Finding the Right Interconnects for eVTOL Aircraft Applications

­Business is returning to normal for the aerospace industry, and manufacturers can start investing in future aircraft development. One area attracting both start-ups and established aerospace brands is electrically powered vertical take-off and landing (eVTOL) aircraft.

In 2020, the global eVTOL aircraft market was worth only $1.1 billion. However, analysts expect it to grow rapidly in the next years to reach $23.2 billion in annual revenues by 2028 (Fortune Business Insights).

Potential eVTOL use cases

There are many applications for eVTOL vehicles in urban air mobility (UAM). In the next three to four years, passengers will be able to fly across urban areas like they ride conventional taxis. eVTOL aircraft can be used to transport passengers between airports and city centers, with landing pads installed on tall buildings. They will be more cost-effective, environmentally friendly, quieter, and safer than helicopters. Many passenger helicopter operators are already looking to extend their offering to eVTOL air taxi services.

eVTOL aircraft can also help make time-sensitive medical deliveries in remote areas. This could significantly simplify the transport of essential laboratory samples, blood products, chemotherapy drugs, and medicines. Swarms of smaller eVTOLs can replace trucks for delivering online shopping orders, supermarket groceries, or other parcels. 

The technology will also enhance disaster relief, especially in remote areas that road vehicles can’t access. eVTOLs can reach places that have been cut off by floods, forest fires, or landslides. They can get food and medical supplies quicker to those in need and help speed up evacuation efforts.

The technology could also be a game-changer in agriculture, replacing conventional tractors to enable precision planting and harvesting. eVTOLs could make it easier to target a specific crop, instead of spraying large areas with water, fertilizers, or pesticides. This would reduce waste and minimize environmental damage.

Connector considerations for eVTOL 

For eVTOL applications to succeed, designers must pay attention when choosing interconnects. They have to provide the power delivery and data communications tasks in the applications they are used in. Aviation designers need the best components to enhance their UAM designs and differentiate their products in a highly competitive sector.

As with any airborne application, size, weight, and power (SWaP) will be key. They determine how far the aircraft can fly before requiring recharging. In conventional aircraft, weight is optimized for greater range. Short-haul flights use about one-third of the overall fuel mass already during take-off. This is reduced to 15-20% for longer flights. In battery-powered eVTOLs, however, the weight remains constant over the entire flight. The aircraft carries fewer passengers and lighter cargo. The operating distances are also significantly shorter. This translates to very different design criteria. Another major difference between eVTOL and conventional aircraft is that eVTOL powertrains operate on considerably higher voltages. 

When selecting electrical connectors for eVTOL designs, aviation engineers have a lot to consider. In addition to the SWaP demands, the connectors must manage the large voltages required for peak output propulsion. They also need to address the high bandwidth needs of control, diagnostic, and in-flight entertainment systems.

Here are some of the main challenges engineers need to bear in mind:

1. The mission-critical nature of aerospace applications makes high-reliability electrical connections fundamental for all designs. The safety of passengers and anyone near the aircraft while it is in flight has to be assured. That’s why the connectors must have an extended operating life with no risk of failure. 
2. eVTOL hardware will be exposed to difficult conditions during take-off, flight, and landing. This requires robust construction. Unlike the electrical connectors used in consumer electronics, aviation-grade connectors must withstand heavy shocks and ongoing vibrations. 
3. Size is vital. eVTOL aircraft are small, but they have to integrate a lot of functionality. This means there is extremely limited space for housing electronic hardware. That’s why connectors need to combine superior performance and functionality with small dimensions. 
4. To optimize space, connectors should offer both power and data functionality. Multifunctional connectors take up less room on PCBs and require less cabling, reducing the aircraft’s weight. This is important because lighter construction extends the range of the aircraft.
5. Electromagnetic interference (EMI) is also a crucial consideration. Engineers need to determine the level of shielding to attain acceptable electromagnetic compatibility (EMC). This ensures that power delivered by interconnects does not interfere with vital circuitry or that external sources don’t impact the signal integrity of data passing through interconnects.
6. In the ideal scenario, these all-electric aircraft completely replace the hydraulic fluid with electrical power. However, this won’t always be possible. That’s why engineers must address the effect of potential hydraulic fluid leaks on electrical circuits. This is done by choosing connectors that offer adequate protection against liquid ingress. 
7. Finally, as eVTOLs spend time at relatively high altitudes, the connectors need to have strong insulation properties to prevent discharge. 

Optimized solutions

Harwin has served the aerospace industry for decades and is working on several eVTOL projects. One of the products currently sampled and specified for eVTOL designs is 1.25mm-pitch Gecko series of high-reliability (Hi-Rel) connectors. The compact devices feature lightweight and highly durable plastic enclosures that are designed to enhance SWaP scenarios. The series also offers right-angle orientations that can make it easier to accommodate the accompanying cabling. Featuring Beryllium-Copper contacts with a proprietary 4-finger design, the connectors can maintain interconnect integrity in extreme conditions. This includes handling shocks of up to 50G and 20G vibrations. Backshells can be integrated into the connectors, and they come supplied with braided cabling to mitigate the effects of EMI.

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Figure 2: Example of one of Harwin’s Gecko Mix-Tek connectors

When both power and data need to be taken care of via single connectors to save space, Harwin offers the Gecko Mix-Tek family. The connectors are available in a range of different layouts, with the latest versions featuring up to 26 data contacts and 8 power contacts capable of carrying 10A currents. 

Harwin’s experts also provide in-depth engineering support to help customers get the most out of the components they choose. Additionally, customers can benefit from short lead times when ordering products through its distribution channels.

Conclusion

eVTOL represents a new era in air travel. The technology will become a highly lucrative and vibrant part of the aerospace sector over the next decades. To allow the market to deliver on its potential, ongoing engineering innovation is needed to fulfill the unique requirements of eVTOL aircraft designs. This covers all components used, including the interconnects, which will need to deliver a combination of performance, compactness, and reliability.

Harwin