Tech Briefs Magazine - March 2022 - 52

APPLICATION
BRIEFS
Advancing Hybrid-Electric
Propulsion Systems for
Sustainable Flight
Collins Aerospace
Charlotte, NC
www.collinsaerospace.com
Pratt & Whitney Canada
Longueuil, Canada
www.pwc.ca/en/
T
o reduce its impact on the environment
and improve the sustainability of its operations,
the commercial aviation industry has
committed to achieve net-zero air transport
emissions by 2050. Among numerous technologies
the industry is exploring to help
achieve this goal, one that holds promise is
hybrid-electric propulsion.
The De Havilland Dash 8-100 flight demonstrator will be re-engined on one side with a 2 megawatt-class
propulsion system. (Photo: Collins Aerospace)
Hybrid-electric propulsion systems, which combine fuel-burning
engines with electric motors and batteries, create
opportunities to significantly improve aircraft fuel efficiency
and lower carbon dioxide emissions, while also offering potential
reductions in maintenance costs. Hybrid-electric propulsion
architectures could have broad applicability across different
aircraft types, with potential fuel savings ranging from 5
percent in large commercial aircraft, to 30 percent for regional
commuter aircraft. These advances in efficiency will also support
the growing adoption of sustainable aviation fuels.
High-power and high-voltage applications at altitude come
with varying challenges including materials, design, and testing
restrictions. Coupled with operation in a harsh environment
and the need to minimize failure rates during flight,
novel architectures including fault-tolerant designs and novel
processes, such as arc detection/HV insulation testing, need
to be investigated and developed. Thermal management optimization
of hybrid-electric propulsion systems will need to be
understood in detail to reduce the overall system weight and
maximize fuel savings. System integration understanding will
also be critical to reducing cost and improving product manufacturability.
Taking these technologies to certifiable standards
will require further understanding of end application requirements,
which continue to evolve in the emerging hybrid-electric
aviation market space.
Collins Aerospace is working with sister business Pratt &
Whitney Canada to advance sustainable hybrid-electric propulsion
technology for the aviation industry. In collaboration with
De Havilland Aircraft of Canada, Collins and Pratt & Whitney
are integrating a new hybrid-electric propulsion system into a
De Havilland Dash 8-100 flight demonstrator. The demonstrator
will be re-engined on one side with a 2 megawatt-class propulsion
system that combines a fuel-burning engine from Pratt
& Whitney with a battery-powered electric motor from Collins
in a parallel hybrid configuration.
52
Both the engine and the motor will each generate about 1 megawatt
of power for a 50/50 power split. The engine will be optimized
for cruise efficiency, while the electric motor will provide extra power
during take-off and climb, demonstrating around 30 percent better
fuel efficiency, compared to existing turboprop engines.
Typically, a regional turboprop aircraft, like the Dash 8, requires
high take-off power to carry large payloads, but flies relatively
slowly under relatively low power. The demonstrator will
leverage this large ratio between peak power and steady-state
power to create significant total energy savings. The electrical
assist is high power and short duration, allowing the size and
weight of the energy storage device to be manageable within
the aircraft maximum take-off weight.
The hybrid-electric system increases the aircraft operating
empty weight, effectively reducing the aircraft's fuel capacity
to allow for electrical equipment and energy storage. Based on
current assumptions of battery energy density and considering
the more efficient hybrid-electric system, the re-engined aircraft
would have a shorter range compared to the base regional
turboprop range of 1,000 nautical miles. However, given that
most regional turboprop missions are shorter than 500 nautical
The electric motor will provide extra power during take-off and climb,
demonstrating around 30 percent better fuel efficiency, compared to existing
turboprop engines. (Photo: Collins Aerospace)
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Tech Briefs, March 2022
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Tech Briefs Magazine - March 2022

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