Unither Bioélectronique test pilot Ric Webb lifted off in a Robinson R44 helicopter powered by a hydrogen fuel cell propulsion system at Roland-Désourdy Airport in Bromont, Québec, Canada, on March 27. A subsidiary of United Therapeutics, Unither is developing hydrogen-powered helicopters, including a hybrid-electric R66, that it plans to use to transport manufactured organs for transplants.

“Our first test flight successfully demonstrated the hover and maneuver capabilities of our innovative hydrogen powertrain,” said Mikaël Cardinal, v-p of program management and organ delivery systems at United Therapeutics. 

The flight of the proof-of-concept demonstrator R44 achieved several firsts, including the first flight of a hydrogen-powered helicopter and the first such flight in Canada. It also validated the proton exchange membrane (PEM) fuel cell technology, which Unither said is “proving its capability to support the demanding power requirements of a vertical takeoff and landing powered-lift profile.”

During the test flight, Webb hovered the hydrogen-powered R44 and maneuvered before touching down. Equipped with two low-temperature PEM fuel cell stacks and a battery pack for transient power demands, the helicopter flew for 3 minutes 16 seconds with about 90% of the power provided by the fuel cells and the rest by the battery. 

A tank mounted under the R44’s tail boom stores gaseous hydrogen, but Unither will replace that with a liquid hydrogen storage system later this year to demonstrate longer-range capability. Two round units that look like turbine engine nacelles are mounted above the skids on either side of the R44 and are part of the high-temperature fuel cell cooling system. The electric motor is manufactured by MagniX.

Smaller units are planned for the next generation of fuel cells, which will require less cooling, according to Unither. The R44’s fuel cells are mounted in the aft cabin. In the next flight-test helicopter, which will be an R66, the fuel cell will be mounted in a way that doesn’t use any cabin space.

Plans call for subsequent designs to feature a liquid-hydrogen storage system that will provide more range needed for organ-delivery flights. “Just as protons from hydrogen atoms drive the mitochondrial powerplants in each of our bodies’ cells, we look forward to using protons from green hydrogen to drive the membrane-based fuel cell powerplants in our Robinson R66 organ delivery electric helicopters,” said United Therapeutics chairperson and CEO Martine Rothblatt.

Unither and Robinson Helicopter are collaborating on the hydrogen-powered helicopter program, called Project Proticity. The Torrance, California-based helicopter manufacturer is responsible for engineering, technical, and regulatory expertise, while Unither is focusing on integrating hydrogen technology and conducting testing toward certification in Canada and the U.S. 

“The importance of this milestone in aviation history cannot be overstated,” said Robinson Helicopter president and CEO David Smith. “Project Proticity has taken an incredible first step forward in the path to long-range, zero-emission vertical flight. We are excited to continue developing this technology with our partners at Unither Bioélectronique.”