H2Fly has an historic aircraft in its fleet, the HY4, as part of the HEAVEN program to, “Demonstrate the use of liquid, cryogenic hydrogen in aircraft.” Originally the G4, the craft won the NASA Green Flight Challenge in 2011, posting a passenger mile per gallon efficiency of 403.5 – equivalent to driving your loaded Prius from San Francisco to Los Angeles on under four gallons of fuel. Resurrected as the HY4 and flown on gaseous hydrogen, the craft has been reconfigured to fly on liquid hydrogen, expanding its range significantly. According to the HEAVEN program, “The hydrogen-electric ‘HY4’ demonstrator aircraft took off from Maribor, Slovenia, and saw safe and efficient operation throughout multiple flight tests.” Announced September 7, these were the first piloted flights of a liquid hydrogen fueled aircraft. Four flights, including one that lasted over three hours, “Lay the foundation for long-range, emissions-free flight, with liquid hydrogen doubling the range of the HY4 aircraft to 1,500[kilometers], compared to …
