The key technologies that power eVTOLs: How Do They Work?

eVTOLs and the technologies behind their development

eVTOL (electric Vertical Take-Off and Landing) aircraft are a new category of aerial vehicles that can take off, hover, and land vertically, offering a new approach to urban air mobility.
eVTOL aircraft use electric propulsion and vertical lift technology to take off, land, and fly without needing a runway. The key technologies that power eVTOLs, include electric propulsion, battery systems, and autonomous flight capabilities

The key technologies that power eVTOLs

• Propulsion Systems: eVTOLs primarily use electric motors for propulsion, which are more efficient and environmentally friendly compared to traditional combustion engines. Different configurations include multicopter, lift + cruise, and tiltrotor designs.
• Battery Technology: The advancement of battery technology is crucial for eVTOLs. Current developments focus on increasing energy density and reducing weight to improve flight duration and efficiency.
• Autonomous Systems: Many eVTOLs are designed to be highly automated, using advanced avionics and artificial intelligence for navigation, obstacle avoidance, and autonomous flight, potentially reducing the need for pilots.
• Safety Features: Safety is a primary concern in eVTOL design, with redundant systems, distributed electric propulsion (DEP), and emergency landing capabilities to ensure reliability.

Key technologies that power eVTOLs: Propulsion Systems

The heart, the electric propulsion system:

The heart of any eVTOL is its propulsion system. It represents a significant leap forward in aviation technology, prioritizing efficiency, sustainability, and adaptability. Unlike traditional aircraft that rely on combustion engines, eVTOLs utilize electric motors for propulsion, which are both quieter and more environmentally friendly.

Most current designs rely on multiple electric motors, each driving a rotor or propeller. This configuration provides the necessary lift for vertical takeoff and landing (VTOL). The number and arrangement of these motors vary widely between different eVTOL concepts. Some designs opt for a distributed propulsion system with multiple smaller motors, enhancing redundancy and safety. Others utilize larger, more powerful motors for increased efficiency.

Distributed electric propulsion (DEP) system:

The design of eVTOL propulsion systems can vary widely, but it could be described into four main categories:
• multicopter configurations, where multiple fixed rotors are used
• tiltrotor or lift + cruise designs that combine vertical lift and horizontal propulsion mechanisms
• Ducted Vector Trust

One of the critical advantages of electric propulsion in eVTOLs is the distributed electric propulsion (DEP) system. DEP distributes power across multiple smaller motors rather than relying on a single large engine, which enhances both efficiency and safety. In case of a motor failure, the aircraft can continue to operate safely using the remaining motors. Additionally, the electric nature of these systems allows for more precise control, enabling smoother and more stable flight operations. However, the effectiveness of these propulsion systems is heavily dependent on advances in battery technology, as the energy density and weight of batteries directly impact the aircraft’s range and performance. As battery technology continues to evolve, so will the capabilities of eVTOL propulsion systems, paving the way for more advanced and versatile urban air mobility solutions.

Key technologies that power eVTOLs: Battery Technology

The energy density is the key:

Among all the technologies that power eVTOLs advances in battery technology are the essential key to the development of the aircraft.
The energy density, power output, and charging speed of batteries directly influence an eVTOL’s range, payload capacity, and overall operational efficiency. Currently, lithium-ion batteries are the dominant choice, but they still have limitations in terms of energy density and charging time.

For eVTOLs to be practical for widespread use, especially in urban air mobility applications, they require batteries that can deliver high energy density while remaining lightweight. This balance is crucial because heavier batteries reduce the aircraft’s range and limit its ability to carry passengers or cargo. To realize the full potential of eVTOL transportation, significant breakthroughs in battery technology are essential.

The usable energy density of rechargeable batteries for eVTOLs varies depending on the battery pack design, system efficiency, and backup energy. Uber’s 2016 report, “Fast-Forwarding to a Future of On-Demand Urban Air Transportation,” outlined a minimum range of 100 miles for eVTOL vehicles. Achieving this requires a battery with a specific energy of approximately 230 Wh/kg. However, considering system inefficiencies and battery pack design, the actual usable energy is reduced by 40-50%. Consequently, the battery pack’s specific energy must be substantially higher, around 380-460 Wh/kg, to meet the necessary range. Given current battery technology, eVTOLs are limited to short-range flights of less than 50 kilometers.

The future of eVTOL development hinges on battery advancements. While lithium-ion batteries have dominated, emerging technologies like solid-state, sodium-ion, and fuel cells offer diverse solutions. These alternatives cater to different operational requirements, such as extended range, heavy payloads, and rapid charging. By providing unique performance characteristics, these new battery types are essential for the widespread adoption of eVTOLs.

Key technologies that power eVTOLs: Autonomous Systems

A machine that can operate independently:

Autonomous systems in eVTOL (electric Vertical Take-Off and Landing) aircraft are advanced technologies that enable the aircraft to operate with minimal or no human intervention. These systems are critical for enhancing safety, efficiency, and scalability in urban air mobility. Here are the key components and functions of autonomous systems in eVTOLs:

• Autonomous Flight Control: This system allows the eVTOL to manage all aspects of flight, from takeoff to landing, without requiring manual input from a pilot. It uses advanced algorithms to control the aircraft’s altitude, speed, and trajectory, ensuring stable and precise flight. These are the core of autonomous operation. They include sensors to perceive the environment, computer vision algorithms to process data, and advanced flight control algorithms to make real-time decisions. These systems are designed to handle complex maneuvers, such as transitioning from vertical to horizontal flight, and can adapt to changing conditions in real-time.
• Traffic Management Systems: To safely operate in dense urban environments, eVTOLs need advanced traffic management systems. These systems include communication and coordination with other aircraft, ground control, and air traffic control.
• Obstacle Detection and Avoidance: A critical component of eVTOL autonomy is the ability to detect and avoid obstacles in the flight path. This is achieved through a combination of sensors, such as LIDAR, radar, and cameras, which provide real-time data about the surrounding environment. The aircraft’s onboard systems can process this data to identify potential hazards, such as other aircraft, buildings, or birds, and make necessary adjustments to the flight path to avoid collisions.
• Landing and Takeoff Systems: Autonomous landing and takeoff systems are essential for safe and efficient operations. These systems include precision landing capabilities, vertiport integration, and automated docking.
• Redundancy and Fail-Safe Systems: To ensure safety, eVTOLs are equipped with redundant autonomous systems. If one system fails, another can take over, preventing catastrophic failures. Additionally, fail-safe mechanisms are in place to guide the aircraft to a safe landing location in case of emergencies, such as battery failure or loss of communication with ground control.
• Communication Systems: Autonomous eVTOLs require reliable communication links to interact with ground control stations, other aircraft, and air traffic management systems. These communication systems ensure that the eVTOL can receive real-time updates about airspace conditions, weather, and other critical factors that may affect the flight.
• Passenger Interaction: In cases where eVTOLs are designed to carry passengers, autonomous systems may include user interfaces that allow passengers to interact with the aircraft. Such as selecting a destination or initiating an emergency landing. These interfaces are typically simple and intuitive, designed to provide a seamless and stress-free experience for passengers.

Overall, autonomous systems in eVTOLs are designed to create a safe, efficient, and reliable mode of transportation that can operate in complex urban environments with minimal human oversight. These systems are integral to the vision of urban air mobility, where eVTOLs can operate at scale, reducing the need for human pilots and making air travel more accessible to the public.

Key technologies that power eVTOLs: Safety Features

No single points of failure:

Safety is a key concern in the design and operation of electric vertical take-off and landing (eVTOL) aircraft, and these vehicles are equipped with a number of advanced safety features to ensure reliable and safe flights.

• DEP: One of the key safety features of eVTOLs is the use of distributed electric propulsion (DEP). DEP involves distributing multiple electric motors across the aircraft, reducing reliance on a single propulsion system. This redundancy means that if one or more engines fail, the aircraft can still fly and land safely using the remaining operational engines. This feature significantly improves the reliability of eVTOLs, making them more resilient to potential technical failures during flight.
• Autonomous Systems: Another critical safety feature is the integration of advanced autonomous systems designed to handle emergency situations. These systems can detect anomalies in real time, such as loss of power, system malfunctions or unexpected obstacles, and respond accordingly. For example, if the eVTOL encounters a critical issue, the autonomous system can take over and perform an emergency landing in a pre-designated safe area. Additionally, collision avoidance systems using sensors such as LIDAR, radar, and cameras are employed to detect and avoid obstacles, including other aircraft, buildings, and birds, further reducing the risk of accidents.
• Emergency: Additionally, eVTOLs are often equipped with parachute recovery systems or similar emergency descent mechanisms that can be activated if the aircraft suffers a catastrophic failure at altitude. These systems provide an additional layer of safety, ensuring that the aircraft can descend safely even if other systems fail.

The combination of these safety features makes eVTOLs highly reliable and positions them as a viable and safe option for the future of urban air mobility.

Future Outlook

The eVTOL industry is rapidly evolving, with numerous companies investing in research and development. While widespread adoption is still in the future, the technology holds promise for revolutionizing air transportation.