The South Korean market is in the crosshairs of plenty of electric vertical takeoff and landing (eVTOL) aircraft manufacturers not based in the country: Joby Aviation, Vertical Aerospace, Jaunt Air Mobility, Hyundai’s Supernal, Embraer’s Eve Air Mobility…the list goes on and on.
And it just got longer.
Santa Ana, California-based Overair is the latest such firm to put down roots in South Korea. The manufacturer of the Butterfly eVTOL—along with strategic collaborator Hanwha Systems, one of its largest investors—signed a trio of agreements with Korean partners during this week’s International Aerospace and Defense Exhibition (ADEX) in Seoul.
The agreements call for the delivery of 20 aircraft to a local helicopter operator, the creation of a nationwide advanced air mobility (AAM) network, and—perhaps most interestingly—the provision of aircraft and training for the Korean National Police (KNP).
“Overair is a company with global ambitions,” said Overair CEO Ben Tigner. “Announcing these agreements at Seoul ADEX2023 not only shows the importance of these partnerships in Korea but also exemplifies our commitment to supporting all aspects of AAM worldwide.”
What’s Being Delivered?
A letter of intent (LOI) between Overair and helicopter transportation company HeliKorea calls for the purchase of 20 Butterfly eVTOLs. The Korean firm will integrate the aircraft into its business to enable medical, executive, and cargo transport, as well as other use cases such as firefighting and inspections of infrastructure, such as high-voltage power lines. Overair will provide pilot and maintenance training.
The company’s six-seat eVTOL is designed to carry five passengers and a pilot, or 1,100 pounds of cargo. The final production model is expected to have a 100 sm (87 nm) range and a 200 mph (174 knots) top speed. Butterfly’s cabin is adaptable for a variety of use cases. In addition to those listed above, Overair also plans to use it for on-demand ridesharing, critical patient and organ transport, military missions, and other applications.
According to the company, a trip between Santa Ana’s John Wayne Airport (KSNA) and Los Angeles International Airport (KLAX)—a distance of 43 sm (37 nm)—is expected to take just 18 minutes with Butterfly’s 180 mph (156 knots) cruise speed. Driving between the two airfields would take closer to 70 minutes by Overair’s estimate.
The aircraft’s propulsion system was developed with the expertise of Abe Karem, considered to be one of the pioneers of uncrewed aerial vehicle (UAV) technology. Boasting what may be the coolest nickname in the aviation industry—“the dronefather”—Karem is widely recognized for his contribution in developing the MQ-1 Predator drone for General Atomics, which laid the foundation for the advanced UAVs deployed by the U.S. military today.
After departing General Atomics, Karem spent decades working on U.S. military VTOL programs with his company, Frontier Systems, that was later acquired by Boeing. His team led the development of what became Boeing’s A160 Hummingbird UAV, breaking numerous altitude and endurance records in the process while keeping noise to a minimum. The propulsion systems aboard the Hummingbird represent the early stages of Butterfly’s architecture.
The aviation pioneer founded Karem Aircraft in 2004, spinning out Overair in 2020 and joining the new company as its principal designer. Karem’s largest contribution to Butterfly is the TR-36 Optimum Tilt Speed Rotor, which was evaluated by the U.S. Army’s Future Vertical Lift program as a component for the next generation of rotorcraft that will replace Army helicopters.
Butterfly’s four TR-36 rotors—each with massive, 20-plus-foot propellers—spin slowly during hover and even slower during cruise. Each blade is controlled individually and precisely by a proprietary system. Since the slow-spinning propellers draw from only a fraction of the aircraft;s motor power, Overair says they increase payload capacity and excess power margins.
The company claims its propulsion system gives Butterfly the broadest flight envelope and smallest sound footprint (55 dBA, by its estimate) of any eVTOL under development. It also describes the aircraft as having the “broadest capability of any eVTOL” to fly in weather conditions such as rain and wind, a common limitation of other designs.
Butterfly relies on fly-by-wire envelope protection for safety and can hover on two of its four propellers with the help of its “quad-redundant” architecture.
Korean Police Get an Eye in the Sky
Also this week, Overair signed a memorandum of understanding (MOU) with Korean construction company Daewoo E&C. The agreement establishes a plan for the firms to jointly develop a series of AAM networks across Southeast Asian markets.
The partners will develop and implement an AAM concept of operations, pick out local operators and vertiport sites, create urban air traffic management (UATM) systems, and work with local aviation and government authorities to develop a regulatory framework for commercial service in the region. Daewoo will build the vertiports, while Overair will provide operational and integration expertise.
But the most interesting of Overair’s three announcements is perhaps the MOU it signed with the KNP. As some U.S. law enforcement agencies crack down on their use of drones, the agreement aims to give Korean police access to a much larger UAV.
The KNP’s Human Resources Development Institute will develop training programs for its officers, which will in part be led by Overair. Topics covered will include vertiport development and integration, pilot training, AAM deployment, maintenance, and more.
Should the agreement come to fruition, Korean law enforcement could use Butterfly for rapid response or dispatch, allowing it to bypass the busy streets below. For example, Jump Aero, a U.S. firm developing an eVTOL for first responders, estimates its aircraft could fly anywhere within a 31-mile radius in as little as eight minutes.
Overair partner Hanwha will provide operational support for all three agreements made this week. It will also lend its technology—which includes air travel infrastructure, communication, surveillance, software management, and other systems—to certify UATM services in Korea and ensure safe operations.
“Overair is committed to supporting South Korea’s strong AAM ambitions through partnerships like these that ensure all facets of the ecosystem are considered,” said Tigner. “Local governments, operators, and infrastructure providers alike will play an integral role as we enter this new era of transportation. We look forward to collaborating with our partners at Hanwha Systems on these exciting new projects.”
Other Plans for Butterfly
This week’s trio of partnerships comes on the heels of an MOU between Overair, Hanwha, and Korea’s Jeju Special Self-Governing Province, signed last week, to bring an AAM ecosystem to Jeju Island. The island is South Korea’s largest and a major tourist destination.
The partners will jointly develop AAM infrastructure, manufacturing, training, maintenance and repair organizations (MRO), and other aspects of the network. It will support public, medical, and tourism operations on the island, helping it reach its commitment to be carbon neutral by 2030.
Elsewhere, 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. Full-scale Butterfly prototype flight testing will begin next year. A collaboration between the FAA and the Korea Office of Civil Aviation (KOCA), meanwhile, aims to harmonize AAM certification and integration between the two nations, creating a path to certifying Butterfly in South Korea.
Following certification, Overair will launch in Korea as well as the U.S. in partnership with Houston-based Bristow Group. An agreement between the two includes a preorder for 20 to 50 aircraft. The firms will also develop commercialization plans and an operational framework, with an eye on flying commercial air taxi routes in Bristow service areas.
In addition, Overair, among other eVTOL manufacturers, is working with Urban Movement Labs, a Los Angeles government-community transportation partnership, to enable AAM infrastructure and operations in the area. It plans to launch there in the future and will highlight Butterfly during the city’s 2028 Olympic Games, alongside other players.
The L.A. Olympics are viewed by many eVTOL manufacturers as a key deadline for air taxi services at scale, in line with the FAA’s Innovate28 plan for early AAM operations in U.S. cities. Several of them are eyeing the City of Angels as a potential launch market.