Building airborne electronic attack (AEA) capability into the U.S. Navy’s F/A-18F Super Hornet fighter/attack aircraft posed packaging and integration challenges for prime contractor Boeing and AEA subsystem integrator Northrop Grumman.
Compared to the veteran EA-6B Prowler it will replace, the EA-18G Growler has less room for the receivers, transmitters and antennas that detect, localize and jam enemy radars and communications. The Growler also has just two crew members instead of four to manage mission workload.
The EA-18G nevertheless offers carrier air wings a more capable electronic attack platform, able to keep up with Super Hornet strike fighters and increasing AEA missions. "We’re faster. We’re much more maneuverable," said Capt. Paul Overstreet, EA-18G program co-manager at Naval Air Systems Command (NAVAIR). "We have a weapons capability to protect ourselves."
NAVAIR’s current program of record calls for 85 new Growlers to retire all Navy and Marine Corps Prowlers between 2009 and 2012. The Northrop Grumman EA-6B entered service in 1971 as a standoff and escort jammer with a tactical jamming system tuned to enemy air defense radars. With successive upgrades, the Prowler acquired expanded frequency coverage, the Raytheon AGM-88 High Speed Anti-Radiation Missile (HARM), an integrated communications jammer, and network connectivity via the Multi-mission Advanced Tactical Terminal (MATT) and Improved Data Modem.
In addition to their air defense suppression role, EA-6Bs reportedly have flown in Iraq and Afghanistan to jam Improvised Explosive Devices and disrupt insurgent communications.
The Growler, now in the development test phase, uses the Prowler’s current Improved Capability (ICAP) III system as an AEA starting point. According to NAVAIR EA-18G co-manager, James Smith, "We took the ICAP III and did some technology insertion into that. It is one generation beyond the Prowler system today."
The EA-18G also integrates the modernized AN/ALQ-218(V)2 tactical jamming receiver and other AEA subsystems with all the features in the Production Lot 30 F/A-18F, including advanced mission computers, HARM air-to-surface and advanced medium range air-to-air missile (AMRAAM) capability, a Helmet Mounted Cuing System, Advanced Crew Stations and the APG-79 Active Electronically Scanned Array (AESA) radar.
‘Major Derivative’
The Growler adds about 1,400 pounds and 1.5 million lines of software code to a two-seat Super Hornet. "It’s a major derivative," explained Boeing EA-18G Program Manager Mike Gibbons.
Boeing nevertheless maximized hardware and software commonality with the F/A-18F, and Growler engineers have plans to further integrate strike fighter and electronic attack systems.
"We currently have a level of integration that’s consistent with a Block One system," said Gibbons. "… In the future we can do a better job. We can do more automatic cuing between the radar and the -218 (jamming receiver)."
Integrated with other Growler sensors, Raytheon’s high-resolution AESA radar, with synthetic aperture mapping and other advanced functions, promises to uncover more threat details than dedicated AEA sensors, and may focus advanced countermeasures on spot targets. "If you treat it as another aperture… our interest is both the jamming and receiver capability," said Overstreet. "How do we integrate that into our overall EA-18G mission?"
The Navy expects EA-18G mission capabilities to evolve once Low Rate Initial Production Growlers start arriving at Naval Air Station Whidbey Island, Wash., this May and achieve Initial Operational Capability in 2009.
Production Efficiencies
Boeing started internal studies of an airborne electronic attack Hornet/Super Hornet in 1993. With Air Force EF-111s retired in the late 1990s and Prowlers saddled with joint-service AEA, the Department of Defense ran an "Analysis of Alternatives" in 2001 and refined the study in 2003.
In December 2003, the Navy awarded Boeing a System Development and Demonstration contract for a Super Hornet derivative to replace the Prowler.
"A big driver for all of us has been the age of the platform," said Overstreet, who was an EA-6B Electronic Countermeasures Officer (ECMO). "We land on ships and take much more of a beating on a daily basis. There are only so many times you can replace metal before it’s time to go."
An AEA version of the new Super Hornet also leveraged the F/A-18E/F logistics and support infrastructure. "If you look at the air wing out there five years from now, it’s really going to be based on Hornets," Overstreet said.
Boeing sought to repackage Prowler AEA capability in the F/A-18F with minimal Super Hornet changes. "One of our tenets was to maintain commonality with the E/F platform for efficiencies in production," Gibbons said. Growler cockpit hardware and software, for example, are identical to that in the two-seat Super Hornet. However, though the Super Hornet had electrical power and cooling capacity to spare, the old Prowler, with its fin-top "football," had more space for AEA systems.
The EA-18G ultimately added 2,500 feet of new RF cabling and 66 antennas to the Super Hornet airframe. New antennas appeared on the Super Hornet nose barrel, aft fuselage and dorsal deck. But the most noticeable Growler change was the wingtip pods for the AN/ALQ-218(V)2 receiver in place of air-to-air missile rails.
A single-seat F/A-18E modified with EA-18G wingtip pods started flight tests at Patuxent River Naval Air Warfare Center in March 2006. The first purpose-built, two-seat EA-18G (G-1) flew in August 2006 and arrived at Patuxent River a month later. It was joined by a second test aircraft (G-2) in November.
Happily, the EA-18G in autumn 2007 was 200 pounds under target weight, providing margin for evolving capabilities.
Though the current Growler system is an evolution of the Prowler suite, the Northrop Grumman ALQ-218(V)2 wideband receiver at its heart is a digital system with advanced processing techniques. "That’s a significant enhancement," said Northrop Grumman EA-18G Director Steve Hogan. "It allows us to identify things and classify things like complex radars and threats."
The receiver is distributed around the Growler nose, mid-fuselage and wingtips. Most of the ALQ-218 and the associated Northrop Grumman Electronic Attack Unit occupy a nose pallet replacing the 20 mm cannon of the Super Hornet.
The Growler has a Raytheon AN/ALQ-227 Communications Countermeasures Set (CCS) in place of the Prowler’s BAE USQ-113 CCS to locate and jam enemy communications. The new digital receiver/exciter records, plays back and, through an ALQ-99 pod, jams more complex waveforms over a broader frequency range. It consolidates four avionics boxes into one.
The EA-18G also introduces an Interference Cancellation System (INCANS), made by ITT Electronic Systems, Communications and Countermeasures Systems, formerly EDO Corp. Communications and Countermeasures Systems, to enhance the situational awareness of the crew during the AEA mission.
In the EA-6B "when you radiate in the low band, we can’t talk when we’re jamming in the communications range," said Overstreet. "With the interference canceller, that finally allows us to communicate when we’re jamming."
Like the EA-6B, the Growler jams threat systems selectively with up to five ITT ALQ-99 transmitter pods mixed on underwing weapons pylons to cover different jamming bands. "The pods themselves have evolved over the years," said NAVAIR Growler co-manager James Smith. "They look the same, but the innards are quite different."
The Navy is defining its next-generation jammer with high- and low-band capabilities, but most ALQ-99 changes for the EA-18G were related to the stores management system that interfaces the pods with the aircraft.
The F/A-18E/F already offered a mix of data buses, and Boeing EA-18G avionics integration manager Tom Kniest explained, "We’re using those existing data bus structures to integrate data across the airplane." The Electronic Attack Unit, for example, connects with the mission computer through a fiber optic network. While the INCANS uses the same fiber channel network, the ALQ-218 receiver and ALQ-227 CCS use Ethernet protocols derived from the ICAP III Prowler. A Mil-Std-1553 bus ties in legacy navigation and jammer systems.
Two Crew
The EA-6B goes to war with a single pilot and two or three ECMOs. However, the pilot, with only flight controls and the right-front ECMO, with navigation and limited radar displays, have little access to electronic attack systems. Identical left- and right-seat displays in the rear cockpit, meanwhile, keep Prowler backseaters from working different systems simultaneously.
In the EA-18G, identical, independent displays with Hands-On-Throttle-And-Stick functionality give both front-seat pilot and back-seat ECMO access to all aircraft and mission information. "If I do something in back, the pilot can see it," said Overstreet. A half-dozen new Growler display formats correlate inputs from on-board sensors and off-board LINK 16/Multifunctional Information Distribution System (MIDS) intelligence sources in a coherent picture.
Northrop Grumman built an EA-18G Systems Integration Laboratory in Bethpage, N.Y., to develop Growler software and make sure AEA systems were compatible with one another and a crew of two.
"We did quite a bit of workload studies," said Engineer Chris Falco, who worked on the complex EA-18G crew coordination issues. "We obviously were looking at the piece of the AEA suite and how we could do some of the functions automatically. We were able to drive down the workload from two guys in the back seat to one operator."
A Growler crew station design advisory group used NASA workload ratings to refine the EA-18G Data Correlation Mechanization. "I think the basic displays are very similar between a Prowler and a Growler," Falco said. "We don’t provide as much detail in the Growler at the top level. We kind of roll it up into a higher level." Full detail nevertheless remains available to the EA-18G operator who drills down into the AEA system.
The Growler crew will also manage new capabilities never available in the Prowler. In contrast to the limited EA-6B radar, for example, the AESA radar in the EA-18G tracks multiple air and ground targets. "For an old Prowler guy, I’m thrilled to see the ground and another airplane out there," said Overstreet.
L-3 Communications Link Simulation and Training is building three EA-18G crew training simulators to be used at Whidbey Island. Growler simulators will be identical to those built for Super Hornet crews, but Boeing will integrate software to provide an AEA threat environment.
The Growler community has just begun learning to crew its new strike-fighter-jammer, and according to Overstreet, "We are finding that the optimum mixture is a guy with Hornet experience in the front and a Prowler person in the back."
EA – 18G Growler Major Suppliers
Following is a list of major suppliers involved in the U.S. Navy’s EA-18G Growler program, provided by prime contractor Boeing.
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Northrop Grumman EW Systems, Bethpage, N.Y.: Airborne Electronic Attack (AEA) system, including AEA subsystem design, development, integration, and test.
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Northrop Grumman Air Combat Systems, El Segundo, Calif.: F/A-18F aircraft center/aft structure.
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Northrop Grumman, St. Augustine, Fla.: Wing tip pod structure, cables and harnesses.
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Northrop Grumman Electronic Systems, Baltimore: ALQ-218 Receiver.
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Northrop Grumman PRB Systems, Maryland and California: Software development for Electronic Attack Unit (EAU) of AEA system controller.
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Northrop Grumman, Logistics Tech Center, Melbourne, Fla.: Logistics support of AEA subsystem.
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GKN Inc., St. Louis, Mo.: Fabrication of complex sheet metal and machined components.
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Harris Corp., Melbourne, Fla.: Data Memory Device (DMD).
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Alion Science & Technology, Inc., Annapolis, Md.: Electromagnetic compatibility analysis.
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ITT, Thousand Oaks, Calif.: Interference canceling system.
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Mnemonics, Inc., Melbourne, Fla.: Electronic Attack Unit.
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Raytheon, Fort Wayne, Ind.: Communications Countermeasures Receiver (CCS). Raytheon in Largo, Fla., will provide CCS receiver antenna.
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Times Microwave, Wallingford, Conn.: RF/IF coaxial cables.
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Ball Aerospace, Westminster, Colo.: MATT antenna.
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Nurad, Baltimore: Wingtip pod radome.
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Cobham Sensor and Antenna Systems, Lansdale, Pa.: Low band antennas.