The successful deployment of the IEEE 1394 networking standard in the F-35 Joint Strike Fighter development program demonstrates the standard’s reliability and flexibility, the 1394 Trade Association said. 1394b is playing a pivotal role in the F-35 Lightning II program, providing guaranteed quality of service with predictable latencies in real-time control applications. More than 70 1394 devices are delivering information about mission details, communication systems, weapon systems, engine controls, and flight controls. Lockheed Martin Corporation and its partner contractors selected the 1394b network standard after a trade study of other networking options including USB, Fibre Channel, and military standard 1553.
The F-35 program evolved in response to the need to deploy fewer types of more cost-efficient tactical aircraft. Current plans call for production of 2,458 F-35 aircraft in three versions: conventional (CTOL), short take-off/vertical landing (STOVL), and carrier (CV). A total of 14 Lightning IIs are now in various stages of assembly. The AA-1′s (CTOL) first flight was last December, and the first three STOVLs are scheduled to fly in 2008. According to Lockheed Martin, the 1394b-equipped AA-1 has completed 19 successful flight tests to date.
1394b in Vehicle Systems Network
1394b has been implemented in the plane’s Vehicle Systems Network based on its speed, bandwidth and long distance capabilities, and also because 1394b enables operational software downloads to network components without the need to remove any component after installation.
Main F-35 flight control and subsystem processing are completed in a trio of the Vehicle Management Computers (VMCs), which act as the master for each bus. There are triplex VMCs that are cross-channeled and data-linked together. Most of the 1394b buses are looped to provide additional redundancy, so if one cable fails, there is an alternate path for communication.
1394b delivers the high bandwidth and predictable latencies that allow the VMC to house all flight control algorithms and all utilities in a highly centralized structure. While there are still some distributed processing functions handled by legacy buses such as 1553, it is 1394b that’s carrying the bulk of the processing load. The architecture also makes use of independent controllers for applications that require dedicated, high-bandwidth control loops. according to Lockheed Martin engineer Mike Wroble.
The VMC incorporates Flight Control Systems (FCS) and Utilities and Subsystems (U&S) processing that has been performed separately on legacy aircraft, according to Wroble. Components residing on the 1394b network serve the following systems:
- Vehicle Systems Processing, VMC and RIO (10 remote input/output units)
- Flight Control Systems with all flight control surfaces, including rudders, flaperons, horizontal tails, ailerons, air data probes, inertial electronics, inceptor control, crash-survivable memory units
- Utilities and Subsystems such as weapons bay door drives, power system controllers, brake controllers, power thermal management system controllers
- Propulsion Systems such as main engine FADEC (full authority digital engine controller), and prognostics health area managers
- Mission Systems including standby flight display, display management computer, helmet display management computer, integrated core processor, lighting controller, communications/navigation/identification, and GPS
- Flight Test Instrumentation, in the form of a high-speed data acquisition unit on each bus for capturing flight test data
1394b Serves F-35′s Distance Requirements
The F-35 design team maximized the distances served by the 1394b specification with physical enhancements, such as the active transformers, quad cabling, connectors, termination method. The enhancements also ensure optimal operation in the harsh temperature and vibration environments that characterize safety- and mission-critical applications for military and aerospace vehicles, as defined in SAE document AS5643/1. A second SAE document, AS5643, defines the deterministic, rate-based communication protocol overlaid on the existing IEEE-1394 standard capabilities.
Modifications made to 1394b for the F-35 have been fully documented and are available for other design teams who might want to use them in future programs.
Test Requirements Met by Commercially Available Tools
To meet the special test requirements for the F-35 design, test tool providers were able to use existing and commercially available technology to provide electrical signaling and protocol level tools.
For example, Quantum Parametric’s Signal Quality Tester provides transmit signal integrity and receiver sensitivity testing, and the FireSpy 1394 protocol analyzer from Dap Technology has been widely used in the program. Both test systems are used as part of system debug and sub-system qualification as well as module acceptance testing.
“The success of 1394b in this high-profile, mission-critical program led by Lockheed Martin reflects the bandwidth, distance and quality of service features enabled by the standard,” said James Snider, executive director of the 1394 Trade Association. “The guaranteed quality of service and predictable latencies provided by 1394 are ideal for these kinds of applications, as well as in the consumer, computer and industrial markets.”
The 1394 Trade Association is a worldwide organization dedicated to the advancement and enhancement of the IEEE 1394 audio video standard.