IEEE Electrification Magazine - June 2020 - 25

must be dispersed. This thermal load, typically, will
require some parasitic power draw for the drivetrain and
aerodynamic drag due to heat exchangers to function
appropriately, which increases the overall challenge of
storing sufficient energy for long-range missions.

Electrified Commercial Aircraft Programs
Driven to make electric flight for commercial transport a
reality, researchers have developed a number of visionary
aircraft concepts under previous and ongoing efforts.
While there are a number of notable concepts, only a
select few will be described here for brevity. Renderings of
these concept aircraft are shown in Figure 8.
For small, single-aisle aircraft, several turboelectric,
hybrid electric, and fully electric concepts have been
developed. The NASA STARC-ABL aircraft is designed as a
partial turboelectric concept, where power extraction from
a pair of turbofans is used to drive a tailcone thruster. By
placing the propulsor at the aft end of the aircraft, the
boundary layer produced by the fuselage is directly ingested into the electrically driven fan.
The ECO-150 concept developed by Empirical Systems
Aerospace is another turboelectric configuration with a

distributed electric propulsion system. Two large turboshaft
generators are used to produce electrical power, which is
then routed to a series of electrically driven ducted fans
mounted within the wing surfaces. This split-wing configuration offers several aerodynamic benefits for the platform
in addition to a substantial aeroacoustic improvement from
having the propulsors embedded.
The Boeing SUGAR Volt is configured with two electric
motor-boosted turbofans in a parallel hybrid architecture,
reducing fuel burn of the propulsion system, and a trussbraced wing for improved aerodynamic efficiency. The
Airbus E-Thrust has also been proposed as a series hybrid,
in which a large engine core drives a turboshaft generator.
This electrical power is combined with a battery system to
run a six-fan distributed electric propulsion system over
the main wing of the aircraft.
Projecting to technologies further in the future, researchers from Bauhaus Luftfahrt have developed the Ce-Liner
concept, which is a fully electric single-aisle transport aircraft. This concept uses an advanced battery system
assumed to emerge with future research developments as
well as high-temperature superconducting electric motors
to meet rated power and specific power requirements.

(a)

(b)

(c)

(d)

(e)

(f)

(g)
Figure 8. The commercial electrified aircraft propulsion concepts. (a) The NASA STARC-ABL (Source: NASA). (b) The ESAero ECO-150.
(Source: Empirical Systems Aerospace; used with permission.) (c) The Boeing SUGAR Volt. (Source: Boeing; used with permission.) (d) The
Airbus E-Thrust. (Source: Airbus; used with permission.) (e) The Bauhaus Luftfahrt Ce-Liner. (Source: Bauhaus Luftfahrt; used with permission.)
(f) The Center for High-Efficiency Electrical Technologies for Aircraft. (Source: University of Illinois Urbana-Champaign; used with permission.)
(g) The NASA N3-X. (Source: NASA).

IEEE Elec trific ation Magazine / J UNE 2 0 2 0

IEEE Electrification Magazine - June 2020

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