E-Champion as E-Surfer
Riding a wave without wind? That can definitely be done with the Audi e-foil, because this surfboard – a so-called hydrofoil – is powered by an electric jet. “What a brilliant idea! I definitely wanted to try it out,” says Lucas di Grassi. “Audi is constantly looking for new challenges in order to create new technologies: even on water, where Audi doesn’t have the massive experience it has on the road and the racetrack. I find that particularly intriguing.” The Formula E drivers’ and teams’ champion, who, on the side, is actively involved in the development of electric bikes and autonomous racecars, shoulders one of the first prototypes of the Audi e-foil: Mediterranean Sea, here I come!
A NEW BOARD FEELING
The Brazilian, now mainly calling the principality of Monaco home, grew up with water sports in his native São Paulo. Surfboards – just like go-karts – used to be part of the childhood of the Formula E factory driver from the Audi Sport ABT Schaeffler team. Finding the perfect balance is child’s play for Lucas di Grassi, so, unsurprisingly, his first attempt to ride the Audi e-foil is successful: get on the board lying flat on your stomach, turn the knob on the wireless remote control and off you go. Then get on your knees. Then on your feet. “Yeah!” the E-Champion is standing – o.k.!
ACCELERATE AND GET AIRBORNE
The next stage of this test on the Côte d’Azur: pick up speed, and then some more. Lucas di Grassi uses his right index finger to accelerate on the e-foil. Then he gets airborne, suddenly hovering half a metre above the sea. Silently gliding along without any water contact. Only hearing the gurgling sound of the blue-green waves below him. Thanks to the hydrodynamic lift produced by the hydrofoil on the mast under the hull of the Audi e-foil. As a result, the electric surfboard lifts itself up out of the water, starting at a speed of 17 km/h. “Wow, what an awesome feeling, like flying!” Lucas di Grassi just can’t help briefly shouting out his riding pleasure.
“As long as the board is still gliding on water, you can influence its angle with the speed controller,” says Lucas di Grassi, describing his initial e-surfing insights. “However, as soon as you’ve become completely airborne you need to steer and control everything with your body balance, just like you would in normal surfing.” No sooner said than done: the South American, not only blessed with strong hips, becomes steadier on his legs with each wave, more secure from turn to turn.
FASTER, HIGHER, FARTHER
“That’s super-cool!” The grin on Lucas di Grassi’s face keeps widening. No wonder! Now the E-Champion is cruising flat-out on his airborne board along the coast of the French Riviera. Expressed in numbers: 45 km/h – the Audi e-foil’s top speed has been reached – gained from 3 to 5 kW of power output. One battery charge yields up to one hour of surfing time and a range of up to 30 kilometres.
In this mode, clear of the ocean, at full speed and heavily reduced water resistance, the Audi e-foil only consumes half the amount of electric power. “This efficiency is very impressive,” emphasises Lucas di Grassi. “The Audi e-foil is a fascinating blend of aircraft, surfboard and electric propulsion technology. And even though I’ve tried it out myself, it somehow remains surreal.”
NEW ELECTRIC LEVEL
“May I please ride again tomorrow?” Lucas di Grassi asks, and has to laugh again. His question is addressed to Franz Hofmann. He’s a fluid dynamics expert at Audi and has developed the Audi e-foil – initially in his leisure time while looking for an alternative to his hobby of kite surfing. Christian Rößler, an old childhood friend and now an experienced aerospace engineer, which made him the perfect assistant, lent him a helping hand. “A foil is ultimately just an underwater aircraft,” says Hofmann.
The principle and technology of the Audi e-foil: propulsion is provided by a three-blade propeller, powered by an electric motor. The required electric power is supplied by a battery inside the hull of the surfboard. At the base of the foil’s mast sits the foil and tail assembly, whose upward force lifts the board out of the water. To achieve the very high stiffness and low weight required, all three components are made from carbon fibre.
It took the two German high-tech enthusiasts only about 100 days to move from the design phase to the first prototype. Since then, Audi has adopted the promising project and unveiled the Audi e-foil to the general public during the CES trade show in Las Vegas/USA at the beginning of 2019. After his enjoyable test ride, there’s no doubt in Formula E racing pro Lucas di Grassi’s mind: “I’d definitely buy the Audi e-foil, because that’s the future of water sports. With it, I’ll never have to wait for wind to go surfing again.”
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