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Electrically powered vertical-take-off-and-landing (eVTOL) aircraft—flying cars are an idea whose time has not quite yet come, but is fast approaching. Many firms are offering various designs. None of these, however, will be Jetson-like family flying cars. Pivotal, based in Silicon Valley, by contrast has crafted something that people can purchase and pilot themselves. Helix is a single-seat vehicle, so "flying motorbike" might be more accurate. From next year, many people will be able to order one for personal use, though they will not be able to take delivery until June.

Marcus Leng founded Pivotal in 2011, and some back-of-the-envelope calculations he made suggested that electric lift-off of a human-carrying craft, using motors powered by the lithium-ion batteries ought to work. He thus built a model and flew it in the garden of his house in Warkworth, Ontario.

Now, after ameliorating it, the firm thinks it has something marketable. The aircraft has, nevertheless, changed little in its fundamentals over the years. It has two pairs of wings and eight propellers(螺旋桨), making it slightly resemble a squashed "H" when seen in the sky from below. And there is no undercarriage. Instead, its belly is curved in a way similar to a humpback whale's, so it rocks to stability after landing.

Pilot's licence or not, buyers will still need some training to fly a Helix. Pivotal insists on this. For the same reason, the craft's software will stop the pilot doing anything that does not fit its safety rules. And if, despite this, something does go wrong, it is fitted with a parachute(降落伞).

The Helix's top speed is a respectable 100 kph, but its range is only 30 km. And refueling it is a bit of a pain. Filling up from the mains takes four and a half hours, though a special high-power system similar to those employed for electric cars can bring that down to 75 minutes. While Helix still doesn't compare to the flying car from the Jetsons, it could be a step forward.

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