When it comes to the US Navy's plans for the Boeing F/A-18, the E/F upgrade is only the start. Having tackled the original airframe's deficiencies, the navy is now keen to get to grips with the limitations of the current avionics.
"We used around 90% of the C/D's avionics to keep the costs down. Now that we are getting close to completing testing, it is time to start making the leap to the next generation of avionics," says Paul Summers, Boeing's manager, F/A-18 new product development. "Around 2005, we will get next-generation avionics into the aircraft."
The baseline for the E/F's avionics at entry into service in 2001 is the latest C/D production standard, known as Block 19. This encompasses a number of upgrades, including the APG-73 multi-mode radar.
Additionally, the avionics baseline incorporates upgrades under development for both the C/D and E/F, including the Advanced Target-ing Forward Looking Infra-Red (ATFLIR) sensor, Joint Helmet-Mounted Cuing System (JHMCS) and Multifunction Information Distribution System (MIDS).
Beyond these improvements, a number of E/F-unique upgrades are planned, ranging from the Integrated Defensive Electronic Countermeasures (IDECM) system already under development, through new mission computers and displays to the hoped-for active electronically scanned array (ASEA) radar.
Boeing's aim, says Summers, is to create an infrastructure that allows continued development of the E/F for the US Navy - and for international customers. "The [Eurofighter] Typhoon and [Dassault] Rafale are good platforms which represent a leap in capabilities. The E/F has to compete," he says.
A technology block upgrade is planned by 2005 that would incorporate many of the advanced features desired by the navy and required for the E/F to be competitive on the export market. The upgraded aircraft would also form the basis of planned derivatives of the E/F, including a command and control warfare (C2W) variant that could replace USN Northrop Grumman EA-6B jamming aircraft.
NEW INFRASTRUCTURE
The basis of the block upgrade is a new avionics infrastructure built around advanced mission computers and displays. Two "commercially based" computers will replace the F/A-18's AYK-14 mission processors, which have run out of throughput and memory, says Summers. The new computers will provide more processing power and growth capacity, and will be upgradable when the next generation of commercial processor comes along, he says.
Boeing has been working on commercially based mission computers under its Bold Stroke initiative. The first production application is the OSCAR programme to replace the AYK-14s in US Marine Corps AV-8Bs. The E/F computer upgrade will offer commonality. "The hardware will be identical and they will both use the same software language and operating system. They will have different operational flight programs, but through Bold Stroke we will make them as common as possible by reusing software modules," he says.
The two multifunction side displays carried over from the C/D will be replaced by liquid-crystal displays, increasing colour capability and sunlight readability. At the same time, the E/F cockpit will transition from "smart" displays, which do their own processing, to "dumb" displays, with all processing performed in the new mission computers. "We have added a very high speed databus between the computers and the displays so they can do all the display processing and not run out of bandwidth," he says.
Another piece of the block upgrade already under contract is the ATFLIR pod. This is being developed by Raytheon Systems to replace the navigation and targeting FLIR pods carried by the F/A-18. "The ATFLIR combines targeting, navigation and laser in one device," says Summers.
The ATFLIR features a "third-generation" midwave infrared sensor, incorporating a staring focal-plane array with twice the performance of existing longwave FLIR systems. "The real benefit is extended range, which is needed for the advanced weapons that are coming," says Summers. The existing FLIR has limited range and resolution, he says, and the ATFLIR will allow target recognition at longer ranges compatible with the maximum capability of the GBU-24 laser-guided bomb and Joint Direct Attack Munition (JDAM).
LOOKING AHEAD
Raytheon (formerly Hughes) was awarded the ATFLIR development contract in March last year, but had been working since September 1997, says deputy programme manager Dave McGorrin, "...to get a head start". A prototype pod has been built on company funds, "...to get things rolling", and 10 developmental units will be delivered beginning in July.
"The schedule is very short, to get the system into the customer's hands," says McGorrin. Flight testing on the F/A-18 is to begin in November, and initial operational capability for the ATFLIR is set for 2002, to coincide with the first deployment of the E/F. A total of 550 pods is planned, and the ATFLIR will also be compatible with the C/D.
The 680 x 480-element staring array sensor at the heart of the ATFLIR is used in Raytheon's other midwave FLIRs, including that for the Bell Boeing V-22, McGorrin says. Other components include the laser rangefinder/designator, laser spot tracker and the staring-array navigation FLIR, which is supplied by GEC Marconi and packaged into the adaptor pylon mating the pod to the intake stores station.
Target detection and recognition ranges are three to four times those possible with the F/A-18's existing AAS-38 Nite Hawk targeting pod, McGorrin says. The ATFLIR's "open systems" architecture is designed with growth in mind, and future enhancements planned include air-to-air and automated targeting modes.
The ATFLIR will contribute to another part of the planned E/F block upgrade - precision strike capability. Says Summers: "This is actually a series of incremental upgrades, most of which are funded and will be in the aircraft before 2005. The [Grumman] A-6 had a unique capability to drop dumb weapons very accurately in weather. This upgrade will give the E/F the capability to deliver smart or dumb bombs very accurately."
Elements include the MIDS, which will give the E/F crew access to offboard sensor data via the Link 16 secure, jam-resistant datalink. An international consortium, MIDSCO, is developing a low-volume datalink terminal small enough to be installed in the F/A-18.
The ATFLIR's increased targeting range will be augmented by new modes for the APG-73 radar. These will give high-resolution synthetic aperture radar (SAR) ground imaging capability that is "fairly fantastic", says Summers. "We will be able to pinpoint targets at extended range with the radar."
The SAR modes have been developed under Phase 2 of a radar upgrade that replaced the F/A-18's original APG-65 with the improved APG-73. The first phase involved upgrades to increase processor throughput and memory, improve the power supply and increase receiver/exciter bandwidth, and was intended to provide growth capacity and increase reliability. Bill Yates, Raytheon Systems' F/A-18 radar programme director, says: "We now have expansion capability of 40% in throughput and memory." Phase 2 added a motion sensor subsystem and other changes to allow the APG-73 generate high-resolution ground maps. The capability to produce SAR strip and spot maps is presently installed only in US Marine Corps F/A-18Ds, but is available for the E/F. "All the software and hardware is developed," Yates says.
INTERLINKED UPGRADES
Two major elements of the planned block upgrade are interlinked - the ASEA radar and an independent aft crew station for the two-seat F/A-18F. Initially, the F is configured as a combat-capable trainer, without the "missionised" aft cockpit developed for USMC night attack Ds. Says Summers: "The navy position is that the two-seater is needed for high-workload, edge-of-the-envelope missions such as all-weather air-to-ground."
The plan calls for an advanced aft crew station to be introduced with Fs built from late 2004 onwards. Design changes are extensive, and centre on a new large, 200 x 250mm, colour liquid-crystal display. The front and rear cockpits will have independent digital maps, multifunction displays, and sensor and radio operation. New hand controllers will give the aft crewmember, for the first time, the ability to release weapons.
The plan calls for both crewmembers to have the JHMCS helmet-mounted display. Under development by Vision Systems International, a Kaiser/Elbit joint venture, the JHMCS will allow either crewmember to cue weapons and sensors visually. The head-tracked display projects symbology on to the helmet visor, providing a 20í monocular field-of-view. Flight testing has begun on the F/A-18, and the helmet-mounted sight - and associated AIM-9X air-to-air missile - are planned to be operational on the E/F when it enters service in 2001.
Development of the AIM-9X, by Raytheon Systems, is also under way, and flight tests on the F/A-18 are due to begin early this year. The improved Sidewinder short-range air-to-air missile features an imaging infrared seeker that provides increased acquisition range and, combined with improved airframe aerodynamics and kinematics, allows higher off-boresight target engagement capability.
Fully exploiting the independent aft crew station's capabilities is tied to the ASEA radar, and its ability to operate almost simultaneously in different modes. The upgrade is expensive, Summers acknowledges, and the navy has yet to identify funding, so Boeing plans to fund initial work jointly with the radar supplier. "The ASEA is a warfighting tool par excellence. It changes the nature of the aircraft," Summers says. "We want to get the radar into the fleet as early as possible, to forward fit as many aircraft as possible."
Air-to-air detection range will be increased by a factor of two to three, he says. Survivability will be improved "dramatically" because of the reduced radar signature of an active array. The antenna will capable of being used for suppressive jamming as well as for passive attack - the ability to detect and isolate other emitters.
The plan calls for the APG-73 to be upgraded with an ASEA, enabling earlier E/Fs to be retrofitted. The navy hopes to be able to fund development beginning in 2001, enabling the upgraded radar to be fielded around 2004/5, and allowing the forward fit of between 260 and 320 of the 548 E/Fs planned.
FOUNDATION FOR THE FUTURE
The block upgrade is the foundation for potential E/F derivatives, beginning with the C2W variant. The navy has an unfunded requirement for 100-140 aircraft but, since Boeing joined forces with Northrop Grumman in 1995 on an electronic warfare variant of the F, the design has changed substantially. The original plan was to develop an all-new receiving and jamming system, based around a multiband electronic attack pod allowing stealthy, supersonic operation. This approach proved too expensive and risky for the navy, says Summers.
"They want us to use as much existing hardware as possible, get the aircraft into the fleet in this configuration, then transition to the advanced system." The latest C2W configuration to be proposed, therefore, uses existing EA-6B jamming pods and is a third of the cost of the original design.
Beyond the block upgrade, and the development of derivatives like the C2W, lies the potential for further long-term growth, Summers says, and the evolution of the F/A-18E/F into the "next-generation Hornet".
Source: Flight International
