Story ID: 
Unither Bioelectronics Plans Hydrogen-powered Helicopters
By: Hanneke Weitering
Caption: Hydrogen fuel cells could power organ delivery flights
Word Count: 1201
Unither Bioelectronics is teaming up with Robinson Helicopter to develop hydrogen-powered variants of the company’s R44 and R66 helicopters. Robinson has agreed to collaborate with Unither to develop supplemental type certificates for the modified helicopters in the U.S. and Canada, contributing its technical and regulatory expertise to the project. As a subsidiary of United Therapeutics—a biotechnology company and public benefit corporation specializing in organ transplant technology—Unither Bioelectronics aims to usher in the next generation of airborne organ delivery systems with zero-emission and autonomous flight technologies.
United Therapeutics had been developing all-electric, battery-powered Robinson helicopters since 2016, working with Tier 1 Engineering to convert the R44 with electric propulsion units provided by MagniX. The partners flight-tested three generations of electric R44 prototypes, and that program showed what could be done with existing battery technology, which is still somewhat limited in terms of the range it can deliver for a light helicopter.
However, noted Robinson president and CEO David Smith, Robinson helicopters are ideally suited for battery-electric propulsion “because of our [low] empty weight fraction, so we have more payload to devote to fuel than our competition. We are an ideal platform to develop as batteries improve.”
He also explained that helicopters have a relatively flat power curve compared to heavier multi-rotor eVTOL aircraft, which have a high power requirement for takeoff, hover, and landing. “You need these huge batteries that can handle big thermal cycling. It’s a much more difficult mission because they’re hot, hot batteries at that point. You have a lot of challenges with those very steep power curves that come from other architectures, so I think helicopters are going to do it first."
Robinson Helicopter shared technical information with the Tier 1 team and recommended some retired employees to be hired for the program, according to Smith. “They had a lot of great success,” he said. “They had a great team working on the project, and we were very impressed by the group there at Tier 1. We see the Unither piece helping us achieve their mission objectives and our long-term objectives of maturing the batteries, the motors, the high-voltage power and distribution, and in this case, the hydrogen containment and the fuel cells. That gives you several building blocks to build the power plant variation of the future.”
“This powerplant is another great example where the laws of physics favor a single, lightly loaded rotor, for a whole bunch of reasons, and it'll be a better user of energy. If you go side by side and you have one [aircraft] that's 8,000 pounds and one that’s 3,000 pounds, physics tells you that you're going to need less energy to hover that [3,000-pound aircraft] before you even think about the fact that they've got a wing.” The aerodynamic interaction of the multiple rotors and a wing requires even more energy, Smith explained.
“The work we did with Tier 1 for the battery-powered helicopter was a very critical building block for what we are doing today in terms of the hydrogen hybrid helicopter development,” said Mikaël Cardinal, v-p of program management and organ delivery systems and head of the United Therapeutics Organ Delivery Systems (UTODS) development program. “When you think about the fuel cell system integration to provide power to the helicopter for certain phases of the flight mission, you still need a battery system that is obviously smaller…to cope with those rapid demands of power for the transient regime of the helicopter. The work under Tier 1 was useful to inform a comprehensive design and manufacturing process for the battery component that is still applicable for a hydrogen-hybrid powertrain.”
By adding hydrogen fuel cells into the mix, United Therapeutics hopes to enable longer-range flights than what it can offer with the purely battery-electric version. The Tier 1-modified R44 holds the record for the longest flight of a battery-powered helicopter at 30 nm, and United Therapeutics has said the aircraft would have a range of 40 nm without reserves.
Hydrogen fuel cells could potentially quadruple the range of the all-electric R44, enabling deliveries of artificially manufactured organs from United Therapeutics’ facilities to transplant centers across North America. “We look forward to working with the expert team at Robinson Helicopter to enable regulatory approval and production of these aircraft,” Cardinal said.
Unither has applied to Transport Canada for certification of the hydrogen fuel cell-powered R44, and the company has had familiarization discussions with the FAA. Plans call for a hydrogen-electric conversion of the turbine R66 as well. “It doesn’t have the complexities of the belts and sheaves that come with the piston heritage of the R44,” Smith said.
The hydrogen fuel cell system that Unither is developing stores cryogenically cooled liquid hydrogen. The company is “deep into the building and testing stage,” he added.
Where Robinson’s experts can help will be with flight testing and certification. “Those are areas that we have a lot of expertise in,” although he said, “our role in flight testing and the safety side is going to be advisory in nature. We won’t have our pilots doing the flying under the current plans. They've got very capable pilots, but we'll help them go through the consideration of how to most effectively do for-certification-credit testing and the envelope expansion that helps establish the readiness to go into certification testing. At the conclusion of the primary certification project, we have to build it. They want to make these organs, and we want to make helicopters. So it's a good opportunity. We'll each stay in our specialty.”
Robinson Helicopter’s agreement with Unither doesn’t limit the helicopter manufacturer’s opportunity to market hydrogen-electric-powered helicopters to other buyers. “We've got several missions [such as] training and ecotourism. But when you get into the ranges that these hydrogen fuel cells can offer, it opens up commercial applications,” Smith said.
These could include customers with needs around zero emissions and quiet operations. Cities might be more willing to allow helicopters with backup electric motor power to fly in areas where conventional helicopters are restricted. “Our R66 has had a great run with no engine failures in the fleet,” Smith said. “So it's less about the actual failures and redundancy as it is sufficient redundancy to get through the regulatory barrier.”
The helicopter program isn’t Unither’s sole venture into electric aircraft technology. “We do have a philosophy of multiple shots on the same goal,” said Cardinal. “Beta Technologies is one of those shots, concurrently to the helicopter hydrogen fuel cell development program.”
On the Unither website, an animated video shows how a medical technician delivers an organ in an autonomous eVTOL. Unither’s ultimate range requirement for an organ delivery service is 250 nm, Cardinal explained, and the goal is to achieve that in a zero-emission vehicle, likely powered by a hydrogen fuel cell. Centralized organ manufacturing facilities would send organs to transplant centers east of the Mississippi River in the U.S., although drones could be used for deliveries over the last mile.
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