History in the making: the inventor of solar aviation aboard SolarStratos
The September flight campaign went as planned for the SolarStratos team, with a moment etched into the history of solar aviation: Raphaël Domjan’s flight with Fred To aboard SolarStratos. Fred To designed the very first crewed solar aircraft, and the flight came nearly 50 years after Solar One’s maiden flight.
Monday: training with the stratosphere in sight
The week began with excellent weather conditions. Raphaël Domjan completed three take-offs and, more importantly, three landings. This training was essential before the planned flight with Fred To in two-seater configuration. The technical sequence also allowed the team to maintain its operational capabilities, which is often overlooked but essential in an experimental project of this kind.
Tuesday: photo and video flight with our partner Heli Lausanne
On Tuesday, the team carried out a flight dedicated to photo and video shooting. SolarStratos flew followed by a helicopter carrying the media team. It was a delicate exercise requiring precise coordination between the two aircraft, and it took place in excellent conditions. Stunning images are on the way for our upcoming communications.
Wednesday: the weather has the final say
On Wednesday, the weather did not allow any flying. This is common with such a light aircraft, which requires stable atmospheric conditions. The team remained on standby at the hangar, ready to take off again as soon as a new weather window opened.
Thursday, September 10: a historic flight with Fred To
On Thursday morning, the conditions were perfect, with clear skies and no wind. Shortly after 8 a.m., the aircraft took off from Payerne airfield for a 30-minute two-seater flight. Raphaël Domjan was at the controls, and beside him sat Fred To. The 88-year-old architect from Hong Kong designed Solar One, the first crewed solar aircraft in history.
Solar One’s first flight took place on December 19, 1978, in Lasham, in southern England. At the controls that day was Briton David Williams, an aeronautical engineer and pilot who had teamed up with Fred To to build and fly this photovoltaic-powered prototype. Fred To himself had never flown aboard a solar aircraft. Nearly 50 years would pass before that changed. That Thursday morning in Payerne, it finally happened.
The idea of designing an aircraft powered by the sun came to him after the first oil crisis of 1973. “It was also a youthful dream,” Fred To said. That dream came true at the age of 88, alongside the man who, in his own way, is carrying the torch. “It is an honor and a privilege to be able to invite Fred To aboard SolarStratos. This pioneer is a role model for me. His perseverance, his vision and his passion have always inspired me. Thanks to him, decarbonized aviation was able to come into being,” said Raphaël Domjan.
Two generations of pioneers and two solar aircraft share one conviction: flying differently, without burning fossil fuels. It was a timeless moment, filled with emotion and history, aboard the only two-seater solar aircraft in aviation history.
What the campaign taught us
This week of flights also highlighted an important technical issue. Some of our cameras are showing signs of failure, including shaking, restarts and unstable images. Nothing serious, but the lesson is clear. These cameras endured the extreme conditions of last year’s record flights, with temperatures dropping below minus 50 degrees. Their replacement was already planned. We will switch to cameras connected directly to our telemetry system, which will simplify the whole setup and make live broadcasts more reliable.
Speed record flight postponed
We did not carry out the additional flight planned for the official speed record attempt for a CS-class solar aircraft. The federations have not yet adapted their regulations for this category, so the exercise had little purpose at this stage. We will wait for the appropriate regulatory framework before making the performance official.
In summary
This was a successful campaign. It brought a historic moment with Fred To, confirmed the team’s operational expertise and provided valuable technical lessons for the future. Thank you to all our partners, our technical teams, and everyone who follows this adventure.
Preview screening: discover “Solaire, l’énergie de demain”
To mark the release of the documentary “Solaire, l’énergie de demain” (Solar, the energy of tomorrow), made with Osons Causer and supported by the PlanetSolar Foundation, SolarStratos invites you to two exceptional preview screenings.
On the program: a screening of the documentary, followed by meetings and discussions about solar energy, innovation and solutions for building the world of tomorrow.
Two events not to be missed:
October 7, 2026 – 5:30 p.m.
EXPLORiT – Avenue des Découvertes 1, 1400 Yverdon-les-Bains
Free admission – 150 seats available, register here.
October 20, 2026 — 5:30 p.m.
Maison des Océans — 195 rue Saint-Jacques, 75005 Paris
Free admission – 150 seats available, register here.
Come along whether you are curious, a student, a teacher, a science enthusiast or simply interested in tomorrow’s solutions. Discover a different way of talking about energy and discuss the challenges that will shape our future.
Post of the month – Footage of Fred To and Raphaël Domjan’s flight
Watch the video of Fred To’s flight aboard the HB-SXA:
