06-05-2025
Hydrogen Robinson Helicopter On The Bleeding Edge Of Organ Delivery
Robinson R-44 hydrogen fuel cell powered world's first flight. United Therapeutics
Dr. Martine Rothblatt, Chairperson and CEO of United Therapeutics Corporation—a biotechnology company—announced that their Unither Bioelectronics subsidiary successfully completed the world's first lift-off of Proticity, a proof-of-concept hydrogen fuel cell-powered Robinson R44 helicopter, on March 27, 2025, at Roland-Désourdy Airport in Bromont, Québec, Canada. The project's milestones and United Therapeutics's broader aspirations were presented by Dr. Rothblatt at the 4th Annual H2-Aero Symposium, held in early April in Long Beach, California. This article is based on that presentation and a follow-up interview with Mikaël Cardinal, Vice President of Program Management – Organ Delivery Systems and the program's chief engineer.
Dr. Rothblatt founded United Therapeutics in 1996 to save the life of her youngest daughter, who was diagnosed with a rare and life-threatening pulmonary condition. Prior to this, she was a pioneer in satellite communications, having founded SiriusXM Radio and played a key role in launching other satellite ventures such as PanAmSat and GeoStar.
Under her leadership, United Therapeutics has become a leader in developing treatments for pulmonary arterial hypertension and other life-threatening conditions. The company has also made groundbreaking advances in organ manufacturing and transplantation, including the restoration of otherwise discarded donor lungs.
The company is also focused on achieving carbon-neutral production and sustainable delivery of organs. United Therapeutics is actively working toward manufacturing kidneys, hearts, and lungs. One of its three organ manufacturing facilities is already operational, with full capacity expected by 2027, enabling the production of several hundred organs per year at each. United Therapeutics plans to deliver these organs using zero-emissions vertical takeoff and landing aircraft. Dr. Rothblatt herself initiated the development and testing of an electrically powered Robinson helicopter securing a Guinness World Record for the longest flight in 2018.
United Therapeutics Proticity team after successful flight testing. United Therapeutics
The hydrogen helicopter project is entirely funded by United Therapeutics, with no current government or investor support. Robinson Helicopter Company contributes significant in-kind engineering support, providing time, expertise, and resources. The core team includes a dozen in-house engineers, supplemented by third-party specialists in fuel cell technology. For local development and proof-of-concept flight operations, the team consists of approximately two dozen engineers and several test pilots, working in close collaboration with Robinson's engineering staff.
From its electrical helicopter demonstration flights, United Therapeutics gained critical insights into the limitations of battery technology, particularly in delivering sufficient power and range in vertical takeoff and landing operations. To overcome these constraints, the team has turned to hydrogen propulsion, which offers an energy density superior to batteries. The company's long-term goal is to develop a helicopter with a 250-nautical-mile range and a 600-pound payload including the pilot, while near-term goals are set at a 200-nautical-mile range with a 500-pound payload. The company is actively developing a pilot-less variant. Once regulatory clearance is obtained, autonomous features will increase the aircraft's useful payload capacity.
In addition to clean air, another key benefit is reduced noise. Without the piston engine of the R44 or the gas turbine of the R66, the electrified version will generate significantly less perceived noise over populated areas. While the company is still quantifying the reduction, early observations show a clear drop in both perceived loudness and psychoacoustic annoyance.
Technical parameters of the parallel hybrid fuel cell battery power plant implemented on the ... More helicopter. 178 kW power is demonstrated. United Therapeutics Technical side of the helicopter
The developed proof-of-concept powerplant is engineered to match the performance of the original Lycoming IO-540 piston engine it replaces, delivering equivalent continuous power at approximately 2,100 RPM, now via a low-speed electric motor, manufactured by MagniX. The system is computer-controlled to maintain a constant main rotor speed, drawing power from a parallel hybrid setup.
During the first flight, the system achieved a peak output of 178 kW, with hover shaft power around 155 kW. The remaining power supported auxiliary systems, such as supply compressors and cooling. The parallel hybrid configuration includes two 92 kW fuel cell stacks and a 45 kW peak-rated booster battery. Over 90% of the time the power during flight came from the fuel cells, with the battery supplementing short bursts of demand—such as rapid torque inputs—ensuring smooth and responsive control.
The prototype helicopter features distinctive side pods resembling jet engines, which house a state-of-the-art liquid cooling system. These pods manage the significant heat generated by the fuel cell system through a dedicated cooling loop. While effective for the current design, this solution is not planned for the conforming production model. Instead, upgraded designs will adopt intermediate-temperature fuel cell stacks, which will require significantly smaller cooling systems. Hydrogen on board
First flights utilized a Type 4 compressed gas hydrogen tank, featuring a thermoplastic liner wrapped in carbon fiber. Later this year, the company plans to transition to a liquid hydrogen system, using a vacuum-insulated, dual-shell composite tank built by Gloyer-Taylor Laboratories, Inc.. Compared to traditional metallic liquid systems, the composite tanks offer lower thermal mass, significantly reducing hydrogen boil-off. Once released, the cryogenic hydrogen becomes a cold gas, which is then warmed via a heat exchanger before entering the fuel cells. The gaseous system operates at 10,000 psi, storing up to 4.5 kg of hydrogen, while the upcoming liquid system will support up to 20 kg, greatly extending range and endurance.
United Therapeutics's R&D test operations are based in Quebec, Canada, where the company benefits from local green liquid hydrogen production via hydroelectric electrolysis, providing essential infrastructure support. To enable on-site refueling, a liquid hydrogen storage tank is being installed at the test facility. The fueling operations will be supplied by tanker trucks from a nearby production plant located just 30 minutes away, ensuring efficient and sustainable fuel logistics.
The name Proticity, chosen for the hydrogen-powered helicopter project, refers to the electrochemical process within mitochondria that generates energy for living cells. This biologically inspired concept reflects United Therapeutics' biomedical roots and underscores their leadership mission to merge sustainable innovation with life-saving technologies across both healthcare and aviation.
