Product
STERNA for
defence
Promise
Unlock superior UAV performance through hybrid-electric propulsion
(Our offer)
A new era for defence aviation
Our sovereign hybrid-electric propulsion platform, STERNA, is designed to maximize UAV performance in the most demanding operational environments.
By intelligently combining thermal and electric power, it delivers extended endurance, reduced acoustic and thermal signatures, and enhanced mission resilience.
From light tactical UAVs to heavy cargo and MALE platforms, STERNA already provides a mission-ready propulsion solution that enables drones to fly farther, stay longer, and operate more effectively in contested environments.
Light tactical UAV
Heavy cargo UAV
Male UAV
Endurance & Payload
Up to four times the endurance of a fully electric UAV and a 40% increase compared with fuel-powered UAVs, thanks to in-flight battery charging and enhanced payload capacity
Discretion & Reduced Signature
Reduce acoustic and thermal signatures compared with fuel-powered UAVs, while enabling fully electric flight phases.
Easy Integration
Seamless integration across multiple platforms, enabled by a unified energy management system capable of supporting high-power payloads.
Our ecosystem
(Our offer)
Hybrid-electric technology at the core
Hybrid Operating System (HOS)
Energy management software and controller for aircraft and UAV
Hybrid Core Unit (HCU)
High performance electrical hub to link electric systems with energy sources Aviation-Grade
High-performance
High-power battery with in-house battery management system
Thermal engine
(not produced by Ascendance)
Our defence
board
By bringing together our team and experienced defence advisors, we provide a solution aligned with real-world operational needs.
Advisor
Board Member
Andreas Loewenstein
Former EVP, Innovation, Int’l Cooperation & Strategy NAVAL Group, former EVP Strategy & Civil Programs Airbus HC Our ecosystem
Advisor
General Philippe Lavigne
Fmr. NATO Supreme Allied Commander Fmr. Chief of Staff French Air & Space Force
Advisor
Pierre Duval
CEO Demetris and Red-X , former VP Open System Servers Bull, former Marketing & Communication Director Sun Microsystems France
Our facilities
Design
Office
Toulouse building
31 400 Toulouse,
France
Production and Flight Test Facility
Muret building
Muret-Lherm aerodrome,
Rue de l'aviation
31 600 Muret, France
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(Our technology)
Hybrid electric propulsion
system
A modular and scalable combination of two sources of energy (fuel + battery).
A hybrid-electric aircraft uses a mix of two energy sources: electric batteries, used during take-off and climb, to benefit from the instantaneous release of optimized, high-power engines that can run on Jet-A1, and sustainable aviation fuel or hydrogen tomorrow, for low-energy phases of flight, such as cruise.
Conventional aircraft
Aircraft equiped with Sterna
A conventional aircraft engine is usually sized for take-off and climb thrust requirements. This leads to an oversized engine for cruise flight, where most of the fuel is burned. Thanks to Sterna, we can decouple these 2 phases and optimize them to reduce overall fuel consumption over the entire flight.
During take-off and climb, the battery is used to provide high power for short periods. Thus, the powertrain does not need to provide the power during this phase, and take-off and climb rating can be removed and/or the powertrain downsized.
During cruising, the powertrain is used at maximum efficiency, as it is now specifically sized to achieve this level of performance.
What does Sterna look like in an airplane?
Sterna is a set of technologies and components for aircraft and rotorcraft OEMs to make them more sustainable, whether for new developments or retrofitting existing aircraft with an STC*. Sterna can take several shapes depending on your aircraft and the program objectives, from turboprops to regional planes.
Hybrid Operating System
Energy management system - handles the energy split in the system
Hybrid Core
Electrical power box - connects all components together safely & distributes the energy in the system
We’re taking aviation
to new heights.
Embedded intelligence
From energy management to flight controls, including a complete set of data from engines, batteries, etc., the hybrid propulsion system simplifies maintenance operations and improves aircraft availability and customer service.
Range & endurance
The combination of different energy sources and top-grade energy management algorithms ensure optimal performance in flight (cruise time and speed) and on the ground. Our technology adapts to existing infrastructures and limits turn-around times.
Energy transition
Our modular architecture can be adapted to new generation aircraft with a wide array of energy sources, from kerosene and biofuels to synthetic fuels and hydrogen fuel cells.
Safe & efficient
Our hybrid propulsion system is engineered to match the requirements of future distributed propulsion systems, and embeds the required algorithms to control the multiplied number of propellers to ensure safe, efficient flight.
Fly clean
Our hybrid propulsion system significantly reduces carbon and noise emissions, for cleaner skies today and tomorrow. Sterna is the key technology and cornerstone of cleaner aviation.
Scalable
The complete hybrid propulsion system architecture can be scaled up to meet the future requirements of regional aviation, from 6-10 PAX up to 70 with current technologies, propelling aviation into a new sustainable era.
Our board of leaders
We combine the pioneering experience of our co-founders with the expertise and experience from the best in the industry.
Our ecosystem
With the support of
Our partners
Our customers
Our board of leaders
We combine the pioneering experience of our co-founders with the expertise and experience from the best in the industry.
Company
Ascendance joins Toulouse Pioneers Collective
Between heritage and future: Ascendance becomes a member of Toulouse Pioneers and a partner of L'Envol des Pionniers
Events
A BIG day at BPI France's BIG 2025
From stage to roundtable to tv set, our CEO Jean-Christophe Lambert carried Ascendance’s vision of sustainable aviation throughout the BIG 2025
Company
Ascendance expands its footprint in Asia
Ascendance signed MoUs with Pen Aviation and Pahang Aerospace City, opening new opportunities for hybrid-electric aviation in Southeast Asia.
You have some questions?
We have answers
STERNA Hybrid Pack is the combination of 3 core components: a novel battery pack co-developed with our partner Exoes and natively designed for hybridization in aviation, a Hybrid Energy Management System (HEMS) who is the “brain” of the system and automatically manage the energy, and a Hybrid Core Unit (HCU) who connects together the engine and battery in a safe & certifiable manner.
More endurance, more range (up to x4 compared to full-electric UAVs), new functionalities such as ability to do stationary flights and reduced turnaround time (thanks to in-flight charging capability), or to switch to full-electric flight if required. Improved stealth (acoustic and thermal signatures reduction) compared to gas-powered UAV.
We have different product families of STERNA Hybrid Pack for UAV, and can equip the most relevant Hybrid Pack version on either UAV of 25 kg MTOW (small tactical UAV), light tactical UAV (from 50 to 150 kg MTOW), or larger UAV such as heavy cargo UAV (c. 300 kg payload) or MALE UAV (several tons of MTOW).
Yes. Our Hybrid Pack is optimized and designed as a whole to offer the best performance when equipped on a UAV, but we can provide parts of this Hybrid Pack if it fits your specific requirements.