5 days ago
Otto Aviation's Phantom 3500 Aims To Massively Disrupt Private Jet Market
Disruptor aircraft company Otto Aviation is aiming to achieve first flight with what could potentially be a revolutionary high-efficiency business jet-type aircraft with a tear-drop-shaped fuselage called the Phantom 3500 by the end of the decade, if not within the next two years or so. Otto has made very bold claims that still have yet to be realized, but if they are, even in part, they could be transformative for the aviation industry, including for military applications. The Phantom 3500 leverages previous work on a broadly similar piston engine design called the Celera 500L, which TWZ was the first to report on the existence of when it was still very mysterious back in 2017.
Otto Aviation highlighted the ongoing development of the Phantom 3500 in a video released earlier this month, seen below. The company first unveiled the design, originally called the Celera 800, in 2023.
It was '10 years of very difficult labor-of-love work to build the Celera 500,' Otto Aviation CEO Paul Touw says in the video. 'That data was used to help refine all of our technology and tools to build the second aircraft, which is now called the Phantom.'
The Phantom 3500 is a significantly different design from the Celera 500L, most immediately in its planned use of two Williams FJ44 turbofan engines, one mounted on each side of the rear of the fuselage, for propulsion. The Celera 500L has a Raikhlin Aircraft Engine Developments (RED) A03 V12 piston engine driving a pusher propeller at the tail end. The RED A03 is a high-efficiency multi-fuel design that you can read more about here.
Otto has also completely changed the wing and tail configuration for the Phantom 3500. The jet-powered design's main wings are much larger and feature a wider chord than those found on the Celera 500L. It also features a T-tail unlike its predecessor, which had horizontal stabilizers on either side of the rear fuselage.
What Phantom 3500 and the Celera 500L do share is a tear-drop-shaped fuselage optimized to take advantage of what is called laminar flow, something that has been central to Otto Aviation's developments to date. In broad terms, laminar flow refers to liquid or gaseous 'fluids,' including air, flowing in smooth, regular layers with little to no mixing between them.
'In traditional aircraft, airflow over the fuselage and wings quickly becomes turbulent, creating drag that wastes energy and fuel,' Otto's website explains. 'Laminar flow keeps air moving smoothly along the aircraft's surface, reducing resistance and improving aerodynamic efficiency.'
'Virtuous cycle is the synthesis cycle of aircraft design. The virtuous cycle that we use, you take laminar flow, apply it to your design, and your drag goes down. When your drag goes down, your fuel burn goes down. When your fuel burn goes down, fuel required goes down,' Scott Drennan, Otto's President and Chief Operating Officer, explains in the video released earlier this month. This, in turn, allows for 'smaller engines, smaller structure to support all that, and it starts to loop down that curve, so you have a lighter, high performance aircraft that still meets all the customer experience expectations.'
In the video, Otto CEO Touw says the Phantom 3500 is expected to burn 115 gallons of fuel per hour. The average burn rate for other comparable business jets like the Bombardier Challenger 350, Cessna Citation Latitude, and Embraer Praetor 500 is around 300 gallons per hour, according to the company, citing data from Jet Support Services, Inc. (JSSI).
In addition to the 'virtuous cycle' around fuel burn, 'there's a wonderful performance cycle. Here, our wings are in complete laminar flow. They almost disappear from a drag perspective. We can actually make the wing bigger to perform a number of beautiful performance tricks,' Touw adds. 'One is a bigger wing allows you to take off on a shorter distance or land on a shorter distance. That bigger wing, with a lot less drag, produces more lift, and that allows you to climb much faster.'
Touw says this will roughly double the number of airports in the United States that the Phantom 3500 can operate from over comparable business jets.
The Phantom 3500 is also expected to benefit from additional efficiencies gained by cruising at altitudes of up to 51,000 feet. Otto is projecting an absolute maximum unrefueled range of 3,500 nautical miles, reflected in the 3500 in the name, and the ability to fly up to 3,200 nautical miles with four passengers on board. Otto has said previously that the Celera 500L flew at altitudes up to 15,000 feet and speeds up to 250 miles per hour during flight testing, which it projected would translate to a speed of around 460 miles per hour at 50,000 feet.
In a recent interview with FlightGlobal, Touw also said that wind-tunnel testing conducted last year 'surprised even us,' especially in terms of data collected on the expected drag of the Phantom 3500 design. 'We didn't think we would be able to take that much energy out of a flight.'
As noted, the results of laminar flow shaping for the fuselage also allows for larger internal volume than comparably sized aircraft with more traditional designs. Otto says the Phantom 3500's main cabin will have a height of six feet, five inches, considerably taller than what is found on many business jets and small airliners. It will also be more spacious overall.
As part of its laminar flow design, the Phantom 3500 also eschews cabin windows entirely. Instead, Otto plans to install what it calls a 'Natural Vision' system that consists of 'state-of-the-art high-definition digital displays that seamlessly integrate real-time external views.'
The Phantom 3500's design is also expected to yield manufacturing benefits, including reductions in total material required for production and overall manufacturing costs. Just today, a firm called Galorath, described as 'the premier AI-powered estimation platform provider,' announced that Otto will also be using its SEER product to help produce 'structured operational intelligence to anticipate costs and streamline production efforts.'
'As we enter the next phase of aircraft development, time-to-market, quality control, and resource accuracy are critical to our success,' Obi Ndu, Otto's Chief Information and Digital Officer, said in an accompanying statement. 'Integrating Galorath's SEER platform into workflows ensures we have the right tools to combat economy-driven constraints and focus on cost, outcome predictions, and meeting design requirements, keeping us ahead of the curve with a strategic advantage.'
Interestingly, in addition, 'at its estimated 8,618kg (19,000lb) MTOW [maximum takeoff weight], the Phantom 3500 sits at the top of the US Federal Aviation Administration (FAA) Part 23 category, rather than the more-stringent Part 25 category occupied by other super-midsize types,' FlightGlobal noted as an aside in its recent interview with Touw. 'Despite the intention to certify the Phantom 3500 as a Part 23 jet, Otto will incorporate some requirements from Part 25, opening the potential to hop up to the higher weight class in the future, adding additional fuel capacity to take range out to as much as 4,300nm.'
Otto has long touted the potential for its laminar flow-focused aircraft to have transformative impacts on the general aviation sector by offering improved performance at lower costs in a package that can also fly in and out of more locations. The company has previously presented these qualities as being particularly advantageous for regional charter flights along routes that would otherwise be unprofitable for large airlines to operate. With its aforementioned expected capabilities, the Phantom 3500, specifically, is poised to compete in the mid-size jet market. It could be particularly advantageous for flights between cross-U.S. city pairs like New York City and Los Angeles. It would also be capable of flying between Hawaii and the mainland United States or across the Atlantic Ocean.
Potential military applications have appeared in Otto marketing materials in the past, as well. In principle, a laminar flow design like the Phantom 3500 could be very well suited to moving cargo and personnel in and out of far-flung operating locations with smaller runways. The U.S. Air Force and U.S. Marine Corps both notably envision future operations, especially during a potential high-end fight with China in the Pacific, as being heavily dependent on the ability to operate from a larger number of often more remote sites to make friendly forces harder to target and otherwise present challenges to the enemy. In those contexts, an aircraft like the Phantom 3500 could also operate as part of a hub-and-spoke logistics concept wherein larger aircraft and ships first bring personnel and materiel to larger bases for further dispersal.
The high-efficiency high-altitude performance Otto is pitching could be beneficial for other military mission sets, including surveillance and reconnaissance. Last year, Aviation Week reported that Otto was working on a 'super-laminar' demonstrator aircraft for the U.S. Defense Advanced Research Projects (DARPA) Agency to be used in experiments to demonstrate power beaming technology that could dramatically extend the endurance of electrically-powered drones, potentially allowing them to stay aloft indefinitely.
Aviation Week's story on Otto's work for DARPA included a computer-generated image showing multiple drones with tear-drop-shaped fuselages, very long and slender wings, and T-tails. Otto has also notably shown a rendering of a concept for an uncrewed derivative of the Celera 500L in the past. The range and fuel-efficiency benefits of a laminar flow-optimized design could be even more extreme in a design that does not need to support a crew, and provide that performance at a lower cost.
When the Phantom 3500 actually flies, and what impact it will have on the aviation industry, remains to be seen. Otto CEO Touw's description of work on the Celera 500L as a 'very difficult labor-of-love' points to challenges already experienced along the way. Though the company is now describing that earlier aircraft as a 'technology demonstrator,' it had previously presented it as a prototype for an expected family of operational aircraft that would include a larger 1000L variant.
In 2022, the company also announced plans for a 19-seat hydrogen-electric-powered version called the Celera 750L that would use ZeroAvia's ZA600 powertrain and have a maximum range of up to 1,000 nautical miles. Whether or not work related to this design, or another variant or derivatives of the Celera 500L, is still ongoing is unclear.
The focus at Otto is now clearly on the significantly redesigned and now rebranded Phantom 3500, which is the only design currently featured on the company's website.
Otto has said the plan is for the Phantom 3500 to fly for the first time no later than 2030, but CEO Touw said in his recent interview with FlightGlobal that the milestone could come as early as 2027. If the company is able to achieve even a decent fraction of what it is aiming for with this aircraft, it could be a major disruptor in the aviation marketplace on multiple levels.
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