Page 47 - European Energy Innovation - winter 2019 publication

Winter 2019 European Energy Innovation
electric system architectures share
inherent challenges such as thermal
management of the heat loads in the
electric components, electromagnetic
interferences at high currents, or
arcing at high flight altitudes where
the thin air no longer serves as an
electric insulating medium. There is a
need for a common roadmap, linking
upstream research and demonstration
to research priorities on the key
enabling technologies, as well as an
adapted regulatory framework for
electric propulsion in aviation. The full design and operation cycles in
technology cycle from exploration,
maturation and demonstration of
the application in a product has to
be accelerated for all components of
the electric power train, ranging from
energy storage, power conversion and
distribution to electric motors and
propulsive devices.
NECESSARY CHANGES IN AIRCRAFT
DESIGN?
The increased number of
components in a hybrid-electric
power train, compared to a
conventional architecture, can lead
to efficiency losses that have to
be compensated with improved
sub-systems and efficiency gains
at the aircraft level. In addition, any
architecture relying on batteries has
a major disadvantage that battery
weight remains constant during a
flight mission, while a conventional
aircraft burns fuel and therefore loses
weight. For these reasons, despite
all improvements with respect to
in-flight emissions, a pure conversion
of an existing design to an electrically
powered aircraft will always suffer a
significant loss of mission range. In
order to overcome these drawbacks,
the designer has to adapt the
aircraft configuration to maximise
synergetic effects when integrating
an electric propulsion system. Such
synergies, for example, can be found
in a distributed propulsion system
providing high lift functionalities, in
a boundary layer ingestion concept
improving drag characteristics, or in
wing tip propulsors for directional
www.europeanenergyinnovation.eu
47
ELECTRIC FLIGHT
Student project 'HyBird' – hybrid-electric 9-seater
control. Also, energy harvesting larger aircraft, where a full-electric
technologies could be of interest, 19-passenger commuter would be
where excess energy is recuperated a feasible target for the European
similar to advanced automotive industry. This would open new flexible
solutions in operation today. In routes to link smaller cities, enabling
summary, efficient electric aircraft air mobility for the European citizens
will look very different to current at zero emissions on thin routes.
aircraft configurations. One step further, hybrid-electric
regioliners with distributed propulsion
A NEW AIR TRANSPORT SYSTEM and a synergetic configuration
Aviation is characterized by long design will surpass the efficiency
and environmental performance of
a highly regulated international the current generation of regional
framework. Therefore, while aircraft. And not least, focussed and
exploration and demonstration of successful research towards a new
innovative technologies for electric sustainable air transport system
flight have finally started on a broader would help ensure the leadership
level, improvements will only become and competitiveness of the European
visible at a global fleet level about a aircraft industry. l
decade after the introduction of the
corresponding advanced products.
It will be increasingly important to
focus on accelerated technology
development, following an aligned
roadmap for three distinct market
segments: a full-electric short-range
commuter network, hybrid-electric
regional transportation and long
range flights powered by ultra-
efficient gas turbines with enhanced
thermodynamic cycles, making use
of sustainable carbon-neutral bio- or
synthetic aviation fuels.
The feasibility of electric and hybrid- Prof. Dr. Andreas Strohmayer
electric propulsion today has been Institute of Aircraft Design
demonstrated with small general University of Stuttgart
aviation airplanes. Now these Email: strohmayer@ifb.uni-stuttgart.de
technologies have to step-up to Web: www.ifb.uni-stuttgart.de