The Future of eVTOL and Interconnect in Flight

By Scott Miller, Director of Product Management, Cinch Connectivity Solutions

What is eVTOL and why could it work?

When it comes to getting from one place to another, current modes of transportation cover almost all environments, whether by land, sea, or air. Despite each of these vectors having been conquered, numerous emerging technologies are providing new options. One such method of transportation called eVTOL is taking inspiration from quadcopter drone technologies, which show extraordinary amounts of freedom, safety, and potential for automation.

The term eVTOL stands for electric vertical take-off and landing vehicle which, as the name suggests, can fly like common commercial drones, being able to take off and land without requiring long airstrips. While drones typically have blades affixed to motors pointing directly upward, more modern eVTOLs can take advantage of movable engines that allow for more forward thrust to be generated, thereby improving efficiency.

Compared to helicopters, which are notoriously difficult to pilot, such vehicles are far easier to manage due to simplified controls. Additionally, the vast amount of software and hardware already developed to create autonomous drones means that eVTOLs are ripe for deploying autonomous flight systems, thus eliminating pilot error.

As most airspace above urban zones is virtually unused, eVTOLs could move around at high speed, significantly reducing transportation times between locations. Thus, eVTOLs could be used to ferry people and cargo between locations in urban environments, reducing dependency on roads, and making highways more suitable for transportation of heavy goods.

Increasing the traffic capacity of roads and rail can be achieved with bridges and tunnels, but the massive infrastructure cost makes such projects hard to justify, whereas eVTOLs would merely need landing pads and charging stations. Not only does this reduce the cost to the taxpayer, but it can also help to reduce maintenance charges if pedestrians can utilize eVTOLs as roads would experience less traffic.

What challenges do eVTOLs face?

Despite all the advantages that eVTOLs present, they are still more of a concept than an actual solution that can be deployed in a commercial environment, and this reality comes down to numerous challenges.

The first, and arguably the most important factor, is weight. Because they are entirely electric, they must carry batteries, which are incredibly heavy. Compared to fossil fuels, batteries have far less energy density, meaning that a battery with the same energy capability as a fuel tank using gasoline would be significantly heavier. For comparison, the energy density of gasoline is 47.5MJ/kg compared to lithium-ion batteries at 0.3MJ/kg.

Due to the need for heavy batteries, the rest of the vehicle needs to be made as light as possible. While this can be achieved with the use of modern materials, such as carbon fiber, this comes at an added price and design complexity.

If eVTOLs become autonomous, then communication between each eVTOL will be essential due to the severity of possible collisions. eVTOLs will need to be able to see the flight path of all other vehicles and plot a safe route accordingly. Such a network would need to be able to handle vast amounts of data in real-time with significantly reduced latency.

At a minimum, an eVTOL network would need to work on top of a 5G network, utilising edge computing to have data immediately routed to other vehicles (i.e., not pass through ISPs). However, the integration of cellular communication systems and on-board artificial intelligence for autonomous flight introduces additional systems and components, which further increase weight and reduce the energy available to the craft for flight.

How do connectors and cables come into the picture?

In the design of eVTOLs, cables and connectors could be argued to be one of the singular most important design decisions that can be made, and when exploring each aspect, their importance is quickly realized.

Starting with power, as eVTOLs are entirely based on electricity, electrical stress can be extremely high with both high voltages and high currents being present. This means that any cable and connector used to deliver power from the batteries to the motors needs to be able to handle such power levels and have sufficient insulation to provide adequate protection.

Regardless of whether a high voltage or current is opted for, the final cable and connector choice must reduce weight as much as possible. Any extra weight in an eVTOL will increase the difficulty faced with take-off and limit its range.

As such, engineers designing eVTOLs need to consider solutions commonly found in aviation platforms, including aluminum cables. However, such choices significantly increase the cost of a design, thus hindering its economic viability.

Such connectors need to handle many mating cycles and must operate safely in extended temperature ranges while retaining a high IP rating to prevent damage during poor weather conditions. Considering that eVTOLs would likely be in cities such as Dubai, poor weather conditions could include sandstorms, extreme temperature changes, sudden torrential rain, and high winds.

Finally, as all these connectors and cables are being used in an environment subjected to shock and vibration generated by motors and landing/take-off, any connector used needs to be able to resist accidental disconnects over extended use. As such, simple screw terminals and/or clips will unlikely be sufficient, requiring the need for locking nuts, press-fit connections, and unique mating mechanisms.

How can RF connectors help power the future of eVTOLs?

The wide range of RF connectors offer solutions for frequencies up to 110GHz, making them ideal for all aviation tracking systems including ADS-B and Pilot Aware, and can be used with cellular systems, including 4G, 5G, and mmWave bands of 5G.

For designs that require communication speeds beyond the capabilities of copper, a range of optical connectors can help engineers achieve extremely high inter-device speeds across the entire eVTOL and do so at significantly reduced weight due to the use of tiny fiber-option cables. Such cables are also immune to electromagnetic interference, making them far safer for use in autonomous environments where sensor data cannot be compromised.

Not all connectors can be replaced with RF or fiber optics. For such applications, a range of micro-D connectors become invaluable. Their design allows for either shielded or unshielded cables to be used, and their specific D shape makes them polarized. Due to their extremely small size, they are significantly lighter compared to larger standard D-Sub connectors, while still offering all the same performance in the harshest environments.

Conclusion

While there is a lot of hype surrounding eVTOLs, they are still in their infancy, and any systems that currently exist are more of a concept than an actual viable design that could be supported through an economical model. The extreme technical challenges faced by eVTOLs along with endless amounts of legislation presents numerous roadblocks to engineers when trying to get such ideas to take off. However, there is growing confidence within the industry that the necessary infrastructure can be built and that technological roadblocks, such as battery density, will be overcome.