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APRIL 2015
AEROSPACETESTINGINTERNATIONAL.COMz More-electric aircraft
operation and maintenance. For
example, without a reciprocating
engine, pilots of electric aircraft would
not need to consider carburetor heat,
mixture settings or fuel selection.
The agency particularly notes
that ‘the only two moving parts’ with
electric power are the motor shaft
and the propeller. It envisages aircraft
systems that monitor and record motor
and battery performance for download
at any time: “Your next inspection may
involve handing over a thumb drive to
a mechanic, or having them connect a
laptop to your motor via a USB cable,”
notes the safety document.
But the FAA also acknowledges that
new technologies involve drawbacks
and unknowns: “This is particularly
true with battery technology.
Questions loom, such as how often
batteries need replacing and whether
their power-to-weight ratios will
improve enough to be viable for
more than just short hops.”VIEW AHEAD
One man keen to promote MEA
technologies, particularly power
electronics, is Professor Patrick
Wheeler, director of the UK’s
University of Nottingham Institute
for Aerospace Technology and of the
EU-funded Clean Sky research project.
He says that, in addition to
providing electrical current for avionics,
in-flight entertainment and lighting, theAIRBUS E-FAN
The 600kg E-Fan is the first
aircraft with fully electric fan
propulsion, claims Airbus Group.
Two 30kW electric motors
powered by 250V lithium-ion
polymer batteries drive ducted
variable pitch fans.
Airbus Group anticipates an
E-Fan family of aircraft, seen as
the first all-electric production
machines, and has signed up
partners for the industrialization
phase of the E-Fan 2.0 two-seat
trainer, for service entry in 2017.
Subsidiary Voltair and
aerospace supplier Daher will
design, develop (including engine
and batteries), build, flight test
and certificate the E-Fan 2.0,
which “will be the first all-electric
production aircraft certificated to
international standards”. The four-
seat E-Fan 4.0 is planned for ab
initio training and general aviation.batteries in the air. Marty Bradley,
Boeing’s principal investigator for the
Cambridge project, sees hybrid electric
as an important element of research:
“We are learning more every day about
the feasibility of these technologies and
how they could be used.”
Airbus Group has used an electric-
powered variant of the minuscule Cri-
Cri aircraft and is developing its own
small E-Fan test aircraft.
Although reserved about battery
technology, US airworthiness
authorities are taking a firm interest.
“Electric propulsion has the potential
to be a real game-changer for GA,”
according to the FAA aircraft
certification service.
The agency’s Small Airplane
Directorate (SAD) studies new
technologies to improve safety and
reliability. “We’re looking at the total
package that electric propulsion can
bring. We must first determine if it is
safe, economical and practical.”
SAD analysis revealed several
factors to consider when integrating
more electric philosophies into aircraft
regulations, such as battery technology
and performance limitations. As
knowledge and experience increases,
officials believe it may be possible to
adapt MEA technology to type-
certificated aircraft.
An FAA safety document identifies
the benefits of electric propulsion
systems, including simplicity of design,“WE ARE LEARNING MORE
EVERY DAY ABOUT THE
FEASIBILITY OF THESE
TECHNOLOGIES AND HOW
THEY COULD BE USED”ATTITUDE CHANGE
As the major airframe, systems
and engine manufacturers move
incrementally into MEA technology,
the most visible progress is among
small aircraft in the GA industry. This
sector, accounting for 90% of civil
aircraft (except commercial airliners),
contains a large element of light, often
non-certificated, designs that
historically have extended
technological boundaries in
aerodynamics, materials, propulsion
and structures. And as the first
certificated all-composites aircraft was
the 1969 Windecker Eagle (not the
new Boeing 787, nor even the 1980s
Beech Starship), GA in fact pioneered
electric propulsion with academic or
larger aerospace partners.
As an example, late last year,
Boeing and University of Cambridge
researchers flew a hybrid gasoline/
electric-powered aircraft that was
claimed to be the first to recharge its
2.2
The number
in billions of
passengers
flying each
year2
The aircraft-
generated
percentage
of all man-
made CO 2
emissions- expected
to grow to
3% by 2050