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 Rules
Introduction 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 2019/245 Normative 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 handy 4 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.
1 Mode 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.
3 Uber 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 why 10 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 altitudes 12 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 interiors 14 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 m2/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].
22 Air Taxi Transportation Infrastructures in Barcelona
The most significant cost component of an electrically powered drone taxi is the cost of electrical energy consumed to carry out the flight. The idea that multicopter concepts are preferable for short to mid-range missions is generally supported by the NASA study “Observation from Exploration of VTOL Urban Air Mobility Designs” published by Wayne Johnson and Christopher Silva8.
Aiming at the electrical motors now, the Volocopter disposes of 18 rotors, 2 kW or 2,7 hp each. The engine type is a 3-phase PMSM9, brushless DC electric motor or BLDC. Again, efficiency comes close to 95 %.
Fig. 2.19 Exploded perspective on a PMSM motor. [21].
The rotor plane distribution is made alongside 6 hub-arms, 1 holm and 3 engine heads per hub arm.
Considering the propellers used for the German ultralight, they are also dual bladed and measure 1,80 meters of diameter. They can be seen mounted on top of the rotors, therefore there are 18 non-tilting propellers.
Fig. 2.20 Volocopter VC2X propeller shown closely. [22].
8 NASA Ames Research Center: “Observation from Exploration of VTOL Urban Air Mobility Designs”. October of 2018. 9 PMSM: Permanent Magnet Synchronous Motor. High performance motor control is characterized by smooth rotation over the entire speed range. Market Study of Drone Taxis 23
Safety
Regarding safety and redundancy concepts, this aerial vehicle is fitted with a full aircraft emergency parachute and multiple redundancy in all critical components such as propellers, motors, power source, flight control, displays and electronics.
It also disposes of a highly reliable communication network between different devices trough meshed polymer optic fiber network. This is system of communication is known as fly-by-light.
Fig. 2.21 The rotor-propeller positioning allows for a safe passage surrounding the cockpit. The parachute compartment can be seen in top of the roof. [22].
2.3. Direct comparison between functional prototypes
From all the prototypes analysed in [Section 2.2.], this thesis seeks to integrate an already functional model within the suburban areas of Barcelona. Consequently, a brief overview of the main characteristics that compose the EHang 216 and the Volocopter VC2X will be shown subsequently in order to simply the choosing process for the decisive drone taxi.
Visual aspects such as their dimensions are a first step towards the understanding of the correlation between the aerial taxi and the infrastructures (please refer to [Chapter 4]) that would come to be deployed trough the city (please refer to [Chapter 3]).
Following the previous reasoning, an initial rapid comparison can be done by considering the next schematics of the 2 candidates: 24 Air Taxi Transportation Infrastructures in Barcelona
Fig 2.22 VC2X dimensions scheme. [24].
Fig 2.23 EHang 216 dimensions scheme. [25].
A remark should be done on the fact that the Chinese model is significantly smaller than the German one, see red marked dimensions.
Next, a tabulation of main specifications for the EHang 216 and the Volocopter put side by side will be shown:
Market Study of Drone Taxis 25
Table 2.1. Specs comparison Main Design Model Specifications Volocopter VC2X EHang 216 Aircraft type eVTOL multicopter AAV eVTOL Autonomous flight NO YES Endurance 27 min 30 min Range 27 km 35 km Cruising speed 100 km/h 100 km/h Service ceiling >2000 m AMSL10 487,68 m optimal AGL11
>1650 m AMSL 3000 m at max. AGL Charging time 40 min fast charging Up to 1 h Battery degradation 600 to 800 life cycle 500 life cycle for 17 kWh for 25 kWh batteries. batteries. MTOW12 450 kg 599,65 kg Payload 1 pilot +1 passanger or 2 passengers or a total a total of 160 kg of 220 kg Rate of climb 3 m/s 2,5 m/s Safety DEP + parachute DEP Connectivity ATM available 5G, specialized centres Noise levels 65 dB at 75 m 75 dB at 75 m Price > 250.000 € > 200.000 € Authorization in Spain NO YES
The table above is intended to disaggregate both models with the objective to highlight (bold marking) advantages and drawbacks regarding the upcoming implementation of a decisive vehicle into Barcelona’s UAM ideal.
Besides the main characteristics, the rate of climb, for instance, it is important to determine the ability of the vehicle to avoid an obstacle vertically and that is why is being taken into consideration as well.
2.4. Final decision for operating as a drone taxi in Barcelona
In this final subsection of chapter 2, the candidate chosen to operate in the simulated airway network system, which will be carefully explained in [Chapter 3], and will consequently determine the modelling of the sky port, shown in [Chapter 4], will be revealed alongside all plausible argument that lead to the final decision.
10 AMSL: stands for Above Mean Sea Level. 11 AGL: stands for Above Ground Level. 12 MTOW: stands for Maximum Take Off Weight. 26 Air Taxi Transportation Infrastructures in Barcelona
Looking at the bold numbers in [Table 2.1.], it is easily seen that the EHang 216 surpasses its German counterpart. The only feature that the multicopter improves it is the battery lifetime and its power delivery per unit of time. This is a fundamental aspect since batteries are the key factor in determining whether or not the correspondent vehicle could manage to serve as a drone taxi in the real world. An 800 life-cycle span is an optimistic value given that most available battery technologies cannot reliably deliver this level of power to life span within the weight and size limits of the aircraft design, it would require a very large and heavy battery. Nevertheless, a 600 life-cycle span is ferly reachable, not to mention the extra 8 kW/h added:
25 kW/h from the VC2X – 17 kW/h from the EHang 216 = 8 kW/h.
Therefore, now the [Reference 8] gains weight. And yet, there is no difference to be seen in the endurance as both models were put to real flight tests: actually, the Chinese model has 3 more minutes to spare even though presenting slightly less capable batteries.
To sum up, the power supply system is better organized and promises to get better with the Volocopter candidate; however, there are not significant differences with the competition to date. Then, the fact that the Ehang 216 is capable of autonomous flight and is already authorized in the country where the subject city is located, means that these are far more important details to consider for what this project is aiming at. Moreover, the maximum take off weight and payload are also superior with the AAV model and yet again, these are more desirable features in contrast with the rate of climb and noise factor. The price does go down, which is always good, and it is best to emphasize that the 8 arms composing the 216 version are designed to be foldable, only taking 5 m2 of parking space. Lastly, the service sailing passes the test of Barcelona’s skyscrapers by far in both cases since the tallest building stands at 154 m (the gemini towers of Hotel Arts Barcelona and Torre Mapfre).
Redundantly it is shown that the EHang 216 model is eligibly the most suitable type of eVTOL for the purposes of this thesis.
Other aspects that lead to the decisive winner were found in news that stated things like:
“The EHang 184, the predecessor of the 216 version and arguably the world’s first flying taxi, was elected for test flights in large cities like Dubai.” This goes as early as the year 2017. As a matter of fact, it was because of this news that this project took root. *Please refer to [26] in bibliography to see the report in detail.
“The local government in Hezhou, Guangxi province (China) is tackling control of the epidemic outbreak using the eHang 216.” This are recent news, 27th of February 2020. *Please check [27] in bibliography. Market Study of Drone Taxis 27
Overall, the now proclaimed drone taxi of Barcelona by this work, better suits the necessities in mobility within suburban areas. Too visualize this statement in perspective, a timeline of the respective model and all other prototypes mentioned in [Section 2.2.] reaching the production scale will be attached next:
Fig. 2.24 Timeline to production scale for all models. [26].
*Note: 7 drone taxi models are shown and analysed in this work, 6 of which appear in the timeline above (figure [26]). It is worthwhile mentioning that the selection of the models was done prior to finding this graphic, courtesy of EHang’s white paper. This indicates that the current work was based on the right trajectory towards an optimal study of the drone taxi market all along.
As far as the last two models shown in the timeline concerns, they are extremely close related to the very first eVTOL presented in this document, the Hyundai S- A1, only that the S-A1 is still stuck at the full-size testing phase.
28 Air Taxi Transportation Infrastructures in Barcelona
CHAPTER 3. AERIAL TAXI SERVICE ASSESSMENT IN BARCELONA
Following with the initial planning, this chapter is meant to analyse the feasibility of an integrated airway network system within the city of Barcelona.
Since this routing system has to be designed to respond to the urban air mobility necessities while providing taxi services; meaning the operations are destined to a wide variety of activities, ranging from governmental emergencies to business and leisure type petitions such as touristic routes, it is essential to evaluate the costal city capacities for undertaking such demanding in a realistic way regarding the near future.
Therefore, points of high touristic interest will be hot spotted in the official maps provided by the council of Barcelona. This is the starting point regarding the positioning of the later described sky ports [Chapter 4] as the tourism stands for 60 % of the total incomes enriching the worldwide known Catalan city.
Nevertheless, tall buildings open to public and endowed with appropriate rooftops to serve as drone ports, which are slightly less demanding regarding the structural resistance of materials than heliports, are needed to physically ubicate the sky port or hub modelled with the help from Solid Works software in the last chapter of this thesis. This statement implies that hotels will be carefully chosen according to their facilities and standards, knowing that the aerial taxi service will be considered as a luxury type of service in the beginning.
Furthermore, a direct correlation with other modes of transportation would be extremely beneficial for the cost operative factor of the whole idea of implementing this aerial transportation system across Barcelona’s skies. More clients should be expected and governmental fundings tend towards big and solid infrastructural models, even if they are the product of an entangled multiple subsystems network. So, proximity to bus and train stations will be desirable; and concerning El Prat airport, this will be a focus point only delimited by the 15 km margin of distance mentioned in [Section 1.2.] which can be cut down to half if low level flight applied (allowing to reach for instance the port of the city).
In short, specific hotels will be elected according to their proximity to touristic attractions and other transport stations for hosting the later to be revealed hub model.
Emergency services could use this infrastructure whenever since it will be designed to cover up in the best way possible the whole city as well.
Lastly, it is imperative to mention that the feasibility determination of this complex correlated transportation system is based on a simplistic routing design (point A- point B) as well as on the social and technological capabilities of the city, the economics are to be left aside almost entirely.
Aerial Taxi Service Assessment in Barcelona 29
3.1. Barcelona Tech and Touristic City
Besides being the home city to Universitat Politècnica de Catalunya (UPC, BarcelonaTech), the metropolis aims at positioning itself as a principal international technological hub, referenced [28] in the bibliography.
In addition to that, the Catalan capital is mentioned, alongside Singapore and London, as one of the smartest cities in the world.13
It was back in 2013 that the city council started working on a strategy to make from this city the first truly intelligent city in Spain. Regarding the smart city concept: it must be attributed to a self-sufficient city with productive neighbourhoods at human speed, within a hyperconnected metropolitan area with zero emissions. Therefore, fully autonomous electric VTOL type vehicles represent a perfect integration in this ideology.
Fig. 3.1 Barcelona Smart City Logotype. [27].
Barcelona intends to use new technologies to promote economic growth and guarantee a better quality of life for its citizens.
With respect to the drone field of technology, the Drone Show is an international exposition and congress held yearly in Barcelona. Its goal is to show the latest technological developments in civil drones and their professional applications and to demonstrate the potential of drone integration in sectors that still not use UAVs regularly. Therefore, an entirely new urban air mobility concept can be presented within this show’s walls as a start up featured activity, and it would receive the attention of more than 10.000 professional visitors.
For all these reasons above mentioned, it is clear that the subject city of this thesis is perfectly suitable from a technological point of view.
Now, concerning the influx of potential customers, official demography and tourism data will be analysed accordingly:
13 “Understanding the Challenges and Opportunities of Smart Cities” Report [Ref 30]. 30 Air Taxi Transportation Infrastructures in Barcelona
The population was sized up to 1.620.809 people living in the metropolis, as far as 2019 data regards. The population density stands at 15,992 (number of people divided by the total area, which is of 101,9 km2).
Tourism will be studied in concordance with the hotel stay and the seasonality of passengers in El Prat Airport and affluency in other transportation systems such as international trains. Since hotels are to proportionate the physical sky ports infrastructures, a dedicated reference to the evolution of number of hotels sorted by category and beds available is provided in [Annex 2: Barcelona tourism activity report 2019].
To proceed with the data gotten on tourism, a series of tabulations and graphs will be supplied shortly. These graphs will contain all relevant information based on a variation timeline model and with special focus on the last couple of years 2018 and 2019. Obviously, all posterior argumentations regarding tourism in Barcelona will be based on the respective data.
But, previously, a clear message on how big is the reliance on tourism with this city it is given by this number: 11.977.277, the total number of tourists that reached the streets of Barcelona in 2019. An increase of 5 % was seen with respect to previous year. Also, up to 47 % of this number are repetitive visitors, fact that gives even more credit to the seeking of a newer and better urban transportation system. These numbers are to be found in reference [34] of the bibliography and they match with another source for news, La Vanguardia.
Fig. 3.2 Graphic showing the evolution of tourists in Barcelona’s hotels [28].
Fig. 3.3 Tabulated numbers from [28] by year. [29]. Aerial Taxi Service Assessment in Barcelona 31
There is no interest in the orange data represented in [28] and [29] since the focus is on the capital city. The representative line should be the middle green one since the dark blue one considers national and nearby tourism as well and it is always better to asset the lower limiting numbers; that is why overnights and least touristic months will be determining the decisive arguments concerning the feasibility of the whole goal of this project, all seen from the tourist perspective. Then, there it is shown:
Fig. 3.4 Seasonality of overnights in hotels [30].
Going for the worst-case scenario, the client affluency is still maintained between the 500.000 and 1.000.000 lines. Therefore, according to a pessimistic prognostic, there would still be more than 7.000.000 tourists visiting hotels.
As a final touch, here it is provided the percentage of hotel’s category choosing:
Fig. 3.5 Tourists in hotels by category in 2019. [31].
By imposing that only 4 and 5 star-rated hotels could deliver air taxi services (cost operative feasible), there it is easily obtained a rough estimation of the number of clients that would have direct access to the taxi service:
[12 + 53,9] · 0,01 · 7.000.000 = 4.613.000 (3.1)
The number speaks for itself:
4.613.000 ÷ 1.620.809 = 2,85 (3.2)
32 Air Taxi Transportation Infrastructures in Barcelona
2,85 times the entire population of Barcelona could use the aerial taxi service within a year if hotel-hub system infrastructures were to be implemented to all 4 to 5 star rated hotels. Feasibility is NOT an issue.
*Note: one-night stands were considered to further reduce the margin error. Official data talks about 2 night stands on average.
Lastly, to correlate the hotels (potentially sky ports) with other transportation stations in order to fully develop a permanently linked network between points of arrival of clients and hot spots of touristic interest mainly (destinations not related to infrastructure destined for the aerial taxi service); AENA and AVE official data from 2019 was recollected to further emphasize the big impact of tourism in these types of transportation systems (by plane and by train respectively):
Fig. 3.6 Seasonality of passengers in Barcelona Airport in millions. [32].
AVE stations accounted for 4.269.287 passengers (tourists or not) in 2018 and 4.300.000 passengers in 2019.
In the end, all numbers come close to the strictly delimited result obtained in (3.1) and that is without considering all possible scenarios which would led to an even larger variety of interested clients in the aerial taxi transportation business. *Please check [Annex 2] for more data.
3.2. Hot spots mapping
In this section, the main tourist destinations in Barcelona will be listed and placed in the maps obtained from the official council of the city webpage.
Following the landmark objectives, the nearest suitable hotels will be mapped and lastly; the 3 train stations, the port and El Prat airport will also be highlighted.
To begin with, 2018 data extracted from [37-bibliography] will be tabulated: Aerial Taxi Service Assessment in Barcelona 33
Table 3.1. Most visited landmarks in Barcelona Ranking Landmark Nº of visitors Ubication 1 Basilica of the 4.661.770 Eixample, Sagrada Família Mallorca str. Nº401 2 Güell Park 3.136.973 Gràcia (south of the Carmelo mountain) 3 FC Barcelona 1.730.335 Les Corts, Camp Museum Nou 4 Aquarium of 1.631.108 Ciutat Vella, Old Barcelona Port. 5 Poble Espanyol 1.234.407 Sants-Montjuïc 6 El Born cultural 1.080.079 Ciutat Vella centre 7 Casa Batlló 1.062.863 Eixample, Passeig de Gràcia 8 Cosmocaixa 1.045.961 Sarrià-Sant Museum Gervasi 9 Picasso Museum 978.483 Ciutat Vella 10 Robert Palace 976.276 Eixample, Passeig de Gràcia
We can see in [Table 3.1.] that Ciutat Vella and Eixample districts hold the most touristic attractions.
In order to simplify the correlation between sky ports, a one-hub distribution per district will be considered, please refer to map on [Section 3.3.]. Therefore, the method implemented for selecting the hotel near to landmarks for these two particular districts, will consist in a cluster14 zone defined by the focus points of tourist attraction; which at the same time will enclosure the hotel/hub system within its area.
Since the intention with the aerial system networking is to cover up the entire metropolis to provide for more than leisure activities; even though knowing that tourism prevails, another table will be provided in order to sort top visited locations by district.
14 Cluster: smallest area possible delimited by a group of points of interest. 34 Air Taxi Transportation Infrastructures in Barcelona
Table 3.2. Main touristic attraction by district District Landmark Nº of visitors 1 - Ciutat Vella Aquarium of Barcelona 1.631.108 2 - Eixample Basilica of the Sagrada 4.661.770 Família 3 - Sants-Montjuic Poble Espanyol 1.234.407 4 - Les Corts FC Barcelona Museum 1.730.335 5 - Sarrià-Sant Gervasi Cosmocaixa Museum 1.045.961 6 - Gràcia Güell Park 3.136.973 7 - Horta-Guinardó Laberint d’Horta Park 703.655 8 - Nou Barris Central Park 644.473 9 - Sant Andreu La Maquinista Shopping Estimation: more than Centre 17 million people, tourists and locals, shop here annually. 10 - Sant Martí Poblenou 790.824 neighbourhood
All previous points of focus are to be seen in a map showing the various districts of Barcelona as they will make for a good starting point regarding the discretization of the large metropolitan area:
Fig. 3.7 Hot spots mapped on districted Barcelona. [33]. Aerial Taxi Service Assessment in Barcelona 35
Legend of chart
- Red numeration: touristic landmarks, see orange column on [Table 3.2.]. - Blue numeration: hotel-hub systems, see orange column on [Table 3.3.]. - Yellow dots: nearest metro/train stations to hotel-hub systems. - Asterisk: representing El Prat Airport.
The red and blue numbers are linked between them according to the order given in the first column in the tables, ordinals that also relate to the landmark and hotel respectively. Example: 1 red goes for the aquarium of Barcelona [Table 3.2.] while its linked to 1 blue, representing the hotel W [Table 3.3.].
Please note that red and blue circles are there to emphasize their centre as the hot spot due to the scale of this map. In the case of 10 square red, it is being depicted the whole Poblenou neighbourhood as it represents a touristic landmark by its own.
A more detailed description of [Fig. 3.7] will be given in the next [Section 3.3] as it stands for vital information regarding the final aerial system network. For this networking distribution to be optimal, the positioning of the blue circles was carefully studied and all the arguments will be provided meticulously.
The hotel-hub systems pointed out in figure [33] were selected in accordance with a promising trade-off between the facilities provided for a convenient rooftop base to serve as drone port, their proximity to the hot spots and the overall reputation. Their name, rating and the overnight clients number per year will be listed in [Table 3.3.].
Regarding the overnight number of visitors, a permutation constant number of 1,2 was found to deliver pretty accurate estimations, therefore leading to a simple formula like this one:
(Nº of bedrooms) · 365 (as days per year) · 1,2 = Nº of visitors (3.3)
36 Air Taxi Transportation Infrastructures in Barcelona
Table 3.3. Hotels to provide for the hub by district District Hotel Name (star rating) Nº of visitors 1 - Ciutat Vella W Barcelona (5) 207.174 2 - Eixample Ayre Rosellón (4) 45.990 3 - Sants-Montjuic SB Plaza Europa (4) 106.434 4 - Les Corts Sofia (5) 219.000 5 - Sarrià-Sant Gervasi ABaC (5) 6.570 6 - Gràcia Ronda Lesseps (4) 26.280 7 - Horta-Guinardó Horta Velodrome (-) 41.611 8 - Nou Barris Turó de la Peira football Estimation of 12.000 field (-) considering surroundings 9 - Sant Andreu La Maquinista (4) Estimation of 46.575 10 - Sant Martí Occidental Atenea Mar 83.658 (4)
*Note: less touristic districts may not offer 4 to 5 star rated hotels in the proximity of the points of interest and then other facilities were taken into consideration. Such is the case with La Maquinista shopping centre, an ideal building regarding structural integrity, proximity to train station and affluency of people. Same principles apply to the velodrome of Horta, where a fifth of its capacity was taken as the variable substituting the number of bedrooms (rough estimation); and Turó de la Peira football field.
Referring back to (3.1) formula, a directly correlated client affluency with the hotels presented in [Table 3.3] can be estimated as the total sum of the third column from the respective table above: a total of 795.292 visitors instead of the percentage applied in the last section with the total of 7.000.000 clients.
Then, reasoning the same as in (3.2):
795.292 ÷ 1.620.809 = 0,49 (3.4)
Yet again, a fairly large amount of the entire population of Barcelona, basically half of it, could use the aerial transportation system in a yearly basis. Then, even though working with approximations, it is easy to see how the number of visitors cells composing all the previous tables may stand for potential customers of the aerial taxi service.
3.3. Airway networking
Once the hotel-hub systems have been placed on the map, the study for the optimal airway network may begin.
The main reference for this section will be the chart displayed on [Fig. 3.7]. Aerial Taxi Service Assessment in Barcelona 37
The philosophy behind the drone ports distribution (hotel rooftops encircled in blue) has been briefly explained earlier; they are meant to provide adequate structural integrity and proximity to touristic landmarks and bus/metro/train stations. Nevertheless, their positioning was far more complex to achieve since the overall system has to be optimized for responding to a maximum number of potential clients and that translates into inner-city proximity between hubs, landmarks and other transit stations; and a maximization of the total area of coverage by separating as much as possible the external hotel-hub blue marks, all providing that proximity to main landmark is not underprivileged.
The previous statement can be supported by naming this 2-stepped methodology applied to map the future drone port infrastructure accordingly:
1. Central distribution: it is easily seen in the last chart provided that inner circles (red and blue) tend to be closer to one another and to comprise near transit stations (yellow dots) while external ones are to form a larger cluster. For a clear visualization please focus on the left side of the map, numbers 1, 3 and 4 clearly depict this scenario.
2. Peripherical coverage: the idea here is to delimit the city by positioning external blue circles (hotels aiming to provide as sky ports) close the most outer limit-lines of the various districts. Now, of course, this intention is clearly affected by the proximity to hot spot condition; but, numbers 1, 3, 7, 9 and 10 help expanding the area significantly by imposing this method. 1, 3 and 10 stand for a perfect balance between enlarging the periphery and responding to touristic locations; while 7 and 9 seem to prioritize the close distancing factor. However, this last two aerial bases ubication represent no issues regarding the fact that 7-red is far north situated already and 9-blue is the rooftop of 9-red itself.
Referring to the whole city coverage, the population density is the main factor to consider. It is impossible to follow the shape of the metropolis silhouette by interconnecting the peripherical sky ports only, simply because of their low number would not allow such a follow-path discretization. Therefore, a map of the population density per district in the year 2018 was searched in the official council webpage [39]; and it was consequentially overlapped with [Fig. 3.7] with the help of Gimp 2.0 software. As a final touch, the external sky ports were connected via straight blue lines to better visualize whether or not the whole cluster matches the hot spots of human density within the capital city.
38 Air Taxi Transportation Infrastructures in Barcelona
Fig. 3.8 Population density by district, enclosed by the sky port bases. [34].
From the picture above, it can be stated that yes: the frontier hubs delimited cluster do indeed match with most dark red spots representing major agglomerations of people.
Only number 8 prevents the cluster from covering the entirety of the dark red zones, top right corner. Yet, the landmark ubication is pre-fixed and 8-blue was chosen in accordance with the drone port distribution mentioned shortly above; in this case a wide green area was elected (Turó de la Peira).
At a smaller impact, 5-blue and 3-blue also leave out some light red spots but that was the best trade-off found to comply with infrastructural disposal and taxi service necessities. Furthermore, 3-blue already stands away at 8,23 km from El Prat Airport, close to the limit allowed by RD1036/2017 (VFR conditions).
Now, to further develop the perception on the coverage regarding the sky ports positioning, 3 km radius circles were centre-focused on the blue numbers of [Fig. 3.7]. The distance of the radius serves as a mere reflection on point A to point B fast travel philosophy.
Aerial Taxi Service Assessment in Barcelona 39
Fig. 3.9 3 km radial coverage from hub. [35].
Fast travel zones are covering all points of interest within the metropolis excepting only the north-western residential area and the southern industrial zone, which is too close to the airport. The red overlining remarks the total area of coverage while the blue curved lines are the initial 3 km radius circles centred at hub.
3.3.1. Restricted areas and other routing barriers
In this subsection, areas to avoid trespassing with the EHang 216 fleet of taxi drones will be pointed out. Special attention will be given to the Controlled Traffic Route zones (CTR) and then, green areas will be dotted through the entire metropolitan area of Barcelona in order to redirect the major fluxes of AAVs to avoid them as much as possible.
40 Air Taxi Transportation Infrastructures in Barcelona
In the top right corner, in green, it is marked the final silhouette of the total area of coverage, attending not to trespass the ATZs of Barcelona and Sabadell, highlighted as big blue dotted circles, nor the CTR area 2 of LEBL15, highlighted in red.
The violet markers are set to focus on the non-complying zones from [Fig. 3.9].
The overall image is printed on a blue background since it represents El Prat TMA.
Reference [40] in bibliography.
Fig. 3.10 Radial hub coverage delimitations. [36].
For a better perspective regarding the delimitations of a controlled airspace; the Terminal Manoeuvring Area TMA, the Controlled Traffic Region CTR and the Aerodrome Traffic Zone ATZ main purpose and dimensions within the Spanish territory will be summarized next:
- TMA: starting at 1000 ft16 MNSL, these areas are ubicated where different airways and airports converge in order to control IFR flights during the arrival and departure phases. 12 TMAs are to be found in Spain in total.
- CTR: space associated to an aerodrome with the aim of protecting IFR arrivals and departures. CTR area 2, marked in red in [Fig. 3.10], applies the normative of extending an initial airport centred cylinder of 12 NM17 of perimeter and afterwards, it progressively extends into 3 main branches related to the 3 main SID/STAR airways.
The complete CTR of LEBL, marked in light blue, is also centred at the airport but it follows an uneven geometrical shape which covers all the littoral from Mataró to Vilanova i la Geltrú. Again, there are 3 main branches extending in a similar pattern as the inner CTR (area 2). However, due to its size, trespassing routing is inevitable. As consequence, all drone activity must obey the 4 steps imposed by AESA, referenced in the [Annex 4: Drone flight in controlled airspace procedures by ENAIRE] and as [41] in the bibliography.
15 LEBL: ICAO code for Josep Taradellas Barcelona-El Prat airport. 16 ft: 1000 feet = 304,8 m. 17 NM: 1 Nautical Mile = 1852 m. Aerial Taxi Service Assessment in Barcelona 41
CTRs are base-limited by the ground and upper-limited by the TMA. - ATZ: this zone corresponds to aircraft movement in proximity to an aerodrome. It is emphasized in [Fig. 3.10] as a big dark blue dotted circle. In Spain, ATZs are restricted to 8 km radius and 3000 ft in height cylinders. Control Towers (TWR) are also established to further control the transit and protect VFR flights.
*Note: Under NO condition the ATZ perimeter will be trespassed.
Once the no-go zones surrounding LEBL airport are delimited, regions to avoid within the city should be taken account off.
Besides the restrictions imposed by the regulations explained in [Chapter 1], there are certain regions such as green spots which are better to free from a high flow of drones traffic. As a means to reduce traffic in these areas, while not jeopardizing the taxi service since it is meant to reach as many customers as possible, a mapping of population and green areas density by districts is displayed next to the clean 10 district metropolis:
Fig. 3.11 Districts of Barcelona shown on the left side. Population density (yellow) and green spots (green) shown on the right side. [37].
It is easily seen in the figure above [37] that there is much free room to spare surrounding the peripheries of the capital city and along an imaginary perpendicular and centric axis which will be referred to as the middle hall from now on.
To completely free green areas of the traffic is impossible to achieve and also not recommended as the goal is to prove the drone taxi service as a suitable candidate for future UAM in the Catalan city; therefore, implying optimization in the number of transports and clients served, which translates to overflights by high populated districts, even if there are many green areas there as well. 42 Air Taxi Transportation Infrastructures in Barcelona
However, an optimal trade-off may be found while the routing design phase, see the upcoming [Subsection 3.3.2.].
3.3.2. Optimal intertwine
As previously mentioned, the main goal now is to find the optimal intertwine between the sky ports as a well-structured airways network system.
The philosophy behind this interconnecting airway system will be similar to that applied in graph theory18. Thus, an imaginary cost will be put to every airway (edge) that connects a pair of sky ports (vertices). The meaning of this methodology is to dismiss larger routes and the ones that cross high green spots density areas.
As a way of granting each airway a cost, the length in km will be measured and to that it will be added a unit if the edge were to pass through a green zone.
[Fig. 3.11] represents the exact location of Barcelona along the Mediterranean coast; but in order to ease the view of the airways network, [Fig. 3.7] orientation will be implemented in the end. As the transition from one to another can be done by rotating to the right 40º [Fig. 3.11], the final image to work with can be disaggregated into left sided green spots and right sided green spots. Then, a closer look at the last figure [37] reveals that the right side of the map is denser in green dots. As consequence, two units of cost will be added to the length of every edge that crosses this side of the plane.
Consecutively, a three-step process will be displayed with the upcoming 3 pictures: the first one depicting a superposition of both images with the actual orientation of the coastal city; the second one representing a sketch of a maximized routing network; and the last one being the final intertwine chosen as the best trade-off option between sky ports reached and cost operation.
18 Graph theory: the study of graphs; mathematical structures that model pairwise relations between objects. A graph is made up by vertices connected by edges. Aerial Taxi Service Assessment in Barcelona 43
Fig. 3.12 Sky ports distribution within the 10-district metropolis coastal orientation. [38].
[Fig. 3.7] was superposed to [Fig. 3.11] in order to ubicate the city in concordance with the Maresme coastline and to point out population and green areas density per district. Afterwards, the sky ports locations from [Fig. 3.7] were once again matched with the current mapping, only now they were renamed as letters instead of number to facilitate the posterior naming of the airways. A blue corresponds to 1 blue in the original figure and so on.
Fig. 3.13 Complete routing network, considering green areas trespassing allowed. [39]. 44 Air Taxi Transportation Infrastructures in Barcelona
To the previous figure, edges (airways) were added to connect the different vertices (sky ports) within the city. Blue edges are meant to represent optimal intertwines considering all restrictions: length of the airway, protected areas trespassing and the overall cost operation per edge, a given sum of both previous factors considered. Therefore, red edges are meant to represent a maximization of the routing system by crossing some green doted areas, all done aiming to reach to as many people as possible.
All other possible connections were discarded due to 2 main reasons:
1. Traffic sectorization: by keeping large edging clusters there is gained much freedom in the airspace used above the crowded streets of Barcelona, therefore aiming to sustainability. Moreover, less protected areas will be endangered and certain unions such as D to B/B to D are to be met by implementing optimal alternative routes like D-E-F-B and vice versa. 2. Airway length: this is the clear case of C to B/B to C. Even though there are no green areas in between, the resulting length of the edge would be too large to be implemented in the final design: C-A-B/B-A-C is a perfect alternative for touristic routing and eliminates the node that would be created between C-B and F-A (and vice versa) otherwise; thus, enabling for a simpler overall airways network system, one without traffic flow crossings coming from other directions (only from other senses allowed if high demand).
Fig. 3.14 Final routing network on clear 10-district map. [40].
Aerial Taxi Service Assessment in Barcelona 45
Lastly, the third image is a representation of the decisive routing network system that complies with all restrictions further above mentioned as well as with all touristic demand for high interest places connection.
From [Fig. 3.13] only the blue edges were left. These edges stand for practical airways above the streets of Barcelona in case of someday implementing this project’s ideal to the real world. What is more, a cleaner map of the Catalan metropolis was chosen to simplify the view of the routing. Each airway is named as XY-C; where X stands for origin, Y for destination and C is the cost added as length in km plus a unit or two if green areas in the left side or right side are to be trespassed (respectively), that is why each edge has two identifications, each one for one sense of travel.
Clear green areas airways are AC located closest to the airport, AF as the middle hall, AJ which will provide for spectacular sea views, EG as the most inner edge and GH as the shortest route. This goes for opposite sense as well. Thus, the cost here will equal the length measured by applying the correct scaling factor from cm to km given by google maps.
The rest of the airways are to be penalized with a unit cost or even two if denser green regions are to be overflown, such in the case with BF and BJ and the counter part sense. For this reason, the cost of BJ/JB is almost as big as the one given to AF/FA yet the last one being the largest route to cover (the middle hall).
As a whole, the system is comprised of 6 different clusters that sectorize the city in the most optimal way possible. In [Section 3.5. Closure] a more detailed explanation about why this shaping was chosen will be given.
3.3.3. Satellite view
To better visualize the integration of the previously revealed airways network system within the real city, a satellite perspective (ESA’s Sentinel-2A) on the routing will be shown next: 46 Air Taxi Transportation Infrastructures in Barcelona
Fig. 3.15 Satellite view on the drone taxi routing in Barcelona. [41].
With the image above, there is a clear perspective on how big the total clustered area and how the sky ports are meant to be intertwined. The routes naming is again displayed with this format too.
As seen in the legend at the bottom right corner of [Fig. 3.15], the total area covered by peripherical airways measures 71,43 km2:
(71,43 ÷ 101,9) · 100 = 70,1 % (3.5)
70,1 % of the total area of Barcelona city is covered by the new airways network system; all while respecting the minimum distance with the airport and guaranteeing to reach the maximum number of people possible (see population density mappings in the previous subsection).
Aerial Taxi Service Assessment in Barcelona 47
3.4. Time derived from operating the final system
Now, a final question that the reader could ask himself is how much time will it take to the clients to reach the destination. This is an important aspect to remark since it can clearly highlight the time related advantage of a drone taxi with respect to other types of transportation methods.
Therefore, a tabulation of time required per each segment from the airways network at EHang’s 216 model cruising speed (100 km/h) will be studied. The order followed is alphabetical so it helps also in pinpointing how many edges converge in one vertex. Afterwards, a small comparison with what is considered to be the fastest method of transportation in the capital city nowadays, the subway, will be discussed.
Table 3.4. Travel time per airway Airway Time Distance [m] AB-5,3 2’35’’ 4300 BA-5,3 AC-4,7 2’49’’ 4700 CA-4,7 AF-5,9 3’32’’ 5900 FA-5,9 AJ-4,1 2’28’’ 4100 JA-4,1 BF-4,3 1’23’’ 2300 FB-4,3 BJ-5 1’48’’ 3000 JB-5 CD-4 1’48’’ 3000 DC-4 DE-4 1’48’’ 3000 ED-4 EF-2,3 0’47’’ 1300 FE-2,3 EG-2,9 1’44’’ 2900 GE-2,9 FG-4,1 1’52’’ 3100 GF-4,1 FH-3,9 1’44’’ 2900 HF-3,9 GH-1,4 0’50’’ 1400 HG-1,4 HI-4,2 1’55’’ 3200 IH-4,2 IJ-5,6 2’46’’ 4600 JI-5,6
48 Air Taxi Transportation Infrastructures in Barcelona
*Note: strong winds drag influence was not considered since the purpose of the table above is to prove how much faster aerial travelling can be. Also, the extra 15 s at take off and the 15 s at landing (approximately 30 s of hovering) were neglected since only the straight route will be directly compared to the subway system time consumption. The cruising speed of the drone taxi stands at 30 km/h below its maximum speed to optimize endurance and reassure safety.
For the comparison with the metro of Barcelona (TMB network), the walking pathways to and from the stations and the waiting time for the subway to arrive were not considered the same way as with queues at hubs and hovering times for the aerial transportation system.
For the direct approach, the 3 main airways considering touristic demand were selected for the comparative:
Table 3.5. Aerial mobility vs. subway system time comparison Route and station Drone taxi time Metro time Gap AB/BA-5,3 2’35’’ 9’00’’ 6’25’’ (La Sagrada Familia)
Barceloneta to Sagrada Familia AF/FA-5,9 3’32’’ 11’00’’ 7’28’’ (The Middle Hall)
Barceloneta to Alfons X AD/DA as AC + 4’37’’ 16’00’’ 11’23’’ CD: road to Nou Camp
Barceloneta to Palau Reial
It is clear that an UAM system would like this would significantly decrease travel time within the city: even the smallest gap stands for a 256 % of the total time required by the respective aerial route.
Aerial Taxi Service Assessment in Barcelona 49
3.5. Closure
To sum up this chapter: it was demonstrated that Barcelona is a suitable city to implement the aerial taxi service since it provides the needed infrastructure (hotels to withstand drone port operating roofs) and a large number of tourists yearly, all summing up as possible clients; then, the initial routing system already implied that high population density areas were to be enclosed by the network clusters, thus ensuring the optimization for maximal services to be provided; continuing with the optimal intertwine of the airways, the best connecting graph was extracted as a means to enhance the most demanded aerial views and landmarks, all while minimizing protected areas crossings; and, as a last touch, time comparison data was decisive at aiming for UAM as the future of transportation.
To further develop on the ideal behind airways sectorization, the whole network can be simplified to a semicircle shape sketch, divided by the middle hall: inner crossings (clusters get smaller near the AF airway and the F vertex possesses the larger number of nodes, 5 as it delimits the middle hall pathway) predict for higher flow of traffic; Eixample and Ciutat Vella are the most demanded touristic districts in the list and that is why this airway in particular would tend to congestion if not because of this smaller segmentations nearby. A flux of more than 2 drone taxi per minute would already be considered as a congestion problem since the fleet disposal is meant to attend a limited number of clients while also complying with visual and acoustic contamination restrictions. Even so, 2 aerial taxis seen alongside the middle hall per minute would mean that at halfway path, another drone is already taking off from the same sky port or either there is a crossing from the other sense of travel (an optimal case of service attendance).
Moreover, the smallest inner two clusters E-F-G-H should serve as bigger stationary bases to lower the risk of traffic saturation since there are many large empty not protected areas to be found inside their perimeter and fewer landmarks to visit. For instance, the velodrome was previously chosen as a sky port base having this mindset. Regarding the bigger clusters, north and south of the city, they provide fast and efficient alternative routes while freeing the residential zones from more unnecessary overflights; otherwise routes like CF/FC would be blue marked, instead, they are to be left for emergency cases since the system is designed to respond not only to leisure activities although them being of main interest (see [Fig. 3.13]).
From the satellite view [Fig. 3.15], sea territory is open to taxi drone flight allowing for spectacular touristic routes in the surroundings of the port. Best attractions connections were always seeked during the intertwining process.
50 Air Taxi Transportation Infrastructures in Barcelona
CHAPTER 4. SKYPORT DESIGN
After an extensive theoretical research for the assessment of the aerial taxi service in Barcelona, including a market study for drone taxis and the normative statements overview; it is now time to enrich the thesis with a more personal and practical chapter, one consisting in designing a sky port meant to occupy the rooftop of one of the listed hotels in [Table 3.3.]. This modelling will be done with the help of SolidWorks software.
4.1. Sky port models
Each major company aiming for the development of drone taxis has also planned for an aerial ridesharing network based on sky ports. Each prototype focuses on a main aspect in particular, such is the case of maximum capacity with the Uber company, but they all share a minimalistic design since simplicity ensures safety, affordable cost operative infrastructure disposal and lower environmental footprint. Basically, these sky ports follow an architectural concept based on a modern simple geometrically shaped building with easy access to the drones; which are to be placed no further from the delimitations of the structure and tend to be reduced to heliport drawings on the floor. This premise will mark the design of the sky port planned to be integrated within Barcelona’s urban aesthetics, wherever there is need for one since there are many places to be left as ground zero due to the massive size of that free space in particular.
Uber, a company which holds partnership with most drone taxi prototypes presented in this thesis, envisions of giving the possibility to access shared VTOL aircrafts effortlessly. Conveniently located sky ports are to offer rides from ground to air to ground. Los Angeles, Dallas and Melbourne will be Uber Air’s first launch markets and urban drones testing started already in 2019.
Fig. 4.1 Uber Air sky port prototype. [42]. SkyPort Design 51
To continue with more examples, Volocopter and EHang’s air hub prototypes will be analysed as these two companies promise the most for the near future UAM.
On one hand, the German company placed its bet for single drone operative sky ports, maximum paired vehicles for big cities. Again, simplicity is the main aspect to follow. Last year 2019, together with Skyports, a British vertiport developer and operator, they developed VoloPort: their idea for the optimal UAM infrastructure, a concept scheduled to be shown for the first time publicly in Singapore. The transparent design and high-quality interior of the VoloPort along with a simple booking option by app ought to provide a seamless and comfortable travel experience to future passengers.
Fig. 4.2 VoloPort prototype in Singapore (left) and its interior schematics which shows the option of a retractile rooftop (right). [43].
On the other hand, the Chinese company vision is sort of a combination of the previous two models. It consists of a drone hangar adapted to support aerial operations on its rooftop and to provide for 4 parking spots. All in all, it is still a modern building adapted to respond to the AAVs operations. EHang is cooperating with a local partner in the City of Hezhou in Guangxi Province, China, to build this E-port, which will accelerate the commercialization of EHang AAVs in the tourism industry. The city of Hezhou is a pioneer in air tourism, and this project will make it model for air tourism innovation around the world. The E-port is planned to be completed and operational by around the end of 2020.
52 Air Taxi Transportation Infrastructures in Barcelona
Fig. 4.3 E-port maquette disposal at Sevilla’s fair. [44].
Therefore, it is a fact that simplicity prevails; from the most futuristic sky port concepts such as the ones from Uber to the almost already operational ones. Following the same philosophy, the design for a sky port in Barcelona should be restricted to accommodate customers to already well-prepared hubs (hotels) as they are to provide the take off and landing site, their own rooftop.
4.2. Infrastructure provided
Once seen that design requirements aim at simplicity, there is now left the integration of a proper sky port within the Catalan metropolis.
Referring back to [Table 3.3.], rows 7 and 8 reflect hubs that are actually large green spaces that allow for total freedom while taking off and landing a drone taxi; therefore, there is no need for additional infrastructure. For the rest of the hotels; one common sky port of modular design, so it can be mounted in all hotels tabulated in [Chapter 3], will be schematized to operate with 2 to 4 AAVs simultaneously. This air hub will be reduced to a simple geometrical figure such as a cube to follow with [Section 4.1.] and from it, 4 sets of arms planned as the docking points for the autonomous vehicles will be extruded (2 docking points if the hotel were to be smaller in size because it would require for the small module of the sky port, half of the cube shaped building).
Then, to exemplify the previous statement, hotel Sofia (marked as D in the routing networks from the previous chapter) was chosen as the main infrastructure in Barcelona to support an operational sky port on its rooftop. The election was made considering its proximity to the third most visited landmark in the city (the Camp Nou, FCBarcelona’s Museum) and its 5 stars facilities that can easily accommodate the bigger module of the two designs for the air hub, the cube or quadrangular prism shaped 4-armed sky port.
SkyPort Design 53
Fig. 4.4 Hotel Sofia, Les Corts District, aerial view. [45].
The idea here is to place the sky port on the highest rooftop, which is also the smallest one. It can be easily spotted at the top of the building since it is all painted in black and marked with a big white crowned “H”.
This small space is sufficient enough to give the hotel clients aerial taxi service with up to 4 EHang’s new model 216 AAVs. A quick measure in Google maps revealed that the larger transversal distance stands at 16,25 m. Moreover, the complete modular design can be fitted in that area as it squared based. The total area of the hotel rooftop would result in:
16,25 · 16,25 = 264 m2 (4.1)
Besides the area being sufficient enough, its altitude of 79 m is ideal for not disrupting drone traffic in height as well as it is optimal for obstacle clearance, a primordial aspect while taking off or landing EHang’s autonomous drones, even though the command centre is at all time monitoring the operations.
54 Air Taxi Transportation Infrastructures in Barcelona
Fig. 4.5 Hotel Sofia to Camp Nou perspective. [46].
The figure above shows in red a 7-minute walk by foot for the potential tourists interested in visiting Camp Nou by taking the aerial taxi transportation system first to reach hotel Sofia, the hub base corresponding to this landmark in particular.
Of course, as it applies for every possible route to take compiled for instance in [Fig. 3.15], a close fly-by with return to hub is available for this case too: offering the opportunity to overfly the stadium after just 22 seconds of leaving the hotel.
4.3. SolidWorks modelling
Simple geometrical shape, modular design and base adapted to hotel rooftops are the main aspects concerning the sky port modelling.
*Note: Refer to [Annex 5: Technical drawing plane] for detailed information.
Having this in mind, an initial sketch can be done with the help of SolidWorks software. All essential drawing dimensions in [mm] included, the result is:
SkyPort Design 55
Fig. 4.6 Sky port sketch on plan view. [47].
Proportions and symmetry are key to model an all base zone fitting hub. The constructive line depicted in the picture above divides the building thought as the main hub for Les Corts district into its 2 modular parts.
Dimensions are associated to the rooftop base of hotel Sofia [Fig. 4.4] but cut down to a square of 15 x 15 = 225 m2 again for standardizing the resulting extruded quadrangular prism (not a cube because of reasons explained in [Subsection 4.3.1.]).
The set of 4 arms aiming to perform as docking ports are identical to each other and unite in a slot by pairs for when the complete module is required, such in this case for the hotel Sofia rooftop hub. The docks were initially sketch as circles of 7,5 m of diameter because of the EHang 216 model span, which is of 5,61 m [Fig. 2.23]. This way, a safety distance of 1 m from the tip of the blades is ensured; plus, 7,5 m of diameter per dock extends up to 15 m per side which coincides with the square base dimensioning. Additional 2 m supporting halls are added to connect the docks to the main structure. These same halls support the whole docking slot structure weight by distributing it across little over half of its own length (the first 1,25 m since 16,25 – 15 = 1,25 m, were the 16,25 m are extracted from (4.1)) to the hotel’s rooftop; again, in the case of hotel Sofia, otherwise, all sky port base could distribute its entire weight directly to the ground.
56 Air Taxi Transportation Infrastructures in Barcelona
Lastly, interior seats and a central desk are mimicked as rectangular shaped solids. Each module is completely identical to its counter part but there is also horizontal symmetry to be found in the sketch, all for the sake of simplicity since the final building represents a real construction project to be made and be placed on top of an already existing edifice.
Now, by extruding the initial sketch according to dimension requirements debated in [Subsection 4.3.1.] there is obtained the following:
Fig. 4.7 Extruded sketch without ceiling viewed in isometric perspective. [48].
The previous figure shows the complete assembly of 6 different components, 6 solids made with SolidWorks software:
1. Piece one, consisting of the main structure, the initial sketch extruded. 2. Lateral windows, 4 sets of double screen windows ubicated on the same wall as the main entrances (one being the emergency exit in the case of the Sofia hotel, the door facing outside the edifice facade). 3. Drone windows, 8 sets of double screen windows that give sight to the drone taxi parking spots. 4. Middle window, 2 sets of four screen windows that are ubicated in the modules separating wall and superpose as one big window. This aims to communicate to the exterior for when demodulating the structure, otherwise to communicate between the 2 waiting rooms. 5. Door, 6 sets in total for the complete modular edifice. 6. Open door, just a visual edition of the regular door.
In order to see the complete sky port edifice from a human and drone perspective here is the next snapchat: SkyPort Design 57
Fig. 4.8 Sky port assembly with clients and drones to scale. [49].
The wall facing the hotel Sofia can be added to the structural integrity of the 5- star lodging or combined via a hallway that elongates till the entrance door.
The green marks are situated there to delimit the drone complete span from central point to tip of the blades. The green colour is meant to signalise leisure- oriented drone taxi operations for taking off and landing. The red colour was chosen as it is very distinctive visually and it is aiming for exceptional drone operations such as governmental or emergency type related. The bigger outer circle gives perspective to the safety zone where people can approach the AAV; it coincides with the edge for the green marking.
58 Air Taxi Transportation Infrastructures in Barcelona
As the modulated aerial port goes, the human and drone perspective is:
Fig. 4.9 One module concept with clients and drones to scale. [50].
The letter markings on the parking spots can be read as E-Port, the name given to the EHang sky port prototype; or as E (Emergency, in red) and EP (standing for E-Port, in green).
People are shown waiting outside the building to emphasize that this type of modular construction can constitute an autonomous edifice by itself, not needing of any hotel-hub system if the surroundings allow for its placement (statement made with regard to the Horta velodrome and Nou Barris park sites, which could use either the modular concept or the integral one).
4.3.1. Dimensioning according to material properties
Modular houses use reinforced concrete, but the sky port concept is designed in dual symmetry and modular integrity; therefore, ordinary concrete can perfectly do the job since all walls sustain centric and peripheric distributed forces while the dimensions of the overall edifice are kept in balance within a relatively small confined space. Ordinary concrete is also a suitable choice for maintaining constant temperature inside while protecting from external atmospheric agents such as corrosion due to rain, wind…
Once the regular concrete was chosen as the main material source, a first question to ask could be: are the docking slots strong enough to withstand a couple of EHang 216s plus at least 4 people as customers to the taxi service? SkyPort Design 59
The answer can be obtained with the help of the following tabulation:
Table 4.1. Load capacities of simply supported concrete slabs Thickness Self- Imposed Total Load Span [mm] Weight Load [kg/m2] [kN/m2] [m] [kg/m2] [kg/m2]
100 240 500 740 7,26 2,4 125 300 500 800 7,85 3,0 150 360 500 860 8,44 3,6
Now, the part that connects the slot to the main room of the sky port is the hall dimensioned as 2 x 2 = 4 m2. The last meter of the hall is suspended on the air; thus, this unit should be added to the total span of the slot structure in order to calculate the thickness needed for it to withstand the imposed load by the drones and people.
Since the radial distance of the two circles that constitute the slot structure is of 3,75 m, adding one-unit results in a span to cover of 4,75 m. The last row of [Table 4.1.] considers a span of 3,6 m, the first column sequence is of 0,25 and the last one goes as 0,6; therefore:
((4,75 – 3,6) · 0,25) ÷ 0,6 = 197,92 mm (4.2)
Approx. 200 mm
200 mm of thickness allows for the operational purposes of this sky port. All considering imbalances such as only one arm support stress in case one drone is on duty.
As a reminder, the empty weight of the EHang 216 model is equivalent to 360 kg while people’s weight of 70 kg each is considered in this thesis. It is clear then that for only one arm support 500 kg could be supported; adding one second arm and the slot structure contribution easily compensates for the weight factor (more than a ton to be supported without danger).
According to civil engineering legislation, external structural walls thickness should be no less than 200 mm; while, internal structural walls can be of 140 mm.
For the quadrangular prism shaped construction, all walls were dimensioned to be 200 mm thick while the internal separator (the wall that allows for modular separation) could not be delimited to 140 mm since it can provide as an external wall as well when demodulating the facility for smaller hotel-hub bases; therefore, 400 mm it is its final thickness in the case of hotel Sofia rooftop (400 ÷ 2 = 200 mm for smaller hubs). 60 Air Taxi Transportation Infrastructures in Barcelona
Regarding the height of the structure, Spanish urbanistic regulations mandate for at least 2,5 m of free space between floor and ceiling. Since the total area covered by the floor is small enough not to demand for extra supporting pillars and an inner large space feeling would help accommodate the client to the upcoming trip, a decision was made to separate bottom from the top by exactly 3 meters.
The inner components were dimensioned freely since they do not compromise the structure in any way: seats of 4 x 1 x 0,5 [m] long, wide and tall respectively and a central divided desk of 7,5 x 3,3 x 1 [m] and 0,5 [m] thick.
The windows and door components conforming the assembly follow these dimensions:
- Lateral windows: embedded in 4 x 1 [m] hollows. - Middle windows: embedded in a 11,5 x 1 [m] hollow. - Drone windows: embedded in 1,5 x 1 [m] hollows.
All windows ubicate their centre at 1,80 meters from the ground aiming for the perfect view; they are all framed by an 80 [cm] thick structure and all screens that compose each window are identical in order to follow with a perfect symmetry.
- Doors: embedded in 2,1 x 0,9 [m] hollows, framed by an 80 [cm] thick structure and with knob situated at exactly 1 meter from its base (1,2 m from the ground).
Materials simulated in SW:
- Main structure: regular concrete. - Windows: thick glass screen framed by chromed aluminium. - Door: wood.
Fig. 4.10 Diedric view of the material simulated sky port. [51].
The figure above represents a more realistic sky port edifice that could easily be integrated within the metropolis landscape.
SkyPort Design 61
4.3.2. Hotel hub perspective
Lastly, to better view how the concept created with SolidWorks could be embedded into Barcelona’s landscape and how taxi drone traffic would impact the city’s skyline; an artistic depiction, result of superposing drone models and the sky port images with the original hotel Sofia-hub system picture, is presented right below:
Fig. 4.11 Hotel-hub system operating taxi drones in Les Corts district. [52].
Drones and sky port are scaled to the original picture even though perspective might not fit perfectly due to software limitations (Gimp 2.0). The concept was left without material simulations in order to easily spot it and immerse the lecturer into the view: a representation of how Barcelona’s future skies may look like.
62 Air Taxi Transportation Infrastructures in Barcelona
CHAPTER 5. CONCLUSIONS
To sum up this thesis, which envisioned urban air mobility for the city of Barcelona as a feasible solution to modern transportation system congestion problems, an inside of each and every chapter and its main contributions that led to decisive changes during the project will be summarized by paragraphs next.
To begin with, the normative is quite restrictive regarding over 10 kg drone operations in the Spanish territory. However, European regulations, and in particular the UE2019/245 treats drone taxis as special passenger transportation systems; an integration which is made alongside commercial aviation and allows for this project to model a future UAM complete network to cover Barcelona’s skylines.
Once declared that this new method of transporting people in suburban areas complies with current and upcoming regulations, it is time to choose a functional drone prototype capable of operating with nowadays technology. Two candidates conformed this list: the Volocopter VC2X German concept and the EHang 216 Chinese model. The final vote for which ought to be the operating AAV in the Catalan capital went for the EHang 216 since most of its specifications surpassed the rival ones and mainly because the Chinese company has agreements with European countries (Spain included) to pilot test and operate package delivery within cites; in fact, many Asiatic cities do make use of this model for a variety of activities, from emergency response to passenger transportation across small distances. Therefore, a functional drone taxi already exists and operates at 30 minutes of range as this project is being written, making from the initial envision a possible reality in the near future.
Then, it is a fact that the aim of this paper is legal and the technology is available already. But what about the city itself, is it ready to adapt such an ambitious project to its architectural skyline and social ambience? Initial tourist data show that Barcelona is one of the most visited cities in Europe, so demand for the taxi service will not be an issue. Obstacle clearance sites and restricted zones mapping also revealed that the Catalan metropolis is a friendly location for drone operations as long as there is kept a constant distance of 8 km with El Prat airport. What is a plus, proceeding with the airway network intertwines, is that there was shown that all important landscapes can be reached within a few minutes without overflying restricted areas and respecting the aerial sectorization idealised in the first place. The final aerial network commits itself to a simple, environmentally friendly and cost-effective transportation system; an aim not easy to reach in most cities that show similar socio-economical potential to Barcelona.
Conclusions 63
As an aside, this whole system can be extrapolated to a bigger area enclosed within the metropolis transportation jurisdiction. In fact, the initial idea for this project also considered larger trips which could communicate Barcelona to the city of Castelldefels. The only downside of this would be the route deviation imposed by the airport and the lower demand from clients since tourists’ goal is to discover all sites located within the capital territory; and tourism mandates at taxi related services and infrastructures associated to them, even if they are aerial.
Finally, the sky port concept created with SolidWorks software revealed that a simple, symmetric and aesthetic as well geometric figure as it is a quadratic prism with a set of external docking arms can easily provide for an aerial taxi service whether it is from ground, tall hotel rooftops, small crowded places (as it is a modular concept) or large green areas: the idea is to make use of the surroundings in order to disguise the infrastructure with the environment and reach to as many people as possible.
Of course, there are downsides to this type of engineering projects, its domain already demands for optimal coordination across an entire metropolis skyline and regarding the ground infrastructure requirements, they could be too cumbersome for practical purposes since many drone taxis still have a low flight time before having to connect to ground for recharging; nevertheless, economical aspects directly linked to infrastructure were left aside for this paper.
Overall, all being discussed, it seems like this project can see the light of reality in just a few years; there are cities out there like Dubai that have already implemented some of the aerial taxi services and do respond better as time goes by. Time indicates that Barcelona will be host to a large fleet of AAVs soon enough too, competing with the big European counterparts and serving its citizens with a faster and improved transportation system for the suburban areas.
64 Air Taxi Transportation Infrastructures in Barcelona
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66 Air Taxi Transportation Infrastructures in Barcelona
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Annex 69
ANNEX
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
70 Air Taxi Transportation Infrastructures in Barcelona
Annex 1: Winner drone taxi for operating in Barcelona
EHang 216 model with doors opened:
EHang 216 model with folded arms:
Annex 71
Annex 2: Barcelona Tourism activity report, year 2019
Statistics on the number of hotels in Barcelona:
72 Air Taxi Transportation Infrastructures in Barcelona
Statistics on the number of hotels according to the star rating in Barcelona:
Annex 73
Statistics on the number of passengers per infrastructure in Barcelona:
74 Air Taxi Transportation Infrastructures in Barcelona
Annex 3: Mapping of Barcelona
Annex 75
Annex 4: Drone flight in controlled airspace procedures by ENAIRE
Given an RPAS (Remotely Piloted Aircraft System) operator authorized by the State Air Safety Agency (AESA) and the desire to fly the aircraft in airspace where ENAIRE provides air traffic control service, these are the steps to follow:
1. Carry out an aeronautical safety study (EAS) based on the SORA
(recommended) risk analysis methodology for the type of operation (ConOps) it is wished to be carried out in controlled airspace. Consult the Guide for the
Coordination of Security Studies schematic (ENAIRE):
76 Air Taxi Transportation Infrastructures in Barcelona
2. Send us the EAS through the Security Coordination Form. The ENAIRE
Security Division will contact you through the email that you have specified in said form and you will initiate the coordination of the EAS. Once this process is completed, we will provide you with evidence of coordination with ENAIRE so that you can request AESA authorization to operate in controlled airspace under the conditions reflected in your EAS. Annex 77
IMPORTANT: only AESA can authorize you to fly in controlled airspace.
3. Once you have the authorization from AESA and all the necessary permits to carry out your operation, consult ENAIRE Drones to check whom to direct your operation request to.
In case it is ENAIRE, use this activity request form with remotely piloted aircraft and the Airspace Operational Coordination Department (COP) will indicate the conditions and requirements that you must meet once the operation has been coordinated.
4. The day you go to fly your drone:
- Check the NOTAMs in force and get your Pre-Flight Information Bulletin (PIB).
- Formulate the flight plan following this specific guide for RPAS operators.
- Remember to act according to the instructions received from the COP.
- Listen to the instructions that the air traffic controller (ATCo) can give you by
radio and follow their instructions as just another airspace user.
- Finally, close the flight plan with the ARO office.
78 Air Taxi Transportation Infrastructures in Barcelona
Annex 5: Technical drawing plane