AOPA Pilot Magazine - August 2019 - 44

Blow off
some steam.

PILOT BRIEFING

Get IFR-Rated Glass for Under $5K

Ampaire 337 unveiled
Hybrid-electric airplane flies in California
BY BARRY SCHIFF

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Copyright 2019 Aspen Avionics Inc. "Aspen Avionics," "Evolution Flight Display System,"
and the Aspen Avionics aircraft logo are trademarks of Aspen Avionics Inc. All rights
reserved. U.S. Patent No. 8,085,168, and additional patents pending.

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LOS ANGELES-BASED Ampaire recently
unveiled and demonstrated at Camarillo,
California, its Ampaire 337. The 3-yearold company claims this to be the "highest
capacity [largest] hybrid-electric airplane
ever flown."
The Ampaire 337 is a Cessna 337
Skymaster with its rear, 210-horsepower Continental engine replaced with
Ampaire's proprietary electric-propulsion
system. This is essentially a battery-powered electric motor. Although called a
hybrid-electric airplane, it is not a hybrid
in the sense of a hybrid automobile. The
two powerplants are completely independent of one another, and the lithium-ion
batteries that power the motor cannot be
charged in flight.
Ampaire refers to this combination of
powerplants as a "parallel hybrid," meaning that "the two independent sources of
power work in concert to optimize power
output." In its current configuration, the
batteries must be charged following a flight
or replaced with a charged battery pack
standing by on the ground, a process that
will eventually be accomplished in less than
15 minutes. In the 337's final configuration,
the ship's batteries will occupy part of a
cargo pod attached to the belly of the airplane so as not to take up space in the cabin.
The centerline-thrust Cessna
Skymaster was the obvious choice for this
Experimental aircraft because it allows differences in thrust to occur without creating
any yawing (such as could result from different types of powerplants mounted on

44 | AOPA PILOT August 2019

opposite wings of a conventional twinengine airplane).
Although the motor installed in the aircraft is capable of producing 180 kilowatts
of power (240 horsepower), it currently is
limited to an output of 160 kW (215 horsepower) so as not to exceed by much the
maximum power for which the airplane was
originally certified. Fully charged batteries
enable the motor to generate maximum
power for 5 to 6 minutes but last substantially longer at lower power settings.
The electric propulsion system adds
approximately 400 pounds to the empty
weight of the airplane, but this enables the
aircraft to be flown with a relatively light
load of fuel. As a result, useful load remains
approximately the same.
Charging the batteries takes about two
hours. The cost of the electrical energy
needed for charging is less than half the
cost of the equivalent amount of avgas.
The electric propulsion system is 85
percent quieter than the reciprocating
engine that it replaces. What noise remains
is created solely by the three-blade, variable-pitch propeller moving air rearward.
The company plans to eventually developing single- and twin-"engine" airplanes
powered solely by its proprietary electricpropulsion system(s).
Ampaire's electric propulsion system
is not yet practical for use by individuals
because infrastructure is required at en
route and destination airports to charge
and exchange replacement batteries.
www.barryschiff.com
http://www.barryschiff.com http://www.aspenavionics.com
AOPA Pilot Magazine - August 2019

Table of Contents for the Digital Edition of AOPA Pilot Magazine - August 2019
