| Boeing
777 Market demand has sized, shaped and
launched the newest member of the Boeing family, the 777.
The airplane design offers features, innovations and
approaches to aircraft development that set the
standard for delivering value to airlines. The 777 -- the
world's largest twinjet -- is available in three
models: a 777-200 initial model, a 777-200 increased
gross weight (IGW, longer range) model, and a
larger 777-300 model.
On Feb. 15, 1996, the 777 was named winner of the
prestigious Robert J. Collier Trophy by the U.S.
National Aeronautic Association. The award honored the
777 as top aeronautical achievement of 1995.
Initially, United Airlines, All Nippon Airways, British
Airways, Japan Airlines and Cathay Pacific were
among a number of carriers with whom Boeing held
intensive discussions, including many group
sessions, to define and develop the new airplane's
configuration. The participating airlines represented a
full range of operations in terms of route structure,
traffic loads and service frequency. Their input to the
design process helps ensure that the final product has
the broadest possible application to the needs
of the world's airlines.
In every respect, the 777 design responds to market needs
and customer preferences. The result is an
airplane offering cabin spaciousness and flexibility
found in no other jetliner and many features to
enhance reliability and productivity -- all with lower
operating costs. The 777 provides the most payload
and range capability and growth potential in the
medium-size aircraft category.
Another benefit of the intensive customer dialogue was a
consensus that many items traditionally
offered as optional, or special-request, features on
other airplanes should be standard (or basic)
equipment on the 777 since they are so frequently
specified by most airlines. About 80 such items --
including satellite communication and global positioning
systems -- are basic to the airplane. This
reduces variability during design and production, while
providing the airlines with a more economical
equipment package.
Wing Design
The 777 wing uses the most aerodynamically efficient
airfoil ever developed for subsonic commercial
aviation. In a further refinement of designs introduced
on the Boeing 757 and 767, the 777 wing features
a long span with increased thickness while achieving
higher cruise speeds. This advanced wing
enhances the airplane's ability to climb quickly and
cruise at higher altitudes than competing airplanes.
It also allows the airplane to carry full passenger
payloads out of many high-elevation, high-temperature
airfields.
Fuel volume requirements for the 777 are accommodated
entirely within the wing and its structural
center section. For the initial airplane, fuel capacity
is 31,000 gallons (117,335 L), while the
longer-range model and the 777-300 model can carry up to
45,220 gallons (171,160 L).
Airlines helping to design the 777 encouraged Boeing to
commit to the performance capabilities of an
optimum wing, which has a span of 199 feet 11 inches
(60.9 m).
Propulsion
The three leading engine manufacturers have developed
more efficient and quieter turbofans to power
the 777, and all three have been selected by 777
customers. United Airlines, ANA, Japan Air System,
Japan Airlines, Asiana, Egyptair, ILFC, Korean Airlines
and Air China selected Pratt & Whitney
engines for their 777s; British Airways, Lauda Air, ILFC,
China Southern, Continental Airlines, Saudia,
GECAS, Air France, Kuwait Airways and Egyptair chose
General Electric engines; and Thai Airways
International, ILFC, Cathay Pacific, Emirates, Singapore
Airlines and Malaysia Airlines selected
Rolls-Royce engines. South African Airways', American
Airlines and Garuda Indonesia engine
selections are pending.
For the initial airplane, these engines are rated in the
74,000- to 77,000-pound thrust class. For the
longer-range model and the 777-300, these engines will be
capable of thrust ratings in the 84,000- to
98,000-pound category. The engines could be developed to
even higher thrust ratings, depending on
future payload and range requirements.
All three makes are more powerful than current engines
and offer excellent fuel efficiency, while
allowing the 777 to be as quiet as a 767, even though the
777 engines provide 40 percent more power.
Key factors in this performance are new, larger-diameter
fans with wide-chord fan blade designs and
bypass ratios ranging from 6-to-1 to as high as 9-to-1.
This compares to the typical 5-to-1 ratio for the
engines of today's widebody jets.
Pratt & Whitney is offering the PW4000 series of
engines, General Electric is offering its all-new GE90
series, and Rolls-Royce is offering the Trent 800 series
of engines.
Materials
New, lightweight, cost-effective structural materials are
used in several 777 applications. For example,
an improved aluminum alloy is used in the upper wing skin
and stringers. Known as 7055, this alloy
offers greater compression strength than current alloys,
enabling designers to save weight and also
improve corrosion and fatigue resistance.
Progress in the development and fabrication of
weight-saving advanced composite materials is evident
in the 777. Carbon fibers embedded in recently available
toughened resins are found in the vertical and
horizontal tails. The floor beams of the passenger cabin
also are made of these advanced composite
materials.
Other composite applications include those on secondary
structures such as aerodynamic fairings.
Composites, including resins and adhesives, account for 9
percent of the 777's structural weight,
compared to about 3 percent on other Boeing jets.
Flight Deck and Airplane Systems
In response to airline preference expressed during the
pre-launch definition phase, the layout of the 777
flight deck is in a horizontal format similar to that of
the 747-400. Principal flight, navigation and engine
information is presented on six large display screens.
Although these displays resemble conventional cathode ray
tube (CRT) screens, they incorporate
advanced liquid-crystal display technology. The depth of
the new "flat panel displays" are about half
that of CRTs. In addition to saving space, the new
displays weigh less and require less power. They
also generate less heat, which contributes to greater
reliability and a longer service life. Another benefit:
they do not require the heavy, complex air conditioning
apparatus needed to cool equipment on current
flight decks. Pilots appreciate that flat panel displays
remain clearly visible in all conditions, even direct
sunlight.
Three multipurpose control display units (CDU), installed
in the center aisle stand provide data display
and entry capabilities for flight management functions
and are the primary interface with an integrated
Airplane Information Management System (AIMS). The CDUs
have color displays, again in response to
market preferences. Adding color allows pilots to
assimilate the information more quickly.
AIMS provides flight and maintenance crews all pertinent
information concerning the overall condition of
the airplane, its maintenance requirements and its key
operating functions, including flight, thrust and
communications management.
The flight crew transmits control and maneuvering
commands through electrical wires, augmented by
computers, directly to hydraulic actuators for the
elevators, rudder, ailerons and other control surfaces.
This three-axis "fly-by-wire" flight
control-system saves weight, simplifies factory assembly
compared
to conventional mechanical systems relying on steel
cables, and requires fewer spares and less
maintenance in airline service.
A key part of the 777 systems is a Boeing patented
two-way digital data bus, which has been adopted
as a new industry standard: ARINC 629. It permits
airplane systems and their computers to
communicate with one another through a common wire path
(a twisted pair of wires) instead of through
separate one-way wire connections. This further
simplifies assembly and saves weight, while increasing
reliability through a reduction in the amount of wires
and connectors. There are 11 of these ARINC 629
pathways in the 777.
In 1993, the 777 flight deck received accolades from the
Industrial Designers Society of America. For
the second year in a row, the 777 received the society's
Industrial Design Excellence Award for its flight
deck design.
Interior
In addition to being one of the most spacious passenger
cabins ever developed, the 777 interior offers
operators unsurpassed configuration flexibility.
Flexibility zones have been designed into the cabin
areas specified by the airlines, primarily at the
airplane's doors. In one-inch increments, galleys and
lavatories can be positioned anywhere within these zones,
which are pre-engineered to accommodate
wiring, plumbing and attachment fixtures. Passenger
service units and overhead stowage
compartments are designed for quick removal without
disturbing ceiling panels, air conditioning ducts or
support structure. A typical 777 configuration change is
expected to take as little as 72 hours, while
such a change might take two to three weeks on existing
aircraft.
Large overhead compartments provide passengers with
increased stowage capacity. Outboard as well
as center stowage units are designed to open downward for
convenient loading. When closed, they fit
neatly into the streamlined contours of the interior
architecture and allow ample overhead clearance.
For improved, more efficient in-flight service, the 777
is equipped with an advanced cabin management
system. Linked to a computerized control console, the
cabin management system assists cabin crews
with many tasks and allows airlines to provide new
services for passengers, including a digital sound
system comparable to the most state-of-the-art home
stereo or compact disc players.
A 1992 Industrial Design Excellence Award was awarded to
the passenger cabin of the new Boeing 777
jetliner, the first time the Industrial Designers Society
of America honored an airplane interior.
Cargo Capacity
The fuselage cross-section of the 777 is circular and
large enough to accommodate not only a
spacious passenger cabin, but excellent capacity in the
lower hold. The lower hold mechanized cargo
handling system is compatible with all unit load devices
(ULD) and pallets. One of the container
arrangements utilizes LD-3s loaded side by side. The
777-200 can accommodate a maximum of 32
LD-3 containers plus 600 cubic feet (17 cubic meters) of
bulk-loaded cargo for total lower hold volume of
5,656 cubic feet (160.17 cubic meters). The 777-300 can
accommodate a maximum of 44 LD-3
containers plus the same amount of bulk-loaded cargo as
the -200 model for a total lower hold volume
of 7,552 cubic feet (214 cubic meters).
Landing Gear
The main landing gear for the 777 is in a standard
two-post arrangement but features six-wheel trucks,
instead of the conventional four-wheel units. This
provides the main landing gear with a total of 12
wheels for better weight distribution on runways and taxi
areas, and avoids the need for a supplemental
two-wheel gear under the center of the fuselage. Another
advantage is that the six-wheel trucks allow
for a more economical brake design. The 777 landing gear
is the largest ever incorporated into a
commercial airplane.
High Reliability and Quality
New design and testing initiatives helped ensure the
highest possible levels of reliability on the very first
777, compared to what had been possible on previous
jetliner introductions.
Design/build teams, which bring together representatives
of the diverse disciplines involved in airplane
development, as well as suppliers and representatives of
airline customers, allowed team members to
work concurrently on the 777 structural and systems
designs.
Continuing the "market-driven" approach, four
777 customers had on-site representatives working side
by side with Boeing designers to ensure that the new
airplane filled their needs. United Airlines, All
Nippon Airways, British Airways, and Japan Airlines had
teams of between two to four engineers who
were actively involved in developing the 777.
For the first time, digital computers were used by Boeing
engineers to design and electronically
pre-assemble the entire airplane, increasing accuracy and
improving quality. New laboratory facilities
enabled the various airplane systems to be tested
together as a single integrated entity in simulated
flight conditions -- before the first jetliner took to
the air. This allowed a smoother transition to flight
testing and service introduction.
Among other initiatives, standard certification flight
tests were supplemented with 1,000 flight cycles on
each airframe/engine combination for the initial 777-200
model to demonstrate reliability in simulated
airline operating environments. The Boeing/United
Airlines 1,000-cycle flight tests for the Pratt &
Whitney engine were completed on May 22, 1995. In
addition, engine makers and the many suppliers
of parts for the airplane intensified their own
development and testing efforts to ensure that their
products met airline requirements.
This thorough test program demonstrated the design
features needed to obtain approval for
extended-range twin-engine operations (ETOPS). All 777s
are ETOPS-capable, as part of the basic
design. To ensure reliability, the 777 with Pratt &
Whitney engines was tested and flown under all
appropriate conditions to prove it is capable of flying
up to 180-minute ETOPS missions. On May 30,
1995, the 777 became the first airplane in aviation
history to earn Federal Aviation Administration (FAA)
approval to fly ETOPS at service entry.
International Team
The skills and resources of a number of international
aerospace companies contributed to the design
and production of the 777. Firms in Europe, Canada,
Asia/Pacific and the United States provided
components and portions of the structure to Boeing.
The largest single overseas participant is the Japanese
aerospace industry. Led by Mitsubishi Heavy
Industries, Kawasaki Heavy Industries and Fuji Heavy
Industries, this group of companies is continuing
its long-standing business relationship with Boeing.
Together, these firms helped design and build
about 20 percent of the airframe structure.
Sources: Boeing
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