Lilium/electric aviation: wing and a prayer
A commercial air taxi service will require better batteries
Aircraft as cheap and convenient as cars are a recurring vision. German start-up Lilium is the latest to dream it, with electric propulsion an added challenge. The best batteries have about 1.7 per cent of the power-to-weight oomph of kerosene. Whipped cream stores energy better.
Lilium has unveiled a flying vehicle it hopes will operate as a commercial taxi service by 2025. The craft is already capable of carrying five people 300km in an hour, it says. This feat does not feature in a video clip. Only a brief hover is demonstrated.
The best lithium-ion packs achieve 200 watt hours per kilogramme. That is about 7 per cent of the figure for whipped cream, according to aerospace experts in Germany. Even accounting for energy wastage in a combustion engine, electric vehicles have poor power to weight ratios. A quadcopter design with current battery technology might get four people 100km, say academics t UCL.
The range anxiety of electric motorists is nothing to that of electric aviators, even if they own parachutes. But Lilium says lift from its vehicle’s wing improves its reach.
Better batteries would help too. Energy density has risen about 4 per cent a year over 20 years. Tesla’s Elon Musk thinks density of 400 Wh/kg will do for flying taxis. UCL believes at least 750 Wh/kg is required to replace short range commercial jets; those will be available in 2050.
Lex is betting on a cream-powered flyer — the Schlagsahnehubschrauber, as it might be known in Germany. If you do not fancy flying, you can use the fuel as a topping for apple strudel.