JetZero Pitches Blended Wing Body Tanker as ’Game-Changer’

When the last Air Force KC-10 tanker flew its final sortie in September 2024, Airmen mourned the loss of an aircraft that carried a “staggering” amount of gas and nearly as much cargo as a C-17. 

But retired Air Force pilots say a new kind of aircraft under development in California could fill the void left by delivering more gas even farther afield than the current fleet. 

Developed by aerospace startup JetZero, the Z4 is a blended-wing body aircraft where the fuselage generates lift, which the startup says will use 50 percent less gas than conventional tube-and-wing aircraft. For tankers, that means fueling larger groups of aircraft at longer range to hold more targets at risk. Higher lift also means the Z4 can use shorter runways, while its unusual cabin allows for taller pallets of cargo. 

“The capability that the Z4 brings, for the tanker mission specifically, is a quantum leap,” said Brian Tighe, a retired B-52 pilot who is now executive vice president of the aviation consulting company Allied Defense Services International, a division of Consolidated Air Support Systems.  

CASS helped JetZero refine its proposal to the Air Force, which in 2023 announced a $235 million contract to fly a full-scale commercial demonstrator in 2027. Nearly two years and many subscale demonstrator flights later, JetZero officials say they will deliver on schedule, with a critical design review and production site selection just around the corner.  

The full-scale fuel tanks are built, the cockpit tooling is complete, and a wing test article is being evaluated, said JetZero’s head of engineering, Florentina Viscotchi. 

“I’m confident about us getting to that path to first flight,” Viscotchi said at a May 2 media day event at the company’s Long Beach, Calif., headquarters. 

JetZero’s pitch to airlines touts unmatched fuel efficiency, a streamlined boarding experience, and dedicated baggage room for each of the 200 to 250 passengers. For the Air Force, JetZero is proposing a KC-Z4 that can send more combat power farther downrange than current options.  

Nate Metzler, head of strategic programs and partnerships at JetZero, said a potential KC-Z4 could carry enough gas after 4,000 nautical miles (about the distance from Joint Base Pearl-Harbor Hickam, Hawaii, to 500 miles off Taiwan) to offload about 10,000 pounds each to six F-35s, while the KC-46 can refuel just one. 

“You could sit in a refueling track for 45 minutes as the F-35s fill up and go on to do their work,” Metzler said. “And then the Z4 could go back to base 4,000 miles and land without having to refuel.” 

But an aircraft like this has never been built at scale before, which could mean headwinds on the way to certification and production. 

Running on Empty 

When it comes to tankers, the Air Force is running out of gas. The KC-135 makes up the bulk of the tanker fleet, but the sexagenarian aircraft will soon be too difficult to keep flying. 

“Over the next decade, the aging KC-135 aircraft fleet will be an ever-increasing readiness concern,” Gen. Randall Reed, the head of U.S. Transportation Command, wrote in a statement for Congress on March 5. The air refueling fleet, he added, is “the most stressed deployment, sustainment, and combat capability” as well as “the lifeblood of the joint force’s ability to deploy forces.” 

The new KC-46 brings fresh iron, but it is plagued by technical problems and the Air Force currently does not plan on buying enough of them to replace every KC-135, even as the joint force is preparing to fight a war across the Pacific. 

Air Mobility Command is nearly done with an analysis of alternatives for the Next-Generation Air refueling System (NGAS), which would replace the KC-135. Air Force officials previously said the performance of the blended wing body would inform the AOA for NGAS and possible airlift concepts. Former Air Force pilots affiliated with the JetZero project said the efficiency of a KC-Z4 could be revolutionary on the battlefield. 

“This is the game-changer,” said retired Maj. Gen. Erich Novak, a former KC-135 and KC-10 pilot who is now chief financial officer at CASS. “Energy efficiency, payload, range, those are the brass rings for tanker aircraft.” 

JetZero expects a maximum gross operating weight of 362,000 pounds, with a total fuel load of 200,000 pounds, comparable to that of the KC-135 and KC-46, though the efficiency of the blended wing could stretch that tank farther.  

The startup found that a KC-135-style boom works better on the KC-Z4 than the larger KC-10 scale. JetZero plans to build a recessed area in the belly where the boom’s V-tail can tuck in to reduce drag when not in use. Removable wing pods would let the KC-Z4 refuel Navy, Marine Corps, and other probe-and-drogue aircraft. 

The KC-Z4 could carry up to 21 full-size pallets, whereas the KC-46 can carry up to 18, Metzler said. JetZero plans on designing the tanker version with a cargo door the same size as the KC-10’s cargo door on the forward left side of the fuselage.  

The aircraft will be able carry about 120 troops, could be converted into an aeromedical evacuation platform, or carry sensors and communications nodes to help the joint force build a picture of the battlefield. The startup also is working on an airlift version with a rear cargo ramp and an overall different shape to accommodate tall cargo, which the Air Force could consider as it looks to replace the C-17. 

User Feedback 

Dr. Ravi Chaudhary, former assistant secretary of the Air Force for Energy, Installations and Environment, is now strategic advisor for commercial growth at JetZero. Chaudhary focuses on the commercial side in compliance with government contracting rules, but he spoke to his own personal experience after flying the C-17 for about 15 years in the Air Force and then trying the Z4 in a simulator. 

“You’re going to have those muscle memories as a C-17 pilot whenever you take the controls,” he said. “My first time in the seat, I flew a full C-17 approach profile in this and they asked me how it flew. I said ‘it flies like a C-17.’ 

“I flew a 500-foot tactical approach and put it on the numbers on the first try,” he added. “I’m not a test pilot, but as a line pilot, I could easily take it into the pattern and fly with precision.” 

Chaudhary and JetZero say they’re making a special effort to make the Z4 user-friendly, from the flight deck to the maintenance hangar. For example, Boeing airliners feature synchronized flight control yokes but no active feedback, while Airbus features active sidesticks that are not synchronized. JetZero takes the best of both worlds by featuring synchronized active sidesticks. 

“I spent a year as an Airbus captain, loved that airplane, but I didn’t know what the guy next to me was doing,” said retired Maj. Gen. Dan Heires, a former KC-135 pilot and CEO of CASS. “That’s a problem … and that was an early input” in the design of the Z4 flight deck. 

As the Air Force gears up for multi-crew sorties across the Pacific, mobility Airmen are figuring out how to stay sharp aboard jets that are often loud, bright, and have extreme temperatures, making it hard to rest or sleep. That wouldn’t be a problem on the KC-Z4, which could feature dedicated crew rest areas like those seen on most long-haul airliners.  

Like the KC-46, the KC-Z4 would use a remote vision system where Airmen operate the refueling boom using cameras mounted to the aircraft’s belly. Depending on Air Force requirements, the boom operating station could be located on the flight deck, a novel feature which officials say would enhance crew coordination, and there would be a curtain to block out any glare that would make operating the RVS more difficult. 

JetZero met with groups of Air Force boom operators to learn from the mistakes that have haunted the KC-46 RVS. The startup aims to provide higher fidelity without the distortion and depth perception problems that gave KC-46 boom operators eye strain and headaches. JetZero also used boomer input to model the layout for the station. 

“It’s understanding even the ergonomics and physiology,” Metzler said. Boomers “are going to be there for hours. We want to have more natural movements so as not to fatigue the small muscles in the wrists and arm. It’s little things like that that you wouldn’t think of, but the guys who have been in these airplanes for hundreds of hours said ‘hey, you better think about this.’” 

Putting It Together 

Developing a new airplane takes billions of dollars from the government, industry, or both. United, Delta, and Alaska airlines are among the major companies that have invested in or partnered with JetZero, but that doesn’t lock them into buying orders, said Richard Aboulafia, a managing director of the AeroDynamic Advisory consulting company. 

“However, there’s also a spirit of ‘hey, if you build it, we will come,’” he added. 

For now, JetZero officials say they are on course to a full-scale demonstrator and are confident about FAA certification. They emphasized the strength of their staff, many of whom previously occupied top positions at Boeing, Airbus, Gulfstream, and other major players. 

Still, major hurdles remain, such as finding a company to actually build the aircraft. Scaled Composites, a subsidiary of Northrop Grumman, is building the full-scale demonstrator, but it’s not yet clear who would help JetZero meet its goal of 20 planes a month five years into production. 

CEO and co-founder Tom O’Leary said he expects the production site to be a “massive, 1,000-acre type of operation.” Made largely out of carbon fiber, most of the Z4 structure will have to be built in one place, he explained. 

The startup is seeking private equity and possibly government loans to get the aircraft to market, commercial aviation news outlets reported. But selling a tanker version to the government may be more difficult, as President Donald Trump’s administration is prioritizing other efforts like homeland missile defense, shipbuilding, and the Air Force’s new F-47 fighter. 

“The Air Force’s $235 million up front was a great idea, but it happened in a very different environment,” Aboulafia said. 

It’s also more challenging to design a crossover product for both civilian and military use today, experts say, than it was in the 1950s, when Boeing developed the KC-135 alongside its airliner equivalent, the 707.  

Engines are one example: for the full-scale demonstrator, JetZero selected the Pratt & Whitney PW2000, which powers the C-17 but is antiquated compared to modern airliner engines. There are also different standards for design and production certification, emergency evacuation procedures, and operating costs which could make development more complicated and expensive. 

Still, there is a large appetite for the advantages of a blended-wing body, Aboulafia said, especially one developed by a new company that could boost competition in the market. 

“People want this, they’re desperate for competition and innovation,” he said. “It’s intriguing, but the devil’s in the details.”