Development of “Aria,” a Compact, Quiet Personal Electric Helicopter

This paper describes the development and flight testing of a personal air vehicle by team Harmony for the GoFly Prize competition. The competition emphasized an open-air flight experience, and the final aircraft was scored by size (≤8.5 ft), noise (<87 dBA), and speed (>30 kt). The highest scoring team would win a $1 million grand prize. Team Harmony endeavored to develop an aircraft which would maximize the competition score. A counterrotating coaxial electric helicopter configuration was chosen to maximize rotor area and reduce disk loading for efficiency and acoustic benefits. The rotors were designed through a parametric study using an in-house aerodynamics code, an in-house acoustics code, and CREATE^TM-AV Helios CFD. A quiet electric power train and custom 11 kWh battery were developed. Flight control was implemented with dual, independent, electronically coupled swashplates. A one-third-scale prototype aircraft was first developed and flight-tested. Then a full-scale, 520 lb (235.4 kg) prototype with an 8.45 ft (2.58 m) rotor diameter was developed and flight-tested. During hovering, the measured sound pressure levels at 50 ft (15.24 m) were 73 dBA. The full-scale vehicle crashed before its speed capabilities could be tested, but the aircraft would have likely scored well, achieving the goal of the project. This work encompassed several design trade-offs, especially between aerodynamic and acoustic performance in the rotor and blade design, and between acoustics and endurance in the power source selection, and in availability and flight-worthiness of off-the-shelf hardware for personal flight.