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Overair (Karem) Butterfly

 

Butterfly
Overair, Inc.
Lake Forest, California, USA
www.overair.com

Overair, Inc. is a spin-off from Karem Aircraft and is located in California, USA. Overair became its own independent company in January 2020 and will be making the production prototype for their electric vertical takeoff and landing (eVTOL) aircraft named Butterfly.

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 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 $25M dollar investment for Karem's spin-off company, Overair. Hanwha Systems now owns 30% of Overair, Inc.

Overair's eVTOL Butterfly aircraft is a sleek and elegantly designed quad-tiltrotor aircraft. The Overair Butterfly uses the company's patented Optimum Speed Tiltrotor (OSTR) technology which has a far higher system performance (than typical tiltrotors) through integrated improvements in multiple technologies. This includes but is not limited to, variable-speed tilting electric rotors (individual blade control), unique blades, lightweight composites and high efficiency aerodynamics. The Butterfly configuration solves the trade-off between hover and cruise efficiency, creating an optimal vehicle configuration for AAM.

The larger slow turning rotor propellers provide more efficient lift, safer flight and quieter acoustics. The larger rotors draw less power from batteries than aircraft with smaller propellers, which provide an immediate economic impact of 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 at 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 AAM missions on a single battery charge with a lot of reserve power and it doesn't need to rely on any exotic power systems. All one needs is batteries. Efficiency also means the aircraft can fly faster from 150 to 200 mph (240 to 322 km/h) , allowing a shorter time period between trips.

Electric motors are quieter 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.

In August 2021, a new configuration for the Butterfly was revealed. While the 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.

A full-scale uncrewed prototype is in the works and is poised to fly in 2022. Overair aims to have the Butterfly certified by 2025 and launch operations in the United States and Korea for use in AAM operations.

Specifications:

  • Aircraft type: eVTOL
  • Pilot: 1
  • Passengers: 5
  • Speed: 200 mph (322 km/h)
  • Range: 100 miles (161 km)
  • Propellers: 4 propellers. A quad tiltrotor with Optimum Speed Tiltrotor (OSTR) technology. A large rotor, slow turning propeller.
  • Electric Motors: 4
  • Power source: Batteries
  • Wing: 1 high wing
  • Payload: 1,100lb (498)
  • Tail: 1 V tail
  • Landing gear: Retractable landing gear
  • Safety features: Distributed Electric Propulsion (DEP), if one rotor stops for any reason, the aircraft can safely land with the remaining propellers

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