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In this module the user prepares to land in a densely populated inner city area. The challenge here could be plenty of traffic in the air and many obstacles around the landing site. The approach corridor could be narrow due to the fact that buildings tend to be very close together in inner city areas. As many users would have the CBD as their destination, the landing areas could be full and parking space also could be scarce. One option to handle the restricted parking space could be, that the PAV drops out the user and moves on alone (autonomously) to a place where parking space is more easily available. Advantages of this landing situation in CBD would be a good connection to other modes of transport and a well-equipped landing site assuming that landing sites used by many PAVs would make it attractive to develop special service facilities. In this module the collision avoidance not only with other vehicles but also with obstacles on the ground plays a major role, and this interrelates with the requirements regarding the sensor technology and the whole performance of the navigation system. If non-skilled users are envisioned, the feature of automatic landing is added to the list of requirements.
Module 5: Landing at an Office Park
In opposition to module 4 the user in module 5 prepares to land in a more open environment which could be a business park located on the outskirts of a city. Questions connected to this landing situation are what the user has to decide during the landing procedure and how automatically the landing approach works. After landing, a solution to park the vehicle or to hand it over to another user must be considered. Additionally, formal things might have to be handled by the user such as to register or to pay service fees. As it cannot always be expected that the landing site is also the final destination, the question emerges of how far away the workplace is and of how this distance is bridged.
These last two modules point out the questions associated with the infrastructure for PAVs, the storage of the PAVs when not in use, and the connection of PAVs to other modes of transport.
It is clear that these modules could be modified in any direction and questions of one module often also apply to other ones. Nevertheless, they help to imagine how PAVs could be used in daily live and requirements for the layout of a future PATS and the PAVs operating in it can be derived from them.
4.1. The Reference PAV
Based on the understanding that a decision for one performance requirement, for example the seating capacity of the PAV does have an influence on other requirements of the PAV (internal dependency) and that some requirements are also strongly connected to the mission the PAV shall provide for, it is necessary to consider these requirements not separately but to be aware of these interactions.
This means that, regarding the design of a PATS, internal dependencies of “performance requirements” of the PAV exist and further on a dependency of the PAV requirements on the system and the desired mission, which the single vehicle shall allow for, are given.
In the context of MyCopter one consistent PAV vision (called Reference PAV) with the associated performance requirements was developed over the first two years of the project by thinking through these modules. Around twenty requirements regarding the physical specification of the vehicle itself as well as performance criteria were agreed on by the partners and can be found on the following Table 1.
Table 1: Specifications of the “Reference PAV” in MyCopter
Three of these specifications are thought to be especially important for the following travel scenario development. First of all the decision for a two seater driven by the knowledge that average car use for the purpose commuting is 1.1 to 1.2 persons. Secondly the decision to go for a VTOL vehicle with all the consequences regarding start and landing abilities connected with the present agreement of the project partners to have only a quite limited maneuverability of the vehicle on the ground. And thirdly the existence of two different levels of automation the full autonomous one and a second option where the system overtakes tasks such as collision avoidance, start and landings.
4.2. Travel Scenarios
In order to gain a better understanding of the expectations the society might have regarding the actual use of PAVs in daily life and the impacts of a broader introduction of such a technology on the environment so called travel scenarios in a narrative format were developed. They will be used as an input for empirical studies such as questionnaires and focus group discussions to be conducted in three countries (Germany, England and Switzerland) in the second half of the MyCopter project.
4.2.1 Full autonomy
The first scenario describes the situation of a full autonomous PAV which manages the whole flight procedure by itself. Besides the destination input and the initial “call” of the PAV no further input from the user at all is needed. This opens up a broad user group (no expensive, time-consuming and challenging training requirements) also old people without a car driver license are thinkable, but does at the same time raise the requirements enormously regarding the vehicle abilities and the system standards.
It is 8 in the morning. Jim Wamugi is late. He is looking for this homeTab, a tablet computer-like device that he uses to manage and control communication, entertainment and household appliances at his recently acquired home, some 20 miles away from downtown Sogal. There it is. While opening the ezPAV app, he grabs another cup of coffee. ‘Good morning sir, what can I do for you?” buzzes the machine. “I need a lift to the office in about five minutes.”, Jim growls.
“No problem, sir. The next myCopt will be at your door in six minutes.” He enters the myCopt and confirms the destination at the HMI. “We will arrive at the FreeDesign PAVpad at 8.25. Do you want to have e-New York Times projected on the big screen? And continue listening to Robbie Williams’ last album? …” Jim smiles. The guy must be in his sixties now, but he is still recording music for twentysomethings.
The myCopt gently lifts off, gains speed and gets into a thick stream of other PAV in a virtual highway in the sky towards the Central Business District. A pretty soft ride at 100 mph today, Jim thinks.
Close to the FreeDesign office building, the myCopt leaves the swarm and descends to the landing pad on the roof. Jim disembarks, and the PAV silently disappears. In the entrance hall he meets his new boss who has arrived a minute before him. “Did you watch the game yesterday evening?”, she asked with a grin … 4.2.2 Augmented Flight The second scenario reduces the PAV capabilities and puts more responsibility and tasks on the human user.
“Frank, did you plug-in the copt yesterday evening?” “Of course, honey.” Mary Tsu leaves her family home and heads toward to the garage right next to it. If he wouldn’t have forgotten it from time to time, she wouldn’t have asked… She presses a button on the remote, the garage door opens and the myCopt slides out. Mary walks around it, checking for visible damages. Then she boards the PAV and calls automated flight control. “Mary Tsu, Registration HS15456MC, Destination SingBang CBD.” “Flight control. Your dedicated parking lot is PL1328. You are scheduled to arrive at the SingMed landing facilty at 8.37. Good to go in three minutes.” Mary lifts off. Apart from the altitude control stick, flying the PAV feels like driving the car she used to have 15 years ago. OK, projections of permitted flight paths on the windscreen weren’t common back then… After the heavy rainfalls in the last week, the flooding around the river was still enormous. She decided to have a closer look and flew another loop, almost hitting a goose that was crossing her path. After that, she returned to the virtual highway in the sky and switched the PAV to automatic.
Close to SingMed, flight control called. “Due to your flight route changes, you have lost your landing slot. You are now rescheduled to land at 8.44. We will put you in position 8 in the arrival cue.” “Dammit”, she thought.
After landing, she manoeuvres her PAV to lot PL1328 and secures it. “OMG, one of the most remote places in this huge facility. A 10 minutes walk to my office…” 5 Existing challenges and problems „Designing the air vehicle is only a relative small part of overcoming the challenges. It seems likely that this small part will be solved in this century. The other challenges remain, although they too are receiving attention“ (EC 2007, p.52) Whenever the idea of personal air vehicles or flying cars is presented and discussed, many questions regarding not only the technical feasibility of the pure vehicles but especially concerns about safety (collision avoidance, controlled flight into terrain, terrorist threats, etc.) are expressed. Further questions arise on how air traffic management for them could look like and on where the aircrafts would be allowed to fly and at what times. Other major challenges are the topics of certification and regulation and the question of how to integrate the PAVs into the existing ground transportation but also into the existing air transportation system (Muller et al. 2010). In the field of environmental issues the uncertainty about energy consumption and emissions is noticeable; especially the issue of noise disturbance seems to be a key one that comes up whenever people are confronted with the idea of PAVs flying around in higher counts in a city environment.
Because of all these uncertainties and questions the first year of the project work from partner KIT was spent to explore the socio-technological environment of PAVs and to look into the infrastructural environment such a development would need. To look in detail into all these questions is way beyond the capacity of this paper but some of these key issues will be discussed further in the following pages. For a much more in detail discussion and description of topics like air traffic management and airspace regulation for such PAVs, the questions regarding qualification of the user (license), the legal and certification aspects as well as the already touched topic of the level of automation please refer to Del. 7.1. Screening Report of Socio-technological Environment of the myCopter project (Meyer et al. 2011).
5.1 Impact on congestion
As one main goal of the project is to reduce the negative impact of congestion in European metro areas through the use of PAVs, a look into the potential effect on the traffic situation on the ground seems reasonable. Because a general assessment of the overall impact of PATS on European road traffic will be difficult for methodical reasons and beyond the possibilities of this project we will present here a rough estimate based on a set of good estimates and heuristics.
Assuming a number of approx. 300.000 people that commute every day into a major city, modal shares typical for European cities and a substitution rate of 10% of car traffic by PAV4, an “automated” ATM for such a prototypical city would have to handle between 2.500 and 10.000 approaches per hour. Between 40 and 160 independent landing sites for PAV would be needed (assuming turnover times of 30 seconds and 30 seconds separation). Further assuming a conventional business model (“individual ownership”) and limited autonomy (no ability of fully automated flying) of PAV, this scenario indicates a required storage capacity for 7.000 to 20.000 PAV within the city.
These rough calculations show a number of challenges associated with the PATS. First of all this is the high number of approaches which the take-off and landing sites would have to handle during the rush hours. These means that an efficient air traffic management system would need to be in place to handle the distribution of incoming air traffic to the available landing sites. Secondly it points out the topic of parking space which is needed to store all these thousands of PAVs in the city and this problem is well known for cars since a long time.
Please note that these considerations do not take into consideration possible rebound effects (e.g. more car use due to less congested road situation)
5.2 Safety One key issue for sure will be the one of safety for the user inside and for the people around. A number of technical and human induced errors can lead to accidents or unsafe situations in aviation.
A main topic regarding flight safety is the weather. Because this topic was seen as a potential major hurdle for a frequent and reliable use of PAVs it was investigated in more detail in the first year of the project. This weather analysis will be presented in condensed form in the next subchapter.
Weather conditions are a big topic for air traffic in general. Even large commercial aircrafts flying under IFR (instrument flight rules) are affected by snow events, freezing rain or other hazards, and airport closures. For smaller air and rotorcrafts with a lower level of instrument equipment even greater restrictions in terms of weather can be expected. This subchapter investigates how tricky it might be to realise the high requirements on the “usability over the year” of 90% for the Reference PAV of MyCopter. This requirement of 90% seems to be at the lower end of what could be accepted and competitive against a car.
As a first step, potentially limiting weather phenomena and the amplitude at which they must occur to prevent a safe PAV flight were collected. Although the propulsion system for the Reference PAV is not fixed, the fact that it will have VTOL abilities and be a quite light weight vehicle gives some clues about where to look for orientation regarding reasonable “no-fly criteria” (e.g. current rotorcraft directives).
Weather phenomena which are addressed in such directives are, for example, surface winds (including gusts), turbulences or the absence of de-icing conditions. Currently, many aircrafts are not approved for flight in known icing (FIKI) conditions according to the FAA (FAA Aviation Safety (2010)).