Page 15 - AAA JANUARY - FEBRUARY 2017 Online Magazine

FEATURE REGIONAL AIRCRAFT

is forecasted.” In all, by 2034, Bombardier should be.” “With this technology, not only do Bombardier, Embraer and Mitsubishi agree,
believes the 60 to 150-seat aircraft segment you (get) optimal speeds but, because it’s now engines alone don’t complete the fuel cutting
will grow by 15,000. From the get-go, Mullot turning slower, it allows for a bigger fan. And package for their aircraft. “The integration
says the goal was to reduce fuel burn and a bigger fan is far more efficient because air of the engine and the wing is extraordinarily
thus emissions significantly compared with is pushed backwards at a lower speed. That nice” in the CS100, Mullot says. “We use the
in-service, in-production aircraft. Compared makes for a far quieter engine, too, precisely latest in aerodynamic technology in order
with the Airbus A318, for example, he says because the speed of the air emanating from to really reduce drag.” Drag and lift are
flight tests confirm a 20 per cent fuel-burn the fan is slower.” constantly at war in aircraft design. ‘Drag’,
improvement for the CS100. This has practical implications, Mullot as the name implies, is the aerodynamic
Key to cutting consumption is the says. “Take a 70 dB footprint around an force that opposes an aircraft’s movement
powerplant, Pratt & Whitney’s PurePower airport, take the C Series and (ask): ‘Where through the sky. Even powerful engines can
PW1500G Geared Turbofan, a member of the can you see that 70 dB limit around the produce drag. Good design can mitigate it.
engine-maker’s PW1000G family. So, fuel- takeoff area? Usually (with the C Series) that The aim is to integrate engines and wing,
stingy is the engine that variants also power noise area is contained within the airport engines and airframe, so structures more
Embraer’s E-Jet E2s and Mitsubishi’s MRJ. limits.” For an equivalent-sized aircraft to aerodynamically interact with one another.
Embraer’s CEO Luis Carlos Affonso is a rated the CS300, such as the 737-700, he asserts Data from Embraer illustrate just how
pilot who holds a degree in aeronautical “the size of that noise footprint would be consummate fuel burn reduction comes
engineering. That gives him an intimate about four times larger.” To prove its prowess, from looking at the whole aircraft. Affonso
insight into how the geared turbofan differs Bombardier took the CS100 to Stockholm’s says the net installed product of Pratt’s
from conventional fan-jet engines: “It’s called Bromma Airport and put the hushed jet powerplant is an 11 per cent reduction in
‘geared turbo-fan’, basically because there through its paces. Bromma is a highly noise- fuel burn. New wings — one for each for the
is a gear, a reduction gear box, between the sensitive airfield, which sits a scant a few E175-E2, E190-E2 and E195-E2 — result in 3.5
turbine and the fan,” he explains. The fan is kilometers from downtown Stockholm. per cent fuel savings. A fourth-generation ‘fly
the big assembly just in front of the engine The PW1000G family is comprised of by wire’ (FBW) control system contributes
and turbines. “Turbines like to turn fast,” ultra-high-bypass powerplants with a bypass 1.5 per cent fuel savings. In fly by wire, the
Affonso says. “They are more efficient if ratio of 12:1. Affonso says many current fan- pilots’ control inputs go to computers,
they turn very fast.” But fans operate more jet engines have a 6:1 bypass ratio. That’s which, in turn, activate hydraulic controls
efficiently at slower speeds. “The (reduction) why the Geared Turbofan (GTF) marks a connected to ailerons, elevators and rudder.
gear allows the turbine and the fan to turn at “huge increase in the bypass ratio … 12:1 This tweaking of the FBW means the E2s
their own optimised speeds. If you don’t have means twelve more (parts of) air are pushed “can be designed with a centre of gravity
a gear, you have a compromise solution: the back by the fan, and just one portion is going to the rear,” Affonso says. “With that, the
(turbine turns) a little bit slower than it would through the engine, through the combustion downward force of the empennage (the tail)
like to; and the fan is a little bit faster than it chamber turning the turbines.” But as can be reduced.” That renders the empennage

WWW.GBP.COM.SG/AAA JANUARY / FEBRUARY 2017 ASIAN AIRLINES & AEROSPACE 15