Otto Aerospace Freezes Phantom 3500 Jet Design

After completing the preliminary design review (PDR) and freezing the design of the Phantom 3500 light business jet, Otto Aerospace is moving ahead with construction of the first flight test vehicle (FTV1) and sourcing key components from suppliers. Although these activities are taking place at Otto’s facility at Meacham International Airport (KFTW) in Fort Worth, Texas, the company will move to a new campus at Cecil Airport (KVQQ) in Jacksonville, Florida, by the end of the year.

Scott Drennan, Otto’s former president and COO, assumed the role of president and CEO in April following the departure of then-CEO Paul Touw. Drennan was credited with leading the PDR, which was completed at the end of February.

The all-composite Phantom 3500, while categorized as a light jet due to its size and 19,000-pound weight, promises the range and cabin comfort of a super-midsize jet. After the PDR, Drennan said, “Our performance looks great. We are going to match the coast-to-coast performance of all the super-mids, and that’s a combination of our own speed at cruise, our cruise altitude, and the advantages we get from that.”

With NBAA IFR range (four passengers, 100-nm alternate) of 3,200 nm, the Phantom 3500 is powered by Williams FJ44 engines, a popular choice for light jets. What makes the jet different from competitors is a flat-floor cabin that is 6.4 feet tall and 7.5 feet wide with a volume of 800 cu ft, giving it almost the same cabin volume as a super-midsize jet that weighs twice as much. To achieve this performance, the Phantom 3500 will have to fly high, often at its 51,000-foot maximum altitude, and this could present certification challenges for a single-pilot Part 23 design.

From the outside, looking at the mockup of the Phantom 3500, the cabin looks massive, and it needs to be to accommodate the large volume. The laminar-flow design of the jet is a critical part of achieving that performance, and one of the design features is a windowless cabin; passengers’ view of the outside world will be via large cabin screens—called SuperNatural Vision—connected to external cameras.

The Phantom 3500’s overall design didn’t change as a result of the PDR, according to Drennan, except for an adjustment to the stabilizer volume, placement of the empennage, and length of the aft fuselage to fix some separation of airflow from the fuselage. This was discovered during wind tunnel testing. “We’re up to revision 14 or 15,” he said, “with many sub-revisions on each of those, but that’s normal, just to make sure we get the fullest laminar flow coverage that we possibly can get.”

In addition to beginning composite layups for FTV1, Otto has ordered long lead-time items such as the landing gear forgings from supplier Mecaer. Wind tunnel tests with ice-protection system provider Cox & Company and The Pennsylvania State University revealed no need for electric heating blankets, Drennan said, so the wing leading edges will be equipped with Cox’s Electro-Mechanical Expulsion Deicing System. “That’s been great news; it takes the power requirement down and makes the integration a lot easier. The empennage is still to be determined. We’ll fly icing shapes on the empennage and make sure we have aerodynamic stability and control volume to handle those shapes. If we can’t, then we’ll put an icing system in.”

Other suppliers include Leonardo, which will manufacture the fuselage, and Sonaca for the wing and empennage. Garmin will supply some federated avionics for FTV1, and the G3000 Prime integrated suite for the production airplanes, including Garmin Autoland.

Otto has also selected F/List to supply interior furnishings and linings, and the two companies are working together on cabin design from an early state in the Phantom 3500’s development. “Collaborating with Otto at this stage gives us the ability to craft bespoke solutions specifically tailored to this next-generation aircraft, allowing our in-house R&D innovation hub, the F/Lab, to explore concepts that will define tomorrow’s interiors,” said Anita Gradwohl, F/List group director customer relations and sales.

Otto Aerospace plans to build four FTVs. “We’re trying to stay within a certain schedule to get onto the market in 2030 or 2031,” Drennan said. “I need to get more aircraft in the air to gather data rather than sequence them over a longer period of time.” First flight of FTV1 is planned by the end of 2027.

More than 200 people work for Otto Aerospace now, and more will be added after the move to Jacksonville. At the new location, the FTVs will be assembled in a 125,000-sq-ft former Boeing hangar while construction of Otto’s new facility is underway on the other side of the airport. This will include the factory, offices, customer delivery center, a maintenance operation, and testing facilities.

Drennan anticipates no major obstacles to achieving FAA certification of the Phantom 3500. “We’ve had some great meetings [with the FAA] so far,” he said. In preliminary type certification board and other meetings around the PDR, “There were no issues. They view us as nothing new and novel, which is a great thing.”

Otto isn’t attempting to break new ground other than the unique cabin design. Flight controls are conventional fully reversible mechanical controls, not fly-by-wire, and the composite manufacturing processes are well understood, although Otto will be using a new Toray composites system that needs to be qualified.

“The laminar flow piece is not a safety concern to the FAA, any different than turbulent flow is,” he explained. “You need your handling qualities, control volumes, reliability or redundancy as required, and that’s it. All of our systems are just off-the-shelf, and a couple are just modified ones, like the landing gear, so there’s a lot of good work already been done on those.”

As for the 51,000-foot maximum altitude, Drennan doesn’t anticipate any problems with certifying the Phantom 3500 for single-pilot operations. “You have to make sure the pilots are ready and trained to do everything they need to do in the emergency case, which is an FAA requirement to get down in time for non-exposure to the [scant] oxygen levels at that altitude, given a breach or a failure of a system. We’ve got an aircraft that’s really slippery, but if you throw things into the wind like flaps, landing gear, or spoilers, it slows down pretty quickly.

“Certification is never easy, and you should never insult it in that way. You should be humble about certification, partner with your FAA colleagues, and do the hard work…but the path is clear when you have an aircraft like ours, and you’re in Part 23.”

On the financial front, Otto Aerospace is raising additional funds in a series C raise now, which will provide enough money through the first flight of FTV1 at the end of 2027 and the first quarter of 2028, gathering data. “We got our first big tranche of [the series C] in [mid-May] from internal investors,” Drennan said, “to indicate their support for me taking over the CEO role.” The cash burn rate is increasing with spending on supplier components following PDR, he admitted, but “we’re covered.”

Some individual buyers have already committed to buying Phantom 3500s, and fractional-share operator Flexjet has made a firm commitment for 300, a deal worth as much as $6 billion at the estimated $19.5 million price. Drennan anticipates officially opening the order book next year.