Otto Aerospace Phantom Makes Last-minute NBAA-BACE Debut

When a large-enough spot opened up on the NBAA-BACE 2025 exhibit floor, Otto Aerospace jumped at the opportunity to bring a mockup of its all-composite Phantom 3500 light twinjet to the show. Showgoers have expressed surprise at the size of the airplane, which is designed to deliver super midsize-jet performance in a Part 23 light jet with an mtow of 19,000 pounds.

Uniquely, the Phantom 3500 has a cabin volume of more than 800 cu ft, much larger than that of typical light jets, and the interior dimensions are also significantly bigger. Cabin height is 6.4 feet and width 7.5 feet, larger than even the average super-midsize jet, according to Otto.

With an NBAA IFR range of 3,200 nm (four passengers), the jet will be powered by Williams International FJ44-4 turbofans and cruise most efficiently at its FL510 maximum altitude.

Even more unique is the Phantom 3500’s lack of cabin windows, except for the mandatory aft lavatory emergency exit porthole. Instead of windows, passengers will be able to view the outside world via external cameras delivering imagery to large 4K displays on the cabin walls and ceiling.

The display is an engineering mockup, according to Otto Aerospace CEO Paul Touw. “We wanted to see how it all looked, to make sure we got all the angles correct. And the only way to do that is to build it.” That said, Otto is building more mockups; this one isn’t the final shape. Subtle changes to the cockpit windows are planned.

Otto Aerospace’s team members are well aware of the challenges of building composite aircraft. With the exception of the Cirrus Vision Jet, composites for business jets have solely been relegated to the fuselage and empennage, but not wings.

Designing and manufacturing the necessary structure for attachment of landing gear and flight controls in a composite wing is much more difficult than with aluminum. However, the Phantom 3500’s performance is greatly dependent on smooth shapes that enable laminar-flow aerodynamics, which would be impossible to achieve with a metal wing.

“We have no choice but to use composites, because the outer surface has to be made in a mold to get that precise shape required for laminar flow,” Touw said. Anyway, he pointed out, military fighter jets have been flying with composite wings for decades—Dassault’s Rafale being a good example.

Otto Aerospace has experience with composites as well, having test-flown a prototype experimental aircraft, the diesel-engine-powered Celera 500.

The Phantom 3500’s composite structure will be made using a Toray 1100 process that is stronger than some conventional composite materials, according to Touw. No fasteners will mar the outside surfaces, and there will be no steps or gaps.

The manufacturing process is called same-qualified resin-transfer molding, which is an out-of-autoclave technique involving laying out pre-impregnated fiber into a mold and injecting resin into vacuum-bagged components and curing with heat, but not the pressure that would require an autoclave. “That gives us the precise surface we need,” he said.

Also contributing to the precision required is the tooling material, which is an expensive specialty Invar metal alloy.

Once made, the airframe components are fastened together from the inside to maintain the outside smoothness. “That way we have no seams or gaps or steps or fasteners on the outside,” he said.

The next step in the design phase is preliminary design review, and that is expected in January. “The next phase is to order all of the parts and then complete critical design review as a preflight situation,” Touw said. “Next year, we’ll assemble the aircraft. We’ll fly in 2027, and it is a production-quality vehicle. We’ll make four flight-test vehicles.” Certification is expected in 2030.

Meanwhile, Otto Aerospace has built interiors and cockpit labs and is working on a mockup of the cabin interior that it will bring to next year’s NBAA-BACE.

Recent news about Flexjet’s order for 300 Phantom 3500s, while surprising, underscores the support for and confidence in the program, which is well-funded, according to Touw. He anticipates spending $1.5 billion to bring the Phantom 3500 through certification and into production at the planned Jacksonville, Florida factory.

That factory will cost about $500 million, and $1 billion is earmarked for aircraft development and certification. So far, Otto Aerospace has raised about $250 million, and it will use $400 million in debt financing for the factory, along with a $515 million incentive program from the state of Florida. A Series C fundraising round is targeting $300 million, and that is expected to take place in January. Customer deposits are expected to raise some $500 million.

Although respondents to an informal poll conducted by AIN indicated a healthy amount of skepticism about the Phantom 3500’s lack of cabin windows, feedback from NBAA-BACE attendees has been overwhelmingly positive, Touw said. “Part of the reason is that most people close their windows to begin with. You’re talking about a cabin with windows versus a cabin with closed windows.

“What happens when people put the shades down, which is what they do 99% of the time, you end up with a windowless cabin. In this particular case, you do not have the glare issues that you have with windows. Human eyes were not meant to see at 51,000 feet.

“People are very excited about the futuristic nature [of this airplane]. We’ve had over 100 people come through that cabin [concept], and we’ve not had a single person say, ‘This will never work.’

“Kenn Ricci [principal of Directional Aviation Capital and chairman of Flexjet] said it best: ‘The industry needs innovators…to move forward.’ There hasn’t been a lot of major innovation. The laminar-flow aerodynamics, the materials and manufacturing processes, everything on this is new. That’s why we say this changes everything. It really changes everything.”