jetliner for missions that include low-level, over-the-water surveillance. Not to worry, says Boeing's Tim Norgart. "We've taken the aircraft [the Boeing Business Jet, based on the B737] out twice now and let the Navy fly it. We put weight on board to duplicate an MMA's mid-mission weight, above 150,000 pounds [68,040 kg], and let the Navy pilots fly it [at] 200 feet off the water at loiter speeds of 208 knots." (MMA's maximum takeoff weight is 184,200 pounds [83,555 kg].)

The high-bypass turbofan engines are fuel-efficient, says Norgart, adding that the fuel burn curve at 500 feet (about 4,000 pounds per hour) vs. 30,000 feet is only about 700 pounds different per hour. He adds that the turbofan is more reliable than the turboprop because it has fewer parts.

The Navy's range and endurance requirements call for 1,200 nm out, four hours on station searching for submarines, and 1,200 nm back home. Boeing says its aircraft exceeds that requirement. Norgart points out that while a P-3 will take four hours to get to the target, MMA will be there in less than three hours. "That equates to a higher probability of target detection, since it can't travel away as far from the tracking aircraft," he says.

Another advantage of the Boeing jet over a turboprop aircraft is the ability to self-deploy faster, according to Norgart. A fully loaded MMA is billed as having a 4,800- to 4,900-nm self-deployment range, cruising at 445 knots. Aerial refueling presumably would need to be infrequent. The Navy has bases that allow deployment worldwide, Boeing maintains.

Boeing claims that its aircraft climbs better on one engine than a P-3 on four engines. The 737 can accelerate from 200 to better than 320 knots in seconds, and can perform ascents and descents in excess of 10,000 feet per minute, the company says.

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