The U.S. Department of Energy (DOE) is funding Piasecki Aircraft Corporation (PiAC) to continue an evaluation into the feasibility of using hydrogen fuel cells to power VTOL aircraft. The Pennsylvania-based company on Monday announced that it has been awarded a small business innovation research (SBIR) contract for an undisclosed amount.
PiAC has already completed the first phase of the project and said it is on schedule to complete the second phase later this year. Under the SBIR contract, the company will conduct a technical economic analysis, develop conceptual and preliminary designs for a fuel cell-based powertrain, and later develop and test a full-scale hydrogen-powered VTOL aircraft. The study is benchmarking hydrogen propulsion against comparable internal combustion engines and battery-electric alternatives for metrics including mission performance, reductions in greenhouse gas (GHG) emissions, cost of ownership, and technology readiness.
In its initial study, PiAC conducted a detailed comparison with an existing piston-powered Robinson R44 four-seat helicopter, comparing it to fuel cell-based systems using both liquid and gaseous hydrogen and battery-powered propulsion. By employing the DOE’s Techno-economic Energy and Carbon Heuristic Tool for Early-Stage Technologies, the company said it has demonstrated that either of these alternatives will have negligible GHG emissions and would eradicate more than 1,300 tons of emissions over a five-year period, compared with the R44 flying the same air taxi missions in an urban environment. The study assumed the notional aircraft would have to operate at altitudes as high as Denver.
According to PiAC, it now views the liquid hydrogen-based option as the most promising on the basis that it will be able to match the range of the internal combustion variant at around 270 nm. By combining the high specific power of high-temperature proton membrane exchange fuel cells with the high energy density of liquid hydrogen, the company reported that it has established that this version of the aircraft would be able to fly five 50-nm trips before refueling, compared with fewer than two trips using gaseous hydrogen.
“The results of our initial study reinforce the potential for hydrogen fuel cells to disrupt the $40 billion light helicopter replacement market and contribute to the growth of the emerging air taxi market,” said PiAC president and CEO, John Piasecki.
The U.S. Air Force has already provided funding for PiAC’s plans to develop its own hydrogen-powered helicopter. The company is working on a 660-kilowatt propulsion system test rig as it works towards flight testing of a full-scale prototype aircraft in 2028.
The planned PA-890 slow-rotor wing compound helicopter is expected to be able to carry a pilot and up to seven passengers on trips of longer than 200 nm. Its predicted payload is 1,660 pounds and the maximum takeoff weight is 7,000 pounds.
Last November, the Air Force Research Laboratory awarded $37 million to the company under its Strategic Funding Increase program to support a flight demonstration of its Aerial Reconfigurable Embedded System (ARES) tilt-duct optionally-crewed VTOL vehicle. The ARES program, which had support from DARPA, involved a collaboration between PiAC, Lockheed Martin, and Sierra Nevada Corp. PiAC is now continuing the work with Honeywell, with backing from both the Air Force and Army.