• 20 Feb 2024 02:57 AM
• 0

Liquid Hydrogen to Power Sirius Jet

Mike Hampson
Vertiflite, March/April 2024

Sirius Aviation of Switzerland unveils liquid hydrogen-electric powertrain

On Jan. 17, Sirius Aviation AG unveiled its hydrogen-electric, ducted-fan propulsion system in a private ceremony at Payerne Airport, Switzerland. The hydrogen fuel cell powertrain will serve as the basis for the Sirius Jet, a long-range hydrogen-electric vertical takeoff and landing (eVTOL) aircraft. The Baar, Switzerland-based company announced that it would also be selling its hydrogen-electric powertrain. Sirius has already taken preorders, deliveries of which are expected in the fourth quarter of 2025.

The January event saw speeches from industry leaders, including Alexey Popov, CEO of Sirius Aviation AG; John Schoenbeck, Director of Strategic Partnership at BMW Group DesignWorks; Tommy Forsgren, Lead Designer at BMW Group DesignWorks; Giuseppe Sernicola, SVP at Leonardo Aerostructures; Zigmund Bluvband, President of ALD Service; and Jonathan Herzog, CCO of Sauber Group F1. The team also includes Israel Aerospace Industries (IAI).

The propulsion system includes a fuel cell stack, a liquid hydrogen fuel tank, battery packs, a booster battery pack, a DC/ DC converter, a power distribution unit, proprietary electric motors, a proprietary advanced two-phase cooling system and integrated power electronics. Each motor powers an 11.8-inch (300-mm) diameter electric ducted fan (EDF); each EDF weighs 21.2 lb (9.6 kg) and has a peak thrust of 225 lb (1 kN).

At the Jan. 17 event, the company also conducted a demonstration — in the meeting room — of the hydrogen propulsion system powering an EDF; the fuel cell stack uses liquid hydrogen and oxygen, which produces a reaction of electricity and water. The exhaust of the aircraft is only water, resulting in zero emissions.

Sirius Aviation was founded in 2021 “by a family of legacy aviators,” with the mission of designing and manufacturing clean, safe, economic, quiet, long-range and fast eVTOL passenger jets for city-wide and regional travel. The company is leveraging nearly a century of aerospace research and development expertise of Kharkiv, Ukraine-based company FED, founded in 1927 and now led by other members of the Popov family.

The basic platform is 36.1 ft (33 m) long with an identical wingspan. Three versions are envisioned: the Sirius Business Jet, the Sirius Millennium Jet and the Sirius Cargo Jet. The jet has a modern sleek design featuring a canard with downward winglets, a high main wing with upward winglets and a V-tail.

The aircraft uses a total of 28 EDFs: The canards tilt with four EDFs on the leading edge of each side of the canard. On the main wing, 10 EDFs are in a row on the rear of each wing and only the EDFs tilt down for VTOL flight. The jets have retractable tricycle wheeled landing gear.

The Sirius Business Jet holds one pilot and three passengers. The estimated cruise speed of the aircraft is 323 mph (600 km/h), range is 1,150 miles (1,850 km) and cruise altitude is 30,000 ft (9,144 m).

The Sirius Millennium Jet holds a single pilot and five passengers, and has a shorter range of 650 miles (1,050 km).

The Sirius Cargo would have similar performance depending on the weight of the payload. The air cargo service capacity is 180 ft³ (5.1 m³).

The Sirius jets are made from carbon fiber composite for a high strength-to-weight ratio. According to Sirius, its jets will be 95% quieter than a helicopter, emitting less than 60 dB at a 330-ft (100-m) distance. There is a whole-aircraft emergency ballistic parachute in the event of an in-flight emergency.

The company’s target market is the business jet consumer. In December 2023, the company envisioned first flight of a full-scale Sirius Business Jet demonstrator in 2025. The estimated price of each aircraft has not yet been announced, but the company has calculated they will consume approximately 4 gallons (15 liters) of liquid hydrogen per hour, making them more environmentally friendly than traditional business jets, and costing less than $0.50 per seat mile for a 1,150-mile journey (for the Sirius Business Jet).

About the Author

Mike Hampson is the owner of HelicopterLinks.com, started in 2002 as the “online yellow pages of the helicopter industry.” He is the webmaster of the VFS World eVTOL Aircraft Directory (www.eVTOL.news/aircraft) and is a past contributor to Vertical, Vertiflite, Rotor & Wing and RotorNews.