Aviation Week & Space Technology - January 15, 2015

AviationWeek.com/awst AVIATION WEEK & SPACE TECHNOLOGY/JANUARY 15-FEBRUARY 1, 2015 53

Graham Warwick Washington

Cleaner Rotors

Reducing emissions and noise are goals

for European rotorcraft research program

A

irbus Helicopters has begun
ground tests of a diesel-cycle
piston engine in an EC120 light
helicopter, with the goal of demon-
strating a 30% reduction in specific
fuel consumption over the existing
turboshaft engine. Flight tests are
planned for the second quarter of
2015.
Testing is being conducted under
the High-Compression Engine (HCE)
project within the European Clean Sky
research program’s Green Rotorcraft
(GRC) integrated technology demon-
stration. The 330-kw (440-hp.) HIPE-
AE440 engine has been developed by
AustroEngine and TEOS.
Diesel-cycle engines are more fuel-

efcient than gas turbines and can burn
the same kerosene jet fuel, but they are
heavy and have previously been unable
to achieve the power output required
at a weight low enough for use in a light
helicopter such as the EC120.
The HIPE-AE440 has been designed
using technologies from the motor-
racing sector. The core engine weighs
197 kg (434 lb.) dry and 249 kg as an
installed powerpack, including cooling,
clutch, harnesses and other ancillaries.
This gives a weight-to-power ratio of
0.8 kg/kw.
“This is the first time a piston engine
delivering 330 kw with a weight-to-
power ratio of 0.8 is being developed.
This was made possible thanks to
proven car-racing technologies; oth-
erwise it probably would have taken
twice as long,” says Sebastien Dubois,
GRC project ofcer.
“Engines with the power range to
replace the turbine did not exist with
the mass required for the EC120, but
there has been tremendous progress
in automobile racing, particularly Le
Mans,” he says.
Started two years ago, the €9.3 mil-
lion ($11.4 million) HCE program was

planned to last 39 months. After some

problems with parts breaking in pre-

liminary testing, the project will now

run for 42 months. Typically, devel-

oping a new engine takes around five

years, says Dubois.

The HIPE-AE440 is a V8 with four

valves per cylinder with common rail

high-pressure fuel injection and two

turbochargers with air-to-air inter-

cooler. Its design combines Austro-

Engines experience producing tur-

bodiesels for aircraft with TEOS’s

race-car engine expertise.

The project will enable direct com-

parison between the EC120 with tur-

bine and diesel power. In addition to

lower fuel consumption, reductions of

40% in carbon dioxide and 50% in nitro-

gen-oxides emissions are expected and

up to 30% lower direct operating costs.

Ground tests are being performed at

Airbus Helicopters’ Marignane plant

in France. Some 15 hr. of flight testing

is planned. This will take the high-

compression engine to a technology

readiness level (TRL) of 6—the objec-

tive for Clean Sky—ready to be used in

product development.

Other Green Rotorcraft projects are

entering the hardware demonstration

phase, including separate eforts look-

ing at actively controlled and passively

optimized rotor blades and an electric

tailrotor drive.

Under the active Gurney flap proj-

ect led by AgustaWestland, model ro-

tor testing is planned for the second

quarter of 2015, followed by full-scale

whirl-tower testing in the third quar-

ter and flight tests on an AW139 in the

fourth quarter.

A small surface that deploys verti-

cally upward from the trailing edge of

the mid-blade section on the retreat-

ing side of the rotor, the Gurney flap

increases lift on the retreating blade

and reduces the power required to

maintain forward speed.

Airbus Helicopters, meanwhile,

is leading the passively optimized

blade project, which promises power

reductions of 5% in hover and 2% in

cruise—and 4-5-db lower approach

noise—through optimization of blade

chord, twist and other features, such

as anhedral.

Aerodynamic and acoustic design is to

be finished in January, says Dubois, with

manufacture of the blades to begin in the

second half of 2015. Whirl-tower testing

is planned for January 2016. Flight tests

on an EC135 in the early summer of 2016

are not yet funded, but a decision will be

taken in mid-2015, he says.

AgustaWestland is leading the elec-

tric tailrotor drive (Eletad) project,

working with Bristol University in the

U.K. The project is developing a high-

power-density electric motor with high

integrity and reliability. The first pro-

totype motor and an alternative solu-

tion have been delivered for evaluation.

The drive motor and control al-

gorithm will run on a tailrotor test

stand in 2015-16. The motor will be

integrated into a helicopter tailboom

and drive a complete AW139 tailrotor.

System power will come from aircraft

air-cooled electrical generators to pro-

vide a fully integrated system.

The rig will evaluate system dy-

namic operation while powering the

rotor through mission-representative

tail load cycles. “We will completely

simulate the working conditions of the

tailrotor with a complete system inside

a tail. The objective is TRL 5 through

ground test,” says Dubois. c

ROTORCRAFT

Ground tests of AustroEngine’s
diesel-cycle HIPE-AE440 in an
EC120 begin this month at Airbus
Helicopters in Marignane.

CLEAN SKY JOINT UNDERTAKING