Hybrid-electric aircraft are preparing for takeoff. In a step toward reducing the airline industry's carbon footprint, manufacturers have started combining electric propulsion systems with traditional aircraft engines (gas turbines and internal combustion engines). But before these hybrids can achieve liftoff, they must meet stringent criteria for performance, reliability and safety.
In 2021, the National Research Council (NRC) Aerospace Gas Turbine Lab (GTL) in Ottawa opened a one-of-a-kind hybrid test facility to help the industry develop sustainable, low-carbon aviation technology. The Hybrid Electric Research Outfit (HERO) offers innovators in the aircraft electrification space a flexible platform to scientifically test new ideas on a ground-based micro-grid, and from there gauge how their innovations will perform in flight.
"Over the years, our meetings with international organizations such as NASA and the German Aerospace Center have yielded input on aviation initiatives toward a carbon-neutral future," says the NRC's Shaji Manipurath, Director, R&D, Gas Turbine Laboratory. "This, together with feedback from the industry, helped us identify the need for a facility like HERO, and gain support for establishing it."
Electric propulsion technology comes with different devices, systems and risks, so global regulatory agencies must devise new certification regimes. Every product from bolts to wings undergoes a rigorous process, and the HERO team provides evidence-based knowledge to feed into aircraft regulations.
The nuts and bolts
Powered by 200 kilowatts of electricity, HERO is a starting point for hybrid testing. "It is a pilot-scale facility that benefits small, short-haul aircraft," says Osvaldo Arenas, Team Leader, Aerospace Gas Turbine Lab, Central Facilities. "And it's gaining traction as internal and external R&D projects grow."
One such project, SEED (Serial-hybrid Electric Drivetrain), was completed in early 2022 at HERO. This work demonstrated continuous electric propulsion power at 90 kilowatts and 800 Volts, with efficiency above 95% in fully electric operation.
The NRC also demonstrated HERO's capability to simulate flight missions using programmed battery discharge profiles. This successful project was completed in collaboration with a Canadian university under the NRC's Low-Emission Aviation Program (LEAP).
Several external projects are either in progress or under discussion with industry partners. Canada's regulator, Transport Canada, is also engaged with the HERO team to better understand the performance, operability and reliability of electric aircraft propulsion technology.
"We conceived the HERO platform to help us learn about this revolutionary technology and propel us into global leadership," adds Arenas. It saves researchers time and money – and lets them conduct critical experiments on the ground before testing their findings in the air. "It was built to accept many different types of devices like motors and power electronics that can be swapped out or removed."
HERO houses a microturbine system, which works like a jet engine but produces electricity instead of thrust. The facility can also be cast into fully electric, turbo-electric or hybrid-electric configurations. It puts tools at researchers' fingertips that allow them to study the limitations of battery technology, work with different components in electric engines, remove them easily and integrate them with others to test their performance.
Toward cleaning up the skies
The Government of Canada's greening goal – shared by the aviation sector globally – is to become carbon-neutral by 2050. In this industry, that means replacing jet fuel with sustainable fuels from renewable sources, or replacing gas turbine engines with electric or hybrid electric ones.
"Aviation is one of the most difficult sectors to decarbonize because of the long distances you have to travel, and the megawatt scale power requirements," says Manipurath. "The biggest constraint is not propulsion but energy storage." Since today's batteries are extremely heavy, fully electric flight is still decades away.
With a view to tackling the additional challenges posed by the need to develop propulsion and energy storage for larger aircraft with longer ranges, the NRC plans to grow the 200‑kilowatt HERO facility into a megawatt-scale capability. It will also continue to investigate using hydrogen instead of jet fuel.
This expansion will increase support to the industry, which aims to launch larger hybrid aircraft by 2040. And it will help the NRC and Canada to not only maintain their leadership position in gas-turbine R&D and green technology, but also gain the experience to remain competitive in the vast new area of clean fuels and technology.
The environmental impact will grow exponentially once larger passenger and cargo planes are deployed around the world. "With many countries coming onto the market with their own solutions, ready access to facilities like HERO become more critical for Canadian innovators," says Manipurath. "It enables them to test their concepts and develop products here in Canada for the world." And through focused collaborations with academia, HERO will also train the next generation of specialists in this field.