GENEVA—French aircraft developer Daher says it will begin narrowing down design options later this year for either a lightly hybridized or all-electric production follow-on to the TBM 900-based EcoPulse hybrid-electric demonstrator, which is under development with Airbus and Safran.

The EcoPulse TBM 900’s standard Pratt & Whitney Canada PT6A turboprop engine and propeller are augmented by a distributed propulsion system, which is made up of six wing-mounted propellers. Each of the propellers is driven by a 45-kW Safran ENGINeUS electric engine powered by batteries or a 100-kW auxiliary power unit.

While Safran is responsible for providing the distributed propulsion system, Airbus has developed the high-energy-density battery that will supply electrical power to four of the six propellers. The European aircraft manufacturer is also leading the aerodynamic and acoustic integration of the distributed-propulsion system, as well as development of the flight control computer system. 

The demonstrator has so far amassed around 15 hr. of flight time with the electric propellers feathered. Flight tests of the hybrid-electric powertrain are due to begin later this summer following the aircraft’s appearance at the Paris Air Show in June. Initial tests will gradually build up from augmenting the turboprop with two electric propellers to later phases involving four and eventually all six props.

“We are going to learn a lot,” says Nicolas Chabbert, senior vice president of Daher’s aviation division.

From the demonstration program, Daher plans to develop its future product roadmap and “basically spec the hybrid aircraft we intend to produce by the end of our five-year plan. We expect by the end of 2027 to be able to offer our first hybrid aircraft to the market,” Chabbert adds.

The program is aimed at identifying the methods, tools and outcomes needed for the design of a distributed-propulsion aircraft, as well as gaining knowledge from flight tests of a new high-voltage-battery configuration. The work is expected to improve alternative-propulsion simulation models for use on larger aircraft and will generate data on the aerodynamic gains from reducing wing surface area and wingtip marginal vortices for less drag.

Daher currently produces the high-wing Kodiak light-utility turboprop aircraft at its facility in Sandpoint, Idaho, and the low-wing TBM aircraft at its facility in Tarbes, France. Either design could be used as the jumping-off point for its production hybrid new-build.

“There are two approaches to light hybridization in search of better efficiency. The TBM will probably be a better candidate for that version. Or, if we have to go for a full-electric version, then the Kodiak is actually going to be a better platform,” Chabbert says.

“We are looking for different formulas and once we know we have one that will answer the market, then we will determine the level of interest. We will basically split the aircraft around what is technologically possible and what is of interest to the market,” he adds.