Changing How We Fly Aviation Technology Today and Tomorrow
- Friday, 01 June 2012
On the Wings of Innovation
Airbus has pioneered the use of wingtip devices in aviation for decades, beginning with its A300 and A310 jetliners. Both were outfitted with wingtip fences, which help reduce the spiral-
shaped vortices that form at the wingtips of any aircraft during flight, creating aerodynamic drag.
These wingtip devices — arrow-shaped surfaces attached to the tip of each wing — enhance the overall efficiency of aircraft, saving fuel by reducing drag, while also lowering noise emissions by improving take-off performance.
The next innovation is the large Sharklets™ wingtip devices for the Airbus A320 family. Introduced in 2009, Sharklets provide aerodynamic improvements that result in multiple benefits including lower fuel burn, reduced emissions, increased range and payload, better take-off performance and rate-of-climb, higher optimum altitude, reduced engine maintenance costs, and higher residual aircraft value.
These fuel-saving devices completed their first flight in November 2011 on an A320 development aircraft. Sharklets are expected to reduce fuel burn over long sectors by at least 3.5%.
A New Generation of Engines
As people who live near airports know, reducing the noise created by planes during takeoffs and landings is an important measure of environmental performance. Boeing has worked to reduce the sound footprint — the distance across which disturbing noise is heard. The 787 Dreamliner uses a number of new technologies — most importantly, acoustically treated engine inlets and chevrons, the distinctive serrated edges at the back of the engine, and other special treatments for the engines and engine casings — to ensure that all sound of 85 decibels (about the level of loud traffic heard from the side of the road) never leaves the airport boundaries.
Conventional airplanes use pneumatic systems powered by hot, high-pressure air diverted from the engines. This requires a complex system of manifolds, valves, and ducts to power secondary systems located throughout the plane. The 787 design eliminates the engine bleed air system and the associated pneumatic system, improving efficiency. Also, the plane’s engines are interchangeable at the wing, making it easier to reconfigure, update, or transition the plane from one fleet to another.
The Dreamliner belongs to a new class of planes made from advanced materials like composites and plastics that are stronger, tougher, and lighter than traditional metal alloys. GE developed a new engine for the aircraft, the GEnx. The GEnx engine uses advanced materials and design processes to reduce weight, improve performance, and lower maintenance. It delivers 15% better specific fuel consumption (which translates to 15 percent less CO2) than the engines it replaces. Its twin-annular pre-swirl (TAPS) combustor will reduce NOx gases as much as 56% below today’s regulatory limits.
The GEnx feature large, more efficient fan blades that operate at a slower tip speed, resulting in about 30% lower noise levels. It is the world’s first commercial jet engine with both a front fan case and fan blades made of carbon fiber composites.
A Material Advantage
Because the 787 Dreamliner is made primarily of carbon-fiber composite material, which is trimmed like cloth, manufacturing processes will produce less scrap material and waste. Today’s airplanes are made primarily of aluminum, which must be milled and machined from large sheets or blocks to create airplane structure. In general, as much as 90 percent of the raw aluminum used to create airplane parts is turned into scrap during the manufacturing process.
A majority of the primary structure of the Boeing 787 is made of composite materials — most notably the fuselage. Composites do not fatigue or corrode, they resist impact better, and are designed for easy visual inspection. Minor damage can be repaired at the gate in less than an hour. Carbon Sandwich is a special class of composites fabricated by attaching two thin, but stiff, skins to a lightweight, but thick core like a honeycomb. The core material is low-strength, but its higher thickness provides the sandwich composite with high bending stiffness and overall low density. Carbon Laminate structures on the plane are composed of strands of carbon formed into a tape infused with resin. The layers are laminated to create the desired thickness and shape of the structure, and then cured through a cycle of high heat and pressure over several hours.