Near Toulouse, France, a small team of engineers is about to fly the first-ever electric helicopter with a conventional architecture – one main rotor and one tail rotor.
The maiden flight of the Volta is slated for late July, after three years of design work. The single-seat aircraft has been designed as a demonstrator, as the team hopes to sell its know-how to a larger company.
“Assembly of our helicopter was completed in May 2015,” Philippe Antoine, founder of the Volta project, told Vertical.
It then took another seven months to ready it for testing.
Engineering school Enac helped design the human-machine interface for testing, ensuring close monitoring of the electric system. Power-on trials enabled the Volta team to correct small issues, which could be found in many places, “but not at battery level,” said Antoine.
The Volta rotorcraft now has a registration and a permit to fly from the French civil aviation authority (DGAC). A pilot was found by the project’s team and the DGAC approved him. He will be ready later this month, after having finished flying for the Tour de France.
“We want to prove we can hover for 15-20 minutes,” said Antoine.
Yet, the electric system was adapted to an existing design. This is not ideal, Antoine admitted, as a cleansheet electric helicopter design would be more efficient.
The Volta helicopter has two motors, which are part of two segregated electric systems. Thanks to electric power, it is expected to be cheaper to operate. Moreover, pilot workload can be reduced, according to Antoine.
The concept is claimed to be more environmentally friendly. This is not only about reduced noise. Over an estimated 350-hour life, the Volta’s batteries save 17,000 liters (approximately 4,500 gallons) of fuel.
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For energy storage, the Volta is understood to use proven lithium-ion batteries. Antoine expressed hope lithium-sulphur technology, in future, will improve safety.
Unlike a combustion engine, the performance of an electric motor is not affected by hot temperature or high altitude. However, cold does impact the battery in the starting phase. The promoters of the Volta project assert this will not be a problem for a flying school.
Antoine’s goal is to find a partner, possibly a large manufacturer, who could fund a development program for a two-seater. The main application would be found with flying schools.
“An electric two-seater would be perfect for the first 10-15 hours of pilot training,” said Antoine.
The target endurance could be 55 minutes in cruise flight or 45 minutes in hover flight. The instrument panel could even replicate that of another helicopter.
To fund the demonstrator, Antoine and a partner created a company called Aquinea. It has no relationship to aerospace but has generated profit, which has been invested in Volta.
Two other electric helicopter projects made it to flight testing in recent years. Volocopter, a German company, is testing a multi-rotor design. This is not as efficient as one large main rotor, in Antoine’s view, and does not allow autorotation.
In 2011 near Aix-en-Provence, France, motor sports company Solution F and engineer Pascal Chrétien demonstrated a six-minute hover flight with a dual, coaxial main rotor and unconventional controls.
The Volta’s airframe uses that of the Microcopter, a conventional helicopter with a piston engine. Antoine designed it as a student, in the 1990s. It first flew in 2004. However, due to instability in the two-stroke engine, the project was put in standby mode.
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Antoine later realized that recent progress in electric power could enable it to be a suitable platform – albeit not optimal – for installing a motor, batteries and accompanying systems. Partners were found in France to supply components.