AEROSPACE RAeS Urban Air Mobility conference report

Waiting for the eVTOL-taxi rank

Considering how close to launch urban air mobility systems claim to be, it may appear strange how little public discussion about it there has been. DAVID LEARMOUNT looked at what steps are being taken to rectify this.

Vertical Aerospace’sVA-1X saw the company shift to a winged concept with tilting rotors.

Developing the enabling technologies for a new age of urban air mobility (UAM) is proceeding apace in many countries worldwide, yet debate in the public sphere about the change this will bring to urban life is almost non-existent.

The Royal Aeronautical Society held an online UAM conference in October 2020 to review progress in this burgeoning new industry – which promises imminent entry into service for the earliest of many competing electrically-powered vertical take-off and landing (eVTOL) air vehicles.

Major cities worldwide have long exploited underground metros to improve intra-urban travel but now the airspace above them is seen as a solution to traffic congestion. James Sheppard, Head of Research and Technology at UK-based Vertical Aerospace told the UAM conference that eVTOL operations should complement public transport, not compete with it, indicating a vision of ‘vertiports’ co-located with rail, metro and bus stations.

Plying the urban skies​

Whatever work helicopters have been doing in urban airspace for decades can now be carried out better and far more extensively by an entirely new category of aircraft. That is the UAM vision. A multitude of start-up companies are pitching for their eVTOL machines to ply urban skies as air taxis and they are attracting serious investment with promises, by some, of entry into commercial service by 2023. But if UAM is to succeed where helicopters have simply stalled at today’s level, the aircraft must be quiet and cheap to buy and operate with smart systems for making safe use of the urban sky’s maximum capacity must be available and approved by the authorities.

The Lilium all-electric air taxi prototype. Lilium

Speaking at the RAeS UAM conference, Robbie Bourke, Vice-President at management consultancy Oliver Wyman, warned that nowhere in the world, at present, are there regulations permitting UAM operations on the scale envisaged by these optimistic analysts and investors. Meanwhile, Munish Khurama, Eurocontrol’s Senior Manager Business Development reported that, while conducting an urban airspace assessment over Riga, Latvia with future UAM operations in mind, he discovered things he had not anticipated: “We found many surprises,” he told the conference. There were, he revealed, large numbers of unauthorised unmanned air systems (UAS) regularly using the lower airspace, and the authorities knew nothing about it.

The eVTOL investment rush

None of this, however, seems to be deterring anybody right now. The rush to invest in eVTOL – both the air vehicle manufacturers and the enabling infrastructure providers – is not surprising, given that the market value of urban air mobility (UAM) providers in the US alone is forecast by some analysts to be in excess of $300bn within 20 years. Indeed, management consultancy Roland Berger, represented at Farnborough’s FIA Connect virtual Global Urban Air Summit 2.0 in July 2020, predicted that 160,000 eVTOL aircraft will be operating worldwide by 2050, serving the intra-urban and near-urban short-haul air taxi marketplace. Duncan Walker, Managing Director of infrastructure provider Skyports, reckons that figure is a massive underestimation.

Here are just two examples of how far advanced some equipment is, thanks to investment. Germanybased eVTOL air taxi developer Lilium – has attracted nearly $400m investment while US-based Terrafugia in Massachusetts, which is backed by Chinese money, demonstrates that the interest is global. Airbus, Boeing, Bell and Embraer have their fingers in the eVTOL pie, as so do car manufacturers Hyundai and Toyota. Meanwhile, the established urban surface transport giant Uber not only published a White Paper in 2017 presenting a global vision for the UAM industry but since then has staged three enthusiastically-attended annual conventions to hype the prospects for this new industry.

Uber intends to provide the familiar ride-hailing app, and was to operate its own air taxi service, Uber Elevate, but has just sold the latter to Joby Aviation. It has also sold its self-driving car company Uber Advanced Technologies Group to Aurora, an autonomous trucking developer, in which it will own about 25% of its shares. Many believe that it was Uber’s high-profile promotion of UAM over the last few years that has led to the large number of companies competing for space in this promised market. However, at the RAeS conference the consensus was that the size of the market, even given optimistic predictions, cannot support the number of wannabe eVTOL manufacturers, so extensive consolidation is expected.”

Meanwhile, the airspace they operate in will inevitably be dependent on new, integrated air traffic management (ATM) digital technology and expertise. Uber predicts an airborne ATM environment using a network of one-way ‘skylanes’, flown by pilots operating under visual flight rules (VFR) to begin with but eventually automating ATM and separation/ anti-collision, permitting freer routeing choices.

Almost all the companies bidding for UAM marketplace success have already flown at least prototype eVTOL machines and are working with specialist infrastructure companies on plans for urban landing site provision and ATM. Also, inevitably, they are having to consult national aviation authorities (NAA) about regulation and airworthiness certification. Germany-based Volocopter, for example, obtained permits to fly its VoloCity prototype air taxi in 2016 and successfully ran manned demonstration flights over Marina Bay, Singapore in 2018, generating great interest there. A permit to fly, however, is not a certificate of airworthiness for public transport operations.

Although 2023 was, until recently, advanced by aircraft manufacturers as the date by which commercial operations could begin, it had always looked implausible to observers. Now the date seems to have slipped to 2025 but that still looks optimistic – except to Volocopter, whose successful Singapore trials have given it the confidence to predict approval within two or three years. It is, presumably, also buoyed by its work in co-operation with Parisian authorities to test an eVTOL shuttle service for the city’s Olympic Games transport infrastructure in 2024.

The eVTOL Volocopter 2X. Volocopter is set to begin air taxi services in Singapore in 2023 and is already selling tickets for 15minute flights. Spielvogel

Certification – a painstaking business

Some of these new eVTOL aircraft will be technically capable of carrying a commercial payload by then but proof of the safety concept, winning public transport airworthiness certification for the vehicles and air operator certificates for the air taxi companies, and creation and approval of the necessary supporting infrastructure, will take longer. A litmus test is the difference between the estimates of the enthusiastic start-ups – who are eagerly pitching to their investors – and those of the established aerospace players such as Boeing, Airbus and Embraer which are familiar with the painstaking business of dealing with NAAs. They favour 2030 as a plausible entry into service date and even then, according to the UK Civil Aviation Authority (CAA) Innovation Services Lead Frederic Laugere: “It cannot happen overnight”.

Speaking at the RAeS UAM conference, Laugere predicted that the service introduction process will be more of a progressive roll-out, “a journey carefully controlled”, as he puts it. In this emerging sector there is so much new stuff for the aviation authorities to test, approve and certify. The testing task is not only about the aircraft’s airworthiness: it has to include ATM procedure testing, because the eVTOL operating environment will be different from any ATM environment that has preceded it and a great deal of surveillance/separation automation and integration is going to be necessary for it to work. The CAA, which takes seriously its commitment to help beneficial innovation, says it is looking for faster ways of doing its oversight duty in this entirely new arena but without sacrificing safety standards.

Laugere implies that, if an entire system gets approved for operation within absolutely minimal testing times, caution is essential during its introduction. This would allow learning and additional testing on the job. The idea of starting with cargo operations – distributors like Amazon Prime might be customers – was one of many proposals floated at the event. One of Volocopter’s products, dubbed VoloDrone, will be pitching for that job.

Getting the public onside

The sheer volume of money, energy, enthusiasm and hard work visibly being invested in the UAM sector is so impressive that even those at the conference who felt they should voice warnings about the multitude of hurdles along the route to commercial operation sounded rather apologetic about raining on the eVTOL parade. Perhaps the most frequent cautionary note voiced at the RAeS was not about the aircraft technology – which everybody accepts is a matter of when, not if – but about how little attention this gestating industry is paying to the need to prepare the public for the arrival of a disruptive new technology. After all, if urban eVTOL operations prove a commercial success, it will affect all citydwellers, most of whom are unlikely to be able to afford to use it – especially in its early days. Failure to get the public onside – or ideally to fire them up with enthusiasm – could be a massively costly omission.

Speaking at the RAeS conference, Professor Iain Gray, Director of Aerospace at Cranfield University asked rhetorically: “who will be the Tesla of this new industry?” He also added that he sees “great products being developed” but not enough working together and liaising with infrastructure providers, cities and NAAs.

The conviction that the new eVTOLs will be able to transform a transport marketplace that helicopters have notably failed to develop is based on wide differences between the two types of vehicle. Commercial transport helicopters are mechanically complex single-rotor aircraft, expensive to maintain and operate, noisy and carbon-fuelled – thus polluting. Finally, even if fatal helicopter accidents are rare, helicopter design incorporates several highly-stressed single-point-of-failure components whose failure usually means disaster.

Meanwhile, all the eVTOLs aimed at the UAM marketplace are relatively mechanically simple, lighter, far quieter (but not noiseless), battery-powered (and thus clean in operation) and powered by distributed electrical propulsion (DEP). DEP is a system of multiple independent power units, each one driving its own fan or fans, designed such that, if one or more engines were to fail, the vehicle is able to land safely. For example, Lilium’s Lilium Jet sports 36 small ducted fans in a hybrid tilt-wing format that allows it to transition to wing-borne flight in the cruise. The competing Volocopter VoloCity has 18 larger unducted fans but no fixed wing and UK-based Vertical Aerospace’s VA-1X has eight fans and a fixed wing.

Vertical Aerospace has imported talent, technology and ideas from Formula One. Explaining part of the VA-1X design philosophy at the RAeS UAM conference, Sheppard pointed out that the control system is digital fly-by-wire. To control its eight independent rotor systems plus aerodynamic control surfaces, the pilot interfaces with an FADFC (full-authority digital flight control) system, basically a computer that takes account of the pilot’s control inputs, and compensates for other factors like wind gusts or power unit failure. Vertical is working with Honeywell on this project, but – like all the aspiring start-up manufacturers – they will still have to convince NAAs that the control system has the necessary integrity, reliability, and redundancy before they get it approved.

Vertical Aerospace’s CEO Michael Cervenka says the first market opportunity that eVTOL will take is to replace helicopters in the urban environment. However, that will be just the start. An argument employed by all the players to justify the ultimate UAM vision is to cite the demographic forecasts that a far higher proportion of the world’s population will soon live in cities than do now, leading to urban sprawl and worsening transport congestion both on and beneath the ground. The recent Covid-19-driven practice of people working from home might – according to current forecasts – may temporarily slow this process, but it will not actually reverse the long-term migration of people to cities. Cervenka sees a large part of eVTOLs’ work being ferrying people who work most days at their rural or suburban home close to the city but need to commute in from time to time for business reasons.

Which cities will be first? ​

Choosing top global cities like London or New York as an example of cities where UAM can flourish is to downplay its ultimate potential, according to analysts. Both are cities with a well-developed public transport system even if the roads are congested, and are home to populations sensitive to aviation noise and to the threat to citizens if an eVTOL aircraft were to have a mishap. After all, in 2013 a helicopter hit a construction crane in London (Vauxhall) and crashed, killing the pilot and two people on the ground. This has not resulted in a suspension of helicopter operations over London but helicopters are a known technology and relatively few operations take place. The eVTOL industry is aware, however, that if a start-up technology were to experience fatal failures over a city in the early days, it could put back public acceptance by years, just as accidents involving autonomous cars have done in the surface transport sector.

By contrast, Cervenka points to Bangalore, India. It is a large city buzzing with business and industrial activity but the transport infrastructure is awful and surface congestion leads to an appalling waste of business time and to high emissions. eVTOL could make a positive difference in cities like it, he points out, and public acceptance is likely to be much higher

Skyports’ Duncan Walker says he sees London as a sound UAM prospect in the longer term but does not see it as a ‘first mover’. Asked which the first movers are likely to be, he forecasts Singapore, Los Angeles and Dubai. As for regions or countries which are already buying into the idea most enthusiastically, he cites Florida, Japan and South Korea. Uber Elevate says ideal target cities have a population of more than a million, a large airport and good weather: it favours Dallas, Los Angeles and Melbourne as examples.

Paris, despite its well-developed surface and metro infrastructure and its relatively compact size compared with the world’s sprawling mega-cities, seems likely to be a first-mover simply because it is hosting the 2024 Olympic Games. The city would love to have eVTOL shuttle services to boast at the event. Trials, involving Volocopter, Skyports, and the Paris airports group ADP, are being set up at Pontoise airfield near Paris.