In air dominance, the past and future converge

Raytheon Technologies is helping fourth, fifth and sixth-gen fighters combine forces

With one change, the F-16 was right back in the fight.

It was the early 1990s, and the fighter jet, approaching 20 years old, had been sidelined on missions where the targets were farther than the pilot could see.

Then came the AIM-120A AMRAAM missile, which could seek and strike targets beyond visual range.

"It was a complete game-changer for the way we operationally employed the F-16," said retired U.S. Air Force Maj. Gen. Jon Norman, who was flying the F-16 at the time. He now leads Air Power Requirements and Capabilities for Raytheon Missiles & Defense, a Raytheon Technologies business. "Those fourth-generation aircraft that before had to stay back – now, all of a sudden, they're part of that combined package."

The integration of the AMRAAM missile onto the F-16, and the way it changed how that aircraft is used, shows how infusing new technology can keep older fighter jets relevant and effective.

That practice is especially important today. With U.S. and allied fourth-generation fighters still in the skies, fifth-generation fighters like the stealthy F-35 fully operational and sixth-generation fighters under development, Norman and his colleagues across Raytheon Technologies are working to ensure all those aircraft – past, present and still to come – can fly and fight alongside one another to achieve what military experts call air dominance.

Engine power and thermal management

The Pratt & Whitney F135 engine supplies propulsion and power to the F-35. Pratt & Whitney is proposing an upgrade called the Enhanced Engine Package to meet the F-35's future needs.

The F-35 is the predominant fifth-generation fighter jet for the U.S. and more than a dozen ally and partner nations. Raytheon Technologies provides many of its parts and systems, including the Pratt & Whitney F135 engine – its source of propulsion and power. And Collins Aerospace, also a Raytheon Technologies business, provides the systems that convert energy from the engine into electrical power and distribute it to the fighter's avionics, sensors, communications equipment and many other advanced features.

To keep the F-35 apace with advances by adversaries, the U.S. Department of Defense is conducting what's known as the Block 4 modernization effort, which calls for new weapons, cockpit improvements and other upgrades.

The F135 can support those improvements, but the increased demand for power and cooling would push the engine even farther beyond its original specifications, diminishing its durability and making it more expensive to maintain. Pratt & Whitney is proposing an upgrade to the F135 known as the Enhanced Engine Package, or EEP, which would save an estimated $40 billion over the life cycle of the program.

"The EEP upgrade comes on the basis of a high-performing, safest-in-the-world platform," said Jill Albertelli, president of Military Engines at Pratt & Whitney. "Now you take that safe, reliable, already-operating engine and you upgrade it. You upgrade it utilizing advanced technology we have been demonstrating in partnership with the services, and you really bring the best of both worlds."

Key facts

The Pratt & Whitney F135 engine powers the F-35, a fifth-generation fighter jet used by the U.S. and allied nations.
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540,000+

flight hours logged by the F135 engine

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>50%

average reduction in production cost since 2009

975+

F135 engines delivered
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>90%

mission capability rate, a common metric for reliability and readiness

Future fighter jets are on the way. In the U.S., there's the Next Generation Air Dominance program; Spain, France and Germany have the Future Combat Air System, and the UK, Italy and Sweden have the Tempest. If those next-generation platforms go farther in the direction of the F-35 – combining traditional fighter capabilities with functions like airborne sensing, data fusion and even commanding groups of unmanned aircraft – engines will need to deliver on all those fronts, Albertelli said.

One key factor in delivering that kind of performance is thermal management, or the control and dissipation of all the heat those high-tech systems produce. Collins Aerospace, for example, provides the heat exchangers used in the Pratt & Whitney F135, and is exploring the use of techniques such as additive manufacturing to produce improved designs.

Better thermal management will address "a very large area of need for all these programs," said Patrick O'Brien, a director of strategy and business development at Collins Aerospace.

"This goes not just to heat dissipation, but also to power generation and distribution because you have directed energy weapons and lots of communications and guidance requirements that are driving power requirements substantially higher," O'Brien said.

 

Advanced and networked weapons

The StormBreaker Smart Weapon autonomously detects and classifies moving targets in poor-visibility situations including darkness, bad weather, smoke and dust.

Much like the AMRAAM missile gave the F-16 new life back in the early '90s, upgrades to those and other munitions are bringing new power and capability to the current fleet. 

Only this time, the new armaments will do more than go farther or faster. They'll work together in groups. They’ll respond to new information in real time. And they'll produce battlefield intelligence of their own to share with the rest of the force.

"We're thinking beyond the way a weapon is traditionally used," Norman said. 

Take, for example, a pair of munitions sent to destroy an adversary surface-to-air missile launcher and clear the way for friendly forces to enter the airspace. Those munitions would work as a team, sharing sensor data directly with one another and fine-tuning their course rather than relying on the long-distance communications link with command and control. Then, when one strikes the target, the other could relay a battle-damage assessment to determine whether further strikes are necessary.

"The weapons are phenomenal sensors. They can help us prioritize targets or retarget in flight," Norman said. "The fourth- and fifth-gen fighters are all depending on that target being down. Instead of them trying to figure it out and having to task another mission, these weapons give them force protection."

And if they're working in a group against multiple targets, and the munition assigned to the main target is destroyed or otherwise lost, another would take the lead in its place. One example of such a munition is the StormBreaker Smart Weapon, a network-enabled weapon that can strike moving targets in all weather conditions. It is fielded on the F-15E Strike Eagle.

Future advanced weapons will likely take years to develop, test, integrate and field, Norman said, so in the meantime, improvements to existing systems can help fill the gap. A series of upgrades to the AMRAAM missile known as F3R, for example, will include new software, 15 upgraded circuit cards in the guidance section and newer, faster processors. 

"We have a lot of growth capability because of the upgrade of the electronics stack in AMRAAM," Norman said. "We provide that gap coverage while the services are working to develop these new effectors." 

Advanced sensors

The PhantomStrike fire control radar, shown in this illustration, weighs about half as much as previous active electronically scanned array radars and uses about 33 percent less power.

Another way to put new power into older fighter jets is to outfit them with the same advanced sensors being built into new generations of aircraft.

The benefits of that approach become clearer as those older platforms take on niche roles that play to their strengths. For example, the F-15 is valuable in strike scenarios because it can carry more weaponry than the F-35, which has to store its armaments inside the airframe to maintain its stealth advantage. So it would only make sense for the mission's best-armed fighter to have the best targeting information available.

"The more aircraft you have flying with capable sensors, the more targets you can detect and track and the more airspace you can sanitize," said Eric Ditmars, president of Secure Sensor Solutions at Raytheon Intelligence & Space, a Raytheon Technologies business. "You get a much more robust set of intelligence, and you bring the pilots home safely, which is what we're all about."

One recent advancement is the PhantomStrike fire control radar, a compact version of Raytheon Intelligence & Space’s previous active electronically scanned array, or AESA, radars. The PhantomStrike radar weighs about half as much as its predecessors, it takes up less room, it uses about 33 percent less power and it requires no liquid cooling mechanism. That leap forward in size, weight, power and cooling would bring fighter-jet-quality radar to unmanned platforms, and, in larger planes, it would free up space for new sensors and power for those already on board.

The radar also uses open mission systems architecture, an approach that makes it easier to upgrade and allows the military to add capabilities continually without being limited by proprietary technology.

"If the system is static, it's not going to be able to grow and meet the ever-evolving threat. We're trying to support that," Ditmars said. "We have to start by meeting the current needs of the customer and then enable them to customize a system with any future component or capabilities they need."

Networked platforms

A U.S. Air Force F-35 takes off at Royal Air Force Base Lakenheath in England, with an F-15 in the background. Raytheon Technologies is developing technology that will help multiple generations of fighter aircraft operate together. (U.S. Air Force photo)

With multiple U.S. friends and allies developing sixth-generation fighters – and using in-country, proprietary technology to do so – making sure those platforms can communicate in a coalition scenario will be crucial, O'Brien said.

But there's more to it than simply getting the platforms to talk. They also have to do all that communicating securely, which means both keeping adversaries from eavesdropping, and making sure joint and partner forces see only the appropriate level of detail. It's similar to the idea of cross-platform play in the video game world, where players around the world participate in a game in real time, even if they're using different consoles, with computer clouds in the middle of it all filtering and tailoring what each player sees.

"It's more than just a network solution for a single fighter platform. It extends across the information cloud they and their allies operate within," said O’Brien, whose business specializes in secure radio communications among military platforms. "They have to figure out how to partition effectively to support both their own security and interoperability. Every nation has to be able to protect its own integrity through what’s accessible in the system. It’s a highly complex problem to solve."

So, too, is refining and coordinating the network that exists within the platforms themselves. With so many sensors ingesting so much information, both from their surroundings and from other platforms, it's easy to see how pilots could become distracted or overwhelmed by data – a condition known as cognitive overload.

Artificial intelligence and machine learning can relieve the burden, Ditmars said, using advanced computing techniques to help keep the pilot focused. For example, rather than reporting flight conditions and leaving the pilot to figure out whether to use radar data or optics on their head-up display, an AI capability would automatically switch to whichever system works best in the moment.

"What they really need to know is, what are the threats that are going to take them out, and what’s going on with the mission they're trying to achieve? Should they continue? Should they turn and burn? Should they call for support? In our new environment, we can anticipate and put together scenarios," Ditmars said. "It's certainly a very challenging environment, but that's part of the excitement. And our engineers are engaged on how to address that and figure out what our warfighters need."