Helix and Zoerkler Develop Compact Electric Propulsion Unit for Next-Generation eVTOL Aircraft
BY Composights
Published: 29 Jun 2026
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Helix, a UK-based developer of high-performance electric propulsion systems, has partnered with Austrian transmission specialist Zoerkler to develop a compact electric propulsion unit (EPU) for next-generation electric vertical take-off and landing (eVTOL) aircraft.
The collaboration aims to deliver a new propulsion architecture that improves efficiency, reduces system size, and provides aircraft designers with greater flexibility for future advanced air mobility platforms.
The jointly developed EPU integrates Helix's high-power-density electric motor with Zoerkler's lightweight gearbox, producing a propulsion package that is approximately 50% smaller in diameter than a comparable direct-drive system while maintaining high torque output. The transmission operates at an efficiency of around 98%, allowing the motor to be significantly narrower and lighter than conventional direct-drive alternatives.
The first propulsion unit developed through the partnership weighs 32.2 kg and is designed to support multiple operating configurations. In lift applications, the system delivers more than 100 kW of power with torque of up to 1,600 Nm. When configured for cruise flight, it provides 250 kW of continuous output and peak power of 400 kW to accommodate high-demand operating conditions.
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According to the companies, the propulsion unit has an overall diameter of just 26 cm, enabling substantially smaller nacelles and lower aerodynamic drag. The compact design is expected to improve payload capacity and flight range while providing aircraft manufacturers with greater freedom in vehicle integration and layout.
The companies stated that the propulsion unit is intended to become the first member of a broader family of electric propulsion systems for advanced air mobility applications, supporting future aircraft with varying performance requirements.
Derek Jordanou-Bailey, Chief Engineer for Aerospace at Helix, said: This new EPU shows that when brought together, best-in-class motors and transmissions can unlock a far lighter and more compact solution than direct drive systems. By combining the world-leading power density of Helix motors with Zoerkler s lightweight and precise transmissions, this EPU provides advanced air mobility applications with a compact, low-mass solution that meets and even exceeds their range and payload requirements.
Karl Lagler, Head of R&D at Zoerkler, added: This collaboration demonstrates how combining advanced transmission technology with high-performance electric motors can redefine what is possible in eVTOL propulsion. By leveraging Zoerkler s expertise in lightweight, high-efficiency gear systems, we have enabled a significantly more compact and scalable EPU architecture without compromising performance. This solution opens up new possibilities for aircraft designers to optimise space, weight, and overall system efficiency in next-generation air mobility platforms.
The development reflects continued innovation in electric aircraft propulsion, where lightweight, compact, and highly efficient powertrain technologies are becoming essential for improving the performance, range, and commercial viability of future eVTOL aircraft.
Source: Helix | News
