NASHUA N.H. – Before anything takes flight in a commercial setting, urban air mobility (UAM) designers need to ensure the vehicle is airworthy and is safe for all occupants in and people outside the aircraft. In years past, that meant a brave test pilot would jump in the cockpit and put his or her faith in the project engineers and manufacturers. With UAM, that is unnecessary as these aircraft will fly sans a cockpit, much less a pilot in the vehicle. In addition, simulation software has gotten sophisticated enough that designers can run their aircraft through an incredible number of scenarios and flight conditions and have a very strong degree of surety before a real motor is even attached to an aircraft.
"This is bringing us the capability to analyze functional safety in a unique environment," ANSYS' Colombo said. "We acquired a number of companies recently in order to create the UAM-specific platform that will be very important for urban air development. We are creating more robustness with full automation. On average, our customers saw a 55% decrease in effort and time to perform functional safety analysis."
Of course, even if the UAM aircraft has demonstrated safety in tests and simulations, regulators like the Federal Aviation Administration (FAA) or the European Union Aviation Safety Agency (EASA) will still need to keep a close eye on this young sector as it comes into fruition.
"This is a long discussion that companies are having with the FAA, and other stakeholders like EASA," said Colombo. "We have a huge number of new technologies that are coming so fast. This is really changing the way the industry should think. If you aren't using these technologies, even if you are one of the leading companies in the industry, you risk falling behind."
Colombo continued, "The industry doesn't have 50 years or more of experience using this technology - automated systems and sensors. We now have more than 30 antennas on a fuselage. You have to find a way to test them, to verify it and certify it. That’s a huge, huge challenge. Nobody has a clear idea of how to do that. There are new ways everyone is exploring. Given that there isn't a single workflow for certification, the FAA and EASA are asking companies for more functional safety analysis and to prove that they have done failure analysis and mitigated that risk as much as possible. They decide if this company can move on or not. This is where we are with this new technology."
Technology, though, has a way to go until it can match human perception of objects moving in three dimensions, as systems decide whether an airborne object is a risk to the aircraft.
"Electronic situation awareness - it’s very important to understand what is really happening," Colombo said. "Sensors can be fooled by stupid things. Just imagine the glare of the sun. Imagine the classical plastic bag (blowing by). You recognize it, and you go on. Sensors do not have this kind of human intelligence. They see an obstacle coming in a very crazy pattern and they can freeze and not know what to do. They can react, creating a very dangerous situation that, for a human person, is basically nothing. We need to be sure the sensor system is always working properly in infinite situations in an urban environment. We need to test these systems forever, basically."
In addition to ensuring safety, noise mitigation will also be an issue. While UAM aircraft designs are nearly all electric vertical-takeoff-and-landing (eVTOL), the large number of propellers needed to transport people and their belongings results in quite a bit of noise. If hundreds of aircraft are crisscrossing Tokyo, Rome, Karachi, Los Angeles, or any other crowded major city, the already noisy landscape will have an additional cacophony of buzzing aircraft. Silent eVTOL flight isn't in the offing, but designers can utilize technology to make their UAM aircraft as quiet as possible.
"For instance, if you take an aircraft with propellers, actually a big part of the noise is coming from the tip of the propeller because they can rotate so fast that they can approach supersonic speeds and this creates a lot of noise," related Colombo. "So maybe you can have a smaller propeller adding more energy and so you know you need to design your aircraft in a very different way to have distributed propulsion that is not only safer because you have more motors, but it is also quieter, so the way you shape your propeller could be part of the noise reduction."
He continued, "Perceived noise can be adjusted; it is not something you must live with. We can simulate the noises perceived by people and identify which frequencies are the ones that irritate the ear. We can work on the entire structure in order to change these frequencies and mitigate or even eliminate them. So, the noise you end up with is something that you can tolerate. So, it is a very interesting and very complex environment, and it is not something you do only for UAM systems. Regulators are also setting noise reduction goals for commercial transportation, and they are working to reduce emissions by having more fuel-efficient, environmentally friendly aircraft. The latter is one of the key initiatives of the industry."
Colombo said that if the noise with UAM can be tackled to the point where the perceived noise experienced by people on the ground is acceptable enough, it may open an otherwise unused block of time to keep business running.
"If you live close to a big airport you probably know that at a certain time, in the evening, nothing is landing or taking off anymore," said Colombo. "So, the airport will be closed during the night and the main reason for that is actually noise. So if you have a new kind of aircraft that is as quiet as we are expecting from electric vehicles, well, maybe you can use these (time) slots to take off and land during the night and because our airports are very congested and this could be actually very, very, very, important in a world where we are thinking about a big rise in air transportation."
While megacities in China seem a natural fit for UAM, they are currently being built up using construction engineered with 21st century standards and road systems made to accommodate an increasingly mobile population. While Zunyi and Guiyang in China are seeing double-digit population growth annually, cities that have foundations in antiquity and wish to hold onto that history, like Rome, may not be experiencing huge population growth, but they are under the burden of incredibly congested roadways and could alleviate that with UAM.
Colombo, who himself resides in Italy, spoke about the unique challenges that are faced in Rome, which, while not a "megacity," has its roads choked with cars, bikes, and scooters.
"Why is Rome so congested? The answer is, Rome was designed 3,000 years ago," informed Colombo. "You have very narrow roads. You cannot just blow everything (up) and rebuild it. Every building in Rome is at least a 1,000 years (old). So, you build a very nice underground (train system), but if you dig five minutes, you hit (an ancient Roman site). You can use 3D space and look to the sky as a possible mobility area. It’s very interesting."
As humankind continues its worldwide migration from rural areas to cities, urban air mobility will likely play a growing role in moving those people around. To do so, UAM manufacturers have the difficult task of developing a whole new system of moving a small number of people or loads of cargo around a three-dimensional environment with numerous other aircraft. With smart design, tested technology, and oversight from regulators, we may be on the cusp on the UAM revolution, and it looks not only to be exciting, but safe as well.
About Paolo Colombo: Colombo was born in Italy in 1970 and joined the Air Force as student pilot in 1992 and, though his career took a different path, he is still regularly flying. From 1999 his passion for advanced technologies brought him to work with companies' managers and executives on emerging technologies in product engineering, rapid prototyping, additive manufacturing and engineering simulation. He joined ANSYS in 2010.