Fresh back from a Royal Aeronautical Society conference in Bristol, Professor Andrew Rae provides insights into air transport of the future, including the possibilities of drone taxis and electric aeroplanes.
Much is being made of the development of driverless cars, especially of the setbacks, as the technology matures towards a feasible application. While driverless cars will alter the way we travel, the concept will not necessarily fundamentally alter the vehicle in which we get from A to B. The cabin layout may change, with the removal of the requirement for a forward-facing driver, but the car will probably still have four wheels, doors and somewhere to put your luggage, your shopping, or your faithful companion, canine or otherwise. The move away from fossil fuels will possibly have more effect on the design of our runabouts than the move towards autonomous operation.
The same cannot be said for the possibility of pilotless aeroplanes. While the move towards electric propulsion will allow the designers of aeroplanes to explore new configurations, the technology behind autonomous flight will open entirely new markets and, thus, new and very different, types of aircraft. All of the major airframe manufactures are contemplating air vehicles based essentially on the technology familiar to many of us who have seen and played with drones, from handheld toys to platforms capable of high-definition aerial surveying. The prospect has also attracted a variety of start-ups or companies not normally associated with building aeroplanes, enticed by the notion of a ‘flying taxi’ or ‘urban air mobility’.
As with most technologies, there are many positive ways to use uninhabited air vehicles (UAVs) and there are those who will seek to exploit them for nefarious purposes. The low-cost and relatively high capability of ‘toy’ drones has allowed us, for example, to explore the notion of a ‘remote pharmacy’, delivering prescription medication directly to those in remote and rural locations or the personal distribution of parcels from your favourite online shopping provider. At the same time, they are being used to supply those in prison with contraband items or to be cheap weapons delivery systems in areas of conflict.
The rapid advance in drone capability and availability has outpaced the legislation needed to ensure the safety of the skies above us. Many of those flying drones will be unaware of, and consequently break, the current requirements of pilots. These include minimum distances to be kept from people or buildings and the need to keep the drone in sight at all times. That said, the ability to do many tasks more easily, more safely and more cheaply than is currently possible, and allow some tasks that were previously impossible, means that the positive uses of drones are only beginning to be explored.
The concept of urban air mobility raises additional questions beyond the mere feasibility of the technology. One of these is the impact on our environment. In a modern urban environment, traffic will often blend into the background noise, with only the occasional siren or loud exhaust piercing our consciousness. Helicopters fall into this same category; we are generally aware of one nearby. The thought of hundreds of helicopter-like vehicles operating constantly would thus present a relative assault on our senses, added to which, drone rotors rotate much quicker and thus produce a higher frequency noise.
NASA has conducted psychoacoustic studies, at its Exterior Effects Room at Langley Research Center, to gauge the subjective response to noise from flyovers of small UAVs against that from road vehicles in residential neighbourhoods. Perhaps unsurprisingly, the UAVs were found to be more annoying than conventional traffic, even when of the same loudness, suggesting that the type (frequency) of the drone noise is more intrusive. However, it is probable that, could the same test have been performed in the Victorian age, when pitting automobiles against horse-drown transport, the same conclusion may have been reached, and look where we are now! Also, the reduction of emissions from electric motors is welcome, but the electricity has to come from somewhere.
As a designer of aeroplanes, I am truly excited by the possibilities offered by autonomous flight. Our UAV work at the University of the Highlands and Islands includes the development, evaluation and operational aspects of new UAV designs, including the ‘Phoenix’ ultra-long endurance aeroplane that is part airship, part aeroplane and is self-sufficient in energy. This 15m-long, 10.5m-wingspan vehicle is being developed as part of an Innovate-UK-funded project and will commence flight tests in October this year.
The advances being made in battery technology and hybrid systems will see the embrace of electric aerial propulsion, and will allow us as designers to move away from the constraints on the configuration made by the gas-turbine engine. Running a ring-main around the aircraft will allow us to put propulsors almost anywhere and everywhere. However, the freedoms offered by these things have had, and will increasingly have, an impact on or lives and our environment.
As an engineer, I am thrilled by the possibility that things which seemed science fiction just a decade ago are now becoming reality, though wary of the way in which humanity can respond to such opportunities.
Professor Andrew Rae, Professor of Engineering, Perth College UHI, University of the Highlands and Islands
For information on the University of the Highlands and Islands’ aircraft engineering and maintenance programmes, visit: www.uhi.ac.uk/en/courses