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The future has taken off and is gaining altitude!
Posted on June 30th, 2016 by Dr. Sina Ebnesajjad in Chemical Manufacturing Excellence
The photo above shows the momentary positions of Dreamliner jets around the world. Boeing Company named its B787 plane (Figure 1) using a public process. Nearly 500,000 votes were cast for naming this mostly composite aircraft Dreamliner, over mundane names such as Global Cruiser. B787 is the product of one of the most comprehensive, perhaps revolutionary, redesigns of passenger planes. It truly qualifies to be called the passenger plane of the future.
Figure 1 Boeing 787 Dreamliner
The design objectives of B787 included reducing operating costs and carbon footprint. The B787’s fuel efficiency and range flexibility is enabling carriers to improve profitability in new flight routes. The plane comes in three sizes with varying passenger capacity and range combinations (Table 1). Passengers travel in more comfort and reach destination less fatigued. Other goals were to allow fleet optimization, network performance, noise reduction and lowering cabin air pollution. How is all this achieved?
Table 1 Passenger Capacity and Operational Ranges of Boeing 787 Family
Boeing 787 is made from composites adding up to 50% in weight, which means a majority of the primary structure of the plane consists of composites (Figure 2). Fuel tanks, engines, landing gear and other parts are made from titanium (15% wt.), aluminum (20% wt.), stainless steel (10% wt.) and 5% other materials. Composites have many advantages including lighter weight, simpler structure, and no risk of fatigue or corrosion. They require less scheduled inspection and maintenance than traditional airplanes. Composites’ resistance to impact is superior to aluminum, the traditional material for fuselage construction. Composites are instrumental to achieving weight savings that result in the key advantages of Boeing 787’s.
Figure 2 Boeing 787 Dreamliner
Figure 3 shows a comparison of composite versus traditional fuselage construction. The barrel (tubular fuselage) is built in sections that are later attached. Traditionally, each barrel piece is constructed from multiple pieces of aluminum assembled by riveting, bonding and bolts. That process requires overlaps, splices and doublers, rendering each barrel piece into somewhat of a custom part. Every one of those joints adds to the weight and requires inspection and repair thus adding to the operating cost.
Figure 3 Comparison of Panelized (traditional) and One-piece Aircraft Fuselage Construction
In contrast, each section of the 787 barrel is a single piece made from composites. Carbon Laminate is a composite structure that is made up of layers of carbon fiber impregnated with a polymer. In 787, strands of carbon are formed into a tape infused with a resin (like a glue). These layers are stacked up in layers to create the desired thickness and shape for the structure followed by curing at high temperatures and pressures for several hours. Carbon Sandwich (Figure 4) is a particular type of composites structure by adhesive bonding two thin but stiff skins (like bread in a sandwich) to a thick core such as honeycomb. Even though the core material usually has relatively low strength, the high thickness provides the sandwich with a high bending stiffness and low density.
(a) Sandwich Structure
(b) Nomex® polyaramide Honeycomb
Figure 4 (a) Schematic Diagram of Sandwich and (b) An Example of a Honeycomb
What has been the early experience? So far 787-8 and -9 (194 operating) have been flying bringing large jet ranges to a medium-sized jet. Boeing 787 matches the speeds of larger jets with a cruise speed of Mach 0.85. Both models use 20% less fuel and have 20% less emissions than similarly sized airplanes. They are much quieter than other planes thus accommodating stringent noise limits in global cities such as Narita, Japan.
This is one “future” for which the initial boarding call has just been made. Much more progress is ahead including the ultramodern Airbus 350, 24 of which have already been delivered.
Watch this space for more information about 21st century aerospace topics.
Information and imagery: The Boeing Company
All opinions shared in this post are the author’s own.
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Dr. Sina Ebnesajjad
President at FluoroConsultants Group, LLC
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