Safran Moving Forward on Hybridization, SAF for Helos

Safran Moving Forward on Hybridization, SAF for Helos

Safran Helicopter Engines is planning to hand over its new 2,500-shp Aneto-1X engines to Airbus Helicopters midyear in preparation for flight trials of the compound Racer next year. Those tests will prove out in flight the “eco mode” configuration of the Aneto-1X engines that is anticipated to produce up to a 15 percent savings in fuel burn. Under the configuration, one of the two engines that will power the high-speed Racer can be placed in standby mode during cruise flight.

The technologies involved are part of a multi-pronged research effort underway at Safran to explore advanced technologies around ultra-high-efficiency engines and fuel alternatives, hybridization and electrification, expansion in digitalization, and additive manufacturing.

Safran stresses that the future of helicopter propulsion lies in the hybridization of thermal and electrical power services and with this view has worked across its divisions to develop technologies involved in the Aneto-1X engines that were announced for the Racer during Heli-Expo 2018.

A demonstrator validated the eco mode during ground tests in 2019, Safran said. The configuration enables the pilot to “pause” one engine while the second supplies full power, increasing range along with fuel savings. When more power is necessary—during acceleration, landing, autorotation, for instance—the idling engine is restored to full power rapidly and automatically using a high-power-density electric motor developed by Safran Ventilation Systems.

While eco mode was developed for a twin, Safran also is looking at a step toward hybridization in the single-engine helicopter, including the use of electrical power assistance to improve safety in case of an in-flight turbine-engine shutdown. In this case, the electrical power source will enable electrical flight for several minutes, Safran said, providing time for the pilot to land. In addition, Safran sees an added benefit of combining the electrical power source with the turbine to reduce emissions during takeoff.

This technology is now available for a new helicopter platform, but not yet in service, Safran said.

Longer range, Safran is working on its distributed Hybrid-Electric Propulsion System (HEPS) for emerging aircraft, such as VTOLs. HEPS distributes electrical power to multiple rotors or propellers using a power supply based on a turbogenerator and batteries and a hybrid power management system.

In 2018, various Safran companies collaborated on the first ground tests of a HEPS that could deliver 100 kW of electrical power, proving out technical feasibility. Flight tests of this technology also are planned for 2022 on the Ecopulse demonstrator developed with Airbus and Daher. Safran is exploring the use of a more powerful turbogenerator with hopes of having a range of offerings for new helicopters and other VTOL and aircraft concepts, it said.

As work progresses on this effort, Safran said it continues to make strides on the use of sustainable aviation fuel (SAF) as well as eying the future potential of hydrogen. Widely acknowledged as the most technologically accessible solution, Safran has launched a project with other aerospace stakeholders to evaluate the ability to burn as much as 100 percent SAF. Currently, all of Safran’s engines are certified to run on up to 50 percent SAF blend, the engine-maker said.

Right now, the 50 percent blend option is a true “drop-in” without the need for technical modifications. To get to 100 percent, Safran needs to work through issues surrounding the lifespan of seals and pumps to ensure efficient combustion, it added. This study also will look at the reduction of other pollutants, such as NOx, involved with the change in the chemistry of the fuel.

Safran Helicopter Engines further has kicked off a feasibility study with partners in southwest France to evaluate local capabilities and skills in the fields of agriculture, chemicals, and energy that could produce and distribute SAF, the company said. “We believe that a circular economy-type production system that could use biomass resources not currently being reused, such as agricultural and logging waste, is key to ensure decarbonization of our industry,” Safran said.

Meanwhile, Safran is looking longer-term at the use of liquid hydrogen, a major push of Airbus. However, this involves a number of other issues that need to be sorted out, including the entire helicopter fuel chain, from storage to distribution. Safran said it has several research projects underway to determine feasibility.

Safran further has turned its attention to production and materials, moving forward with its Add+ technological demonstrator that is based on the Arrius helicopter engine but has 30 percent of content made through additive manufacturing (3D-printed). That demonstrator completed a test campaign earlier this year involving 2,500 operating cycles and Safran said, the “first parts analyses have been very conclusive.”

Trials evaluated components such as nozzle guide vanes, combustion chamber, and stator rear module made through a “selective laser melting” process. “What were formerly assemblies of hundreds of separate pieces can now be molded into a single piece,” Safran said. For example, accessory gearbox casing is now made of two pieces instead of 12.

A second phase of tests is planned and Safran is continuing its evaluation of the parts before introducing them in serial production. But the ultimate results will pave the way for use of 3D-printed parts throughout the group. 

All of this work has progressed against the backdrop of the Covid-19 pandemic, Safran noted. The engine maker expanded the use of its digital tools and remote operations to manage through the pandemic but has been able to keep its design offices, production, customer support, and MRO centers open. Safran conceded that “like most aerospace manufacturers our business has been impacted by the Covid-19 crisis with a drop in flight hours and orders.”

However, certain markets of the helicopter segment were less affected such as medical transport, anti-terrorism, sea and mountain rescue, firefighting, and aerial work.

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