All the ultra-modern capability of the Boeing F/A-18E/F Super Hornet's Block 2 upgrade will soon be coming together
Less than a year from now, US Navy technical evaluation pilots at China Lake, California will be turned loose on the first production representative examples of the Boeing F/A-18E/F Super Hornet fitted out with all the elements of the long-awaited Block 2 upgrade.
This milestone, which paves the way towards operational evaluation in February 2006 and planned initial operational clearance the following September, opens the route to the most significant step change in overall capability since the original Super Hornet programme was launched in 1992. At the core of the upgrade is the highly capable Raytheon APG-79 active electronically scanned array (AESA) radar which, at a stroke, allows the Super Hornet to take pole position among the most modern of 21st century fighters.
The upgrade, which includes a wide array of cockpit display, computing, countermeasures and other system and sensor improvements, is also one of the most comprehensive ever undertaken on a US Navy aircraft and gives the F/A-18E/F not only a key role in the network-centric environment, but also a sharp competitive edge for forthcoming export contests for the rest of the decade. Block 2 is also a vital stepping stone towards the US Naval Aviation Plan, which sees the Super Hornet and Lockheed Martin F-35C as the two main elements of the future carrier air wing. By embracing the roles of all-weather precision attack, maritime strike, close air-support, air-defence suppression, air superiority, electronic attack, reconnaissance, fighter escort and tanker, the Super Hornet and F-35 will together replace earlierF/A-18A/Cs, Lockheed S-3Bs and Northrop Grumman F-14A/Ds and EA-6Bs.
Fitting out the Super Hornet for such flexibility involves more than simply plugging in the new equipment, says Randy Harley, programme manager for what was to become known as engineering change proposal (ECP) 6038. Radical surgery was required on the front fuselage to encapsulate the AESA, its greater liquid-cooling requirements and five additional new mission systems, including a much larger 200 x 250mm (8 x 10in) tactical display in the aft cockpit. "We were after two primary things - to enhance the war fighting capability of the aircraft and, second, we wanted to significantly reduce the recurring unit cost of the forward fuselage," says Harley. Boeing set goals of a 25% cut in unit costs, a 50% cut in cycle time and a 90% reduction in defects. Making these tough targets even harder to achieve were the demanding constraints imposed on the scope of the redesign by having to stay within the existing outer mould lines.
"We also had to maintain the existing in-flight refuelling probe interface, the pilot's eye location, the same windscreen and canopy, gun position, nose landing gear and interface, and we wanted to keep the equivalent stiffness," says Harley. "The big issue was the splice and the interface loads where it joined the [Northrop Grumman-built] centre fuselage at station Y383.0." Ultimately, ECP 6038 involved redesigning 81% of the forward fuselage, taking out 40% of the detailed parts and 51% of the fasteners. At the same time, Boeing faced the challenge of slotting the major redesign into the existing production line without causing an interruption or delay. "It was like a development programme within an aircraft production programme," says Harley. "We didn't have an engineering and manufacturing development phase. This was introduced into full production, and we have done it seamlessly into both the overall programme and into the fleet."
Boeing took the opportunity of ECP 6038 to invoke significant and long-lasting changes in its product design and definition methodology. "We were already going from mylar drawings and wire-frame models to solid models," says Harley. "This time we did it paperless from 3D models, including all product definition, buy-in packages and work instructions." To hit targets and keep costs from rocketing out of control, Boeing adopted a rigorous integrated product team approach to the redesign. "We got together a team that worked together on subsystem redesign, product definition, procurement, the assembly process, capital equipment, the layout of the facility and delivery of the work instructions. What started out as an airframe redesign soon affected all the disciplines," he says.
Lower parts count
Going back to basics to make it affordable, the IPT started by replacing costly sheet-metal fabrications with monolithic structures with a lower parts count. Even composite parts, such as skins, were simplified by eliminating cores or stiffeners. "We had daily 'virtual reality' reviews involving everybody in the product redesign and the flow," says Harley. "Both production people and engineering folks thought I was crazy at the start when I asked them things like 'what's your favourite fastener and hole size and we'll only use that'."
The advanced design was also aimed at achieving a neutral weight impact at completion. "You can't afford growth, so at the very beginning we took away 10% of all the team's weight allowances," says Harley. At the start of the ECP 6038 effort in February 2000, the overall target weight of the forward fuselage was reset at about 150lb (68kg) below the neutral point and did not cross the "zero" line until September 2001. Although Boeing declines to specify exactly where the production unit now rests, figures shown to Flight International indicate the weight performance stayed at or slightly below the neutral line from 2002.
Simplified design and assembly concepts led to major improvements in areas such as the Z111 cockpit floor, where the parts count was reduced by 54% from 177 to 81, and fasteners cut by 66% from 2,373 to just 798. Similarly, the lower cheek skin assembly, previously comprising 20 formers, three skins and 461 fasteners per side, was redesigned with just two formers, two skins and 278 fasteners per side - a cut of 83% in parts and 40% in fasteners.
The cheek redesign was also key to accommodating the higher-capacity liquid cooling system (LCS) of the 16kW APG-79 and to simplify subsystem integration. The system uses about 26.5 litres (7USgal) of polyalphaolefin, a synthetic coolant more efficient than the traditional glycol/alcohol mix used in previous applications, which quickly cycles through to dump excess heat into the fuel and engine exhaust to maintain a radar system target temperature of 27°C (80°F), ±10°.
Changes to the design process also led to streamlining of the St Louis Super Hornet production line with four new splice tools, and compact nose barrel and lower fuselage assembly lines occupying the space formerly used by eight low-rate expandable tools, four of which have been converted to splice tools.
Certification of the redesign has been taking place using fatigue/static test airframe FT76, an existing F/A-18 test article. Two full-lifetime fatigue tests were completed before a full static test was run, during which the specimen was subjected to 150% of design limit load. "We are 100% through the tear-down of the forward fuselage looking for cracks and we've only found 14 so far - and they're all extremely minor," says Harley. The structure has also completed acoustic and ground vibration tests, as well as a series of flight tests using the first ECP6038-fitted airframe, F84. Flight tests of the two-seater included catapult launches and arrested landings, cockpit noise, vibration and ground gunfire tests.
As well as achieving major cuts in parts and fastener counts, the new forward fuselage takes 26% fewer "standard hours" to complete, has 80% fewer defects than the former unit and can be produced with a 31% reduction in cycle time and at 23% less cost. Overall, the ECP6038 exceeded its unit cost reduction goals by 41%.
Boeing is well on with implementing the Block 2 upgrade, which is being introduced progressively from production Lot 26. The AESA radar - the highest-profile element of the upgrade - will be installed in 280 new-build F/A-18E/F and EA-18G aircraft, as well as being retrofitted from 2007 in up to 135 E/Fs built from Lot 26. Flight tests of the radar began last July on a single E and two F (Lot 26) models at the US Navy's China Lake Centre in California. A series of operational tests (OT) coming up this month and August will be pivotal to a favourable LRIP 3 (low-rate initial production) decision in December covering 22 AESA-equipped aircraft in the forthcoming Lot 29 production batch, with an LRIP 4 milestone due in December 2005. Eight aircraft in Lot 27 will be AESA-equipped, and all aircraft from Lot 28 will be fully provisioned.
Tests to date have proved "extremely favourable", according to F/A-18E/F AESA programme manager Don Thole, who adds: "By December, all functionality will have been introduced. We're getting five times the reliability in terms of what we get with the [mechanically scanned] APG-73, so the life-cycle cost savings are going to be huge." The radar's solid-state "Generation 6" transmit/receive modules, for example, have no maintenance requirement for 20 years. Significantly higher-resolution synthetic aperture radar (SAR) imagery has been captured during the California tests, which have concentrated on ground imaging for the air-to-ground role as well as airborne target acquisition and tracking for the Super Hornet's enhanced air-to-air mode.
The "inertialess" electronically scanned beam also allows air-to-air and air-to-ground modes to interleave sequentially, giving the effect of virtually simultaneous capability in both modes. The AESA processing capabilities also allow the pilot to scan in air-to-air mode, while the aft crewmember uses the radar for air-to-ground tasks. "We never, ever thought we would have this capability so soon," says Thole. Technical evaluations, involving the US Navy's VX-9 dedicated OT unit, are scheduled for May 2005 after completion of an "expanded OT" test period in March and April. Six of the eight AESA aircraft from Lot 27 are then due to enter operational evaluation (opeval) with the navy around February 2006. "This will involve carrier performance and EMI [electromagnetic interference] testing at Patuxent River, Maryland," he says. Opeval is due to be undertaken by fleet evaluation pilots from VX-31 before initial operational capability (IOC) in September 2006.
An earlier element of Block 2, the Raytheon-developed ASQ-228(V) Advanced Targeting Forward-Looking Infrared (ATFLIR), achieved IOC in September 2003 after Opeval with VX-9, which it "passed with flying colours", says Boeing ATFLIR programme manager Dave Weissgerber. The third-generation targeting pod replaced three pods on earlier F/A-18s, and has already seen active service in Afghanistan and Iraq. "The pod has unrivalled capability to discern the latitude and longitude of a point on the Earth from its zero-point line of sight," adds Weissgerber, who says moving-target tracking capability will be added in later upgrades. The system provides target detection/recognition ranges up to five times further than previous targeting pods.
Mounted by the engine intake, the pod houses a mid-wave IR, electro-optical (EO) camera and both tactical and training laser rangefinder/designators, all sharing a common optical path. There is also a separate laser spot tracker "to get target data, which fits in with what we're doing for network-centric capability", says Weissgerber, who adds the tracker gives the aircraft crew "the ability to work with the snake-eaters [ground troops]". The system can also be fitted with a navigation FLIR in a pod adaptor, "but the navy is probably not going forward with it", he adds. A follow-on test and evaluation of the laser spot tracker and EO is under way as part of the Block 2 development. Full-rate deliveries of the ATFLIR begin in February 2005.
The latest upgrade also introduces the full-up Integrated Defensive Electronic Counter measures (IDECM) capability first introduced with the Block 1 standard. This includes the Northrop Grumman ALQ-214 techniques generator and the radio-frequency countermeasures system's associated BAE Systems ALE-55 fibre-optic towed decoy. Thole describes this as an essential part of a suite that shows "less of a brute-force integration". He adds: "We are making sure the various parts don't step on each other by integrating the whole system first in the lab. From the RF compatibility standpoint, we've done some initial flight testing, which will continue to the end of the year."
Behind the scenes, the vast amount of AESA radar and sensor data travelling throughout the Block 2 system is handled by an extensive Harris-developed fibre-optic network and a more powerful advanced mission computer (AMC). The fibre-optic data network has more than 1,000 times the throughput of the conventional 1553B databus, and allows for capacity to handle high-resolution digital video. The ultimate aim is to provide the crew with greatly enhanced situational awareness. "It's all about getting the data to the pilot more quickly so they can have more time to think," says Thole. Tactical aircraft mission systems director Shelly Lavender adds: "We've gone from having data, to having information, to having knowledge. The decision time is compressed and the whole 'kill chain' comes down."
Two redundant Fibre Channel network switch (FCNS) units are fitted to each aircraft, together providing a total of 16 independent input and output channels. Each channel provides a 1Gb serial network link to other Fibre Channel-equipped avionics systems networked to the AMC. Harris is also developing the Fibre Channel network interface controllers (NIC) used for the AESA radar, with each NIC providing a 1Gb serial network link to other AESA radar systems.
The AMC is being updated as a direct result of the increasing data throughput in Block 2, the inevitable onset of obsolescence and the coming requirements of network-centric warfare. The initial plan was based on evolving the General Dynamics Information Systems-developed AMC Type I version, used in Block 1-standard aircraft, into a more capable AMC Type II. This was based on the PowerPC G4 processor, but with the capability to upgrade using "object-oriented" or compartmentalised software modules.
However, as the pace of change threatened to overtake the planned capabilities of even Type II, in 2003 Navair's F/A-18 programme office brought together a team that was tasked with developing an upgraded AMC Type III. "It is a highly aggressive schedule, but we felt we needed to add capability for the Lot 30 jets," says F/A-18 mission processing team leader Tim Brunns.
The team included Boeing, General Dynamics, Honeywell and the F/A-18 Advanced Weapons Laboratory at China Lake as well as the Patuxent River, Maryland-based programme office, and worked together to produce a new design in less than four months. A preliminary review was held at the start of 2004, and a critical design review for the Type III took place in late June. Leveraging commercial off-the-shelf technology, the new AMC will use thefourth version of C++, a high-order language (HOL), allowing the same software module concept originally developed for AMC Type II to be used in the newer processor.
"There are over 1.5 million lines of C++ software code," says Brunns. "We write that at Boeing and it enables us to rapidly integrate new systems." The use of object-oriented design software in an open-system architecture has completely transformed the programme, says Brunns. "Previously, in Lot 23 and 24, it was slow and intensive to add new capabilities. Now with HOL it's a lot easier." HOL Version 2 is now being supplied in production aircraft, with HOL Version 3 in test to support initial Block 2 aircraft. The AMC Type III with HOL Version 4 is due to be supplied in Lot 30 aircraft as well as retrofitted into aircraft already serving in the fleet starting in 2007, and will be a key enabler to development of the EA-18G.
The new AMC will also help development of the advanced crew station in the two-seat F/A-18F, the only fully integrated two-crew tactical aircraft planned for the carrier air wing in 2015. As the intended replacement for the F-14 in both air-superiority and precision-strike roles, the new aft crew station has become even more critical since the go-ahead of the EA-18G. Driven by the need for increased operator functionality, the upgrade supports decoupled cockpits, allowing simultaneous air-to-air and air-to-ground capability. The redesigned cockpit is dominated by the 200 x 250mm full-colour liquid-crystal advanced tactical display flanked on both sides by 130 x 130mm multifunction LCDs. A touch-sensitive "upfront control/display" data entry panel is situated directly above the tactical display, prominently mounted above the glareshield.
The big display, with 30% more area than the 130 x 130mm cathode-ray tube it replaces, will also provide higher resolution to support digital sensors including the AESA, ATFLIR and the SHARP reconnaissance pod. To drive the display, the tactical aircraft moving-map capability (TAMMAC) is upgraded with a digital map computer (DMC) that allows independent maps to be displayed in front and rear cockpits. Harris is also integrating a US Navy-developed early terrain awareness warning system (eTAWS) into the TAMMAC DMC. A card with an image processing module is being added to the AMC to drive the tactical display, which will be in production aircraft from Lot 28, starting in 2005.
Beyond Block 2, Boeing is focused on developing EA-18G and "Block 2 Plus" - a spiral upgrade path keeping pace with the evolving world of network-centric operations. "We are taking a two-pronged approach," says business development manager Bob Farmer. "We are getting information about network-centric requirements and we are focusing on precision multiple-target engagement. That means talking about areas such as unmanned air vehicle co-ordination, tasking things in flight, forward air control, mission tactical reconnaissance, close air support and, of course, network-centric operations. Block 2 provides capabilities, but we are continuing this growth and we're laying out a road map for getting a whole new set of capabilities in terms of sensors, weapons and materials."
Live network-centric demonstrations in 2003 using the first two-seat F1 aircraft will be extended by early 2005 to "include broadband capability, and will lead eventually to working with UAVs," says Farmer. By then the first Super Hornet Block 2 pilots will be discovering the potential of the upgraded aircraft.
GUY NORRIS / ST LOUIS
Source: Flight International