Legacy of Solar Impulse takes flight

Solar Impulse 2 landed in Dubai, United Arab Emirates, in July, more than a year after it departed in March 2015 on a voyage around the planet powered strictly by the sun in an airplane with the wingspan of a jumbo jet and a takeoff weight very close to the maximum gross weight of a Beechcraft Bonanza.

It was a brilliant display of energy efficiency and modern battery and power system management, albeit at a slow and stately speed with more than a few delays along the way. Borschberg took turns with co-founder Bertrand Piccard, each flying legs in the cramped cockpit that lasted for hours, sometimes for days on end. Borschberg’s final Solar Impulse 2 flight was not by a longshot the end of his interest in electric aircraft.

On April 18, Borschberg posted on social media an invitation to “follow me on my new adventure,” with a link to a new company called H55 that is testing an electric-powered single with the elliptical wing of a Supermarine Spitfire, the sleek aerobatic lines of a modern aerobat, a single seat, fixed gear, electric motor, and flaps. That much can be discerned from the photos posted by the company online; details were provided sparingly.

Borschberg, the company said in the online announcement, co-founded H55 to “develop and leverage the potential of electric propulsion in the world of aviation, making air transport cleaner, quieter, safer, and more affordable.”

Solar Impulse and now H55 co-founder Borschberg is confident that electric aircraft will do more than find a market.

“Electric air transport will undoubtedly disrupt the aviation industry,” Borschberg said in the online announcement posted on the H55 website. Fifteen “years ago when I started with Solar Impulse, electric propulsion was anecdotal. Today [it] is a major development path of every large aeronautical organisation as well as attracting many start-ups and new players. What is science fiction today will be the reality of tomorrow.”

The company posted photographs of an electric demonstrator dubbed aEro1, reporting that it has logged more than 50 hours to date with battery endurance exceeding 1 hour. The demonstrator appears to be smaller than the electric Extra 330 powered by a Siemens motor that recently set world records for speed and time-to-climb, though the Siemens logo is painted on the nose of aEro1, suggesting the Swiss prototype has something similar under the cowling.

Borschberg has been joined in his new endeavor by other Solar Impulse veterans including Sebastien Demont, who led the electrical engineering of Solar Impulse.

“H55 focuses on the entire propulsion chain starting from the energy source and management, right through thrust and power, as well as pilot interface and all control systems,” the company stated.

“Due to the flexibility and reliability of software, innovative designs such as VTOL are in fact possible,” the company statement continued. “Electric airplanes are therefore cost efficient and considerably less expensive to operate than traditional combustion aircraft. And all with much less noise and an environmental foot print. All combined, electric airplanes offer new possibilities for urban transportation and will play a key role in changing the way people travel.”

That change will ultimately include removing the human pilot from the equation, it seems: The company website includes a mission statement that includes making aircraft “ultimately autonomous.”

Borschberg's new company acknowledged its debt to the work done by the Solar Impulse team, noting that "H55 represents Solar Impulse's technological heritage," and adding that Piccard has his own mission underway with initiation of the World Alliance for Efficient Solutions, "a platform to federate the main actors in the field of clean technologies with the objective of showcasing profitable and tangible solutions to environmental challenges."