Modified R44 Flies Hydrogen-electric Helicopter Circuit

Canadian biotech company Unither Bioélectronique has made what it claims is the world’s first piloted hydrogen-electric helicopter circuit flight. This was completed on April 10 using a modified Robinson R44, one year after the demonstrator first flew, but not announced until May 7.

The test flight was conducted under an experimental flight permit as part of the ongoing Project Proticity. Announced in August 2024, this partnership between the United Therapeutics subsidiary and Robinson Helicopters is looking to develop zero-emission helicopters based on the latter company’s R44 and R66.

The hydrogen-electric circuit flight builds on the inaugural flight of the technology demonstrator in April 2025. This was performed using gaseous hydrogen powering two low-temperature proton exchange membrane fuel stacks, with an adjacent battery pack. The hover lasted just over three minutes.

Project Proticity now intends to scale the system to the larger R66. Unither states that its intended end-use of the aircraft is to “help deliver manufactured organ alternatives to patients in need, while creating a scalable zero-emission transportation network.” The partners are targeting future certification pathways with the U.S. and Canadian regulators.   

In May 2024, Unither revealed that it was looking to add hydrogen-enabled capabilities to its existing battery-electric research. Having flight-tested three generations of electric R44 prototypes, it explained that it was “deep into the building and testing stage” of cryogenically cooled liquid hydrogen cells. These, explained Unither, could potentially quadruple the all-electric R44’s range: enabling deliveries of organs to transplant centers across the U.S.

Meanwhile, the FAA has issued special conditions that will apply for a supplemental type certificate to install Skyryse's fly-by-wire flight controls in the R66 helicopter. Skyryse, which applied for the approval in April 2023, described its technology as "the first fully digitized aircraft operating system that enhances safety and offers optionally piloted capabilities.” The company has been working on autonomous flight systems for several years.