F-35 Joint Strike Fighter: Flying high

The bigger picture

Presenting an update on the F-35 program in Sydney prior to the Avalon Airshow 2013, Lockheed Martin Aeronautic business development director Dave Scott said the program delivered 30 airplanes in 2012, and expects to complete 36 units in 2013. Australia’s F-35 planes are currently being built, and will be delivered in 2014.

The F-35 will be available in three versions: the F-35A is conventional take off and landing (CTOL) variant, the F-35B, short-take off and vertical-landing (STOVL) variant, and the F-35C, carrier-based CATOBAR (CV) variant.

The commonality between these variants will allow them to be built on the same production line, allowing for improved economics of scale.

“There will be a large base of airplanes,” Scott said. “This keeps the cost to buy the airplane down, and also the thru-life cost down, because there will be more players to share the cost of any new upgrades and spare parts.”

According to Lockheed Martin, it plans to build nearly 4000 F-35s, of which 2400 will be bought by the US. 700 planes will be bought by international partners in the program, and additional international players will make up the other 800 sales.

While media reports over the years have indicated problems with the progress on the plane, Scott says the flight test program has been on-schedule or ahead of schedule since 2010, although it is uncertain if the February 2013 fleet grounding will derail the program’s schedule.

The test fleet currently consists of 17 airplanes, which are flown from two different test locations. The F-35 has seen over 4000 flights on the airplane, and over 5000 hours in the air.

The battery of tests carried out thus far include aerodynamic testing, high angle of attack tests, in-flight weapons release, night flights, re-fuelling, air-starts, and ground-based arrestment and catapult launch tests.

Australia has been involved in the program for more than a decade, with Australian pilots flying classified simulations of the F-35 to gain an understanding of the capabilities of the plane, in order to prepare them for flights on production units.

A large degree of the need for new fighter planes is the result of other regional players buying fifth generation airplanes, with current fourth-generation units such as the F-15, F-16 and F-18 having to contend with more sophisticated aircraft and surface-to-air missile systems.

“There is a fundamental shift occurring in the capability of the airplanes, the fighter fleets throughout the world, especially in Asia Pacific. We can see it in the actions being taken, in the airplanes being purchased,” Scott said.

The Chinese, for example, have test-flown two stealth airplanes, the J-20 and J-31, which are currently in prototype stages. The Russians have also embarked on their fifth-generation plane program with the PAC-FA now in the test program.

“This is the move from VCRs to DVDs,” Scott said. “You do not want to be left buying the last VCR. This is a fundamental shift in capability that is taking place as we move to the next generation of fighter airplanes.”

Fifth generation

As military technology advances, a common approach has been to upgrade existing planes with new technologies in order to stave off obsolescence, while keeping up to date with the latest capabilities. Why then, the need to build an entirely new plane?

“You cannot [retrofit] if you want to design a stealthy airplane,” said Scott. “Stealth requires us to make some fundamental changes to the airplane.”

Stealth allows the planes to get closer to potential threats without being detected, improving the outcomes from the deployment of electronic and/or kinematic attacks.

In order to reduce the plane’s visibility to radar systems, the entire unit must be designed around the purpose, meaning fuel tanks and weapons systems mounted on the wings were the first things to go.

The fuel tanks were moved inside the plane, as were the weapons, with two bays on either side of the fuselage.

The design team moved the inlets to the side of the plane so the front of the engine is not visible. The engine was moved to the back to reduce the reflectance surface for radar.

The edges of the airplane were aligned so that the cant of the tails matches up with that of the fuselage, and concentrates the radar waves into very small controllable zones.

To maximise the smoothness of the plane’s surfaces, the antennae were integrated into the plane body. The nozzles in the back were also treated to attain 360 degrees of stealth around the airplane.

A key role for electronics

Talking to Lockheed Martin’s F-35 test pilot Elliot Clemence, it is obvious that fighter planes have come a long way since the dog-fighting days of World War II, and electronics systems are now a critical part of flight systems in ensuring pilot survivability.

According to Clemence, the F-35 has been undergoing tests of its missions systems.

“We have gone very quickly from something that was moderately stable to operate to very stable, as far as radar stability, electro-optical targeting systems stability and electronic warfare stability,” said Clemence.

With no fixed heads-up display (HUD) in the canopy, the F-35 integrates a virtual HUD in the helmet. Additionally, the helmet is the focal point of the plane’s distributed aperture system, which provides key information for missile and aircraft detection.

“This system is essentially six electro-optical infrared sensors around the airplane. The data from these sensors are stitched together to give the pilot a 360 degree spherical image of the outside world,” said Clemence.

Based on the sensor information from the distributed aperture system, a pilot who is deprived of an optical view of the outside world can still virtually see the situation from within the visor, and execute tasks like rejoins, tracking maneuvres, air-to-ground roll-ins, and low level flight approaches.

In addition to the stealth design of the F-35, test pilots say their survivability benefits from two major technologies: sensor fusion, and electronic attack and protection.

Sensor fusion refers to the electronics and computer system on the plane which collates the information from the various sensors located on the plane, combining the data into a coherent common operating picture for the pilot. If the system detects a missing piece of information, it will task the sensor to obtain the additional data.

This is a marked improvement on fourth-generation fighters, which were upgraded by bolting on new sensors, making it necessary for the pilot to hunt around for the information, then form a coherent picture of the situation from the data.

“The engineers’ goal was to make the cockpit a manageable workload in a high threat environment,” Clemence explained “Realistically, you can’t have a low workload in a high threat environment – that’s impossible. But to make it a manageable workload for a single pilot in a high threat environment has been the design since inception.”

“The pilot no longer has to cue his sensors, search for information, or do distracting tasks. That enhances situational awareness, and enhances survivability. Sensor fusion simplifies our tasks in the cockpit, allowing the pilot to focus on the tactical picture.”

Describing the electronic attack/protection systems, Clemence says success in modern air combat now hinges on first-detection and first-attack advantages, with most detection and attacks occurring well beyond visual range.

“With a good jamming platform, you can blind the other guy,” Clemence explained. “If you have good electronic protection, you can prevent him from blinding you, and you can see him first and get your missiles off first. That is extremely important, and where the F35 shines well above the Hornet, Super Hornet and all legacy fighters.”

Australian involvement

Being a partner in the program, Australia industry has received over $300 million worth of supply contracts.

According to Lockheed Martin, this economic value expected to grow to $5-6 billion as production ramps up over the next three decades, with another $3 billion on top for maintenance and support parts.

Goodrich Australia and Rosebank, for example, are providing actuators for the landing gear and bay doors. Quickstep is providing centre fuselage composites, and parts of the vertical tails, and Ferra is providing parts of the airframe as well as weapon adapters.

For the electronic systems, Cablex is providing wiring for the ejection seat, while Micreo, a Brisbane-based contractor, is involved in supplying a microwave-frequency switch filter bank for the radar system.

Partech Systems, based in Yerriyong, NSW, provided Test Program Sets (TPS) for the F-35, through subcontractor Northrop Grumman.

Electronics News talked to Lad Miklos, one of the directors at Yerriyong (NSW)-based Partech Systems, regarding the company’s work for the F-35.

Partech Systems provided Test Program Sets (TPS) for various components on the F-35, through subcontractor Northrop Grumman. It provided the test software, hardware interface devices, and associated documentation. It is now working to upgrade the TPS for use on the production version designs of the F-35.

Test Program Sets are used in conjunction with Automatic Test Equipment systems (ATE) to send stimulus signals to the aircraft’s avionics system, taking measurements at appropriate points to ensure that the system is functioning according to required parameters.

In the case of the F-35, the ATE suite used is the Lockheed Martin LM-Star, which hosts the TPS created by Partech Systems.

The test software analyses the results of the measurements to determine the probable cause of failure, allowing the technician insight into the faulty components to replace.

Partech’s first project involved working with CSC Australia to develop a TPS for the communications, navigation and identification (CNI) avionics interface controller unit (CAIC) of the F-35.

While CSC focused on developing the environmental stress testing machine for the CAIC module, Partech Systems was responsible for the TPS which would be run on the LM-Star system. During the six-year development period for the CAIC TPS, Partech Systems had the only LM-Star system in Australia on its premises.

“The CNI system consists of 24 cards but [the CAIC] was a massive card, and employed quite up-to-date technologies, so we had to deal with fibre optics, 1394 Fire Wire, and JTAG to load the software on it, as well as Xilinx FPGAs,” said Miklos.

In 2007, Partech Systems took on its second contract for the F-35, developing a TPS for the F-35’s AIS line replaceable unit (LRU), which consists of six multi-layered PCBs. According to Miklos, the TPS allowed technicians to isolate faults to a single card for replacement.

While the software was a key part of the TPS, the Partech Systems was also responsible for the interface hardware, which was manufactured in Australia to American standards.

“We fitted all the cables, plus we designed the PCB in Altium, to be manufactured in Melbourne by Precision Circuits (now Precision Electronic Technologies),” said Miklos.

“The metalwork, because we needed punch holes for connectors and interface, painting and engraving, was done by Air Affairs.”

According to Miklos, the company has seen some work with repeat builds of the Test Program Sets, and also took over the environmental tester work from CSC Australia. It is still a preferred supplier for the F-35, but has yet to see substantial new work from the JSF project since the completion of the two TPSs.

For now, Partech Systems’ core business is in supporting TPS for the Australian Navy’s F-18 and Sea Hawk planes.

Conclusion

The F-35 development effort has been the subject of high-profile criticism and controversy, beset by delays, budget blow-outs and technical problems.

At its core, however, the JSF’s systems represent a radical advance in air combat technology, with the integration of electronics and information systems providing pilots with unprecedented situational awareness.

Australian industry, with its focus on specialised high-tech capabilities, is well-poised to supply expertise and parts to the JSF, although it remains to be seen if Australia’s electronics sector will see any substantial work flowing on from the JSF program.