Imagine Brussels a decade further in the future with electric flying VTOL taxis taking off and landing vertically on ‘vertidromes’ at several places in the inner city, picking up passengers to fly them in no time to the national airport high above a congested city. An airborne ride that would cost you four to eight euros per kilometer.

The German Aerospace Center DLR developed an overall system simulation and methodology for forecasting the global demand for Urban Air Mobility (UAM) services – not for Brussels specifically, but for Hamburg and 990 urban areas with more than 500 000 inhabitants worldwide. It tested an air taxi scenario on a 1:4 scale at its Cochstedt site in Germany.

DLR’s HorizonUAM research project was set up to determine what requirements must be met so that airborne urban mobility can be used in a few years. What demands on safety, efficiency, sustainability, and affordability must be met to make these concepts feasible?

Investigate the entire system

Ten specialized institutes and facilities of the Deutsches Zentrum für Luft- und Raumfahrt (DLR) collaborated on the HorizonUAM project since 2020 to take the entire future system under observation.

That includes concepts for aircraft, flight corridors, and stopping points on small city airports called ‘vertidromes’ that integrate into the existing infrastructure. But the research was also done into the acceptance by people of this new kind of urban transport with drones or air taxis with or without pilots aboard and the costs involved.

“Future urban air transport places a wide range of demands on safe and efficient operations with suitable take-off and landing sites and flight routes that carefully integrate into the existing infrastructure and the everyday lives of local people,” says Anke Kaysser-Pyzalla, Chair of the DLR Executive Board. “To achieve this, we need a whole-system approach to research and development, which the project addresses.”

Numerous stops and affordable prices

It turned out that numerous stops and affordable prices are the first requirements for the demand for air taxi transport services. The study showed that a price range of four to eight euros per kilometer is necessary for profitable operation.

So what should an air taxi ideally look like? “We made several preliminary designs for vertical take-off air taxis. For one of the concepts with six swiveling rotors, we also produced a detailed cabin design, which we optimized for UAM operation regarding safety, passenger comfort, and operational procedures,” explains Bianca Schuchardt, HorizonUAM Project Manager.

Test-passengers

That concept should have a maximum take-off mass of 2 000 kg and a 350 kg payload, carrying up to four passengers. After a vertical take-off, the electric swiveling rotors turn horizontally like a normal plane with a range of approximately 100 km.

A group of 30 ‘test passengers’ got the experience of flying with it in a newly built cabin simulator using mixed reality at the DLR site in Braunschweig. Most seemed quite confident in a remote-controlled air taxi flight without a pilot. But in the case of unexpected events, such as a change of route, they preferred to have a crew member aboard.

One thing is finding people willing to take an air taxi and pay for it. How to integrate that into the existing infrastructure of cities with hundreds of thousands of inhabitants and how to monitor and manage this safely is another.

Of the 990 cities investigated, the researchers identified more than 200 cities worldwide as ‘UAM-suitable’. In addition to large cities such as New York and Tokyo, Hamburg also appeared very suitable.

So they built a model of Hamburg on a scale of 1:4 at the DLR site in Cochstedt to test ‘vertidromes’ integrated into the existing urban infrastructure. The model included a vertidrome on the Binnenalster Lake in the inner city and a ‘vertiport’ with several pads for take-off and landing at Hamburg Airport. The latter was not too close to the classic airplanes for safety reasons.

Flying over the scaled-down city

Several multi-copter drones represented air taxis that moved between Hamburg Airport and the vertidrome on the Binnenalster Lake, flying over a residential area at a scale of 1:4. According to DLR, the fast-time simulations with 20 different positions for vertidromes examined within Hamburg showed the possibility of 2 800 flights with a total of 275 air taxis in 24 hours.

Several scenarios were tested with air traffic controllers in a control tower simulator. It proved feasible for the air traffic control at Hamburg Airport to manage manned and unmanned air traffic together. But it also showed an increased workload on the shoulders of today’s already stressed air traffic controllers.