The A&D industry is experiencing innovation on a scale we have never seen before, perhaps most evident in the urban air mobility market.
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Written by: Dale Tutt, Vice President of Aerospace and Defense Industry, Siemens Digital Industries Software
The A&D industry is experiencing innovation on a scale we have never seen before. This innovation is perhaps most evident in the urban air mobility (UAM) market. Have you seen the imagination and creativity going into these aircraft? In fact, there is so much activity, UAM is splintering off into a subsegments that include winged eVTOLs, wingless eVTOLs, single-person eVTOLs and many more.
What is truly fascinating is that we are not only seeing startups enter the UAM market, but also established commercial aircraft OEMs are entering the fray. And lately, we have seen major automobile OEMs getting in, as well.
Regardless of eVTOL design or shape, one thing is for certain: OEMs will need the advantages of a digitalized environment for greater efficiencies, faster time to market and significant cost savings in all phases of product development. This can be achieved by introducing a digital twin and implementing the necessary digital threads.
Enter the Comprehensive Digital Twin
UAM platforms represent unique challenges. Design and engineering teams need answers to multi-domain solutions that require complex platform trade-offs. Placing emphasis in the wrong area or overlooking a critical aspect could sacrifice performance or jeopardize compliance. How do teams address these types of challenges?
The answer is a multi-disciplinary digital twin, which is a virtual representation of a physical product or process to understand and predict the actions of the physical counterpart. A digital twin can capture performance characteristics throughout the product lifecycle to simulate, predict and optimize—delivering “fly before you build” insight prior to investing in physical prototypes or committing to manufacturing.
A closed-loop digital twin gives teams critical data on how product attributes and domains perform as one interconnected structure. There is more sharing of critical data across domains or more integration of technologies and as a result, there is a greater understanding among all teams. With the availability of this data, individuals can focus on the interaction of their specialized disciplines and, with the time saved, they can explore optimizing discrete functions—vitally important when talking about aircraft with electrical motors, weight limitations and other design trade-offs to consider.
The Importance of Digital Threads
A digital thread weaves processes and relevant data together. A thread can be thought of as a collection of solutions, software and best practices digitalized to provide visibility, automation and traceability within a particular domain—connecting to other digitalized domains. Digital thread-based solutions enable multi-disciplinary processes and weave relevant data together to present a full view of product, production and process in an actionable manner.
The great thing about digital threads is they allow A&D teams to take complexity head on, allowing for greater productivity and innovation.
What is a Digitally Transformed Work Environment?
It is one thing to talk about the merits of digitalization; it is quite another to actually demonstrate how a domain can benefit from a digital twin and thread. To demonstrate the importance of digitalization in the design and manufacture of an eVTOL, let’s take a look at how it can impact a few of the common design disciplines/domains. Keep in mind the disciplines mentioned below are done in parallel; this is not a serial process, which is a huge advantage in a digitalized workplace.
Aerodynamic Design
With UAM vehicles, propulsion type and configuration impact aerodynamics. There are so many different configurations to consider: from tiltrotors or tiltwings, to the number of rotors for vertical lift, to pusher props for the thrust. Because of the electric nature of an eVTOL, teams need to be conscious of how to manage weight, performance, speed and efficiency in order to manage battery capacity. A key to all of this is simulating different flight phases, from hovering low to the ground to cruising at a higher altitude at high speeds. If a vehicle flies low to the ground, it has to manage wind and turbulence in a totally different flight regime.
Computational fluid dynamics (Figure 1) and wind tunnel testing can be used together in a digital twin environment. Within this scenario, teams are able to do multidisciplinary design, analysis and optimization. With this type of tool integration, UAM companies are more likely to optimize eVTOL performance much faster by discovering design implications earlier in the simulation phase.
Power Density and Thermal Management
A comprehensive digital twin is also critical when it comes to simulating physical phenomena to capture the integrated thermal balance of a UAM aircraft.
Teams need to understand the structural, thermal and electromagnetic behavior at the component level, up to a fully integrated aircraft level. At this level, a virtually integrated aircraft model can be created, which gives teams insight on how the different systems interact with one another.
That’s one example of the digital twin; what about the digital thread in this domain?
A digital thread in this domain can manage the processes with the many different teams involved. A digital thread can document a diverse set of processes from early requirements to verification. When used as part of verification management, a digital thread allows teams to couple requirements and other information around test benches. Teams can take data and connect it to simulations already completed, which in turn keeps all requirements updated as the process moves forward.
Electrical, Electronic and Mechanical Software Integration
Increasingly, the more sophisticated eVTOL platform developers are taking a multi-disciplinary systems approach to platform development. For the best possible platform, mechanical and electrical systems are being developed in concert with knowledge of how innovative ideas in one discipline impact the implementation objectives of the other. Further, model-based descriptions of the functions required from both disciplines are being brought together and assessed in tandem. All of this is made possible via the digital twin.
A digitalized environment allows teams to understand how electrical architecture impacts performance earlier in the process. By extending the digital thread, integrating the tools that perform certification and connecting with the platform’s electrical and mechanical digital twin, teams know how implementation changes impact regulatory compliance.
The challenges that many UAM companies face today are quite novel and often unique. With the many new tools and solutions now available, along with the need to innovate, companies are embracing the digital transformation as a way to operate and compete more efficiently.
Structural Design Using Composites and Additive Manufacturing
eVTOL designs have all the same challenges as conventional aerostructures: they need to be lightweight with high strength-to-weight ratios. They have the same issues with vibration and noise. The one aspect that makes UAM vehicles different is the expectation that the production rate will be much higher. UAM companies have to think about incorporating more automation and how to get higher production rates—and at the same time utilize advanced material technologies.
One of the best ways to address a higher production rate and use the latest in composite technologies is to introduce agile product development.
Introducing Agile Product Development
When we talk about agile product development it’s more than people, tools and processes. It is about having a digital backbone that ties everything together (Figure 2). Agile product development is based on a comprehensive digital twin for simulation models, 3D CAD and additive manufacturing, to name just a few possibilities. Agile is a continuous, iterative approach that builds verification, validation and testing of the product and manufacturing into the entire development process. Agile is about breaking a program down into sprints, and within each sprint teams verify, validate and test until the goals of each predetermined “sprint” are met.
A sprint breaks a program down into manageable “chunks” so that teams can focus on completing one aspect of the program before moving to the next (Figure 3). The best thing about sprints is that teams can focus on short-term goals that meet the long-term goals of the program. When looking at an eVTOL in a mid-stage, sprint teams are probably looking at designing and perfecting structural integrity, aerodynamics and propulsion. As they move through each sprint, they do more simulation-driven design. And what if there is a change? It is easy to make changes because all the data is connected, and teams can draw upon previous sprints.
Let’s not forget certification. Certification is likely to be one of the most expensive aspects of any UAM program due to the revolutionary design of these vehicles where there is no historical data or certification guidelines from the FAA and other governing bodies. A sprint with active feedback loops can serve as an invaluable tool in this phase—and remember, being part of the digital thread means all kinds of data is available with full traceability to accelerate the process.
The idea of having a digital thread—managing and sharing data from early product requirements to simulation or test, and ultimately to manufacturing—is in many respects a means to faster compliance. With the digital thread, companies have a trail of information so teams can audit themselves, giving them confidence that it is time to certify. Without that digital thread, companies are at risk of their programs hitting a brick wall when it comes time for the certification process.
Conclusion
Siemens is helping UAM companies and their partners with their digital transformation through Xcelerator. The Siemens Xcelerator is a portfolio of software, services and an application development platform that helps teams move along—at their own pace—as they embark on their digital journey. Xcelerator encompasses our comprehensive digital twin and digital threads and delivers a robust understanding of technical data throughout the entire eVTOL program from engineering to manufacturing to sustainment.
UAM is quickly becoming a tight and highly competitive market. There is no question that only the strong will survive; the ones with the stamina, perseverance and insight that only a digitalized workplace can offer.
Learn more at Siemens with Urban Air Mobility is Seeing Significant Progress, Is It Time to Climb Aboard? Or download the eBook “eVTOL Design and Engineering: It’s Time to Talk.”
