Home' Asian Aviation : AAV June 2011 Contents 18 AsianAviation | JUNE 2011
European aircra manufacturer Airbus has
caused upheaval in the industry with its
launch in December of the re-engined
A320neo -- standing for 'new engine
Orders have been coming in thick
and fast for the aircra , which combines the bene ts
of a proven airframe with an all-new engine to o er
substantial reductions in fuel burn and emissions. By early
April, Airbus already had 330 orders and commitments
for the new model on its books, including a 100-unit
order from lessor International Lease Finance.
e aircra , being o ered with a choice of CFM
International's new Leap-X engine or the Pratt &
Whitney (P&W) PurePower PW1100G geared
turbofan, is threatening to pull the rug out from under
some rival single-aisle programmes, such as Bombardier's
CSeries. An unproven, clean-sheet design from a new
market entrant may be seen as a riskier proposition than
an upgraded version of a well-established aircra type.
Boeing has yet to respond, but seems inclined to wait
until the end of the decade, when technolog y is expected
to become available to justify an all-new single-aisle
design that will o er even more dramatic performance
In the meantime, the Leap-X and the PW1100G have
opened up new possibilities for airlines in e ciency, fuel-
economy, performance and emissions reduction -- all of
which are more crucial than ever for operators still reeling
from the global recession, facing soaring fuel costs and
ever stricter environmental regulations.
P&W has based its PW1000G family of engines on its
geared turbofan (GTF) technolog y, which has been
ight-tested on Airbus A340 and Boeing 747SP testbeds.
e GTF engine o ers a 15 percent reduction in fuel
burn compared with today's equivalent powerplants.
Selected as the lead engine for the A320neo -- with a
target in-ser vice date of 2015 -- it is also the exclusive
powerplant for the Mitsubishi Aircra MRJ regional
jet and Bombardier's CSeries jetliner, scheduled to enter
ser vice in 2014 and 2013, respectively.
Essentially, GTF technolog y allows the engine's fan to
operate at a di erent rotation speed than the low-pressure
(LP) compressor and turbine, allowing each to operate at
its optimal speed.
" e only challenge that we see for the conventional
turbofan is that the fan is actually connected to the LP
turbine section, and that creates some sort of compromise
in performance," Shigeaki Nakano, P&W 's vice-president
of sales for Greater China said. "To resolve that, we have
decoupled the fan and the LP turbine by putting a gear
The Fan Drive Gear System (FDGS) comprises
a central sun gear connected to the LP turbine and
compressor sha , surrounded by ve star gears, which
then drive an outer ring gear, which drives the fan. is
allows the fan to spin two-thirds more slowly than the
engine's low-pressure compressor and turbine.
at permits an increase in fan diameter, which means
an increase in bypass ratio, boosting fuel-efficiency
and reducing noise. Meanwhile, the LP turbine and
compressor are free to spin faster, so they need fewer
stages and fewer blades to do the same amount of work
-- this simpli es manufacture of the engine, making it
cheaper to build and maintain.
Today, the General Electric GE90 155B has the
highest bypass ratio of any in-service engine, of between
10:1 and 11:1. GTF technology allows P&W to take
even smaller engines to a bypass ratio of at least 12:1.
Simulations performed at various airports suggest that
the GTF engine may yield a 73-77 percent reduction in
noise footprint. e manufacturer says that a Boeing
737NG or Airbus A320 aircra fall about 5dB below
the International Civil Aviation Organisation (ICAO)
Stage 4 noise standard. By comparison, Nakano says the
MRJ will be 15dB below, while the CSeries is expected
to be 20dB below the limit.
In 2009, Pratt & Whitney o cials con rmed that they
had found no thrust limitations to the GTF technolog y,
which means it could be o ered as a solution for larger
aircra as well, including any potential successor to
In April last year, the manufacturer formally inked
"The only challenge that we see for the conventional turbofan
is that the fan is actually connected to the LP turbine section." --
Shigeaki Nakano, P&W vice-president of sales for Greater China
A new generation of single-aisle aircraft, offering substantial fuel savings and emissions reductions, has been enabled
thanks to the latest engines being developed by Pratt & Whitney and CFM International, writes Andrzej Jeziorski.
Powering narrowbody evolution
The PurePower geared turbofan offers
airlines a 15 percent fuel reduction
compared with today's equivalent engines.
PRATT & WHITNEY
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