How the sixth-generation fighter jet will revolutionize air warfare

The next generation of fighter jets could offer greater speed, range and penetration into enemy airspace — and it could even feature a revolutionary new type of engine, experts and a retired U.S. Air Force officer say.

The aviation world has seen five generations of fighters, from the subsonic F-86 Sabre after World War II to today’s stealthier F-35 Joint Strike Fighter. Today, militaries around the world are working on jets that they believe will represent technological advances significant enough to qualify as sixth-generation aircraft.

And while the precise definition of a sixth-generation aircraft is not yet set in stone, experts agree on some common attributes, retired Air Force Lt. Gen. Clint Hinote told Defense News.

The Air Force’s effort to build a family of sixth-generation fighter systems is known as Next Generation Air Dominance, or NGAD, and experts say the platform will be called upon to do a lot of things.

“We want it to be fast, we want it to fly high,” said Hinote, a former Air Force deputy chief of staff for strategy, integration and requirements. “We want it to fly far. We want it to be as stealthy as possible, not only in radar frequency … (but also) in the infrared spectrum.”

Hinote and Heather Penney, a retired F-16 pilot and senior resident scholar at the Mitchell Institute for Aerospace Studies, said speed, stealth and range will be among the most crucial elements of a sixth-generation fighter, especially if it is required to fly long distances across the Pacific and penetrate Chinese-controlled airspace.

“Range and penetration capability will be absolutely critical for sixth-generation aircraft, especially as we see the Pacific theater and China as our primary threat,” Penney said.

Fifth-generation aircraft such as the F-22 and F-35 were designed at a time when the U.S. military still had a Europe- and NATO-centric mindset, Hinote said.

“The requirements (for the F-35) were developed right after the Cold War,” Hinote said. “It’s a short-range fighter. It makes perfect sense in NATO, where there are hundreds of runways everywhere you can operate. It doesn’t make sense in the Pacific, where the situation is very different (and) you only have a few runways.”

It must be able to communicate without revealing its location, Hinote said, and it must be able to carry larger payloads than those carried by fifth-generation aircraft today.

“This allows you to achieve a position in the battlespace and in the airspace where you can impose your will through the use of force, if necessary, the concept of air superiority,” Hinote said.

And the ability to maintain an aircraft without damaging its stealth coating will be crucial, Penney said.

Early versions of stealth technology on aircraft such as the F-117A Nighthawk and B-2 Spirit bomber were delicate and difficult to maintain, she said.

Stealth has made significant strides over the years to be more practical and reliable, Penney said, and a sixth-generation fighter’s stealth capabilities must also take another step forward to be maintainable and deliver better performance.

Hinote and Penney said the next generation of aircraft must both absorb large amounts of detailed data and fuse it in ways that adjust the battlespace.

A sixth-generation aircraft “should be able to not only have these advanced sensors, not only forward-looking, but also sideways and rearward-looking, looking at (multiple) phenomena” such as radar, infrared and other frequencies, Penney said.

The Air Force wants the NGAD to partner with artificial intelligence-driven drones, known as collaborative combat aircraft (CCAs), under the “family of systems” concept. The CCAs could carry out strike missions, jam enemy radars, conduct reconnaissance or even serve as decoys.

The Air Force plans for the NGAD to feature a new type of propulsion system called an adaptive engine, which can switch to different, more efficient configurations depending on the flight situation. Pratt & Whitney and General Electric Aerospace are each developing their own adaptive engines under the Next-Generation Adaptive Propulsion program.

An adaptive engine, however, would be very expensive, Hinote said. And as severe budget constraints prompt the Air Force to reconsider its plans and designs for the NGAD, the service is considering downsizing its engine to bring down the NGAD’s price.

Air Force Secretary Frank Kendall said in a June interview with Defense News that making the NGAD engine smaller and less complex was an option being considered.

But better air combat capability is unlikely to be on the wish list for sixth-generation fighters, Hinote said. He doesn’t expect the planes to benefit from advances in low-speed maneuverability or an emphasis on guns that would allow fighters to compete against each other in relatively close quarters.

“The F-22 can achieve a high angle of attack like we’ve never seen,” Hinote said. “The Sukhoi Su-57 is the same. I don’t think it’s relevant to building air superiority in the Pacific.”

The Defense Department doesn’t have a precise taxonomy of aircraft generations. But in 2017, a spokesman for Joint Base Langley-Eustis in Virginia looked into the matter.

In his column, Jeffrey Hood of the 633rd Air Base Wing’s public relations office said the first generation of fighters that emerged after World War II took advantage of new jet technology and swept wings, as opposed to the perpendicular wings that had previously been the norm. But those fighters, like the F-86 Sabre, were limited to subsonic speeds and machine guns.

That all changed after Chuck Yeager broke the sound barrier in 1947. That opened the door to a second generation of jets, like the F-104 Starfighter, which could reach Mach 1 and even Mach 2, and carry onboard radar and air-to-air missiles, Hood wrote.

The third generation, which included the Vietnam-era F-4 Phantom, incorporated advanced radars and better-guided missiles capable of attacking enemies beyond visual range. Next came the F-14 Tomcat, F-15 Eagle, F-16 Fighting Falcon, and F-18 Hornet, fourth-generation fighters capable of maneuvering at high G forces, using digital data links to share information, tracking multiple targets, and striking surface targets using lasers or GPS guidance.

In a 2016 study published by the Mitchell Institute for Aerospace Studies, retired Gen. Jeff Harrigian said that fifth-generation fighters such as the F-22 and F-35 include stealth, improved self-defense, detection and jamming capabilities, integrated avionics, and much more.

And depending on your point of view, the first sixth-generation aircraft could already be flying.

Northrop Grumman has billed its B-21 Raider bomber as the first sixth-generation aircraft. In an interview with Defense News ahead of the B-21’s 2022 launch, a Northrop official said the bomber’s advanced stealth, use of an open systems architecture, and use of advanced networking and data-sharing technologies to connect sensors to shooters across multiple domains make it “the first of the sixth-generation systems.”

Those capabilities are likely enough to qualify the B-21 as a sixth-generation aircraft, Penney said, although she added that its high classification levels make it difficult for outside observers to judge whether it lives up to the hype.

Hinote views Northrop’s claims with a little more skepticism and thinks it’s more of a marketing angle, but notes that these generational definitions are largely matters of opinion.

“If they want to call it sixth generation, sure,” Hinote said. “I don’t necessarily think the stealth characteristics and the open architecture of the B-21 automatically make it a generational change. It’s an incremental step, it’s a good step, I’m glad we’re doing it, but it’s probably not significant enough to really be a generational evolution.”