الجمعة، 22 يناير 2016

What is the 787 Dreamliner?


 ??What is the 787 Dreamliner


Dreamliner is the nickname of the Boeing's 787 jet airliner. The 787 Dreamliner made it's public debut on July 8, 2007, or 7/8/7 in American date notation. With orders for well over 600 airplanes at the time of the debut, totaling over $100 billion US dollars, the Dreamliner is the most anticipated new commercial aircraft in history. Sporting interchangeable jet engines, large auto-dimming windows at eye-level, high cabin humidity and air pressure, and super-quiet operation, the new airplane is designed to please everybody from maintenance crews to travellers to ground-based observers.
Boeing is initially producing three versions of the Dreamliner. The 787-3 is the short-wingspan version of the plane. Seating about 300 passengers, the 787-3 has an operating range of about 5500 kilometers with about 125 cubic meters of cargo volume. The standard-wingspan plane, termed the 787-8, increases operating range to over 14,000 kilometers, however it can carry no more than 250 passengers. While the long-wingspan Dreamliner 787-9 has only a slightly longer operating range than the 787-8, it's lengthened body sits up to 290 passengers and increases cargo volume to over 150 cubic meters. All three versions of the plane can comfortably cruise at Mach 0.85 while burning 20 percent less fuel than the planes they replace. Many of these performance breakthroughs are due to the large amount of composite material used in the Dreamliner's construction. Over half of the 787's weight will be composite material, as compared to conventional steel being used in only about 10% of the airplane.
Most of the composite material used in the Dreamliner will be in the airframe itself. The fuselage and wing structures are almost completely carbon fiber-reinforced plastic and titanium graphite laminate, and many other smaller components are made of similar materials. As the plastic does not rust, higher cabin humidity can be maintained, greatly increasing passenger comfort. The Dreamliner's plastic fuselage has special geometry which allows for extra-wide spacing between beams, facilitating unusually wide windows and doors. The lack of welds and rivets reduces component costs, and the super-light structure helps the Dreamliner achieve it's remarkable fuel efficiency. However, concerns regarding composite material's inherent crack and fatigue hiding properties has caused concern about maintainability. Critics note that conventional routine airframe examinations would not discover stress faults in the airframe, and that damage repair would be very costly.
the 787 Dreamliner logo
Although final assembly of the Dreamliner is done in Boeing's Everett facility in Washington State, the 787's main structural components are manufactured in numerous facilities around the world. Transporting these large components necessitated development of a super-large aircraft capable not only of lifting the pieces, but also of physically storing them inside it's airframe. Instead of designing yet another airplane for the purpose, Boeing engineers have retrofitted three 747s with wide, centrally split bodies capable of swallowing the large 787 components. Dubbed the Dreamlifter, these 747 variants replace more conventional shipping methods such as rail and ship. Not only does the Dreamlifter make for faster component delivery, it allows for the delivered components to be much larger than rail or ship can transport. Additionally, as the larger components are at a further stage of completion at the time of their delivery, final assembly time can be reduced from two weeks to three days. The 747 Dreamlifter is considered to be one of the key technologies enabling the construction of 787 Dreamliner.

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