Apus at the Apex

Hydrogen fuel goes airborne

Following a successful presentation at the 2022 Aero Friedrichshafen event in Germany, APUS Group will bring its hydrogen-powered twin-motor APUS i-2 airplane’s model to the big stage at Hannover Messe next week. The full-scale model "has been equipped to highlight the fuel cell and power controller installation in the forward fuselage, with the tubular spar hydrogen storage system efficiently integrated into the wings’ structure," the company said in a press release sent to Electrical Apparatus.

APUS says it is attending the Hannover Messe international trade fair to bring a clear message to the public: zero emissions and uncompromisingly climate-neutral air transportation is possible.

APUS' hydrogen fuel-cell aircraft, the APUS i-2.—APUS photo

In this case, the oft-abused term "zero-emission" means for APUS not only that pure water-vapor is the sole emission of the hydrogen fueled power train, but also that considerable noise reduction is achievable. To reach this ambitious goal, APUS has partnered with industry leaders like PowerCell (Hydrogen Fuel Cell), Fraunhofer (High-Voltage applications), COTESA (hydrogen storage solutions) HEGGEMANN (hydrogen supply and safety systems) and Rolls-Royce (aircraft propulsion).

The APUS i-2 (pictured above) is a four-seater aircraft that can accommodate one pilot and three passengers. When fully fueled the aircraft has a payload of 400 kg; Mtow is 2,200 kg. Assuming a hydrogen price of 7 €/kg and an AVGAS price of 3 EUR/l, the direct cost saving will be 40% compared with a conventional aircraft of the same category, for example the Cirrus SR22 and including the amortization of the powertrain cost.

APUS has been developing an efficient hydrogen storage system aerodynamically integrated in the structure of the aircraft since 2015. The wings contain four tanks, which are not only used to store the gaseous hydrogen, but also as a load-bearing structure. The pressure of the stored gas is 300 bar. The pressure system ensures that the aircraft can be easily refueled with low cost non-cooled hydrogen that is already available at existing hydrogen fuel stations for cars and trucks. Fully filled, the tank has a capacity of 23 kg of hydrogen. Two electric motors, 135 kW each, consume the energy of 5 kg of hydrogen per hour. This allows a range of 500 nautical miles (926 km) and a cruise speed of 160 knots (ca. 300 km/h).

APUS is now testing the power train and hydrogen tanks and plans to roll out the first i-2 early next year. First flight should take place at the end of 2023.

Along with the i-2 program, APUS is also developing a larger multi-mission model, the APUS i-5, that features the same tubular spar hydrogen storage system. This airplane will have four 150 kW Rolls-Royce motors mounted on the leading edge of the wing. The focus of the APUS i-5 will be regional aviation and regional logistics.