ADVANCED MATERIALS & PROCESSES | MARCH 2024 24 In less than 100 years, aluminum has revolutionized the possibilities and experience of human flight. During this time, aluminum aircraft have carried passengers and cargo all over the world, helped fight wars, and saved lives in natural and manmade disasters. Measured by tonnage, the aluminum used in aircraft is modest (10-15% of the transportation market), but the quality and performance expectations for this market are rigorous and demanding. After the Wright brothers used aluminum in the engine of their first plane, it took only 16 years for aluminum to replace most of the wood and canvas traditionally found in aircraft. The German aircraft company Junkers introduced the first all-aluminum airplane in 1919, and regularly scheduled passenger airlines were in service by the 1930s (Fig. 1). Jet airliners were introduced in the 1950s. Today, the widely used Boeing 737 commercial aircraft is approximately 75% aluminum by weight[1]. COMMERCIAL AIRCRAFT Airline fleets of today encompass a variety of aircraft ranging from com- muter planes to jumbo jets. After safety, the primary concerns for aircraft include the range prior to refueling and the cost of operations and maintenance. Larger aircraft are often used on long routes, making the range critical. In terms of design and construction, wing size, engine power, and overall weight have a combined influence on range. Currently, the Airbus A350-900ULR can fly 17,900 km (20 hours from New York to Singapore) without refueling, one of the longest nonstop routes serviced by the commercial airline industry[2]. Smaller aircraft used on shorter routes must be low cost and reliable. Extending the range of these smaller planes, if necessary, is possible with changes to the wing or engine sizes. In fact, the biggest benefits to fuel economy come from the engines rather than weight reduction. In today’s aircraft industry, single-aisle airplanes are mostly produced from standard aluminum alloys and tempers to minimize cost: Commuter aircraft: These light aircraft carry up to approximately 20 passengers. Although they are often considered air taxis, they operate as scheduled airlines. These short-range planes are powered by turboprops or piston engines and use aluminum extensively in the airframe structure. Regional jets: These aircraft typically seat less than 100 passengers and are used for traffic between large airline hubs and small regional airports. They are operated by the major airlines or smaller regional partners. Bombardier and Embraer produce a large percentage of the regional jets used in North America and Europe. As with ALUMINUM CONTINUES TO SHINE IN COMMERCIAL AIRCRAFT APPLICATIONS This article explores a brief history of the special alloys, tempers, and product forms required to meet the unique challenges of flight. Robert Sanders,* Novelis Global Research and Technology, Kennesaw, Georgia Graeme Marshall, Novelis Global Research and Technology, retired *Member of ASM International Fig. 1 — Aluminum aircraft: (a) Junkers F13 (Germany), circa 1919; and (b) Douglas DC-3 (U.S.), circa 1935. Courtesy of Alcoa Inc. (a) (b)
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