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Overair Butterfly V2 (concept design)

Overair Butterfly eVTOL passenger aircraft flying over a city landscape


Butterfly V2 (concept design)
Overair, Inc.
Santa Ana, California, USA

Overair, Inc. is a spin-off from Karem Aircraft and is located in Santa Ana, California, USA. Overair became its own independent company in 2019 and is in the business of making passenger electric vertical takeoff and landing (eVTOL) aircraft for advanced air mobility (AAM). Some of the major goals for the company is to have has fewer moving parts than traditional tilt-rotor aircraft and  to have no single points of failure with multiple redundancies in the aircraft's systems. In addition, to create a spacious, technically advanced and pleasing cabin, to make a safer aircraft, have very efficient aerodynamics, have a quieter aircraft and a more reliable eVTOL aircraft. The company has named their aircraft the Butterfly.

Some history
Karem Aircraft was founded by Abe Karem in 2004 in California, USA. Ben Tigner was the President and CEO of Karem Aircraft and as of January 2020, is now the President and CEO of Overair. Uber Elevate announced on May 8, 2018 that it was adding Karem Aircraft (now Overair) as one of its aircraft partners to design an eVTOL aircraft for Uber's Elevate ecosystem. In December 2020, Uber sold Uber Elevate to Joby Aviation.

In July 2019, it was reported that Korean industrial conglomerate Hanwha Systems, pending regulatory approval, will invest $25M in a subsidiary of Karem Aircraft to develop the Butterfly eVTOL aircraft for Uber Elevate's mission. On Jan. 15, 2020, it was announced that Hanwha Systems was approved for the $25 million dollar (USD) investment for Karem's spin-off company, Overair. Hanwha Systems now owns 30% of Overair, Inc. Uber Air was purchased by Joby Aviation in December 2020.

Butterfly passenger eVTOL concept design aircraft (Version 2)
Revealed to the public in August 2021, the new Overair's eVTOL Butterfly passenger eVTOL concept design aircraft is a sleek and elegantly designed quad-tiltrotor aircraft. The Butterfly has one pilot and carries five passengers with their luggage.

The aircraft's estimated cruise speed is 180 mph (290 km/h), the anticipated maximum speed is 200 mph (322 km/h) and has a predicted range of 100 miles (161 km). The calculated maximum payload weight is 1,100 lb (499 kg). The aircraft has four tilt-rotors, four electric motors and is powered by battery packs. The propellers are located near the ends of the aircraft's tandem high main wings. While the new design is mostly similar to its previous configuration, the size of the rear props has been increased to allow the Butterfly to land if one prop is damaged.

The fuselage is made from carbon fiber composite for a high strength and low weight ratio. The windows are larger than conventional aircraft providing passengers with better views. The tail has one vertical stabilizer. The aircraft has retractable tricycle wheeled landing gear.

Optimum Speed Tilt Rotors (OSTR)
The Overair Butterfly uses the company's patented Optimum Speed Tiltrotor (OSTR) technology which has a far higher system performance than typical tiltrotors (according to Overair), through integrated improvements in multiple technologies. Optimum Speed Tiltrotor technology has the following characteristics of variable-speed tilting electric rotors (individual blade control), uniquely designed blades, lightweight composite blades, high efficiency aerodynamics and more. The Butterfly configuration solves the trade-off between hover and cruise efficiency, creating an optimal vehicle configuration for advanced air mobility (AAM).

The larger slow turning rotor propellers provide more efficient lift, safer flight, quieter acoustics and draw less power from batteries than aircraft with smaller propellers. This design feature provides an immediate economic impact by making the Butterfly less costly to fly. The most recent information from Overair as of August 2021 includes claims that the Butterfly will be the quietest eVTOL in the industry when they launch. Two statements were given to support this claim, the noise produced by the aircraft is low and the frequency of the noise is one which humans are less likely to register. If this is the case, it stands to have a major advantage over competitors in both public acceptance and passenger comfort.

According to Overair's Ben Tigner, using large slow tiltrotors makes the Butterfly a more efficient and faster aircraft on less power. While efficiency sounds academic, efficiency translates into real economic and operational advantages. For example, the Butterfly can fly multiple advanced air mobility missions on a single battery charge with a lot of reserve power and it doesn't need to rely on any exotic power system. All one needs is batteries. Efficiency also means the aircraft can fly faster, for example, the aircraft will increase it's cruise speed from 150 to 200 mph (240 to 322 km/h), allowing a shorter time period between trips.

Individual Blade Control (IBC)
The company has precise control of each blade which overcomes the physical limits on rotor sizing, providing greater time between overhauls (i.e., reduced maintenance) and best-in-class ride quality. Overair calls this Individual Blade Control.

Safety And Efficiency Features
The electric motors on the aircraft are quieter than conventional combustion and turbine engines, and provide a higher margin of safety. High efficiency allows the aircraft to perform well with unexpected wind gusts or unexpected traffic, the aircraft can easily maneuver through these situations where turbine jets or planes might have more trouble.

On June 14, 2022, Overair announced they received $145 million in funding from Hanwha Systems and Hanwha Aerospace, headquartered in Changwon, South Korea. With this new investment, Overair plans to use this money to fly its eVTOL prototype aircraft in the second half of 2023 and to help commercialize their eVTOL passenger aircraft. In addition to their investment, Hanwha will also provide electric motors and battery packs for Overair's prototypes.

On December 14, 2023, it was announced that the United States Navy has awarded Overair a Small Business Innovative Research (SBIR) contract to further develop the high-integrity individual blade control (IBC) technology. Overair states their IBC technology significantly reduces vibration, extends component life and improves safety and ride quality.

On December 19, 2023, Overair announced it completed assembly of the first full-scale prototype of its Butterfly eVTOL aircraft. Initial flight tests are scheduled to begin in early 2024 and will focus on validating Butterfly’s propulsion systems, flight control mechanics, safety features and operational efficiency. The testing will also assess the aircraft’s 55-decibel noise target and performance envelope across diverse flight and weather conditions.

On January 18, 2024, Overair announced it has received a letter of intent from JetSetGo in India to purchase of 50 Butterfly eVTOL aircraft. Overair is the only eVTOL manufacturer selected for JetSetGo’s initial $1.3 billion advanced air mobility (AAM) investment.

The company foresees their aircraft used for air taxi service, VIP air service, medical transportation, air cargo, government use,  military use and more.

Butterfly eVTOL in forward flight

Butterfly eVTOL in forward flight

Butterfly eVTOL hover mode

Butterfly eVTOL hover mode

Butterfly eVTOL in forward flight

Butterfly eVTOL in forward flight


  • Aircraft type: Passenger eVTOL concept design aircraft
  • Pilot: 1 pilot
  • Passengers: 5 passengers with luggage
  • Cruise speed: 180 mph (290 km/h)'
  • Maximum cruise speed: 200 mph (322 km/h)
  • Range: 100 miles (161 km)
  • Payload: 1,100 lb (499 kg)
  • Propellers: 4 propellers. A quad tilt-rotor with Optimum Speed Tiltrotor (OSTR) technology (a large rotor, slow turning). propeller.
  • Electric Motors: 4 electric motors
  • Power source: Batteries
  • Windows: The windows are larger than conventional aircraft providing better views for the passengers
  • Wing: Tandem wings with winglets
  • Tail: 1 vertical stabilizer
  • Landing gear: Retractable tricycle wheeled landing gear
  • Safety features: Distributed Electric Propulsion (DEP), provides safety through redundancy for its passengers and/or cargo. DEP means having multiple propellers (or ducted fans) and motors on the aircraft so if one or more propellers (ducted fans) or motors fail, the other working propellers (or ducted fans) and motors can safely land the aircraft. There are also redundancies in the sub-systems of the aircraft.

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