Air taxis

The field of air taxis has recently experienced extremely dynamic development, enabled by advances in vehicle and drone technology. Various concepts are competing in the still young market, fuelled by ambitious announcements of further development by the respective manufacturers. Despite questionable sustainability, air taxis could thus make a relevant contribution to mobility in the coming decades, especially in urban areas. Batteries usually play the decisive role as an energy source. Particularly high demands are placed on their performance.



Relevance of the field of application

Air taxis (also taxi or passenger drones or eVTOL for electric vertical take-off and landing aircraft) are colloquially referred to as electrically powered, vertical take-off aircraft for passenger transport. Most models resemble a helicopter, but are powered by a number of small propellers, each with its own electric motor.1 In addition, there are also designs with wings that can be counted in the class of tilt-wing or tilt-rotor convertible aircraft.2 In principle, designs with or without a pilot are possible, whereby the majority of development projects are aimed at autonomous operation of the air taxis.

Research and development on air taxis has recently experienced a considerable boom. In addition to established aviation companies, a number of start-ups are also making a name for themselves with designs that are considered to have a high degree of market maturity. The prerequisites for these developments were advances in the field of vehicle electrification, not least the increasing degree of autonomy in vehicle control, as well as innovations in the field of drone technology.1

Three fields of application for air taxis can be distinguished: City taxis are designed to cover distances of 15-50 km within densely populated urban areas and are available on demand. Airport shuttles are used to transport passengers between inner-city hubs and airports on a scheduled basis, also covering distances of 15-50 km. Finally, inter-city flights will serve commuter routes between major cities at intervals of up to 250 km.3

Current studies show that air taxis have a sometimes significantly higher electricity consumption than electric cars, especially on short routes, but also for distances over 100 km. For longer distances and with several passengers per flight, the result of a sustainability assessment depends crucially on the premises set.4 However, air taxis can be of social benefit in other respects with regard to the shortened travel time or their flexible use, for example in the form of rescue drones.


1 Jetzke, Tobias (Büro für Technikfolgen-Abschätzung beim Deutschen Bundestag) (2018): Flugtaxis – bemannte, vollelektrische Senkrechtstarter.
Link ↗ (accessed 29.09.2021)

2 Wikipedia (2021): Wandelflugzeug. 
Link ↗ (accessed 29.09.2021)

3 Hader, Manfred; Baur, Stephan; Kopera, Sven; et al. (Roland Berger) (2020): Urban Air Mobility.
Link ↗ (accessed 29.09.2021)

4 Kasliwal, Akshat; Furbush, Noah J.; Gawron, James H.; et al. (2019): Role of flying cars in sustainable mobility. In: Nature Communications 10 (1555). 
Link ↗ (accessed 29.09.2021)

Use of battery storage

Almost all existing air taxi models are purely battery electric. However, more detailed information on the characteristics of the batteries used is only available for a few cases. A survey study by TU Delft gives the battery capacity of the CityAirbus as 110 kWh and of the Lilium-Jet as 320 kWh.5 The Archer Maker is said by the manufacturer to have a 75-kWh battery; other sources speak of a 143-kWh battery, of which the "lower" 16 kWh are not usable and the "upper" 28 kWh are planned as aging loss.6,7 For a current General Motors air taxi study, a 90-kWh battery is planned.8

The battery design for air taxis is characterized by the fact that the weight of the aircraft must be kept low. As a result, the ranges that can be achieved with current battery technology are also relatively low. The gravimetric energy density of the batteries used is therefore of decisive importance for whether air taxis will be widely marketed in the future. Volocopter, for example, estimates a range of 35 km with current battery technology; with 400 Wh/kg, a range of 65 km would be feasible in the future.9 Lilium states that it currently uses batteries with an energy density of 240 Wh/kg and is testing batteries with 300 Wh/kg in the laboratory.10

Hydrogen-based fuel cell air taxis are also being discussed sporadically, in which battery use - if planned at all - is significantly lower. However, the discussion about sustainability and market opportunities is more controversial than for battery-powered air taxis.11,12


5 Polaczyk, Nicholas; Trombino, Enzo; Wei, Peng et al. (2019): A review of current technology and research in urban on-demand air mobility applications. In 8th Biennial Autonomous VTOL Technical Meeting and 6th Annual Electric VTOL Symposium 2019. 
Link ↗ (accessed 29.09.2021)

6 Archer (2021): Homepage. 
Link ↗ (accessed 29.09.2021)

7 Randall, Chris (2021): Electric air taxi startup Archer to collaborate with FCA. 
Link ↗ (accessed 29.09.2021)

8 Pluta, Werner (2021): GM-Designchef Simcoe zeigt Konzept für Flugtaxi.
Link ↗ (accessed 29.09.2021).

9 Volocopter (2021): The roadmap to scalable urban air mobility. White Paper 2.0.
Link ↗ (accessed 29.09.2021)

Performance requirements

Battery storage for air taxis must meet the highest safety requirements. Fires represent an existential danger for aircraft - and thus for crew and passengers. Therefore, the batteries used should be as far as possible neither flammable nor explosive.

Furthermore, the long-term available storage capacity per unit of weight should be as high as possible, since weight reduction is one of the central requirements of aircraft construction. It should be borne in mind that several battery properties play a role in determining this size - not only the specific energy (the amount of maximum storable electrical energy in relation to the battery mass, specified in Wh/kg) in the narrow sense, but also aging resistance, deep discharge resistance and fast charging capability. In their combination, they determine the size of the required battery storage and thus weight, range and payload.


10 Aerokurier (2020): Dossier zum Lilium Jet. Hoffnungsträger oder Hochstapler? 
Link ↗ (accessed 29.09.2021)

11 Skai (2021): Homepage. 
Link ↗ (accessed 30.09.2021)

12 Höland, Christoph (2019): "Skai" von BMW vorgestellt: Dieses Flugtaxi wird das Klima wohl kaum retten. Ostsee-Zeitung, 05.06.2019. 
Link ↗ (accessed 30.09.2021)

Market outlook

Despite questionable sustainability and existing technological and regulatory challenges, air taxis have recently experienced a boom. This is affecting both media coverage and the development of the corresponding business scene and its financial support. For example, United Airlines has announced that it will purchase 200 Archer air taxis with the aim of putting them into service as early as 2024, if possible.13 ADAC-Luftrettung has reserved two air taxis from Volocopter and is planning operational tests of multicopters in rescue services from 2023.14

Assessments of future market development are mixed. While the Office of Technology Assessment at the German Bundestag assumes that air taxis will most likely represent only a niche service in the future transport mix,1 management consultancies expect the market to develop rapidly. Roland Berger, for example, estimates that as many as 160,000 commercial air taxis will be in operation by 2050.15 According to a market study by Horvath, 23,000 air taxis are expected to be in service by 2035; a study by Citygroup even expects 20,000 air taxis to be sold annually by 2030.16

13 Pluta, Werner (2021): US-Fluggesellschaft bestellt 200 Flugtaxis. 
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14 ADAC Luftrettung (2020): ADAC Luftrettung reserviert zwei Multikopter von Volocopter. 
Link ↗ (Zugriff am 29.09.2021)

15 Baur, Stephan; Hader, Manfred (2020): Die Zukunft des urbanen Verkehrs liegt in der Luft. Und vor der Branche liegt eine goldene Zukunft. 
Link ↗ (Zugriff am 29.09.2021)

16 Zängl, Wolfgang (2020): Elektrische Flugtaxis. 
Link ↗ (Zugriff am 29.09.2021)