A new full-scale electric vertical takeoff and landing (eVTOL) prototype is ready to spread its wings.
Overair, maker of the Butterfly eVTOL air taxi, said Tuesday that it completed the build of its first full-scale prototype aircraft, which is set to begin flight testing early next year. The company will start with vehicle-level testing at its Santa Ana, California, headquarters before moving the aircraft to its flight test facility in nearby Victorville.
Early tests will aim to validate different aspects of Butterfly’s technology: propulsion systems, flight control mechanics, safety features, and operational efficiency, to name a few. Overair will also evaluate how the aircraft meets its noise target (55 decibels) and performance envelope under an array of flight and weather conditions.
Overair hopes to certify Butterfly with the FAA and is working through its G-1 Stage 3 means of compliance, which will establish the criteria for validating its certification basis. Those criteria will be assessed in future “for credit” testing under the regulator’s watchful eye. The company expects Butterfly to enter service in 2028, in line with the FAA’s timeline for early advanced air mobility (AAM) operations.
“Assembling our first full-scale prototype vehicle marks the culmination of years of industry expertise, meticulous development planning, innovative engineering, and the hard work of the entire Overair team,” said Ben Tigner, CEO of Overair. “This seamless transition from propulsion testing to a full-scale prototype underscores our dedication to redefining the eVTOL landscape with safer, quieter, and more reliable aircraft.”
Butterfly deploys two technologies Overair says have never been integrated on an eVTOL design: optimum speed tilt rotor (OSTR) and individual blade control (IBC).
The OSTR system is essentially a power saver. Throughout vertical, transition, and forward flight, it varies propeller revolutions per minute, which Overair says boosts efficiency. The company claims OSTR reduces power demand in hover by as much as 60 percent.
IBC, meanwhile, reduces propeller loads by limiting the vibration of each blade, which the firm says results in safer, smoother, lower-cost flights. Last week, the technology was awarded a U.S. Navy Small Business Innovation Research (SBIR) contract, which will see it developed for potential Navy use.
Matt Rhinehart, aeromechanics senior engineer of the Naval Air Systems Command, said IBC opens up a long list of potential benefits for the Navy’s “next generation of rotorcraft.”
Overair claims Butterfly’s combination of OSTR and IBC produces efficient, quiet propulsion in nearly any weather, temperature, or altitude. In addition, the design features four oversized rotors, a large cabin, and a payload of about 1,100 pounds—enough for five passengers and their luggage. The company says Butterfly is ideal for passenger, medical, cargo, and military applications.
“Since day one, Overair has been committed to developing an aircraft that extends efficient air transportation to a broader audience; an aircraft that will be welcomed by local communities, passengers, and operators alike,” said Valerie Manning, chief commercial officer at Overair. “Our prototype is where we begin real-world, full-scale validation of these fundamental design principles.”
As Overair rolls out its first full-scale prototype, it joins a handful of other eVTOL air taxi manufacturers to reach that stage. Archer Aviation was one of the first in the U.S. to hit the milestone, completing the build of its first Midnight prototype in May. Joby Aviation in June rolled out its initial production prototype, following the introduction of its full-scale preproduction model in 2019. Both firms have begun flight testing.
Germany’s Volocopter, meanwhile, has assembled two prototypes: the two-seat VoloCity and the larger VoloConnect. Another German manufacturer, Lilium, started building its first Lilium Jet this month, while Embraer subsidiary Eve Air Mobility expects to complete a full-scale prototype by year’s end.
Once Butterfly makes it through the gauntlet of FAA certification tasks, Overair plans to deploy it in a few key markets.
In November, the company announced partnerships with Dallas/Fort Worth International Airport (KDFW) and the city of Arlington, Texas, to launch air taxi flights out of DFW Airport and Arlington Municipal Airport (KGKY). No firm commitment has been made to purchase aircraft, but the partners plan to introduce vertiports, charging stations, and new policies to the region to build a full-fledged AAM ecosystem. Eventually, it’s expected to span the entire Dallas-Fort Worth metro area and North Texas region.
In addition to those agreements, Overair has a partnership with helicopter operator Bristow Group, which placed a preorder for 20 to 50 Butterflys. Bristow plans to fly the eVTOL on commercial air taxi routes in its service areas, including several cities in and around Texas.
Farther to the west, Overair and several other eVTOL manufacturers are working with Urban Movement Labs, a Los Angeles government-community transportation partnership. It expects to highlight Butterfly during the city’s 2028 Olympic Games, alongside other players.
Overair in October also agreed to deliver 20 aircraft to South Korean helicopter transportation provider HeliKorea. The partnership followed plans to launch services on Jeju, the country’s largest island and a major tourist destination.