Toulouse, June 10, 2025 – At the 55th International Paris Air Show, Ascendance, a European pioneer in
decarbonized aviation, announced the launch of the STERNA Hybrid Pack, its proprietary
hybrid-electric propulsion system. This modular solution natively integrates a propulsion battery
designed specifically for hybrid-electric aviation, an energy management system, and an electrical
distribution unit. The system is engineered to combine performance, energy efficiency, and compliance
with stringent aviation certification requirements.
To develop this high-performance battery, Ascendance partnered with EXOES, a leading French
specialist in thermal systems and batteries for mobility.
This strategic partnership is based on a shared vision to accelerate the industrialization of certifiable,
hybrid-electric propulsion solutions manufactured in France that meet the demanding standards of
the aerospace and defense sectors.
Hybrid-Electric: The Pioneering Choice for Decarbonizing Aviation
Since 2018, Ascendance has been convinced that hybrid-electric technology is the most realistic and
effective way to reduce aviation's carbon footprint in the short and medium term. Unlike all-electric
solutions, which are limited by range and charging constraints, and unlike hydrogen, which is not yet
mature, hybrid systems can reduce emissions while maintaining operational flexibility.
When combined with sustainable aviation fuels (SAFs), hybridization optimizes environmental
performance by reducing SAF consumption and lowering operating costs for operators while easing
pressure on alternative fuel production. This pragmatic solution is designed for a credible transition.
EXOES, a committed player in decarbonizing mobility, views hybrid-electric aviation as a strategic
means of combining safety, energy performance, and emissions reduction while creating new
industrial opportunities in France and abroad.
Ascendance and EXOES have formed a key industrial partnership focused
on performance.
Leveraging their respective areas of expertise, Ascendance and EXOES have joined forces to design
and produce batteries tailored specifically for the needs of hybrid-electric aviation.
These unique batteries power the STERNA Hybrid Pack, which offers a comprehensive hybrid-electric
propulsion solution. This partnership is a significant milestone for Ascendance, demonstrating its
ability to produce and industrialize hybrid-electric propulsion systems in France.
Ascendance is responsible for the system architecture, the Hybrid Energy Management System,
onboard control and safety devices, and the Hybrid Core Unit, ensuring performance and compliance
with aviation certification standards.
EXOES contributes cutting-edge expertise in cell assembly, advanced thermal management, and
extreme testing to guarantee robustness, reliability, and compliance with aviation requirements.
"This partnership with EXOES demonstrates the consolidation of our hybridization strategy. Since
Ascendance's founding in 2018, we have developed and tested our hybrid technologies in order to build
a decarbonized, certifiable hybrid aviation industry. The Hybrid Pack is not a transitional technology; it is
the foundation of a new generation of propulsion.” —Jean-Christophe Lambert, CEO of Ascendance
“Since 2017, EXOES has specialized in designing and manufacturing high-performance batteries with
enhanced safety. Aerospace and defense are our top-priority markets. This partnership with Ascendance
has already attracted our first customers, and we are eager to accelerate the market launch of our joint
products and services." —Arnaud Desrentes, CEO of EXOES
An integrated system ready for multiple markets!
Unveiled exclusively at the Paris Air Show, the STERNA Hybrid Pack, owned by Ascendance, represents
a major technological breakthrough. It is designed to meet the operational, economic, and
environmental needs of tomorrow’s aviation.
It is modular and compact and can be easily integrated into a wide range of platforms, including
VTOLs like ATEA, long-range drones, light helicopters, and regional aircraft, to boost range, reduce
emissions, and enable a gradual transition to cleaner aviation.
Designed for constrained environments, the STERNA Hybrid Pack offers dual charging capabilities:
● In-flight for time savings and total independence from ground infrastructure
● On the ground, to leverage existing networks when available
This operational flexibility enables a wide range of real-world use cases, such as medical or
surveillance missions in remote areas, regional connections on short runways, and logistics or tourism
services in non-electrified regions. These markets all seek immediately deployable, certifiable solutions.