Building on the Legacy of Solar Impulse

When the world’s first round-the-world flight in a solar electric-powered plane whispered to a stop on the tarmac in Abu Dhabi in 2016, many thought of Solar Impulse 2 as simply another entry in a book of world records. Its two pilots and creators had far more in mind.

By Seabright McCabe, SWE Contributor


One grand flight deserves another. On the fifth anniversary of Solar Impulse 2’s historic flight, Bertrand Piccard and André Borschberg, who took turns piloting the plane around the world, took to the skies once more — this time together, in another history-making aircraft: the Bristell Energic fully electric, two-seater trainer, powered by H55. It’s another world first for the two pioneers, and though their flight was a celebration, it was also a leap forward.

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The Bristell Energic, a fully electric trainer, on the tarmac in Sion, Switzerland Photo Credit: Solar Impulse Foundation

“The Bristell Energic is the first commercial step as an electric airplane following our round-the-world flight with Solar Impulse,” Borschberg, co-founder of H55, said. “Many more aircraft will be either converted into electric airplanes or newly designed to benefit fully from the tremendous advantages of the electric propulsion technology developed by H55. In 10 years, we will see the first commuter airplanes transporting passengers from cities to cities with limited noise impact and CO2 emissions.”

H55’s highly efficient and clean electric propulsion technology is one of the first 1,000 solutions certified by Piccard and Borschberg’s Solar Impulse Foundation, which seeks resolutions worldwide that combine environmental protection with economic profitability. “Success is never a goal in itself; it is only a way to go further,” Piccard said. “When I landed in Abu Dhabi five years ago, I predicted that electric passenger airplanes would fly within 10 years. Today’s flight shows that we are on track.”

The mission of H55 is to make air transport quiet, clean, and affordable. The company’s patented and certified electric propulsion and battery management technology can serve in existing aircraft designs, future vertical takeoff and landing (VTOL), and eCommuter concepts. At its core, H55’s proprietary technology focuses on an integrated power, propulsion, and battery management system that includes battery packs, connectors, motor, motor controller, pilot interface, and power controls.

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Clean, efficient, quiet. Bristell Energic’s propulsion system, designed by H55. Photo Credit: H55

Under the cowling

The Bristell Energic is a sleek, low-wing trainer built by Czech aircraft company Bristell, with a maximum takeoff weight of 1,873 pounds (850 kg) and a climb rate of 800 feet (240 m) per minute. Its lithium-ion batteries can be fully charged in one hour, with a maximum flight time of 90 minutes, which includes a 30-minute reserve — just the right length for a one-hour flight training session. With a cruising speed of about 125 mph (200 km/hr), the cost of powering that hour of flight is $7.

The plane’s electric motor is quiet, but practically shouts the future of commercial aviation. Even its three-blade, hydraulic and adjustable propeller is designed to reduce noise; in the air, the motor competes to be heard above the rush of wind.

And to Borschberg, who co-founded H55 with two colleagues as a spinoff of the original Solar Impulse project, the need to soar past the roar of internal combustion engines and the pollution they create couldn’t be more immediate. “We all know that we cannot continue wasting our resources and destroying the environment,” he said. “Innovation will be the key to making our world more sustainable. It is my life mission.”

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Co-pilots at last: Aviation pioneers Bertrand Piccard (left) and André Borschberg, who each flew alternating legs of the Solar Impulse 2 flight, join forces aboard Bristell Energic, the world's first fully electric flight trainer. Photo Credit: Solar Impulse Foundation

A continuing legacy

Borschberg and Piccard believe that electric propulsion will revolutionize aviation. “Electric motors and software created the world of drones as it will create VTOL and flying taxis,” Borschberg said. “H55’s first application is to make this electric flight trainer. This is the first step toward clean aviation.” Together with Czech Republic-based BRM Aero, H55 is trailblazing that future, and the Energic’s function as a trainer ensures that a new generation of pilots will be actively engaged in electric flight.

On that sunny day in Switzerland following their celebratory flight, Piccard and Borschberg clearly enjoyed the moment. “It’s a special emotion to share for the first time the cockpit of an electric airplane with my partner, André,” Piccard said. “H55 is the perfect proof that clean and efficient technologies allow us to do so much better for the environment and all fields of the industry. And on top of that, this low-carbon flight reminded me how great it is to fly without noise! A fantastic experience.”

The Bristell Energic will be fully certified and available to flight schools in late 2022. “For 30 years, we developed Solar Impulse,” Borschberg said, in a video introducing the electric trainer. “In 2016 we could fly around the world in an electric-powered airplane. With H55, we want to take Solar Impulse’s know-how and legacy one step further.”

He continued, noting that, “We are at the beginning of a revolution. And I tell you that we will not understand in the future why we did not start earlier with these technologies.” Standing in a hangar, he gestured toward a jet-fueled commuter plane, its engine blasting as it readied for takeoff: “This is the sound of the past. This will be in a museum very soon.”

The race to electrify aviation

The partnership between H55 and BRM Aero is far from the only innovation in electric-powered flight. Almost every company in the aviation industry is reaching new milestones on the path to clean, safe electric propulsion.

Hybrid business aircraft: Airbus, Daher, and Safran are developing the EcoPulse™, a hybrid aircraft that employs distributed propulsion through numerous small engines arranged along the wingspan.

Vertical takeoff and landing (VTOL): Airbus is also developing fully electric flying taxis that can take off, land, and hover vertically for urban-area transport. Currently in the design phase, the goal for this four-seat “multicopter” is a flight range of 50 miles (80 km) and 75 mph (120 km/hr), operating at less than 70 decibels — a significant noise reduction.

eVTOL: A partnership between Rolls-Royce and Vertical Aerospace, another four-seater flying taxi is also intended for autonomous urban commuting and product delivery. With a range of 120 miles (190 km) and a top cruising speed of 200 mph (320 km/hr), it’s on track for certification in 2024.

Electric seaplanes: Vancouver-based Harbour Air is continuing to work toward converting its entire 40-seaplane fleet to electric propulsion. Partnering with Seattle-based electric motor company magniX, and with André Borschberg’s H55 providing the high-density energy, redundant battery packs, Harbour Air’s goal is to become the world’s first all-electric airline.

For major airlines, electric propulsion still faces major challenges, and it’s a matter of marshalling resources, investment, and the will to make a paradigm shift that will result in either newly designed aircraft or conversion of existing aircraft. But with so many innovations in the pipeline, and more on the way, hope is building for cleaner, quieter skies.