It’s airborne! VoltAero’s hybrid-electric power module for Cassio takes to the skies

Cassio 1 made its maiden flight equipped with the power module on Sunday, October 11, from VoltAero’s Royan-Médis Airport home base in southwest France, followed by two additional in-flight evaluations during the following two days.

The proprietary power module is installed in an aft-fuselage “pusher” position, and combines three 60 kW high-performance electric motors (arranged in a triangular “barrel” configuration), with a 370-hp. internal combustion engine.

This configuration of the power module prefigures the full-up powertrain for VoltAero’s largest production Cassio aircraft version – the 10-seat Cassio 600 – which is to deliver a total hybrid-electric power of 600 kW (800 hp.), enabling the 200-kt. cruise (360 km./hr.) – which is fast for an aircraft in its category.

The patented series/parallel hybrid module design

“The startup of power module flight testing represents a true milestone for hybrid-electric aviation, and it keeps us on track toward our goal of having initial Cassio production aircraft entering service during late 2022 or early 2023,” explained Jean Botti, VoltAero’s CEO and Chief Technology Officer.

In regular operation, the power module’s electric motors will be used for low-noise takeoffs and landings, with the internal combustion engine serving as a range extender and for recharging the Cassio’s batteries while aloft. With VoltAero’s unique patented series/parallel hybrid design, the power module can operate in modes from full electric to full hybrid, depending on the customer mission profile and range requirement.

Additionally, as both the electric motors and internal combustion engine are linked to a common shaft that drives a five-blade “pusher” propeller, the ability for each to operate independently provides a high level of propulsion safety – with one source acting as a backup in case of a problem or failure of the other.

Applying integration and system expertise to production Cassio aircraft

VoltAero Technical Director and test pilot Didier Esteyne, who was at the controls of Cassio 1 for the flight tests, said he was impressed by the power module’s operation. “I felt very comfortable with its performance from the first takeoff,” Esteyne explained. “The power module provides a real propulsive ‘kick,’ and I look forward to opening the aircraft’s flight envelope.”

By installing and flight testing the power module on Cassio 1, VoltAero is gaining significant expertise that will be applied directly to its family of production Cassio aircraft. This includes integration of the entire battery power management system, the configuration of a new “glass cockpit” with optimized ergonomics for operation of the hybrid-electric power module, and the use of company-developed battery packs with their cooling systems.

In addition to the power module on Cassio 1, the testbed aircraft is equipped with two wing-mounted ENGINeUS 45 electric motors, which were supplied by Safran Electrical & Power and are installed in the forward-facing “puller” position. Prior to last weekend’s maiden flight with VoltAero’s addition of the aft-mounted “pusher” power module, Cassio 1 had logged 14 hours and 25 flights aloft with these 45 kW (70 kW maximum) electric motors in a full range of operating conditions, giving VoltAero unmatched in-flight experience with cutting-edge electrical propulsion.

In its latest configuration, the Cassio 1 testbed aircraft will be presented publicly for the first time during a VoltAero flight demonstration and program update event on October 21, to be streamed live via the VoltAero.aero website. (See the e-invite for details).

VoltAero’s aft-mounted hybrid power module and the forward-facing electric motors undergo a ground static run at VoltAero’s Royan-Médis Airport headquarters in the Nouvelle-Aquitaine region of France.