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TREBALL FINAL DE GRAU TÍTOL DEL TFG: Air taxi transportation infrastructures in Barcelona TITULACIÓ: Grau en Enginyeria d’Aeronavegació AUTOR: Alexandru Nicorici Ionut DIRECTOR: José Antonio Castán Ponz DATA: 19 de juny del 2020
Títol: Air taxi transportation infrastructures in Barcelona Autor: Alexandru Nicorici Ionut Director: José Antonio Castán Ponz Data: 19 de juny del 2020 Resum El següent projecte parteix de la visió d’un futur on la mobilitat urbana es reparteix també al medi aèri. A partir d’aquesta premissa, s’escull el dron de passatgers com a mitjà de transport i es busca adaptar tot un sistema infrastructural per al vehicle autònom dins el perímetre d’una ciutat, Barcelona. En un inici, la primera pregunta a respondre és: permet la normativa actual l’ús de drons de passatgers autònoms en zones urbanes? Tant les regulacions europees com les nacionals espanyoles han estat estudiades i resumides per determinar que sí es permeten operacions amb aquest tipus de vehicles i es preveu la seva integració dintre de l’aviació civil. Seguidament, un estudi de mercat de taxi drons és realitzat amb l’objectiu d’esbrinar si la tecnologia d’avui dia permet operar a paràmetres òptims i oferir el servei de taxi d’una manera completament segura i satisfactòria per al client. Prototips en fase de test i actualment funcionals han estat analitzats; per finalment, elegir un d’aquest últims com a candidat apte per al transport de persones dins la capital catalana. Un cop es té el vehicle de transport, cal mirar si la pròpia ciutat ofereix garanties d’èxit per aquest servei de transport aeri. Un anàlisi estadístic del turisme com a demanda del servei; un estudi de la sectorització aèria i una recerca de zones restringides al sobrevol determinen que sí: Barcelona és una ciutat apta per a una reforma en la mobilitat urbana a nivell aeri. Diferents mapes amb una xarxa de rutes aèries optimitzades complementen aquest apartat. Finalment, un disseny modular d’un dron-port, anomenat sky port, és realitzat amb ajuda del programa SolidWorks. La idea és integrar aquest edifici que connecta a terra el complex sistema de transport aeri amb el paisatge arquitectònic de la ciutat; una ubicació idònia la ofereixen els terrats d’hotels prèviament escollits com a nodes en la xarxa de vies aèries. La simplicitat geomètrica i la estandardització del model són prioritat. Aquest últim capítol pretén enriquir el treball amb una aportació personal per part de l’estudiant.
Title: Air taxi transportation infrastructures in Barcelona Author: Alexandru Nicorici Ionut Director: José Antonio Castán Ponz Date: 19 de juny del 2020 Resum The next project is based on the vision of a future where urban mobility is also distributed in the air. Based on this premise, the passenger drone is chosen as the means of transport and the aim is to adapt an entire infrastructure system for the autonomous vehicle within the perimeter of a city, Barcelona. Initially, the first question to answer is: do current regulations allow the use of autonomous passenger drones in urban areas? Both European and Spanish national regulations have been studied and summarized to determine whether operations with this type of vehicle are allowed and their integration into civil aviation is envisaged. Next, a drone taxi market study is conducted with the aim of finding out if today’s technology allows to operate at optimal parameters and offer the taxi service in a completely safe and satisfactory way for the customer. Prototypes in the test phase and currently functional have been analyzed in order to choose one of the latter as a suitable candidate for the transport of people within the Catalan capital. Once had the transport vehicle, there is need to see if the city itself offers guarantees of success for this air transport service. A statistical analysis of tourism as a demand for the service; a study of the air sectorization and a search for areas restricted to overflight determine that yes: Barcelona is a city suitable for a reform of urban mobility at the air level. Different maps with an optimized network of air routes complement this section. Finally, a modular design of a drone port, called a sky port, is made with the help of the SolidWorks program. The idea is to integrate this building that connects the complex air transport system to the ground with the architectural landscape of the city; an ideal location is offered by the roofs of hotels previously chosen as nodes in the airway network. Geometric simplicity and model standardization are to be a priority. This last chapter aims to enrich the work with a personal contribution from the student.
Acknowledgments
To the director of this thesis, Jose Antonio Castán Ponz,
for guiding me through the whole project
and granting the SW software.
Also, to my dear family, friends and girlfriend.
CONTENTS
INTRODUCTION…………………………………………...………………………….1
CHAPTER 1. NORMATIVE……………………………………………………….….2
1.1. European directives………………………………………………….2
1.2. Spanish regulation…………………………………………………...3
CHAPTER 2. MARKET STUDY OF DRONE TAXIS……………………………….5
2.1. Methodological approach…………………………………………...5
2.2. Types of drone taxis………………………………………………….5
2.2.1. Non-functional prototypes……………………………………...5
2.2.2. Functional prototypes…………………………………………12
2.3. Direct comparison between functional prototypes……………23
2.4. Final decision for operating as a drone taxi in Barcelona…….25
CHAPTER 3. AERIAL TAXI SERVICE ASSESSMENT IN BARCELONA…….28
3.1. Barcelona Tech and Touristic City……………………………….29
3.2. Hot spots mapping………………………………………………….32
3.3. Airway networking…………………………………………………..36
3.3.1. Restricted areas and other routing barriers…………………39
3.3.2. Optimal intertwine…………………………………………….42
3.3.3. Satellite view…………………………………………………..45
3.4. Time derived from operating the final system………………….47
3.5. Closure………………………………………………………………..49
CHAPTER 4. SKYPORT DESIGN………………………………………………….50
4.1. Sky port models……………………………………………………..50
4.2. Infrastructure provided…………………………………………….52
4.3. SolidWorks modelling……………………………………………...54
4.3.1. Dimensioning according to material properties……………58
4.3.2. Hotel hub perspective………………………………………...61 CHAPTER 5. CONCLUSIONS……………………………………………………...62 BIBLIOGRAPHY……………………………………………………………………..64 ANNEX………………………………………………………………………………..69
LIST OF FIGURES CHAPTER 1. NORMATIVE…………………………………………………………..2 1.1 Latest communitarian normative endorsement……………………………..2 1.2 Schematics of a SORA safety risk management……………………………3 CHAPTER 2. MARKET STUDY OF DRONE TAXIS……………………………….5 Non-Functional prototypes 2.1 S-A1 drone taxi model…………………………………………………………6 2.2 Nexus 4EX model………………………………………………………………7 2.3 Boeing Aurora Pegasus model……………………….……………………….8 2.4 Lilium Jet prototype…………………………………………………………….9 2.5 The A3 on Alpha One stage…………………………………………………..11 Functional prototypes 2.6 EHang 216 model…………………………………………………………….12 2.7 Carbon composite materials and aerial aluminum alloy………………….13 2.8 Inside view of the cabin………………………………………………………14 2.9 Agreement between LLíria’s council, Valencia, and EHang……….……..14 2.10 NMC lithium Battery pack for the EHang 216 model………………………15 2.11 Depiction of the 3-generation motors……………………………………….16 2.12 Depiction of the 3-generation propellers……………………………………16 2.13 EHang 216 graph……………………………………………………………..17 2.14 EHang command centre……………………………………………………..18 2.15 Volocopter VC2X functional multicopter……………………………………19 2.16 VC2X’s cockpit and its 200-5W rotor……………………………………….20 2.17 Inside view of the cabin………………………………………………………20 2.18 The battery swapping technique…………………………………………….21 2.19 Exploded perspective on a PMSM motor…………………………………..22 2.20 VC2X propeller………………………………………………………………..22 2.21 Rotor-propeller positioning and parachute compartment…………………23 Comparison 2.22 VC2X dimensions scheme…………………………………………………..24 2.23 EHang 216 dimensions scheme…………………………………………….24 2.24 Timeline to production scale for all models…………………………………27 CHAPTER 3. AERIAL TAXI SERVICE ASSESSMENT IN BARCELONA……28 3.1 Barcelona Smart City logotype………………….…………………………..29 3.2 Graphic of tourist evolution in Barcelona…………………………………...30 3.3 Tabulated numbers by year………………………………………………….30 3.4 Seasonality of overnights in hotels………………………………………….31 3.5 Tourists in hotels by category in 2019……………………………………...31
3.6 Seasonality of passengers in Barcelona’s airport in millions………..……32 Maps 3.7 Hot spots mapped on districted Barcelona…………………………………34 3.8 Population density by district………………….……………………………..38 3.9 3 km radial coverage from hub………………………………………………39 3.10 Radial hub coverage delimitations………………………………………….40 3.11 Population density vs green spots per district……………………………..41 3.12 Sky ports distribution within 10 districts, coastal orientation……………..43 3.13 Complete routing network……………………………………………………43 3.14 Final routing network in clear 10-district map………………………………44 3.15 Satellite view…………………………………………………………………..46 CHAPTER 4. SKYPORT DESIGN…………………………………………………50 4.1 Uber Air sky port prototype………………………………………………….50 4.2 Voloport prototype……………………………………………………………51 4.3 E-port maquette disposal at Sevilla’s fair………………………………….52 4.4 Hotel Sofia, Les Corts District………………………………………………53 4.5 Hotel Sofia to Camp Nou perspective……………………………………..54 SolidWorks 4.6 Sky port sketch on plan view………………………………………………..55 4.7 Extruded sketch, no ceiling, isometric…………………………………......56 4.8 Sky port assembly with clients and drones to scale……………………...57 4.9 One module concept…………………………………………………………58 4.10 Material simulated sky port, diedric………………………………….……..60 4.11 Hotel hub perspective………………………………………………………..61
LIST OF TABLES CHAPTER 1. NORMATIVE…………………………………………………………..2 None CHAPTER 2. MARKET STUDY OF DRONE TAXIS……………………………….5 2.1. Specs comparison……………………………………………………………25 CHAPTER 3. AERIAL TAXI SERVICE ASSESSMENT IN BARCELONA…....28 3.1. Most visited landmarks in Barcelona………………………………………..33 3.2. Main touristic attraction by district…………………………………………..34 3.3. Hotels to provide for the hub by district…………………………………….36 3.4. Travel time per airway………………………………………………………..47 3.5. Aerial mobility vs. subway system time comparison………………………48 CHAPTER 4. SKYPORT DESIGN…………………………………………………50 4.1 Load capacities of simply supported concrete slabs………………………59 CHAPTER 5. CONCLUSIONS……………………………………………………...62 None
ACRONYMS and ABBREVIATIONS
Acronym Meaning
AAV Autonomous Aerial Vehicle
AENA Aeropuertos Españoles y Navegación
Aérea/Spanish Airports and Aerial
Navigation
AESA Agencia Estatal de Seguridad
Aérea/National Agency for Aerial
Safety
AGL Above Ground Level
AI Artificial Intelligence
AMSL Above Mean Sea Level
ATCo Air Traffic Controller
ATM Air Traffic Management
ATZ Aerodrome Traffic Zone
AVE Alta Velocidad Española/Spanish
High Speed (Renfe, railway lines)
AWY Airway
CES Consumer Electronic Show
CTR Controlled Traffic Region
DEP Distributed Electric Propulsion
Drone taxi Unmanned aerial vehicle capable of
giving taxi service
EASA European Aviation Safety Agency
ENAIRE air navigation manager in Spain and
Western Sahara, certified for the
provision of enroute, approach and
aerodrome control services
ESA European Space Agency
EVTOL Electrical Vertical Take Off and
Landing vehicle type
GPS Global Positioning System
ICAO International Civil Aviation
Organization
IFR Instrumental Flight Rules
MTOW Maximum Take Off Weight
RD 1036/2017 Spanish Royal Decree concerning
drone operations within the territory
PAV Personal Air Vehicle
SC-VTOL Special Condition – Vertical Take Off
and Landing
SID Standard Instrument Departure
Sky port/Hub Docking site for drones, resembling a
small heliport/air to ground base.Smart City Urban area that uses different types of
electronic Internet of Things (IoT)
sensors to collect data. Overall, a
technology advanced city
SORE Specific Operations Risk Assessment
STAR Standard Instrumental Arrival
Startup Emerging company founded on a
technological base in this case
TMA Terminal Manoeuvring Area
TMB Transports Metropolitans de
Barcelona
TWR Tower Control
UAM Urban Air Mobility
UAS Unmanned Aerial Systems = dron
UE 219/245 Delegated regulation ensuring drone
operations safety within the European
Union
VFR Visual Flight RulesIntroduction 1
Introduction
The present project aims at optimizing the near future urban air mobility (UAM)
transportation system by implementing a fully scaled air route network modelling
in the city of Barcelona.
5 different chapters compose the thesis: each one containing essential
information for the whole integrity of the envision that gave birth to the project in
the first place. The first chapter is merely informative about the normative
regarding UAS operations in urban territory; while the true content of the paper is
held within chapters 2, 3 and 4, this last one consisting in a summary of what has
been done with SolidWorks software, snapchats included. The final chapter is for
the conclusions.
Therefore, chapter 2, consisting in a market study of drone taxis, aims at selecting
the most suitable AAV type vehicle for the taxi service implementation in
Barcelona. The focus is put on the functional prototypes, giving extent details
about their specifications and a definitive comparison between them in order to
better understand the reasoning behind the final decision; one which is based at
all time on the technical specs and their correlation with the demands of the city.
Chapter 3 is a compilation of advantages for which the Catalan metropolis
promises to compete against cities such as Dubai and Los Angeles in the reform
of the UAM program. It is 2020 and experimental flights can already be seen
across the globe with drone type vehicles.
The most important contribution from chapter 3 to this thesis is to be found with
the pile of maps that depict an optimal airway network to be overflown by
autonomous taxi drones. These airways will be connected to specially designed
heliports ubicated in predefined areas meticulously thought as being hot spots
that enclose top priority landmarks.
As a reminder, the air route network will have to obey the restrictions imposed by
the Spanish government regarding the use of drones in urban areas; thus, we will
carefully treat the upcoming normative [please refer to Section 1.1.].
Statement: we are only 5 years apart from the first commercially used urban air
mobility routes.
Chapter 4 is the hands-on activity attached to the previous more research
focused sections of this paper. Based on existing sky port prototypes from
companies that manufacture drone taxis; all mentioned in the second chapter,
another similar sky port model is created with SW and it is explained why its
characteristics should totally adapt to Barcelona’s skyline and the chosen aerial
vehicle specifications. A final assembly drawing plan constitutes the final annex.2 Air Taxi Transportation Infrastructures in Barcelona
CHAPTER 1. NORMATIVE
In this passage, a brief presentation of all laws and regulations the normative
regarding drone usage within metropolitan areas has will be analysed in order to
enclose the goal of the entire project in a legal framework and to guarantee safety
at all cost.
The focus will be on European directives and especially the Spanish regulation
since they cover the area of study and it is mandatory to proceed according to
their statements, even tough the envision of this work may not become reality
until 5 years from now; therefore, flexibility is vital in this law field.
1.1. European directives
Seeking for the latest approved directives it was found that Spain belongs to the
communitarian normative involving UAS operations which goes from 2019 to
2022. *Please refer to [1] in bibliography for further information.
This directive, alongside previous ones which will be mentioned in the next
subsection [1.1.2.], refer to all kinds of unmanned and autonomous or remotely
controlled drones (UAS) excepting military, police, research or salvage activity
wise destined aircrafts. Since this work seeks to model a suitable transportation
system above the streets of Barcelona, meaning it responds also to leisure
activities, it is mandatory to answer to its call.
Figure. 1.1 Latest communitarian normative endorsement. [1].
Now, taking a deeper look at the normative concept itself, there are 3 main
categories in which we can split the drones:
- Open category low risk Plug and Play
- Specific category medium risk Predefined Risk
Assessment
EASA
- Certified category high risk Delegated
Regulation
UE 2019/245Normative 3
These categories separate UAS according to their intended operations and
surroundings. For the purpose of this work, all type of drones analysed here will
be classified within the certified category because it implies:
- People transport
- Flying over high concentrations of people
- Large drones, the 3 m barrier is surpassed in some dimension.
Therefore, it is mandatory to comply with all articles mentioned in the delegated
regulation UE 2019/245.
It is worth mentioning the SORA (Specific Operations Risk Assessment)
aeronautical study: a way to ensure safety for each operation carried out in
aircrafts belonging to the specific category or to higher risk ones.
Figure. 1.2 Schematic of a SORA safety risk management. [2].
1.2. Spanish regulation
All Spanish regulations pay special attention to commercial aviation and
discriminates large and heavy drone operations within metropolitan areas. For
this reason, civil drone usage regulation inside Spanish territory will be closely
discussed as it precedes the European directive mentioned in [section 1.1.], a
communitarian regulation that allows for large drone services since they are
treated as special passenger transportation systems: an integration alongside
commercial aviation (small aircrafts, helicopters) which allows for this project to
proceed with its idea of conquering city skies via drone taxis.
To see the evolution from this territorial regulation to the UE 2019/245, a closer
look into the first one’s most important statements, the Royal Decree RD
1036/2017, will come in handy4 Air Taxi Transportation Infrastructures in Barcelona
1. It is mandatory to own an AESA (Spanish agency ensuring aviation safety)
certificate in order to operate a drone taxi type, whether the subject is an
individual or a company, and a valid medical certificate.
2. All drones must carry a plate containing the manufacturer, the model and
the operator’s name, the serial number and the contact information.
3. Inside a controlled airspace it is required for the aerial taxi to have a mode
S transponder1 and not to go beyond 120 m of height.
4. For nocturnal flights, the operator needs to present a safety study to AESA
in order to obtain authorization.
5. Minimal distancing from airports have to be of 8 km for VFR and of 15 km
for IFR, rules applied at Barcelona’s airport El Prat.
6. In order to fly over crowded cities, the drone must not surpass 10 kg of
empty weight, operate always within the sight of the pilot and maintain at
least 50 m of horizontal distance between buildings.
*Please refer to [4] in bibliography for the complete RD1036/2017 pdf. For further
information about AESA certificates and authorizations refer to article 42.
It is clear that from statement 3 beyond there would be no point in continuing the
search for developing such an infrastructure in Barcelona since all drones
capable of offering a taxi service surpass these limitations or do not work
properly. A perfect example of why the UE2019/245 regulation is essential.
1Mode S transponder: advanced radio transmitter that provides ATCos with a squawk code for
emergency, tail number and altitude.Market Study of Drone Taxis 5
CHAPTER 2. MARKET STUDY OF DRONE TAXIS
Aiming for a realistic new method of transportation in the Catalan capital, it is
essential to first examine the current market of drones so that all infrastructures
may be modelled accordingly to a preselected type of aircraft; which in turn will
determine the flexibility of the airways network plus hubs system whether the
chosen model matches with other options or future replacements.
Consequently, the search for the optimal aerial vehicle will also consider modern
prototypes to enable flexibility in the system; but ultimately will select from a
narrow range of current working UAS.
2.1. Methodological approach
There are many drone taxis from which to choose since all major aircraft
manufacturers and taxi transportation companies wish to be at the forefront of the
upcoming urban air mobility.
In the upcoming sections, a listing of all major prototypes will be done in order to
select the optimal model for air taxi transportation in the city of Barcelona. To do
this selection, mechanical and electrical specifications such as batteries
autonomy for the range and safety features; design features that involves the
number of passenger seats and economical aspects like availability in the
European market and pricing will be strongly analysed.
2.2. Types of drone taxis
Two main categories of drone taxis will compose this market study: the non-
functional prototypes to this day and the functional ones.
Since this project foresees global UAM for the major cities in the next 5 years,
the functional prototypes will be preferred; even so, it is essential to get to know
the market of top listed still in development aerial taxis as they can be inspiring
models for current generation of transportation drones.
2.2.1. Non-functional prototypes
Hyundai S-A1
Hyundai Motor Company in collaboration with Uber, the world-famous
multinational ride-hailing company, announced on January 6, 2020 during the
Consumer Electronics Show (CES) in Las Vegas their new electric vertical takeoff
and landing (eVTOL) aircraft.6 Air Taxi Transportation Infrastructures in Barcelona
Fig. 2.1 S-A1 drone taxi model. [3].
This prototype was designed for Uber Elevate2, aiming to transform the world
through aerial ridesharing at scale.
3 main systems for a complete UAM ecosystem according to Hyundai:
- S-A1 eVOTL PAV (Personal Air Vehicle).
- Purpose Built Ground Vehicle.
- S-Hub and S-Hub Skyport.
Out of these 3 systems, this project focuses on the first and third ones to develop
a fully interconnected aerial network able to deliver to the clients an alternative
more efficient way of transportation across a crowded city.
Specifications
• Aircraft type: eVTOL.
• Piloting: 1 pilot, will be initially piloted and will transition into an
autonomous aircraft.
• Capacity: 4 seats, without middle seat, with enough space for baggage
• Cruising speed: Up to 290 km/h.
• Range: 97 km.
• Cruising altitude: 1,000-2,000 feet (305-610 m).
• Recharging time: 5-7 minutes.
• Propellers: 4 tiltrotor propellers (with 5 blades each) for forward and
vertical lift and 4 sets of stacked co-rotating propellers (each propeller with
2 blades) used only for vertical flight.
• Forward flight: Uses 4 propellers.
• VTOL flight: Uses all its propellers.
• Electric motors: 8.
• Batteries: 7 high density batteries with quick recharge capabilities.
• Fuselage and wing construction: carbon composite material.
2 Uber Elevate: Uber’s network for fleets of small electric VTOL (Vertical TakeOff and Landing)
aircraft planned for the year 2023.Market Study of Drone Taxis 7
• Safety features: Distributed electric propulsion, DEP, powering multiple
rotors and propellers around the airframe to increase safety by decreasing
any single point of failure. An emergency parachute will also be a standard
feature in case a catastrophic would occur.
Bell Nexus 4EX
This is a model designed by Bell Helicopter, the American helicopter construction
specialist, in partnership with Uber. It was announced at CES 2019 as a
revolutionary transportation system in cities. It is expected to dominate the
marketplace by 2050, according to Mitch Snyder, Bell president and CEO.
Fig. 2.2 Nexus 4EX model. [4].
Bell Nexus program has safety, accessibility and sustainability as its 3 main
goals. All of these goals go alongside the vision of this task: the making of a
secure and optimal aerial airways network within Barcelona, a metropolis aiming
to become one of the firsts smart cities in Europe.
Specifications
• Aircraft type: eVTOL or hybrid-electric VTOL.
• Piloting: Piloted until autonomous flying is available.
• Capacity: 4 passengers with luggage and 1 pilot; when autonomous flight
is available, will hold 5 passengers.
• Cruising speed: 241 km/h.
• Range: 97 km.
• Hybrid-electric range: More than 241 km.
• Weight of aircraft: 3175 kg.
• Propellers: 4 ducted propellers.
• Propulsion: 4 electric motors.
• Power source: Batteries or another source, depending upon customer
requirements.
• Dimensions: 40 X 40 feet (12.2 X 12.2 meters).8 Air Taxi Transportation Infrastructures in Barcelona
• Fuselage: Composite.
• Wing type: One rear high wing.
• Tail: Vertical rudder, no horizontal flaps.
• Landing gear: Tricycle landing gear.
• Safety features: Distributed Electric Propulsion (DEP), means having
multiple propellers and motors on the aircraft which provides safety
through redundancy for its passengers.
Boeing Aurora Pegasus
The next prototype is the envision of Boeing subsidiary Aurora Flight Sciences
for autonomous aircrafts. It consists of a Passenger Air Vehicle (PAV) that
managed to take off, hover and land successfully during its first flight last year
2019 in January.
Fig. 2.3 Boeing Aurora Pegasus model. [5].
Same as the previous S-A1 and 4EX models, the Boeing Aurora Pegasus is one
of Uber Elevate’s vehicle partner. The aircraft stands as an Air Taxi designed to
operate within a metropolis with easy access to Uber’s Skyports3. Yet again, the
UAM market is enriched, now with a proposal coming from Boeing.
Specifications
• Aircraft type: eVTOL PAV.
• Piloting: Piloted until autonomous flying is available.
• Capacity: 2 passengers.
3Uber Skyports: A network of distributed skyports is being planned to enable Uber Air operations.
The aim is to engineer infrastructures capable of handling up to 1000 landings per hour in areas
no bigger than 8000 m2.Market Study of Drone Taxis 9
• Cruising speed: 180 km/h.
• Range: 80 km.
• Weight of aircraft: 565 kg, empty weight.
• Max gross take off weight: 800 kg.
• Useful load: 225 kg.
• Propellers: 8 VTOL propellers.
• Propulsion: 8 electric motors.
• Power source: 8 batteries of 75 kW each.
• Dimensions: 9,14 x 8,53 [m] as (L x W).
• Fuselage: Composite.
• Wing type: Fixed wings with canards.
• Landing gear: telescopic feet.
• Safety features: DEP redundancy technology.
Lilium Jet
Next, it is shown the most far-fetched prototype; coming from Lilium GmbH, a
Germany based start-up co-founded in 2015 by 4 aerospace engineers and
product designers from the Technical University of Munich.
On May 16, 2019, Lilium revealed they had announced its first flight of an
untethered and unmanned 5-seater Lilium Jet. What differentiates Lilium jet from
the previous models is its propulsion system: the full-scale prototype is powered
by 36 all-electric ducted fans which allows for a vertical take-off and landing with
an efficient horizontal flight.
Fig. 2.4 Lilium Jet prototype. [6].
In the quest for manufacturing an affordable, reliable, eco-friendly and overall a
feasible drone taxi in the short run; simplicity is key and that is the reason why10 Air Taxi Transportation Infrastructures in Barcelona
Lilium jet is mentioned here: it gets rid of folding propellers or wings, the tail, the
rudder, gearboxes, the water-cooling system, use of liquids (fuel/oil) and single
points of failure4.
Moreover, Lilium GmbH implements smart manufacturing facilities5 and seeks to
make affordable, electric, on-demand air taxis a reality by 2025, a similar time
table to Bell Nexus’ schedule with the 4EX model.
Specifications
• Aircraft type: eVTOL Jet.
• Piloting: Piloted until autonomous flying is available.
• Capacity: 5 passengers.
• Cruising speed: 300 km/h.
• Range: 300 km.
• Max flight time: 60 min.
• Propulsion: 36 electric ducted fans and 36 electric motors. The electric
ducted fans are located in pairs of 3 in the wings for a total of 12 fan units
or flaps. There are 2 flaps on each forward wing and 4 flaps on each rear
wing. Each flap can tilt independently of one another and operate at
different speeds of each other.
• Power source: Batteries.
• Fuselage: Composite.
• Wing type: Fixed wings with canard configuration.
• Landing gear: Tricycle landing gear with wheels.
• Safety features: DEP redundancy technology and whole aircraft
parachute.
Airbus Vahana A3
Pronounced A-cubed, this full-scale prototype coming from the gigantic Airbus
company is self-piloted and intended for a single passenger or cargo. As of
February 2019, the model has gained more than 50 hours of flight due to its first
unmanned demonstrator, the Alpha One, and now a second one is being tested,
named Alpha Two.
4 Single point of failure: A plane with a single engine is predisposed to failure, a single point of
failure.
5 Smart factory: future factories are expected to implement the use of artificial intelligence (AI),
robotics, analysis, big data and the internet of things in their manufacturing processes.Market Study of Drone Taxis 11
Fig. 2.5 The A3 on Alpha One stage. [7].
The A3 Vahana’s main objective is to be implemented as a single or double
seated air taxi serving the necessities for urban mobility. It is a great example for
what this project stands for: autonomous flight that follows only predetermined
routes while adjusting for minor deviations in case of obstacle detection.
Specifications (Alpha One)
• Aircraft type: eVTOL PAV.
• Piloting: autonomous flying.
• Capacity: 1 to 2 passengers (Alpha Two) or intended for cargo.
• Cruising speed: 200 km/h.
• Range: 60 km, with reserves.
• Weight of aircraft: 475 kg, empty weight.
• Max gross take off weight: 815 kg.
• Useful load: 90 kg.
• Altitude: 1524 m at 35 ºC.
• Propellers: 8 propellers mounted on tilted wings.
• Propulsion: 8 electric motors.
• Power source: 8 batteries of 45 kW each.
• Dimensions: 5,7 x 6,25 x 2,81 [m] as (L x W x H).
• Fuselage: Composite.
• Wing type: Tilted wings.
• Landing gear: Tricycle landing gear.
• Safety features: Also equipped with DEP technology and an emergency
parachute deployment system functional even at low altitudes12 Air Taxi Transportation Infrastructures in Barcelona
*Note on specs: some characteristics are yet to be determined in certain
prototypes although the current work shows mainly the same attributes for each
one of them in order to ease a direct comparison.
2.2.2. Functional prototypes
Since there is a narrow marketplace for already fully operative drone taxis, this
project seeks to detail the specs of a couple of the most promising candidates,
make a direct comparison between them and finally argument the decision as
why the winner suits Barcelona’s skies better.
EHang 216
Born as the evolution of the EHang 184, which had only 4 arms instead of 8 and
a capacity for only 1 person instead of 2, this fully operational model is a dominant
player in the quadcopter drone market.
This AAV (Autonomous Aerial Vehicle) is a product of the Chinese autonomous
aircraft developer EHang, which entered a partnership with Austria-based
aeronautical systems manufacturer FACC in November 2018 for the serial
production of the aircraft. In April 2019, during the 4Gamechangers Festival held
in Vienna, the vehicle was introduced to the general public.
The Ehang 216 AAV is powered by 16
electric motors, which are connected
to 16 propeller blades in coaxial
double-bladed design.
The electric engine on board the
aircraft enables a cruise speed of 130
km/h. The minimum flight duration of
the aircraft is 30 minutes, while the
maximum flight range is 35km.
Fig. 2.6 EHang 216 model. [8].
In addition to the brief mentioning of basic characteristics done earlier, in this
subsection, a detailed information is meant to exploit the resources of each model
for integrating it into the subject city. This information is split into 3 main
categories, looking to distinguish better both functional prototypes:
- Ergonomics: materials, user accommodation, docking to hub facilities,
urban aesthetics, noise factors and general public recognition. This
category is the insight of a business plan intended to a large scale.Market Study of Drone Taxis 13
- Performance: type of power, sustainability, range, maintenance,
propulsion and power supply. This category represents the engineering
challenges for the selection of the optimal vehicle.
- Safety: mechanical and electrical safety implementations, flexibility with
the hub systems and accommodation to urban safety demands. This
category stands for the social factors.
Basically, the intention with this 3-part categorization system is to answer in order
the following questions: Would you climb on it? Would you arrive on time at
destination and at a convenient price? Would it be a safe ride with minimal
incidences?
And thus, the 3 questions from above should respond to the ultimate one: Is this
the most indicated aerial machine for this project goal and its chosen city?
Ergonomics
The EHang 216 aircraft is made using carbon composite material, which
constitutes the majority of its structural integrity, including the skeleton chasis;
alongside metals, mostly for the key components such as the electric motors.
This balance allows for achieving the required strength to weight ratio.
Fig. 2.7 Carbon composite materials shown by layers inside the door (left).
Aerial aluminum alloy composing the electric motor that joints the set of blades
(right). [9].
Regarding the user accommodation, the Chinese drone features a small aero-
cab structure, which can accommodate up to two passengers with sufficient leg
room and baggage space. The cabin is air conditioned, internet enabled and
features well-furnished interiors14 Air Taxi Transportation Infrastructures in Barcelona
Fig. 2.8 Inside view of the cabin. The aircraft features a dual touch screen as
command and control platform which runs at 5G. [10].
Regarding EHang’s recognition as a brand in the aeronautical industry, it is worth
mentioning that beginning with March 2020, two European countries, Norway and
Spain, already authorized the EHang 216 model for flight testing.
Fig. 2.9 Signing agreement between Llíria’s council (Valencia, Spain) and
EHang. Hu Huazhi as founder, president and CEO of EHang appears on the
bottom right corner of the photo. [11].
Clarifying on figure [11], EHang arrived at the same agreement with the city of
Seville too, accounting for the total of 2 major cities in Spain that already allows
minor taxi drone operations.Market Study of Drone Taxis 15
Performance
The AAV operates based on electrical power, which is supplied by a set of NMC
lithium batteries6 disposed under the cockpit. The theoretical energy storage is
about 220 Wh/kg7 which is reduced to a 140 Wh/kg due to weight addition for the
cooling system. Globally seen, there it is a 17 kilowatt battery that can charge in
4 hours from a 50 amperes socket.
According to the official white paper, batteries are the largest cost items that
accounts for over 60 % of total operating costs for this particular model which
runs on a 500-charge life cycle. Also, the study shows that a 1 % increase in
battery life would increase operating profit by 2 %.
As batteries make up for 1/3 of total empty weight of the AAV, the flight duration
time is cut to a maximum of 30 minutes. Respecting the charging time, 1 hour is
needed. Both numbers are sufficient enough for what this thesis aims at.
Fig. 2.10 NMC lithium battery pack for the EHang 216 model. [12].
Overall energy conversion efficiency between battery and airstream is composed
of battery efficiency ηb, motor efficiency ηm, and propeller efficiency ηp.
η = ηb · ηm · ηp = 0.93 · 0.95 · 0.85 = 0.75 (2.1)
*Note: The previous formula applies for wingless flying cars, which makes for
both functional prototypes that will be shown in this subsection.
6 NMC lithium battery: lithium blended with nickel manganese cobalt oxide battery to improve the
specific energy and prolong the lifespan.
7 Wh/kg: 1 Watt hour per kilogram = 3600 m 2/s2.16 Air Taxi Transportation Infrastructures in Barcelona
The EHang 216 electric motors, 16 rotors in total distributed across the eight
arms, depicted in grey on the right side of figure [9] in this same subsection,
enable a cruise speed of 130 km/h.
Fig. 2.11 Depiction of the 3-generation motors. [13].
In the figure 2.11 up above, from left to right, there are represented the magnetic
cylinder motors 13830, 12845 and the 18030 as the latest generation motor which
has promoted power up to 27 kW and a maximum drag limit of 100 kg at propeller
level.
*Note: The electric motor efficiency for both the winged and wingless air taxis can
approach 95% if the motor is designed specifically for the cruising flight
conditions.
Now, considering the propeller configuration, 16 rotors organized as 8 dual
rotors are encharged with providing the lifting task via the 16-set propellers of
dual blades, mounted in dual composition as they go above and below the rotos.
They can be mounted and dismounted with ease.
Fig. 2.12 Depiction of the 3-generation propellers. [14].Market Study of Drone Taxis 17
These are the same blades mounted on the 184 model, the ancestor of the 216.
The third-generation propeller design not only improved the aerodynamic
efficiency by 10%-15%, but also reduced the noise generated by rotation.
*Note: The lift/thrust propellers are operating in crossflow and the efficiency is
likely to be close to 85%. Yet again, same number can be applied to the last
model presented in this chapter.
Safety
To mention a few mechanical features, the aero-cab fuselage is supported by
rigid skid-type landing gear, which ensures sufficient clearance between the
ground and the rotors. The V-shaped struts, that can be seen in the figure below,
also help to enlarge the space for entry and exit of the client by being spread
equidistantly.
As an electrical safety feature, a computer visual system is installed in the aircraft
to ensure accurate vertical take-off and landing. The aircraft follows an inverted
U-flight path, which reduces the need for excess manoeuvres.
And, as seen in [subsection 2.2.1.] with every non-functional prototype, DEP
technology is present, having multiple propellers and motors provides safety
through redundancy for its passengers. EHang Command Control Centres also
increase the safety of the aircraft.
Fig. 2.13 EHang 216 graph. [15].18 Air Taxi Transportation Infrastructures in Barcelona
Fig. 2.14 EHang command centre. [16].
*Note: a request was sent to the company for me, the author of this thesis, to be
able to visit the experimental centres near Llíria (Valencia) and further document
the behaviour of the drone within a confined space. Although the HR department
from EHang did respond, the covid19 global emergency forced them to close
doors and so every bit of information presented here is extracted from official
whitepapers instead. *Please refer to [25] in bibliography for the local news.
Volocopter VC2X
Volocopter GmbH was founded in 2011 and the company is now based in
Bruchsal, Germany. Alexander Zosel and Stephen Wolf envisioned an eVTOL
type multicopter aircraft for fast and efficient urban travel.
To better understand the philosophy of the company and why its multirotor
helicopter proposal suits perfectly as candidate for the purposes of this project,
here it is referenced its slogan: “Pioneering the urban air taxi revolution”.
The Volocopter VC200, with 18 non-tilting propellers, accomplished its first
unmanned flight in November 2013. The first manned flight was done on March
30, 2016 and Volocopter claimed his product as the world’s first 2-seat electric
VTOL aircraft.Market Study of Drone Taxis 19
Fig. 2.15 Volocopter VC2X functional multicopter. [17].
In order to coordinate the specs and features with the EHang 216; the speed, the
flight duration and the range, respectively, are quantified next:
100 km/h at cruise ; 27 minutes ; 27 km
At fist glance, the numbers seem to close on the Chinese model ones even
though they are of a slightly lower value.
Nevertheless, the selection between the two aircrafts has to be made in
accordance with the 3-categorization information system defined at the beginning
of [Subsection 2.2.2.]. Therefore, for the German candidate there are highlighted
the following features:
Ergonomics
As it is usual with aerial vehicles and especially those designed to offer a taxi
service, the Volocopter is made out of a light weight, fiber composite material.
Yet again, the components that constitute the electrical motors are made out of
metallic alloys to allow for the required drive torque input.20 Air Taxi Transportation Infrastructures in Barcelona
Fig. 2.16 VC2X’s cockpit manufactured with composite materials, courtesy of
alamy production hall in Bruchsal (left). The 200-5W rotor manufactured by
Hacker Motor GmbH (right). [18].
Considering now the user accommodation, the German model seeks for
practicality in their design as the goal is to produce a common everyday mode of
transport. Consequently, embarking and disembarking is improved here by
mounting the rotors overhead; an integrated luggage compartment is also
available; air conditioning system is integrated into the design and the Volocopter
noise signature is intrinsically low: 65 dB(A) at 75 m of altitude, around 10
decibels quieter than its Chinese competitor.
There are 2 seats at clients disposal in a well-furnished ambient and the dual
control panels do not lack any feature with respect to the EHang’s product; just
to mention a few: ATM options, GPS point tracking and UAV technology available
for integration at any time.
Fig. 2.17 Inside of the cabin while in flight (left) and on parking mode (right). [19].
*Note: please remark the joystick on the [figure 2.17] just above, this is a clear
indicator that this drone taxi will not fly autonomously, which represents a major
drawback compared to the EHang 216 model.Market Study of Drone Taxis 21
As far as the general public recognition goes, Volocopter is a well-known
European company aspiring to bring urban air mobility to life via eVOTLs
multicopter aircrafts. Among its many recognitions, it is worth mentioning that the
company is the first Air Taxi developer to be awarded SC-VTOL Design
Organisation Approval by EASA; it also challenges its Chinese counterpart by
lifting the standards of package transport to the heavy-lift cargo drone category
with the VoloDrone; and lastly but not least important, it keeps the tracking with
the sky ports networking system by displaying the Voloport prototype (please
refer to [Chapter 4]). All this accomplished in the year 2019.
Performance
The eVTOL multicopter operates based on electrical power, which in turn is
supplied by lithium-ion batteries.
There are 9 independent battery systems with quick release. 9 batteries supply 2
motors each.
Those batteries can be charged in less than 120 minutes as the maximum time
of charging goes, but also in no longer than 40 minutes if the fast charging option
is chosen. The multicopter disposes of a quick-change battery system,
denominated as a plug-in system and an active air-cooling system.
The Volocopter can fly a complete mission with less than 50 kWh of energy. The
battery package delivers up to 25 kWh and its cost is managed by maximizing
useful battery life and, differing from the EHang model, the German concept
should run on 600 to 800-charge battery life cycles. A direct consequence is that
Volocopter does not apply fast-charging to its batteries. Instead, it swaps the
batteries after every flight as it is depicted in the following image:
Fig. 2.18 The battery swapping technique is used to maximize battery lifetime
and minimize turnaround time. [20].You can also read
