VoltAero Flies Cassio Hybrid On 100% Sustainable Fuel

VoltAero’s Cassio S propulsion testbed has flown on a 100% sustainable fuel developed for motorsports.

Credit: VoltAero

French startup VoltAero has flown its Cassio S hybrid-electric propulsion testbed on 100% sustainable fuel.

The modified Cessna 337 Skymaster’s combustion engine was fueled with a bioethanol produced for motor racing by France’s TotalEnergies using waste from wine making.

VoltAero’s planned Cassio 330 production aircraft is powered by a hybrid module that integrates an internal combustion engine and an electric motor, both driving the single pusher propeller via a gearbox. Kawasaki Motors is supplying the four-cylinder piston engine, which is based on the engine for the Kawasaki Ninja H2R motorcycle. Safran is providing the motor and Electric Power Systems the battery.

VoltAero is testing a biofuel-burning variant of the H2R engine on the bench, with plans to demonstrate a hydrogen-fueled version by the end of 2024. The Cassio S testbed is powered by a modified Nissan V6 car engine developed with France’ Solution F, a specialist in developing engines for motorsports.

For the test flight from Royan, France, the Cassio S testbed was fueled by Excellium Racing 100, an SP98-type higher-octane unleaded motorsports fuel, which TotalEnergies says enables at least a 65% reduction in life-cycle CO2 emissions. Based on initial results, VoltAero says, the life-cycle CO2 reduction is about 80% when the Cassio powertrain is operating in electric-hybrid mode.

“It underscores the opportunity for production Cassio aircraft to represent a major step closer to aviation’s decarbonization goals by replacing standard Avgas 100 high-octane fuel for aviation piston engines,” says Jean Botti, VoltAero’s CEO and chief technology officer, in a statement.

The test flight “demonstrates our desire to continue our research and development efforts to offer an alternative to aviation gasoline containing lead, thereby meeting the challenges of general aviation’s decarbonization,” says Joël Navaron, president of TotalEnergies Aviation.

“We already have initiated several actions–such as the installation of several electric charging stations for general aviation aircraft and the launch of a pilot program aimed at offering SP98-type fuel for compatible aircraft,” he says.

Graham Warwick

Graham leads Aviation Week's coverage of technology, focusing on engineering and technology across the aerospace industry, with a special focus on identifying technologies of strategic importance to aviation, aerospace and defense.