Touching the sky...
We are proud to announce that Helix Propellers played a key role in a historic, record-breaking flight with SolarStratos. On the 12th of August, 2025, Raphaël Domjan piloted experimental HB-SXA to 9,521 meters, making it the highest manned flight ever achieved by an electric, solar-powered aircraft.
The SolarStratos team’s 5-hour-9-minute flight from Sion Airport in Switzerland used solar energy (plus local thermals) to climb to 9,521m (nearly 6 miles) – a new mark that surpasses the Solar Impulse record and is now being submitted to the FAI for official validation. It was a spectacular moment for the project: even crossing paths with a commercial airliner at altitude.
Powered by solar, propelled by Helix
Built by Elektra Solar, the HB-SXA boasts a 24.8m (81ft) wingspan and 22 square meters (237 square feet) of high efficiency solar panels which powers its dual electric motor setup, generating a peak output of 70KW (95 horsepower). Mounted in front of all of this, is a Helix H40A LTM in-flight adjustable propeller with a massive 2 meter (over 6 feet) diameter. The H40A-LTM’s large diameter and its in-flight pitch adjustment gave Raphaël and the engineers at SolarStratos the flexibility to maintain efficient thrust over a very wide range of air densities and speeds – a decisive advantage when climbing to above 31,000 feet.
The future of solar flight and SolarStratos
The altitude record achieved by the incredible team at SolarStratos brings the full potential of solar-powered flight into the spotlight, proving once again the viability of alternative propulsion systems. This may have been a pivotal flight for SolarStratos and Helix Propellers, but it is far from the last. We at Helix are proud to be both partner and sponsor of the SolarStratos project and are dedicated to working with the SolarStratos team to further develop propeller systems for future flights.
