Southern California air taxi developer Overair on 19 December revealed the first full-scale prototype of its electric vertical take-off and landing (eVTOL) vehicle.

The company says the uncrewed aircraft’s assembly marks a major milestone in its development programme of Butterfly, building off earlier ground-testing of its propulsion system with a truck-mounted rig. 

“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,” says Ben Tigner, chief executive of Overair. 


Source: Overair

Overair’s uncrewed full-scale demonstrator introduces a pair of critical propulsion technologies, the start-up says 

”This prototype is specifically for vertical flight mode,” Overair adds. ”We are simultaneously working on the next prototype, which will demonstrate transition and forward flight mode.”

The remotely piloted aircraft is the first eVTOL design to feature two systems – optimum speed titlrotor and individual blade control – which together represent “a completely novel approach to aviation that unlocks a new standard in quietness, performance and reliability”, according to Overair. 

Optimum speed tiltorotor technology varies propeller revolution per minute to increase efficiency throughout all phases of flight, including take-off and transition to forward flight. Overair says this approach can reduce the aircraft’s power demand while hovering by 60%. 

Individual blade control, meanwhile, reduces vibration and stress on propellers, while also reducing maintenance costs and allowing for smoother rides. Overair recently disclosed that it has a contract with the US Navy to advance the technology. 

”Together, these technologies deliver an efficient, quiet and reliable propulsion system in almost any weather, temperature or altitude,” the start-up says. ”Additionally, with fewer moving parts than traditional tiltrotors and no single points of failure, Overair owns a unique position in the market.”

Overair prototype

Source: Overair

Overair’s production aircraft will be marketed for missions currently performed by helicopters, in addition to air taxi operations. 

Overair will soon begin a test programme at its headquarters in Santa Ana, with an eye on first flight early in 2024. Then, the aircraft will be moved to the company’s fight-test facility in Victorville. 

Those test flights will validate the prototype’s propulsion system, fight characteristics, safety features and operational efficiency, the start-up says. The aircraft’s sound signature will also be evaluated in different flight and weather conditions. 

Though the prototype is pilotless, Overair’s eventual production eVTOL will seat one pilot and five passengers. The vehicle is being aimed at commuter, medevac and military markets. 

Equipped with four slow-moving rotors which are twice the size of those on most other air taxis, Butterfly will be among the quietest eVTOLs, Overair says, producing estimated noise levels of about 55 decibels. 

Overair is positioned in the second wave of US air taxi makers, targeting a commercial service launch ahead of the 2028 Summer Olympics in Los Angeles.