Following the end of flight testing, the three partners behind the EcoPulse hybrid-electric aircraft demonstrator are already contemplating next steps, with a series of follow-on projects to debut next year.
A joint effort between Airbus, Daher and Safran, the EcoPulse aircraft accumulated 100h across some 50 test flights running from 29 November 2023 until July this year.
Based on a stock TBM 940 turboprop and its Pratt & Whitney Canada PT6 engine, the EcoPulse was modified with a Safran-supplied powertrain – including a turbogenerator, 800V distribution system and six air-cooled ENGINeUS 50 electric motors installed on the wing – plus a high-power battery system from Airbus, which also contributed flight-control software.
The 300kW-rated battery powered four of the six electric motors while a 100kW auxiliary power unit supplied energy to the other pair.
Describing the initiative as a “major milestone on the road to decarbonisation”, Pascal Laguerre, chief technology officer at Daher, says EcoPulse is instrumental in paving for the way for future programmes. “We now have a better idea of what is the maturity of the technology, the technological bricks we can put inside an aircraft.”
And while the partners continue analysing flight-test data, they are already preparing next steps.
Laguerre says next year Daher and Safran will launch a new project funded by French civil aviation research council CORAC “to work on these hybridisation and electrical technologies” ahead of a potential future programme launch.
That follow-on effort will allow further assessment of technological maturity levels, preparing Daher to “propose a design and manufacture an aircraft… by the end of 2027”, he says.
An additional CORAC-backed project is already up and running, adds Christophe Robin, Daher’s head of aircraft design, “in which we are thinking about a high level of hybridisation on the propulsion of one aircraft”. This is not a distributed system, he adds.
Airbus too is planning a further demonstrator, says Jean-Baptiste Manchette, head of propulsion of tomorrow at the airframer, as it keeps “exploring” the potential of different propulsion architectures, including electric, hybrid-electric and distributed.
“We are working jointly with Safran about how we move on with the integration of propeller onto a wing to see how we maximise both the efficiency of the engines with potential hybridisation and the efficiency of the engine installed on the wing,” says Manchette.
While no details are immediately available, he promises that “we are planning to have a quite impressive demonstrator coming”.
Most of the testing was conducted without the main turboprop engine providing thrust, to fully assess the performance of the distributed propulsion system; typical flights were performed at speeds of around 100-150kt (185-280km/h).
Manchette says the blown-wing effect of the six distributed electric motors increased the efficiency of the wing, leading to an “increase in performance at take-off [and] during some manoeuvres”.
Additionally, by varying power to each motor “you can play with the trajectory of this aircraft, you can handle the aircraft with this distributed propulsion”, he adds.
Eric Dalbies, chief technology officer at Safran, says the EcoPulse project was an opportunity to test its end-to-end electrical capabilities.
“This was a way for us to group all the components and arrange them in a system to check whether they have a chance to work in the appropriate way when grouped and connected together.
“That’s the first real-time experiment for use – especially with a flight at altitude.”
Dalbies also notes that the decision to use air-cooled motors was validated by the flights. “No active cooling means lighter electric motors – which is once again an enabler for aviation.”
Development of the Eco-Pulse was first announced at the Paris air show in 2019. France’s DGAC civil aviation authority part-funded the work.
