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H55's Battery Technology and the RTX Hybrid-Electric Flight Demonstrator

The ambition to enhance aviation technology has taken a tangible step forward with H55's cutting-edge battery technology, which has been integral to the RTX Hybrid-Electric Flight Demonstrator. Recently, H55 announced further advancements in the development of a 200 kWh Energy Storage System (ESS), marking an important phase in the project that had previously achieved a significant milestone in June 2025 with its first full-power system test.

The demonstrator, led by Pratt & Whitney Canada and Collins Aerospace, aims to showcase up to a 30% improvement in fuel efficiency for regional aircraft through a hybrid-electric propulsion architecture. This innovative system combines a state-of-the-art combustion engine, a 1-megawatt electric motor, and H55's advanced battery system. By leveraging H55's framework and safety protocols, Pratt & Whitney Canada has established a robust compliance foundation for the demonstrator's propulsion system.

Rob Solomon, CEO of H55, emphasized the significance of their collaboration with Pratt & Whitney Canada, stating, "There is a crucial difference between being selected as a component supplier and being chosen as the basis for certification. They haven't just purchased our batteries; they've built their compliance foundation on an architecture that's proven its reliability over more than 2,000 hours of flawless operation, validated through EASA test campaigns. This milestone signifies the first full-power ground test of such a large-scale hybrid-electric propulsion system, showcasing the whole team's capability."

H55's Energy Storage System has been meticulously designed to meet the stringent requirements for aviation certification. Its lightweight, modular design allows for flexible integration within aircraft and optimal weight distribution. This aligns with H55’s extensive experience in developing electric propulsion systems, having completed rigorous safety validation for their battery modules—a crucial phase towards certifying next-generation electric propulsion architectures.

Sébastien Demont, H55's Chief Technology Officer and co-founder, remarked on the milestone's importance, stating, "This achievement in integration is a pivotal moment for both H55 and the electric aviation sector. Our certified battery architecture developed for the CS23 aircraft has demonstrated scalability. The same cell-level safety philosophy and technical discipline are now collaborating with Pratt & Whitney Canada to create a battery system that serves as the core of a hybrid-electric CS25 demonstrator. We're not just adapting a concept; we’re scaling a proven platform. That’s what it means to advance certifiable technology."

Emerging from the groundbreaking Solar Impulse project, which demonstrated the feasibility of electric propulsion for long-haul flights, H55 has continually expanded its expertise by developing various electric aircraft platforms and gathering operational insights that influence future power system advancements.

As the RTX Hybrid-Electric Flight Demonstrator progresses towards aircraft integration and flight tests on a modified De Havilland Canada Dash 8-100, H55's battery technology will play a crucial role in validating hybrid-electric propulsion systems at a regional aircraft scale. This program signifies an essential shift for H55, expanding the application of its technology from smaller electric aircraft to the Part-25/CS-25 category of regional transport planes.

By supporting a hybrid-electric propulsion system for regional aircraft, the demonstrator allows H55 to further validate its Energy Storage System architecture in environments that represent future commercial applications. Entering the regional aircraft market significantly broadens the potential for H55's propulsion technology as hybrid-electric architectures become increasingly viable for next-generation regional aircraft platforms.

With aircraft manufacturers exploring hybrid-electric propulsion to enhance efficiency and reduce emissions, scalable battery systems meeting aviation certification requirements are set to be critical in the architecture of future regional aircraft. Solomon added, "Programs like this allow us to demonstrate that the same certifiable battery architecture developed for smaller aircraft can transition to the regional aviation market. This shift is vital in realizing the commercial potential of electric propulsion."

This critical milestone underscores the growing maturity of electric propulsion technologies and their contributions to more efficient, lower-emission aviation. As hybrid-electric aircraft come into operation, energy storage systems will become vital to every element of the flight operation lifecycle, presenting long-term opportunities for certified propulsion technology providers.

About H55

H55 is a Swiss-based company specializing in certified electric propulsion and certifiable energy storage systems for aviation. The company is facilitating the scaling of electric aviation by transforming commercially available lithium cells into flight-ready energy storage systems recognized by regulatory bodies and repeatedly validated by OEMs as certified propulsion platforms across various aircraft programs. H55's approach combines independent cell characterization, stringent incoming inspections, redundant safety architectures, and regulatory-approved testing tailored to worst-case failure scenarios. Founded as the technological legacy of the Solar Impulse program, H55 builds on over 20 years of practical experience in electric aviation, having designed, built, and flown multiple electric aircraft while accumulating over 2,000 hours of incident-free electric flight operations related to batteries. This depth of operational experience allows H55 to maintain and execute certification programs effectively. H55 is led by a strong, experienced management team that melds deep expertise in scaling technology companies with practical operational implementation, enabling a smooth transition from certified design to repeatable mass production. H55's platform-based methodology, where certification evidence accumulates programmatically, mitigates deployment risks while facilitating capital-efficient utilization of electric and hybrid-electric aircraft.