VIVAERO

A guide to connector selection for eVTOL aircraft

PEI Genesis reveals how electrical connector specification informs eVTOL design and performance.

The electric vertical take-off and landing (eVTOL) aircraft market is a high-growth sector, with Fortune Business Insights estimating it will grow from $1.4bn in 2025 to $17.4bn by 2034. Like conventional aircraft, a core component of eVTOL aircraft is the humble electrical connector. However, specific requirements for these can vary significantly compared with their traditional counterparts. Here Sean Fitall, European product manager at aviation connector specialist PEI-Genesis, explores the role of electrical connector selection in good eVTOL design programmes.

When specifying interconnects for aircraft systems the main considerations are voltage, current, size and weight.

At the heart of eVTOL aircraft performance is the need to manage high-voltage electrical power systems. As eVTOL are typically powered by advanced lithium-ion or solid-state batteries, they need connectors capable of handling large voltages and currents while minimising power loss and heat generation. 

Material selection...Higher voltage applications like those found on board eVTOL aircraft require high levels of insultation as well as careful design to mitigate discharges. For conventional aircraft, the primary voltage of systems is 270 VDC whereas for eVTOL platforms voltages tend to be between 450 V DC and 1,000 V DC, meaning insultation requirements for cables and connectors are much higher.

For higher current applications, accurate wire gauge selection is crucial as well as the use of high-temperature materials that can operate reliably under high current. Connectors on board traditional aircraft tend to handle currents below 100 A whereas those on board eVTOL aircraft often handle up to 1,000 A.

Both the voltage and current conditions on board eVTOL influence the materials used in connector assembly as any material specified must be able to handle the harsher conditions founds on board eVTOL compared with traditional aircraft. To make matters more challenging, they must do this while also being lightweight and not having unnecessarily large footprints that negatively impact the overall system architecture.

Take the MIL-DTL-38999 connector type commonly found on board aircraft systems, for example. They can be specified using materials including heavy brass, stainless steel, cadmium-plated aluminium, titanium, carbon fibre composites and lightweight polymers such as polyether ether ketone (PEEK) or polyetherimide (PEI). 

On board conventional aircraft, stainless steel and cadmium-plated aluminium are traditionally used as they meet all the design requirements while being cost-effective, robust and reliable. 

However, inside eVTOL aircraft, carbon fibre composites are preferred due to more stringent weight requirements as they weigh five to ten times less than equivalent stainless steel assemblies. PEEK and PEI offer comparable weight savings to carbon fibre when compared with traditional metal assemblies and are also often used in connector assemblies for eVTOL applications.

Furthermore, multi-functional connectors can be used to consolidate power and signal paths into a single interconnect module to streamline design while simultaneously reducing excess weight.

Durability and reliability...As electrical components on board eVTOL can be exposed to harsh environmental conditions, including moisture, dust, UV radiation and electromagnetic interference (EMI). Therefore, connectors for these applications should be engineered with high levels of ingress protection, generally IP67 and above, to ensure they remain free of environmental contaminants. 

Vibration and shock resistance are also key considerations for connectors in eVTOL applications. Systems are exposed to ongoing mechanical stress of varying degrees during take-off, continuous flight and landing and the aircraft must maintain structural integrity throughout, including uninterrupted connectivity. Therefore, ruggedised locking mechanisms and vibration dampers should be incorporated into interconnect designs to ensure connectors remain securely in place throughout the aircraft’s operational lifecycle.

Shielding should also be built in to the system to protect against EMI and wider electrical noise, which could otherwise cause malfunctions in navigation, communication and control systems if left unaddressed. Therefore, designers should opt for connectors with advanced shielding options in order to ensure ongoing operational reliability for eVTOL aircraft.

As eVTOL aircraft use continues to soar over the next decade, it is critical that designers and manufacturers properly consider connector specification early and consult with a specialist supplier who understands both the available options and the operational requirements and restrictions. 

For example, all on board electrical systems must adhere to aerospace standards like RTCA DO-160 and MIL-STD that dictate requirements for factors like arc resistance, fire retardancy and fail-safe mechanisms to prevent electrical failures. This is much easier when working with someone who is fluent in complying with regulations like these as well as how to build this into good system design.

Only by following this approach can it be ensured that the design and build phases are completed as efficiently as possible and aircraft operate at maximum performance throughout their lifecycles.

www.peigenesis.com