By John McHale
FT. WORTH, Texas, 18 Dec. 2009. Designers of the avionics systems for the F-35 Lightening II Joint Strike Fighter (JSF) aircraft are using commercial-off-the-shelf (COTS) avionics wherever and whenever possible throughout the advanced fighter's cockpit.
"Performance, affordability and maintainability of the platform over time are big part of why COTS is so important," says Eric Branyan, vice president and deputy program manager for the F-35 Joint Strike Fighter program at Lockheed Martin.
COTS technology contributes to major parts of the F-35 avionics and electronic warfare capabilities, such as the electro-optic sensors, synthetic aperture radar maps, radio frequency systems (RF), etc., Branyan says. The aircraft also takes advantage of common data links such as SINCGARS and Link 16 to pass high bandwidth between the F-35 and other aircraft and ground stations, providing a common operating picture.
F-35 designers have found success with COTS technology mostly because they have been able to successfully manage the obsolescence headaches that accompany COTS, Branyan says. "We've been careful to develop the architecture so that if one part goes obsolete, we don't have to redesign the entire system to replace it," Branyan says.
There are different ways to approach obsolescence management such as life time buys of components that suppliers decide to obsolete, Branyan says.
He notes that the F-35 program does make lifetime buys when it is economical, but says the real key for the F-35 program is a Lockheed Martin-designed middleware that enables COTS hardware and software to be upgraded without having to "rectify or rewrite 8 million lines of code."
"We built the middleware to protect us so we can make changes without overhauling the software code," Branyan says.
The middleware enables key COTS components such as the Freescale PowerPC processors to be refreshed without any major changes to the avionics system, he continues. In the past certifying a refresh of multifunction displays would take three to four years, now with the isolated middleware the most recent refresh was completed in only six months, he adds.
On top of the middleware the F-35 avionics uses the Integrity DO-178B real-time operating system (RTOS) from Green Hills Software in Santa Barbara, Calif. The fact that the Green Hills RTOS is already certified to FAA regulations is huge advantage to Lockheed Martin, he adds.
Lockheed Martin also requires all software code to be written in the C++ programming language, which is the most common code in use today and enables faster code development, Branyan says.
COTS is also a big part of the cockpit display, Branyan says. "We use an active matrix liquid crystal display (AMLCD) from L-3 Display Systems in Alpharetta, Ga.," he adds. The pilot's helmet-mounted display (HMD) is provided by Vision systems International (VSI) in San Jose, Calif. VSI is a joint venture between Rockwell Collins in Cedar Rapids, Iowa, and Elbit Systems of America.
"The VSI system provides the F-35 warfighter with unmatched situational awareness throughout the operational profile of the jet," says Drew Brugal, VSI president in a VSI public release. "By keeping eyes out while viewing all critical information and video on the helmet visor, the pilot has a significant advantage in both air-to-air and air-to-ground mission execution."
The L-3 display uses COTS processors and standard glass, Branyan says. Tweaks were made to militarize it for the F-35 with antiglare and night vision capability, but otherwise it is very similar to what one might see on commercial television, he adds.
Three years ago Lockheed was looking at multifunction displays that were based on projection technology, which was considered leading edge at the time, Branyan says. Now the technology is plasma and liquid crystal display (LCD) solutions. Having a COTS architecture makes it easier to adapt to these shifts in technology development, he adds.
Other common standards in use on the aircraft include the MIL-STD 1553 database for weapons systems and 1394 for high rate systems, Branyan says.
The communication navigation, and identification friend or foe suite (IFF) system relies on field programmable gate arrays (FPGAs) from Xilinx in San Jose, Calif., Branyan says. The COTS devices enable Lockheed Martin to add new waveforms to embedded software radio systems in the F-35, he adds.
The FPGAs also provide vice processing capability in real-time, Branyan notes.
All the avionics systems -- hardware and software -- have been continually tested in the air in the F-35 CATBIRD test system, Branyan says. The CATBIRD also enables refreshes of key electronics during the development of the program, so that when the F-35 is deployed it will have state-of-the-art systems, Branyan says.
These systems, largely made up of COTS standards and components, enable the fifth-generation fighter jet to have stealth capability and conduct air and ground attacks simultaneously, Branyan says.
What separates the F-35 from other fighter aircraft is its ability to fuse sensors, communications from all elements of the battlespace – land, air, and sea, so the pilot can just respond to threats without having to play around with sensor modes, etc., Branyan says.
The F-35 also has anti-jamming capability and can block enemy emitters as well, Branyan says. This is a key game changer for how the F-35 can engage attack targets long before the target is aware of the F-35, he adds.
The aircraft will be manufactured in three variants – a conventional takeoff and landing (CTOL) for the U.S. Air Force, a carrier variant (CV) for the U.S. Navy, and a short takeoff/vertical landing (STOVL) for the U.S. Marine Corps and the United Kingdom Royal air force and navy, Branyan says. The single-engine F-35 Lightning II will be manufactured in three variants: