An unusual way to break a world record
In 2015, Swiss pilot André Borschberg spent almost five continuous days in the air.
Borschberg’s flight from the Japanese city of Nagoya to Honolulu in Hawaii took four days, 21 hours and 52 minutes in total. Occupying a coffin-sized cockpit, the pilot was exposed to extreme temperatures as his craft reached altitudes of over 9,000 metres, and kept his energy up with food packets resembling astronaut dinners.
The marathon trip earned Borschberg the world record for the longest non-stop solo flight ever conducted, an accolade he still holds today. What made his achievement all the more impressive is that he broke the record in a highly unusual aircraft: Solar Impulse 2, a purpose-built solar-powered plane, as part of the first ever successful circumnavigation of the world in a solar aircraft.
With Solar Impulse, Borschberg and his co-founder and fellow pilot Bertrand Piccard wanted to demonstrate that harnessing solar power could allow aircraft to complete long-haul journeys without consuming any fuel. Fresh from the success of the project, in 2017 Borschberg co-founded a new venture with Sébastien Demont and Gregory Blatt: H55, a Switzerland-based aerospace engineering company which aims to break the aviation industry’s reliance on carbon-intensive fuels.
The most carbon intensive form of travel
Decarbonisation is a major challenge for the aviation industry, which accounts for around 2.5% of global CO₂ emissions. Rising global prosperity means more passenger and commercial flights, resulting in a wide range of environmental impacts – mile for mile, flying is the most carbon-intensive of all modes of transit. Jet engines emit gases at high altitudes (including carbon dioxide, nitrogen oxides and sulphur aerosols), which contribute to global warming. While various non-polluting biofuels, known as sustainable aviation fuels (SAFs), are available, they have yet to transfigure the aviation industry. SAFs tend to be highly expensive and less efficient than their traditional, fossil-based counterparts. To hit net-zero targets, uptake of low-carbon alternatives like electric propulsion, hybridisation and SAFs will be crucial.
Building an electric aircraft
The company specialises in the production of electric propulsion systems, including modular electric engines and battery packs designed to work with several types of aeroplanes. H55’s battery systems use a chemistry similar to that of car batteries, though the design is very different. Thousands of miniature cells power each of the firm’s systems, with the temperature and voltage of each cell monitored throughout flights. The B23 Energic, for example – an experimental two-seater craft built by BRM Aero – runs on a 104kW H55 system. The craft is expected to start deliveries in 2026.
Today, Borschberg says, H55 is hard at work refining its propulsion systems for a fully electric craft ahead of its commercial debuts, as well as larger hybrid systems designed for use with regional passenger jets, which have a development timeline of around a decade.
Soaring over hurdles
While planes carrying multiple hundreds of passengers are likely to require liquid fuel, the H55 team hopes to make a meaningful contribution to reducing emissions from smaller aeroplanes.
“We’ve faced several challenges – not so much the technology,” says H55 co-founder and marketing chief Gregory Blatt, who also worked on Solar Impulse. “One of the largest is certification. If your car catches fire, you can stop and get out. But you can’t get out of an aeroplane, so you have to make it safe – you have to think about things like batteries exploding and fire propagation.”
A runway for the future
H55 represented uncharted territory for certification authorities in Europe, the US and Canada, Blatt continues; few aerospace regulators had experience with electric propulsion systems, and there was no rule book to consult. “This is something new for [the certification authorities],” Blatt says. “We were educating them in these processes. We’ve taken [the space] very far.”
Next year, H55 expects to receive final regulatory approvals that will allow its technology to be put to practical use in flight school applications. “We have two aeroplanes that fly with our fully electric system today,” says H55 chief executive Martin Larose. “We’re now on the path to final certification, which will allow us to deliver these aircrafts to European, American and Canadian flight schools. They’ll be able to give lessons on a fully electric aircraft.”
Larose expects electric propulsion to grow significantly over the next ten years. While hybrid systems may not be the norm for a regional passenger flight by 2034, he expects “a significant portion” of such flights to use the cleaner technology. “In aerospace, it’s relatively easy to make an experimental aircraft and install an experimental system; the key is getting it certified and commercialised,” he says. “We have excellent applications today, and our employees are super motivated. We have a great relationship with the Swiss government, and we’ve been well supported by the government of Quebec. Step by step, we’re going to go into larger and larger aeroplanes.”