German startup E-volo GmbH for the first time prodded its battery-powered, 18-propeller multirotor aircraft off the ground during a series of brief test flights Nov. 17 in an indoor arena.
The two-person vertical-takeoff-and-landing Volocopter VC200 craft — neither a helicopter nor a drone – may offer an alternative to cars and air taxis as the newest competitor in the field of personal airborne transportation.
Composites and batteries
The VC200 is topped with 18 carbon-fiber blades, each nearly six feet long. They are arrayed in two concentric rings made of advanced, lightweight composite materials. The structure supporting each blade’s motor remains stationary. Only the spinning rotors themselves provide lift.
A two-person cockpit outfitted with a tablet computer and game-console-like joystick sits beneath the motors on flexible skids. Hidden behind the seats are multiple, redundant computers.
Physicist and Volocopter inventor Thomas Senkel says safety is built into the craft’s design; it could theoretically land with only one of the computers and as few as a dozen rotors operating as long as the remaining working blades aren’t all clustered on one side. Future versions will have an emergency parachute stored in the hub among the motors.
Such elements are not the only ways that Senkel’s craft differs from the helicopters that are its closest relatives flying today. Pilots of a conventional chopper use many more complicated controls, most of which are physically connected by cables to the engine and rotor assembly.
But the VC200 is a purely fly-by-wire craft where flight is controlled electrically rather than mechanically. Computers using E-volo’s operating system translate pilot commands into actions — change of direction or speed, climb, descend and so forth. A Volocopter pilot might set a GPS course, choose an elevation or indicate a turn, he says, but the system does the rest.
The vehicle is powered entirely by a 17.5 kilowatt-hour battery, and can now fly for up to 40 minutes depending on weight and air speed. E-volo is working toward a private-aviation version of the Volocopter that weighs about 661 pounds with batteries, rises to 6,500 feet, cruises as fast as 62 miles per hour and stays aloft for an hour or more.
That kind of endurance would require the addition of a small combustion engine, not to directly power the propellers but to generate electricity and recharge batteries. Including the engine, which would make the Volocopter a so-called serial hybrid craft, would demand more development resources than going with battery power alone, says Stephan Wolf, E-volo’s managing director and head of software development.
Because of this, the company is focusing on battery use for the foreseeable future, but even that has its technical hurdles.
“Yes, it is a challenge,” says Wolf. “Sixty minutes of flight time for the Volocopter on batteries alone is comparable to driving an electric car for 500 miles.”
“An hour is a challenge, but we are optimistic” that battery technology will improve enough to make this possible “within the next few years,” he says.
In the meantime, the aircraft needs money as much as advanced battery technology. E-volo has so far received at least 2 million euros, or $2.7 million, from the German government.
The company is running a crowdfunding campaign on Seedmatch to take their plans to the next step.
He expects to receive a preliminary airworthiness certificate from the local government in spring 2014. Then, things move outdoors for the Volocopter.
“We plan to use the airfield right in front of our plant for the tests,” he says.
The motive behind efforts by multiple inventors to develop personal aircraft —most of which have failed to get off the ground—has been to create a vehicle that is safe, affordable, simple and convenient to use. Past attempts have compromised one or more of those factors, resulting in market and engineering dead ends.
E-volo is looking to create a pure aircraft for the masses. The company breaks from the land-and-air model of personal transportation envisioned by enterprises like Terrafugiaand Moller International, which are trying to build cars that can fly. Inventor Chris Malloy’s Hoverbike is a proposed helicopter/motorcycle hybrid. Another exception to the two-in-one strategy is Project Zero, by British-Italian helicopter maker AgustaWestland, an experimental personal tilt-rotor aircraft.