David Ziegler
By David Ziegler

David Ziegler, vice president, Aerospace & Defense at Dassault Systèmes, leads the worldwide business and development of the company’s industry solution experiences based on the 3DEXPERIENCE platform. He held multiple positions in the aerospace industry, most recently at Paris Aéroports. Prior to Aéroports he spent 14 years with Airbus, based in both France and the U.S., holding positions in sales and business development.

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How software simulation can bring eVTOL air taxis one step closer to reality

The urban air mobility market represents tremendous opportunity for eVTOL developers. It also presents many challenges, including a number of very strict safety requirements from aviation authorities to fulfill. But meeting safety requirements alone isn’t sufficient to guarantee success in the air taxi market — there’s also the question of community acceptance.

Our research indicates a great potential user base for eVTOL air taxis, with one Dassault Systèmes and CITE Research survey finding that 43% of U.S. adults expect to be using personal air taxis by 2030. However, gaining support for low-flying aircraft in densely populated areas will hinge to a large extent on the noise levels of the aircraft. Yes, the elimination of an internal combustion or jet engine significantly reduces any vehicle’s decibel output, but the fact remains that the propellers needed to lift and propel any future air taxis will generate significant sound, both annoying those on the ground and necessitating hearing protection for the vehicle’s passengers.

Dassault Systèmes eVTOL simulation
Dassault Systèmes predicted noise levels for this concept vehicle using its high-fidelity Simulia PowerFLOW CFD solver. Dassault Systèmes Image

The truth is most aircraft were historically designed for good aerodynamic performance, and noise was something that was either ignored or mitigated as best as possible late in the design phase. But for eVTOLs to succeed, noise needs to be a core design consideration from the start. How do you account for noise, both inside the cabin and outside the aircraft, before you have a working prototype? The answer can be found in modern simulation software, which can account for the aeroacoustics produced by a digital model, allowing noise to be a design parameter early in the process. 

Traditional aviation designs, such as fixed-wing aircraft and helicopters, have decades of experience and expertise to make informed design decisions. But eVTOLs are uncharted territory, and designers don’t have the benefit of knowing what has worked, and what hasn’t worked, in the past. eVTOLs are somewhat more complex, with new challenges in aerodynamic and aeroacoustics domains. A trial-and-error approach when building physical prototypes is slow and expensive.

By using simulation software, designers can proactively understand how the aeroacoustics of air taxis and their rotors generate noise and how sound propagates to the cabin interior and the ground below. They can understand what blade designs offer the highest amount of lift at the lowest acoustic cost. They can virtually test whether two large rotors will create less noise than six smaller ones, then determine the most effective placement of these rotors on the aircraft structure.

By creating a complete virtual twin of the aircraft, and the urban and residential environments in which these aircraft will operate, eVTOL manufacturers can consider factors like noise when designing the architecture of the aircraft, and verify design choices along the way rather than waiting until the end. At any point in the development process, they can fly their virtual aircraft through virtual neighborhoods and cityscapes, hear what the virtual passengers are hearing, and subject them and their vehicle to virtual thunderstorms, unexpected wind shear and other environmental conditions. All of this and more can be done without leaving the ground. More importantly, it can be done without bending a single piece of sheet metal or running a single foot of electrical cable, saving countless dollars in prototyping costs.

Keep in mind, the noise produced by any vehicle is a function of the vehicle’s design, but also the way the vehicle is operated. The acoustics of aircraft flying through a canyon will be much different than flying over a flat body of water. In the three-dimensional urban landscape in which eVTOLs will operate, there are multiple trajectories between one skyport and another, and the building and objects on the ground will play a role in dictating which route produces the least noise. Weather conditions could play a role as well, making one route quieter than another on a rainy day, for instance. Simulating the environment in which eVTOLs will exist can give designers new insights into the requirements for the design.

Success in the eVTOL market will require manufacturers to solve numerous unique design challenges, and being first to market won’t be enough. Consumers will obviously demand that eVTOL services fulfill safety requirements while offering a competitive price, but as importantly, the overall experience needs to be seamless and delightful. An aircraft that offers a much quieter ride than its competitors is a big step toward achieving this goal, but everything from in-cabin entertainment to the chair armrests will need to be carefully considered as well. “Flying taxis” have been a fixture of pop-culture science fiction for decades, creating a level of expectation that will be a high bar to clear. The right simulation solutions can help designers succeed in all phases, and when a manufacturer finally solves this puzzle, there won’t be a trickle of customer demand — there will be a flood.

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