How Simulation Accelerates the Development of eVTOL Aircraft for Taxi Services

Unlocking the Potential of eVTOL Aircraft for Taxi Services: Advancing On-Demand Transportation Safely and Efficiently

The world is rapidly advancing towards an integrated and accessible on-demand transportation network. Electric Vertical Takeoff and Landing (eVTOL) vehicles have emerged as the ideal solution for the near future, offering faster and more efficient travel options. However, ensuring the safety and reliability of these innovative aircraft is paramount. This blog explores how simulation models play a vital role in evaluating eVTOL designs, identifying potential issues early, and paving the way for reliable and sustainable air mobility solutions.

Understanding the Aging Challenges of Li-ion Batteries in eVTOL Aircraft

Limited durability of lithium-ion batteries poses a significant obstacle in developing long-lasting eVTOL aircraft. Lithium-ion batteries experience capacity decline, increased impedance, and decreased power output over time. A deep understanding of battery aging is crucial to predict lifespan accurately and optimize battery management systems (BMS) for longevity and reliability. Let’s learn how addressing these challenges is vital for ensuring the success of eVTOL technology.

How Simulation Plays a Role in Electric Aircraft Designs

Simulation platforms such as GT-SUITE offer practical, efficient, and reliable solutions for studying various aspects of electric aircraft design. This comprehensive simulation suite allows for in-depth exploration of critical areas such as aerodynamics, flight control, mission definition, propulsion, and battery pack systems (see Figure 1 below). With GT-SUITE, engineers can comprehensively assess and optimize each subsystem, ensuring optimal performance and safety throughout the eVTOL aircraft’s operation. Check out our blog on eVTOL design and this study co-authored with Advanced Rotorcraft Technology on a comprehensive simulation for eVTOL aircraft. 

Figure 1. Integrated eVTOL model

Real-World Aging Scenarios: Using Simulation for Battery Degradation Prediction

To ensure the economic viability of an eVTOL taxi service, maximizing the number of trips during peak traffic hours is crucial. However, it is essential to consider the limitations imposed by the battery pack. In a recent case study, we discussed the evolution of an eVTOL’s range over a span of four years, exploring a scenario where ten trips were scheduled each weekday between 6 AM and 10 AM in the morning, and from 4 PM to 8 PM in the evening. To maintain optimal performance, a 10-minute recharge was performed between each trip, with a full recharge between the morning and evening shifts. The proposed aircraft utilization was inspired by the UberAir Vehicle Requirements and Mission study. The vehicle requirements and mission have been developed through extensive analyses of current and predicted demand, understanding the capabilities of enabling technologies, and focusing on creating the optimal rider experience. Extensive analyses of current and predicted demand, understanding the capabilities of these technologies, and focusing on creating the optimal rider experience. 

By leveraging the advanced capabilities of another simulation platform GT-AutoLion, we were able to extrapolate the battery power demand during a representative mission flight from GT-SUITE and simulate the long-term degradation of the battery pack in a real-world scenario. In Figure 2, the evolution of the state of charge (SOC) of the eVTOL battery pack during the morning shift is plotted. 

Figure 2. State of charge evolution during the morning shift

The focus of this study was the ability to model the aging mechanism using GT-AutoLion. GT-AutoLion offers solutions that empower engineers to leverage cycle and calendar aging data, extracting valuable insights into battery degradation within more realistic scenarios. GT-AutoLion’s physics-based and postdictive degradation models can be calibrated to align with this data and subsequently applied to predict the aging behavior of Li-ion cells in various applications. These applications include li-plating, active material isolation, cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) layer growth and cracking. These can all be modeled and investigated as aging mechanisms in Gamma Technologies’ software (see Figure 3). 

Figure 3. Calendar and cycle aging data used in GT-AutoLion aging models

The GT-AutoLion aging simulation generates an external file (.cellstate) capturing the Li-ion cell’s state at each cycle during the aging process. Each cycle represents a mission flight of the eVTOL aircraft. This external file serves as valuable input for the system-level models, enabling accurate predictions of how the aged battery will impact the product performance (see Figure 4).  

Figure 4. Simulation workflow

By harnessing the power of this invaluable tool, we were able to project the anticipated range of the battery pack over a four-year operational period (see Figure 5).

Figure 5. Range evolution for 4 years operation

Such insights provide a comprehensive understanding of the technology, aiding both technical exploration, and supporting the business development of the latest eVTOL advancements. 

With the ability to simulate and predict battery performance and aging, operators of eVTOL taxi services can make informed decisions about their operations, keeping an eye on profitability while maintaining reliable and sustainable service. By accurately estimating the range evolution over the course of four years, they can strategize the optimal scheduling of trips, maximizing efficiency during peak traffic hours, and mitigating the impact of battery pack limitations. 

Learn More About our eVTOL Simulation Solutions 

The future of on-demand transportation is bright with eVTOL vehicles leading the way. Through the use of cutting-edge simulation models and advanced battery management solutions like GT-SUITE and GT-AutoLion, the safety, reliability, and performance of eVTOL aircraft is elevated to new heights. Embracing innovation and overcoming obstacles, the sky’s the limit for this exciting and sustainable mode of transportation! 

Watch this great video case study of coupling GT-SUITE and Advanced Rotorcraft Technology’s FLIGHTLAB simulation capabilities to provide an easy-to-use, holistic solution for simulation-supported system design during the early design stages of eVTOLs.   

If you’d like to learn more about how GT-SUITE and GT-AutoLion are used to solve eVTOL simulation challenges, contact us!