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Tuesday, May 1, 2001

JSF Down the Wire

Downselect for perhaps the largest fighter aircraft program ever is scheduled only months away. Demonstrator aircraft are flying. We look at how development of thecompeting avionics packages fared.

James W. Ramsey

Competition for the multiservice, multinational Joint Strike Fighter (JSF) program is tightening between Boeing and Lockheed Martin. Small wonder. The JSF program is cited as one of the largest fighter production programs ever: up to 5,000 aircraft worth $300 billion. Both Boeing and Lockheed Martin submitted their engineering and manufacturing development (EMD) phase proposals in February, on schedule, and are now awaiting the U.S. Defense Department decision to select a program winner, expected this October.

Three versions of the multirole JSF are being developed currently for four customers:

  • The conventional takeoff and landing version (CTOL) for the U.S. Air Force, to replace the F-16 and A-10;

  • The carrier-based (CV) version for the U.S. Navy and U.S. Marine Corps, to replace the F/A-18E/F;

  • And the short takeoff and vertical landing (STOVL) version, to replace the Marine Corps’ AV-8B and the UK Royal Navy’s and Air Force’s Sea Harrier and GR.7.

Other countries, too, are showing interest in this flexible fighter.

The U.S. Department of Defense has made affordability a top priority for the JSF program–not just affordability in operation, but also in the aircraft’s development. So, with the downselect nearing, Avionics Magazine decided to examine the development efforts for electronic packages proposed by the two teams.

The Boeing JSF

Utilizing its 737-200 Airborne Flying Laboratory (AFL), Boeing claims it has achieved its major goals during tests of its avionics package for JSF. These included demonstrating multisensor integration, combined with an open systems architecture approach to allow future updates.

In addition, according to Karl Timm, Boeing’s JSF AFL manager, "The preferred weapon system concept [PWSC] has been defined and is in our proposal for the EMD phase of the program."

Also, Boeing showcased its capability to generate pilot-vehicle interface (PVI) software using off-the-shelf design tools. The same process in the EMD phase, Boeing claims, will reduce software development costs. To decrease avionics systems development risk, Boeing also had potential customer pilots from the U.S. Air Force, Navy and Marines, and UK forces conduct mission simulations, using the AFL.

The converted B737 jetliner was intended to reduce costly flight test hours by enabling evaluation and troubleshooting before the avionics are installed on an actual Joint Strike Fighter. Boeing tested sensors on the AFL, using military targets under realistic conditions.

However, the focus has not been on the sensors alone, but on "taking the computer, which is a whole bunch of commercial computing boards that are high-speed networked together, and showing that we can integrate the sensors and the software architecture and make it run," says Rod Leitch, AFL mission systems lead engineer.

Boeing and team members Raytheon (radar) and Sanders (electronic warfare system) began testing the Boeing JSF’s integrated avionics on the AFL in December 1999. Avionics testing culminated Aug. 21, 2000, after 75 mission flights and nearly 170 flying hours. Boeing subsequently began dismantling the B737 for another unspecified program.

Twenty-two engineers would board a typical AFL flight, to test systems and analyze results. Equipment racks and operator seats were installed throughout the 737’s cabin. Test director stations and instrumentation consoles also were mounted in the AFL, with room for observers in the front and back. Each station for the engineers included a personal computer using Windows NT. An intercom system allowed engineers to monitor radio communications from the ground and from the 737’s pilots, i.e., gain outside-world information.

Equipment on-board included General Digital flat panel displays, for the engineers’ stations, an example of commercial off-the-shelf (COTS) technology used on the program.

The JSF’s integrated avionics were operated from a simulated cockpit, installed in the forward section of the AFL cabin. The cockpit included multifunction displays, as well as a throttle and stick. The integrated core processor mounted near the middle of the cabin was a brassboard for the computer to be used on the actual JSF. Instrumentation on the AFL had the capacity to record data from at least 10 flights, Leitch says, and the test director was provided video recording (to record JSF cockpit display imagery), the ground truth and telemetry display, and some engineering displays.

Test Highlights

Last June, Boeing demonstrated the JSF’s integrated weapons system capabilities during a live-fire exercise conducted in conjunction with an Air Force F-15 at White Sands Missile Range, N.M. During the exercise, the JSF’s mission systems suite in the AFL combined targeting data from on-board and off-board sensors, providing refined targeting information to the F-15, which attacked the target.

The AFL used its Joint Tactical Information Distribution System (JTIDS) to send and receive information to the F-15 in LINK-16 data format. JTIDS enabled the AFL to receive off-board data and then process and transmit it. The AFL’s on-board sensors also provided a target damage assessment to both airborne and ground-based exercise participants. The JSF system’s ability to obtain information via off-board systems allows the pilot to locate and attack enemy targets without emitting signals, making the aircraft less vulnerable to detection.

In the live-fire exercise, the F-15 did not emit any signals since its target data came from the AFL (JSF), according to Dan Cossano, JSF avionics manager. "The ability to fuse inputs from multiple sensors, and display the information in an easy-to-use format for the pilot and other members of the joint force is a key element of the Boeing JSF mission systems suite," he adds.

This multisensor fusion was demonstrated during earlier flights when the synthetic aperture radar (SAR) and targeting forward-looking infrared (TFLIR) collected target-area information. Automated target-cueing software processed this information to locate and identify the targets. The resulting data was fused to present the pilot with a composite situation display. Additional target information, detected by the electronic warfare sensor, also was fused, allowing the pilot to locate and identify the threats without emitting signals.

Boeing claims to have accomplished each function using COTS equipment. Combining data from multiple sensors helps the pilot more quickly determine target and threat location and take the appropriate "attack" or "evade" steps faster, Timm says, adding, "Our multisensor fusion solution will free the pilot from having to actively manage data flow in the cockpit."

The JSF sensor suite includes Raytheon’s radar and infrared for missile warning (IRST), search, track and targeting; Sanders electronic warfare (EW), which detects enemy radar; and TRW’s communications, navigation and identification (CNI). The TFLIR, mounted in a turret on the bottom of the aircraft, is borrowed from an SH-60B LAMPS III helicopter. Radio frequency (RF) and electro-optical (EO) sensors also are on Boeing’s JSF. Used with the JSF’s helmet-mounted display (HMD), the sensors provide the pilot primary flight, defensive threat, and target information along with a panoramic view of the surroundings–all displayed on the helmet visor.

Radar Change-Out

Another key program highlight, according to Boeing, was change-out of the radar. The company swapped an earlier radar for the JSF with a lower-weight, lower-power version of the Raytheon active electronically steered array system. It would be much like the radar used in production aircraft; no exterior modification is required for the change-out.

While Raytheon has been the radar system supplier during the AFL tests, the JSF architecture will allow for a different radar, as was proven by the change, Timm says.

"We started the day after we got back from the live-fire exercise, took the radome off, and 11 days later had the airplane flying with the [new] radar working with the same or better performance in both the air-to-air and air-to-ground modes, fully integrated," Leitch says.

"Plug-and-play we call it," Timm interjects, referring again to the open systems architecture.

"We run multiple versions of software and also run multiple copies of software," says Leitch. "We run certain pieces–one from one company, one from another–and run both simultaneously.

"We can switch back and forth," he adds. "The system certainly does not have everything it needs for the real jet, but we have made a lot of progress in demonstrating what kind of architecture we have to have."

Simulations

In addition to tests in the AFL, Boeing last June conducted simulator exercises designed to demonstrate that the company’s weapons system concept meets customer requirements. Boeing completed the fourth and final week-long mission simulations at its Seattle facilities with pilots from the four customer services flying 100 simulated air-to-air and air-to-ground missions. The manufacturer incorporated data gathered from several sources, including the AFL, into the simulation.

Using operational mission scenarios, Boeing demonstrated new functions for two-ship operations, its intraflight data link, and its off-board data information concept. It also showed improved capability for features simulated in the first three demonstrations. Those features were air-to-ground and air-to-air weapons deployment, sensor management, sensor fusion, and radar and pilot-vehicle interface.

In a two-hour exercise monitored by U.S. government JSF officials, Boeing linked its JSF full mission simulator in St. Louis with four high-fidelity, networked F-15 operational training devices (simulators) at Eglin AFB, Fla. The training scenarios, with JSF and F-15 pilots flying together in the same threat environment, demonstrated how aircrews at different locations, with different types of aircraft, can practice JSF-type missions together via a government-standard high-level architecture (HLA) data network. (HLA is a protocol that ensures simulation devices can talk and share data over the network.)

The networked F-15C mission training devices, provided by Boeing, are part of a U.S. Air Force initiative to create a joint synthetic battle space. The devices at Eglin are regularly networked with an identical setup at Langley AFB, Va.

"The demonstration shows we are already successfully using our full mission simulation to support JSF training requirements," says Dixie Mays, Boeing JSF training manager.

Boeing also has tested a full-scale "pole model" of the JSF in the anechoic chamber at its Seattle facilities, checking radar cross-section signatures and performance of built-in antennas on the stealth aircraft. Raytheon and TRW supplied the sensors. The antenna performance exceeded expectations, Boeing says.

Boeing’s actual JSF aircraft is designated the X-32A. The concept demonstrator, used as both the CV and the CTOL variants, made its maiden flight Sept. 18, 2000, and completed flight tests on Feb. 3, logging 50 flight hours. The X32B STOVL variant was scheduled to first fly in late March.

The Lockheed Martin JSF

Lockheed Martin, like Boeing, has completed development and integration of its version of the Joint Strike Fighter’s avionics systems under the competitive phase of the program. And like Boeing, the Lockheed Martin team has used a flying laboratory, a converted BAC-111, to test and validate mission systems.

Although two months behind Boeing’s Airborne Flying Laboratory in beginning flight tests, the Cooperative Avionics Test Bed (CATB) aircraft, provided by program partner Northrop Grumman, has logged more than 100 hours of flight test hours. And like its competing test aircraft, the CATB was instrumental in validating systems integration and sensor fusion while in flight, Lockheed Martin maintains.

The company says it has defined the preferred weapon system configuration for the JSF. It "has a good handle" on the software to be required and has demonstrated the technologies identified as potential risk items entering the program’s concept definition phase (CDP), according to Peter Shaw, JSF mission systems product director for the Lockheed Martin team. Shaw is with Northrop Grumman, which, along with BAE Systems, are the key partners on the Lockheed Martin JSF team.

"The CATB was a tremendous platform for demonstrating that we can take the results from sensors and integrate them together to find ground targets and identify what they are, which is the toughest problem the military has found in recent engagements in Europe," says Shaw.

Keeping Costs Down

The product director adds that the team has focused on affordable technology, including that used in its radar system. "The multimode radar has twice the functionality of legacy systems, and does it with half the weight and cost," Shaw says.

"Key to affordability of the active electronically scanned array [AESA] radar are the little transmit/receive modules," says Shaw. "We’ve proven that with our production techniques, we can develop these modules in quantity, to get the cost down."

Northrop Grumman, which also provides the radar for the U.S. Air Force’s new F-22 air superiority fighter, was selected as a logical radar supplier for the JSF. Other sensor systems on the Lockheed Martin JSF team include: the Lockheed Martin Sanders electronic warfare (EW) suite; a distributed infrared (IR) system, provided by a Northrop Grumman-Lockheed Martin Missiles and Fire Control Systems team; an electro-optical (EO) targeting system, provided by the same Lockheed Martin unit, and the TRW communications, navigation, identification (CNI) system. Also on the CNI team are Rockwell Collins, BAE Systems, Litton Advanced Systems, Harris Corp., and Kaiser Electronics.

In the Cockpit

Lockheed Martin’s JSF prototype employs a helmet-mounted display (HMD) that presents typical head-up display (HUD) flight information, but also provides the pilot with 360� situational awareness through the IR sensor system. A joint venture of Kaiser Electronics and Elbit Systems (of Israel) supplied the HMD. Kaiser also provided the cockpit mounted multifunction display (MFD)–two large 8-by-10-inch screens, which have touch screen and voice control capabilities.

"The pilot can access information from the sensors, receive information on what the air vehicle is doing, all the things needed for a tactically efficient PVI [pilot-vehicle interface]," Shaw says.

In its effort to reduce pilot workload, the Lockheed Martin team "started with an empty cockpit," he adds. "Everything has to buy its way in. It is not populated with switches. We made the cockpit focus on what the pilot needs.

"We got rid of the data entry panel," says Shaw. "Why would a 21st century fighter pilot need a keypad to change radio channels?

"We conducted tests with pilots and gave them options. They quickly became comfortable with voice control, which can be used easily for frequency changes and for mission plan changes.

"The pilot can also use the MFD touch panels to change displays and use the cursor," Shaw continues. "The pilot can get details on the fuel system or the aircraft’s health management system. He gets a heads-up if anything is amiss. There are multiple ways of getting information to the pilot."

Lockheed Martin’s JSF entree uses an integrated core processor–the "brains" behind the systems–integrated with key sensors and subsystems. It handles most of the JSF’s processing needs, but some systems have their own processing capability, such as displays.

Lockheed Martin has met all schedule commitments for mission systems, Shaw maintains, although first flight of its X-35 demonstrator model aircraft was delayed until Oct. 24, 2000. No full mission systems are on the demonstration aircraft. Lockheed Martin will continue to use its flying test bed to evaluate and verify avionics systems; it is, the company claims, the most cost effective approach to systems integration. "When the actual aircraft systems are flying, we will be verifying work that has already been done," says Shaw.

Software

"We’re exploiting commercial off-the-shelf technology [COTS]," he adds, of the on-board processing. "It’s such a dynamic environment, legacy systems fall into obsolescence.

"We look where the commercial segment is going and use open system standards wherever feasible. We have made our applications software independent of underlying hardware.

"We’re going to be able to insert [commercial processing] technology when it is available. We had to develop software architecture insensitive to those types of technology infusions."

Lockheed Martin has used its mission systems integration laboratory in Fort Worth, Texas, to evaluate sensor subsystems and their integration into the overall JSF avionics package. The lab contains a full-scale mockup of the team’s JSF aircraft mounted on a 40-foot tower. The mockup has embedded sensors, which are connected to processors and a remote cockpit station.

Other Test Facilities

Suppliers to the Lockheed Martin JSF have used the sensor integration facility to evaluate data on, as well as verify computer simulation models of, their subsystems at several stages in the design process. The Lockheed Martin team also makes use of a Northrop Grumman laboratory in southern California to conduct trade studies–determining the capabilities of sensor options.

Like its competitor, Lockheed Martin has conducted full mission simulations at its Fort Worth facilities, drawing pilot input into avionics systems development, as well as to demonstrate PVI performance to program officials.

Perhaps not unusual at this stage of the program, both Boeing and Lockheed Martin use a number of the same subcontractors, including Sanders and TRW. In mission systems work, "it’s about half and half," Shaw says, dividing the separate team members from the shared team members. "With all the consolidations, there is bound to be overlap."

Flight testing of the X-35A in the CTOL configuration has been completed, and the aircraft is now ready to be converted into the X-35B STOL demonstrator. Lockheed Martin claims the STOL variant is identical to the CTOL version, except for the propulsion system. Meanwhile, test flights of the X-35C carrier-landing and takeoff version began last December and were completed at Patuxant River Naval Air Station March 11; it logged 58 hours and 73 flights.

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