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general manager for product strateg y and market.
Some LEAP-X technology can be adapted to the open
rotor design, but there will still need to be dedicated
technology acquisition to develop such an engine,
Lacorre adds. Challenges to be overcome include
installation and integration with the airframe and fan
Rival engine manufacturer Pratt & Whitney (P&W)
has taken a di erent approach to next-generation
engines, with its Geared Turbofan (GTF) technolog y
already having undergone ight testing on Airbus
A340 and Boeing 747SP testbeds.
e GTF engine, now known as the PurePower
PW1000G, o ers a 15 percent reduction in fuel
burn compared with today's equivalent powerplants.
It has also been selected as 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.
" 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
in a presentation in 2009. "To resolve that, we have
decoupled the fan and the LP turbine by putting a
e 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-
e ciency 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 an in-ser vice engine, of
between 10:1 and 11:1. GTF technolog y 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 while 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 technology, which means it could be o ered
as a solution for larger aircra as well, including any
potential successor to Boeing's 777.
In April, the manufacturer formally inked a deal
with Russia's Irkut to begin preliminary design
activities on the PW1000G as the powerplant for the
manufacturer's planned MS-21 narrowbody jetliner.
The aircraft is being jointly developed by Irkut,
Yakovlev and Tupolev as a replacement for Tupolev
Tu-154 and Tu-204/214 aircra .
Pratt & Whitney will power the MS-21 with
a higher-thrust variant of its engine, designated
PW1400G, rated at 25,000-32,000lb thrust.
Full engine tests on the PW1000G for the CSeries
and MRJ aircra are scheduled to begin this year. e
rst ight of the MS-21 is expected to take place in
2014, with entry-into -ser vice in 2016. ●
Pratt & Whitney says there is no thrust
limitation on its geared turbofan technology.
PRATT & WHITNEY
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