German start-up Lilium has just unveiled its first full-sized five seater all-electric ‘flying taxi’, but could flying taxis really provide the solution to gridlocked cities? Photo Credit: Lilium

Flying Taxis and the Future of Intra-City Travel

Munich-based Lilium claims to have built the world’s first all-electric, five-seater passenger jet which it plans to develop into an uber-like taxi service by 2025. In production since 2013, the jet is one of many flying taxi prototypes being developed by tech firms across the globe, with Uber planning to release their own autonomous flying taxi service by 2023, and Airbus, Ehang, Rolls-Royce, Boeing and Kitty Hawk developing their own autonomous electric passenger drones.

Lilium’s USP is one that many have been waiting for if it to be believed – a reasonable range (300 miles), high efficiency and multiple occupancy flying taxi. Rivals Airbus and Kitty Hawk have based their designs on a 1-2 person capacity, whereas Lilium’s taxi purports to hold five people, including the pilot. This paired with its claim that at cruising speeds it is only slightly less efficient than an electric car could see it as a true alternative to road travel. Utilising a winged design, Lilium engineers hope to utilise lift to increase the efficiency of the vehicle – using only 10% of the maximum 2,000hp delivered by its 36 all-electric engines to propel it to 300km/h. Lilium representatives have said that the price of the service would be comparable to that of a road-taxi once scaled up, but the how much of this is purely marketing is hard to say.

More broadly speaking, eVTOL (Electric Vertical Take-Off and Landing) vehicles – and more specifically taxis – are becoming more and more feasible due to advances in battery, electric motor and automotive piloting technologies and much of the delay in their production comes from the regulations surrounding low-altitude travel rather than the technologies themselves. The tightest bottleneck in electric aviation technology, however, has been in the batteries used to power the electric motors. Current lithium-ion batteries achieve 250 watt-hours per kilogramme, compared to jet fuel’s ~12,000Wh/kg, leaving long-range suitability out of the question for quite some time. Battery density has been improving at a rate of around 4% per year, however, and Lilium and the other aviation innovators are betting on battery technology improving enough to sustain their short-range flying taxi plans over the next six or so years.

Even when technologically feasible, flying taxis will face a number of regulatory, economic and logistical problems before they become as ubiquitous as ride-sharing car services. One such problem is the need for landing pads. Flying taxis will presumably need landing pads of similar sizes to current small helicopters, which require landing pads of at least 1.5x the length of the craft in question – in Uber’s case, their partner Bell’s Nexus is roughly 40ft long, thus requiring a roughly 60ft landing pad. There are only so many spaces large enough in densely packed cities, leaving only rooftops as viable landing spaces. Such spaces will only be able to hold a maximum of one or two such landing pads, without even taking into account the cost of constructing the large number of pads needed for the ubiquitous use model Uber and Lilium have in mind.

Huge regulatory hurdles will perhaps be the biggest challenge for flying taxi providers. The safety of automated flying passenger vehicles is yet to be fully tested, and regulations surrounding passenger drones currently do not exist. Recreational drones are currently limited to flying in separate airspace to manned aircraft, meaning they can’t fly higher than 400 feet above ground level and aren’t permitted to flying near airports. This would create a set of problems for many cities across the UK and further afield, as many buildings in large cities are higher than 400 feet, and many cities are situated near to airports. Considering the delay in automated road vehicles coming to market caused by regulatory difficulties, unfortunately it is unlikely that flying taxis will be coming to the UK any time soon.