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When the emerging history of electric VTOL aircraft is written, Thomas Senkel will undoubtedly be one of the first names that comes up. You might recognize him better sitting in a chair on top of a levitating yoga ball in the Wright Brothers moment of the eVTOL world; back in 2011 he became the first person ever to take flight on an electric manned multicopter.

The team that built that flying yoga ball called themselves e-Volo at the time, but soon changed their name to Volocopter and were one of the earliest companies to strike out after the goal of building an electric air taxi. Senkel parted ways with Volocopter in 2016, unhappy with the comically short range the company's Volocity aircraft would offer. "I've always been unhappy with pure multicopters," he tells us, "because they are so inefficient. There must be a better way: combining an efficient aircraft with VTOL props leads to five times more range and endurance."

If he had stuck around a few more years, he might've had his chance to work on something closer to what he was thinking; earlier this year, Volocopter announced a longer-range lift & cruise winged aircraft called the VoloConnect. But Senkel was long gone, and after a brief diversion into flying electric para-scooters, he teamed up with engineer, entrepreneur and pilot Michael Kügelgen in 2018 to create a more efficient, transition-capable winged eVTOL from a blank sheet.

Kügelgen came up with a concept and design for a tandem-wing lift & cruise aircraft. The large rear wing and thinner front wing would be joined at the outer tips by rails, each holding four large lift props for VTOL operation. A regular propeller at the front would provide forward thrust, either taking over as the aircraft moved from VTOL into cruise mode, or allowing conventional takeoff and landing where runways were available. Slightly flexible landing gear would offer some shock absorption on landing.

While Kügelgen got to work on the airframe, Senkel got to work on the electric drivetrain, starting from first principles to design his own motors, using a Halbach array magnet configuration. Adding the lightest controllers on the market and a huge set of specially designed, thin-bladed, 2.25-meter diameter props, he tells us each propulsion system weighs in at just 5 kg (11 lb) including motor, controller and prop. At 13 kW of power, each creates 100 kg of thrust.

"The parallel development and independent testing of aircraft and copter was a huge advantage," Senkel tells us, "which probably saved us many expensive carbon fiber parts." It also gave him the chance to bust out a bicycle helmet and get crazy again. In true Senkel style, he tested the propulsion system on a bare-bones steel frame earlier this year, strapping himself to a seat and flying a few gentle maneuvers at heights that make it clear that the 10 years since that first yoga ball flight have done little to tarnish his cojones.

At the same time, Kügelgen was regularly flying the prototype of the main airframe as a fixed-wing, and Senkel's had a crack at that too. "The tandem wing configuration gives excellent flight characteristics," says Senkel. "It's impossible to stall it. It softly goes into a higher sink rate when the stick is pulled, but it remains controllable all the time. This behavior is very useful for transition between flight modes."

Now, the aircraft and the lift system have been put together, and Senkel says it's been flown as a fixed-wing with everything attached, and it's also been flown by remote control in VTOL mode. Thanks to what Senkel describes as a "nasty German winter," it'll be spring 2022 before they get a chance to flight-test the transitions between VTOL and cruise modes. "I am confident," says Senkel, "that everything will work fine. And then, we will have public demo flights to show our capabilities."

They've called their hitherto self-funded operation "eMagic Aircraft," and this prototype the eMagic One. They came out of stealth mode yesterday, unveiling the prototype for the public at the European Rotors Fair in Cologne. It's got an empty weight of just 250 kg (562 lb), a max takeoff weight of 420 kg (882 lb), and it'll cruise for a full hour at 144 km/h (90 mph) on a charge of its dual battery packs. Five times the range, Senkel claims, than a pure multicopter design can manage on the same energy.

This, however, is just a proof of concept. And while it might look like a competitive design to run as a buy 'n' fly personal aircraft (especially since it disassembles to fit in a trailer), the eMagic team has loftier ambitions. "The next steps," says Senkel, "will be to develop a serial production aircraft with all the lessons learned from this prototype. It will be a 3-seater, for a pilot and two passengers. That's probably the right size for use as an air taxi. We've financed the prototype out of our own pockets. But for the next steps, we will definitely need an investment round."

A piloted air taxi that can only take two passengers looks like a pretty niche vehicle at this early stage, although it's also fair to say that most regular taxi rides only take one passenger on board. It'll be interesting to see how the idea strikes investors; getting successful prototypes in the air is no mean feat, but the challenge and expense thus far pales in comparison with the task of getting a commercial eVTOL air taxi designed, built, certified and into production. As Lilium, or indeed Volocopter will attest, that's a monumental undertaking indeed.
"You know," says Senkel, "there are a lot of eVTOL projects out there. But we didn't want to show just computer animations. We wanted to have a functional prototype when we went public." That they have.

Source: eMagic Aircraft