Electronic vertical take-off and landing drones (eVTOLs) are one of many products that groups have announced plans to build but never actually produced. However, this is not the case for Overair's Butterfly, whose just-unveiled prototype will soon begin flight testing. Looking back at our previous reports, "Butterfly" is an electric vertical take-off and landing aircraft (eVTOL) being developed by California aviation startup Overair. Overair's parent company, Karem Aircraft, has been involved in many U.S. military projects related to vertical lift since its establishment in 2004.
According to the plan, the commercial version of "Butterfly" can carry a pilot and four passengers, can reach a top speed of 200 miles (322 kilometers) per hour, and has a battery life of up to 100 miles (161 kilometers).
Propulsion is provided by four three-bladed rotors, two on the wings and two on the V-shaped tail, which tilt from horizontal to vertical when transitioning from vertical to forward flight.
One of the main features that sets the Butterfly apart from other electric aircraft is the size of its rotors, each more than 20 feet (6 meters) wide. These rotors produce more thrust per kilowatt of power than other designs with smaller rotors.
In addition, the rotor's rotational speed (revolutions per minute) and the angle of the individual blades can be continuously and automatically adjusted. According to reports, adjusting the rotational speed can improve efficiency in all flight modes - power requirements in hover can be reduced by 60%, while adjusting the blade angle can reduce vibration and propeller load, improve safety, provide smoother flight quality and reduce maintenance costs.
The full-size prototype announced on Tuesday (December 19) uses the above technology, but it is an unmanned remote-controlled stand-in for the mass-produced model. Ground testing has already begun at Overair's headquarters in Santa Ana, California.
Flight testing will begin early next year at the company's test facility in the nearby city of Victorville. Initial testing will focus on validating the propulsion system, flight control machinery, safety performance and operational efficiency, as well as the aircraft's 55 decibel noise target.
"Assembling our first full-scale prototype aircraft marks the culmination of years of industry expertise, rigorous development planning, innovative engineering and hard work from the entire Overair team," said CEO Ben Tigner. "This seamless transition from propulsion testing to full-scale prototypes demonstrates our commitment to redefining the eVTOL space with safer, quieter and more reliable aircraft."