The Innovative 787 Carries Boeing, And Aviation, Ahead

Automobiles 3555 Hits > 2009-12-24 09:17:45


Boeing’s 787 Dreamliner looks like any other airliner, so it might be hard for anyone but an airplane geek to get so excited about its inaugural flight. But the energy-efficient airliner is a bold step forward for Boeing, and for aviation.

As much as the 787 Dreamliner looks like the jet that carried you on that cramped, uncomfortable flight last month, almost everything about it is new. From the extensive use of composite materials and advanced aerodynamics to its fuel-efficient Rolls Royce engines and all-electric systems, Boeing is betting the 787 will be the plane to usher in a cleaner, greener future for the airline business.

Boeing claims the 787 is 20 percent more fuel-efficient than comparably sized jets. With fuel being airlines’ number one cost after payroll, Boeing’s plan to build a thriftier airplane came at just the right time, said analyst Richard Aboulafia of the Teal Group.

“You get one shot a decade to launch an all-new product, and in terms of what customers were looking for, they got it right,” he says. “They designed something that is just what airlines want for their premium customers, an efficient airplane for point-to-point international routes.”

Getting the plane built has been a long haul marked by delays and setbacks that pushed last week’s 787 first flight more than two years behind schedule. But Boeing says it is on track to deliver the first 787 to Japan’s All Nippon Airways within nine months.

Boeing is taking a different approach to improving efficiency and cutting emissions than its arch-rival, Airbus. And to get a sense of where the 787 comes from, it is important to look at the state of the industry when the idea was announced in 2002.

Less than a decade ago Airbus was garnering all the headlines. The European consortium was touting its new superjumbo, the A380, as the future of airline travel. The massive double-decker airplane was shown with spas and luxurious amenities and room for more than 500 passengers. Airbus also floated the idea of squeezing 800 seats into the plane for maximum economy. It claimed the A380 would be the pinnacle of flying.

But Airbus was betting the future on the hub-and-spoke method or air travel, where passengers fly from one major city to the next, then board smaller planes to reach their final destination. Airbus was counting on volume, figuring the ability to fly huge numbers of people in relatively few planes would keep tickets cheap enough to keep the hub-and-spoke way of flying attractive.

Boeing thought differently. It is the reigning king of jumbo jets with its 747. The iconic airliner has flown every hub-to-hub route in the world. But the company thought the future wasn’t in saving money by carrying lots of passengers to hubs because passengers want more direct flights. It decided that airlines could save money flying an airplane that was more efficient and cheaper to fly than anything else in the sky — while capable of flying directly to more cities than the A380. The 7E7 was born.

Boeing’s board greenlighted the project in 2003. Eventually the “E,” which many thought stood for “efficiency,” was dropped and the “8″ added. Boeing claims the “E” stood for eight all along.

But building a fuel-miser airliner was just the beginning. How Boeing would build it proved to be the real shocker. Boeing said the 787 would be made mostly of carbon composite plastics. In particular the fuselage structure would be just a few large composite tubes joined together. Gone was the traditional aluminum tube with aluminum wings that had been the mainstay for more than 70 years. In its place would be a rivetless airframe that won’t corrode and won’t fatigue like aluminum.

Of all the impressive new tech in the 787, the use of composite materials is the biggest game changer, according to Aboulafia.

“It is a fairly ambitious collection of new technologies,” he says. “But it’s dominated by the 800-pound gorilla, which is the monolithic carbon-fiber fuselage construction. That’s a big one.”

Composite construction offers big weight savings over traditional aluminum construction. About 50 percent of the 787’s roughly 220,000-pound empty weight is composite (80 percent by volume). Boeing says it estimates the 787 will be 30,000 to 40,000 pounds lighter than the similarly sized Airbus A330. However some of the weight savings has been lost solving problems Boeing experienced with its first foray into composite airliners.

The delay that postponed the first flight was caused by a problem where the wing joined the fuselage. During static testing of the 787 some of the composite material delaminated when the wings were flexed near their limit. Boeing had to redesign the area and retrofit several airframes, adding some weight back to the design.

Such are the pitfalls of using new technology. Boeing is building the first large jet mostly of composite materials, so it naturally will experience some problems as the early adopters. Airbus is developing a competitor to the 787, the A350 XWB. Although it also uses composite materials, Airbus is being more conservative and using a composite skeleton fuselage overlaid with composite panels. Airbus claims this design will make for easier repairs, while Boeing claims its composite fuselage tube offers better weight savings.

“The 787 approach is considerably riskier and more aggressive,” Aboulafia says.

Aboulafia says the risk isn’t about safety. Instead it’s a business risk due to modifications (read: weight) that will be needed to compensate for any further changes that might be needed down the line such as the need for more reinforced areas or for other yet to be flight tested things such as lightning protection. Too many modifications — too much weight — could mean the Dreamliner doesn’t meet the performance specifications that have led to Boeing’s getting a record 840 orders for the plane. Too much weight is bad for business.

But if Boeing’s bet pays off, its composite technology could put it years ahead of its competitors.

The composite structure saves weight and also allows for aerodynamic improvements. A new, higher aspect-ratio wing design with raked-back wing tips is possible because of the composite wing. These weight savings and aerodynamic improvements are two of the big factors in the 787’s increased efficiency. Another big technological step in efficiency comes from the engines.
Rolls-Royce engine on the Boeing 787

Last week’s flight was powered by Rolls-Royce Trent 1000 jet engines, though customers also can order General Electric GEnx engines. Both engines were developed specifically for the Dreamliner, and they’re significantly different than conventional jet engines.

Traditionally a jet engine uses some of the compressed air produced for thrust and diverts it to power the systems on board the aircraft. This “bleeding” of air is a reliable source of generating power, but it robs power from the engine and increases fuel consumption. It also increases drag.

Boeing is using a bleedless system on the 787. Generators running off the engine and an auxiliary power unit power the aircraft’s systems. This is why many are calling the 787 an electric airplane. Engine generated electricity will power cabin pressurization, de-icing and other systems typically powered by the pneumatic bleed air.

This makes the engines more efficient — and cleaner, since emissions are related to fuel burn. It also reduces weight and complexity with the elimination of the ducts, valves and other things needed to direct bleed air to the various systems.

From the outside, the most visible difference with the 787’s engines is the nacelle. The trailing edge of the engine cover has a distinctive, serrated appearance. This design reduces noise by controlling how the fast moving air coming out of the jet engine interacts with the surrounding air. The design is so effective it allows a reduction in sound-insulation material from the airplane which in turn saves more weight.

This is one of several features of the new airplane aimed at making the Dreamliner quieter. For the airlines, a quieter airplane is a friendlier airplane for airport neighbors. This potentially means the 787 can fly into places other airliners are not allowed. Boeing says the noise footprint of the 787 will be 60 percent less than a similar size airliner, adding all noise louder than 85 decibels will be confined to within the airport boundaries.

Tomorrow we’ll take a look at the interior of the 787 and what passengers can expect when riding in the new Dreamliner. We will also take a look at the innovative, yet problematic, global supply chain used to build the 787 including the massive 747 Dreamlifter that serves as the delivery truck for parts from all corners of the globe.








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