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Tuesday, February 1, 2011

Eagle’s Eye

Named after Australia’s Wedgetail Eagle, the RAAF’s airborne early warning and control aircraft will provide leading-edge surveillance capabilities

By Frank Colucci

The Royal Australian Air Force graduated its first mission crew for the Wedgetail airborne early warning and control (AEW&C) aircraft last November and should achieve Initial Operating Capability with the long-endurance, multi-sensor platform by the end of 2011.

The heavily modified Boeing 737-700 airframe with its radar “top hat” and nose-to-tail antennas is a key component in Australian plans for network centric warfare. The Airborne Mission System collects, fuses and traffics data for surveillance, air defense, maritime support, force coordination and civil support missions.

Boeing Integrated Defense Systems in Kent, Wash., integrated the Wedgetail sensors, workstations, data links and mission computers in a client-server architecture. “This design is more like a large business network than the traditional mission computing architecture employed by legacy surveillance aircraft,” noted Egan Greenstein, Boeing senior manager for AEW&C business development.

Wedgetail mission computing hardware is made up of commercial off-the-shelf (COTS) equipment ruggedized and integrated by BAE Systems in Greenlawn, N.Y. It hosts a Boeing mission system that generates a common integrated tactical picture shared by the mission crew and networked forces.

Highly automated, multi-sensor integration and decision support systems combine multiple tracks for the same target to show Air Combat Officers a de-cluttered battlespace on workstation displays. Ten identical workstations connected on a Local Area Network enable cabin operators to share workload and can be programmed to accommodate mixed specialists for specific missions. The cockpit crew, meanwhile, has a filterable, scalable tactical monitor that shows the big picture and relevant threat warnings from the aircraft self-protection suite.

Wedgetail tactical displays will be datalinked to RAAF F/A-18F Super Hornets and other networked players to increase the agility and operating tempo of Australian and allied forces. In late 2009, a Wedgetail in initial operating configuration used Link 16 to work with Australia’s Vigilare Network Centric Command and Control System. The Airborne Mission System can also tap off-board intelligence sources. Early in 2009, a Wedgetail over Washington state controlled three ScanEagle unmanned aircraft systems using a UHF satellite link and ground relay.

Integrating Multi-role Electronically Scanned Array (MESA) radar, Identification Friend or Foe (IFF) functionality, Electronic Support Measures (ESM), Electronic Warfare Self Protection (EWSP) and Link 11 and Link 16 connectivity on Wedgetail posed challenges. Initial plans called for first aircraft in service by late 2006. The Australian Defense Material Organization now expects its six aircraft to be in final operating configuration by April 2011.

Despite the technical and contractual struggles, Wedgetail has captured orders from other countries. Turkey will complete three of its four Peace Eagle aircraft in-country on a schedule to be determined. The Republic of Korea is due to receive its first Peace Eye aircraft in 2011 and three more in 2012. Boeing cannot discuss specific customer requirements, but the Turkish and Korean systems are nearly identical to those of the Australian Wedgetail.

Sensor Suite

Unlike the familiar E-3 Sentry and E-2 Hawkeye airborne warning and control aircraft with their rotating, mechanically scanned radars, Wedgetail introduces MESA radar from Northrop Grumman Electronic Systems in Linthicum, Md. The MESA top hat uses hundreds of small, high-power transmit/receive modules in fixed arrays for all-round coverage. The side arrays cover 130 degrees left and right; the end caps provide 50-degree fans fore and aft.

The powerful track-while-scan sensor provides beam agility previously unavailable in airborne surveillance radars to focus energy in the areas of highest interest. While the mechanical rotodome on the Sentry generates target updates every 10 seconds, electronically scanned Wedgetail radar points coordinated beams instantly for faster, more accurate updates. The active array also apportions energy to look farther in threat sectors than in safe sky.

Wedgetail operators can vary target update rates in different sectors or use different pulse modes to spot-select targets in specific areas. “This kind of advanced capability is such a fundamental change that it alters the tactics, techniques and procedures that an air force uses in employing its air battle management platforms,” said Boeing’s Greenstein.

Unlike the lightweight X-band Multi-Function Actively Scanned (MFAS) radar planned for the U.S. Navy’s unmanned Broad Area Maritime Surveillance (BAMS) system, the current Wedgetail radar has no Ground Moving Target Indicator (GMTI) or Synthetic/Inverse Synthetic Aperture Radar (SAR/ISAR) modes for surface surveillance. The Wedgetail radar operates in L-band to track targets at ranges significantly greater than 200 nautical miles.

According to Paul Kalafos, vice president of surveillance systems for the Northrop Grumman ISR Systems division, “The L-band radar signal is attenuated less than higher frequencies such as X-band and is able to search the high volumes of space needed for wide area air and surface surveillance.” IFF functionality integrated into the MESA radar also provides high-quality friend-or-foe information simultaneously with radar tracks.

Northrop Grumman teamed with Boeing in 1996 to put active electronically scanned array radar on a Boeing 737 platform and launched the MESA radar development program for Australia in 2000. “The challenge with MESA was to operationalize a capability that only existed in prototype form prior to the RAAF Wedgetail,” said Greenstein.

High power, in-flight radar testing began in 2005 and MESA effectiveness was verified independently in 2009 by MIT Lincoln Laboratory in Lexington, Mass. The 6,000-pound antenna on the Boeing 737-700 Increased Gross Weight airframe is about 35 feet long, 10 feet high and 5 feet wide. The radar power supply and antenna shifters are located in the base of the antenna, and the core computer and supporting electronics are contained in the Wedgetail cabin.

MESA radar functions are controlled by COTS processors programmed using COTS software standards. Mercury Computer Systems, Chelmsford, Mass., and Northrop Grumman collaborated on the MP510 processing subsystem used for the radar signal processor. Subsequent radar upgrades will leverage the software programmability to accommodate new customer requirements.

In addition to the big radar, the Wedgetail integrates the BAE Australia/ELTA Systems ALR-2001 Electronic Support Measures evolved from the ESM on Australian AP-3C maritime patrol aircraft. The subsystem detects, locates and identifies threat radars for surveillance, target identification and target tracking. It also feeds threat data to the Wedgetail Electronic Warfare Self Protection (EWSP) suite and flight deck tactical monitor. The EWSP suite itself integrates chaff and flare dispensers with the Northrop Grumman AN/AAQ-24(V) Nemesis Directed Infrared Countermeasures system, including a multiband laser.

Crew workstations in the Wedgetail cabin access all the sensors and systems through COTS hardware, ruggedized for the military platform. “Over the life of the aircraft, we’ll be able to take advantage of this COTS basis to provide more seamless and timely technology refreshes as commercial technology evolves,” explained Greenstein.

Adaptive Architecture

Since the Wedgetail program started, evolving COTS technology has increased mission computer RAM from 2 to 8 Gbytes. Wedgetail hard drives have grown from 146 to 300 Gbytes. The main computers themselves have evolved from a single central processor unit to dual CPUs.

The Wedgetail Mission System makes each crew workstation a client on an aircraft network and affords access to all mission data at every station. “The system is inherently redundant because each console — a client on the network — has the same capabilities as every other console,” said Greenstein.

Operators log into the system in an assigned role such as mission commander or surveillance control officer and access data allocated to that role. Multi-sensor integration software from EADS Defense Electronics automatically fuses data from on-board and remote sources into a single track per target and identifies and classifies each track. Boeing decision support system software helps operators assess the threat and recommends actions based on pre-determined rules.

Each cabin console has two operator stations, each with a 21-inch flat-panel monitor and keyboard-and-mouse controls. The color displays are flanked by programmable function panels with 20 touchpad switches to select menu pages. Two display processor computers drive the flat-panel monitors and associated operator controls.

Two redundant Sun Microsystems Blade mission computers with Oracle Solaris-based software process and manage the mission system. Each server is comprised of a large number of individual processors with distributed processes and applications. They work with the flight deck computer to generate workstation map displays. Assisted by intelligent input/output processors, the mission computers host Boeing application software and operate in tandem to share the normal processing load, or switch over automatically if one fails.

The 6.25-inch-square tactical monitor on the center pedestal of the Wedgetail flight deck is driven by the flight deck computer and has a RS-232 port for keystroke data and Built-In Test functions.

COTS hardware and partitioned software are meant to evolve the Wedgetail mission system in service. Additional radar and IFF modes and high-bandwidth communications links can be added to system menus. Boeing expects to leverage developments on all of its large ISR platforms, including the E-3 Sentry and P-8 Poseidon, to develop a common mission computing architecture.

The Wedgetail program started with two aircraft modified by Boeing Integrated Defense Systems in the United States. Subsequent testing and aircraft modifications were done by the Boeing Australia facility at RAAF Base Williamtown in New South Wales, home of No. 2 Squadron. A new facility being built at RAAF Base Tindal in the Northern territory will support a permanent AEW&C detachment.

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