Airframe means the mechanical structure of an
aircraft[cite book | author =Ed Rouen | title=Airplane Names | publisher=San Diego Aerospace Museum | year=2005 | url=http://www.marchfield.org/rouen01.html Names and dates of more than 2,800 aircraft models produced since 1900.] and as generally used does not include the engines. Airframe design is a challenging field of engineering, combining aerodynamics, materials technology and manufacturingmethods to achieve favorable balances of performance, reliabilityand cost. The airframe industryis complex. Its modern history began in the United Stateswhen a 1903 wood biplanemade by Orville and Wilbur Wright showed the potential of fixed-wing designs.
Many early developments were spurred by
militaryneeds during World War I. Well known aircraftfrom that era include the Dutch Fokkerand U.S. Curtiss triplanes and the Italian Taube monoplane. These used hybrid wood and metal structures. Commercial airframe development during the 1920s and 1930s focused on monoplane designs using radial piston engines. Many, such as the Ryan model flown across the Atlanticby Charles Lindberghin 1927, were produced as single copies or in small quantity. The all-metal Ford 4-AT and 5-AT trimotors [cite book | author=David A. Weiss | title=The Saga of the Tin Goose | publisher=Cumberland Enterprises | year=1996 ] and Douglas DC-3twin prop [cite book | author=Peter M. Bowers | title=The DC-3: 50 Years of Legendary Flight | publisher=Tab Books | year=1986 ] were among the most successful designs to emerge from the era. During World War II, military needs again dominated airframe designs. Among the best known were the Douglas C-47, Boeing B-17, North American B-25 and Lockheed P-38, all revamps of original designs from the 1930s. The first jets were produced during the war but not made in large quantity.
Postwar commercial airframe design focused on larger capacities, on turboprop engines, and then on jet (turbofan) engines. The generally higher speeds and stresses of turboprops and jets were major challenges. [cite book | author=Charles D. Bright | title=The Jet Makers: the Aerospace Industry from 1945 to 1972 | publisher=Regents Press of Kansas | year=1978 | url=http://www.generalatomic.com/jetmakers/index.html ] Newly developed
aluminum alloys with copper, magnesiumand zincwere critical to these designs. [cite book | author=Key to Metals Database | title=Aircraft and Aerospace Applications | publisher=INI International | year=2005 | url=http://www.key-to-metals.com/PrintArticle.asp?ID=96 ] The Lockheed L-188 turboprop, first flown in 1957, used some of these materials and became a costly lesson in controlling vibration and planning around metal fatigue. Eventually Boeingin the U.S. and Airbusin Francebecame the dominant assemblers of large airframes. Numerous manufacturers in Europe, North Americaand South Americatook over markets for airframes designed to carry 100 or fewer passengers. Many manufacturers produce airframe components.
Four major eras in commercial airframe production stand out: all-
aluminumstructures beginning in the 1920s, high-strength alloys and high-speed airfoils beginning in the 1940s, long-range designs and improved efficiencies beginning in the 1960s, and composite materialconstruction beginning in the 1980s. In the latest era, Boeinghas claimed a lead, designing its new 787 series flagship airframes scheduled for first delivery in 2008 with a one-piece carbon-fiber fuselage, said to replace "1,200 sheets of aluminum and 40,000 rivets." [cite web | author=Leslie Wayne | title=Boeing Bets the House on Its 787 Dreamliner | publisher=New York Times | date=May 7 2006 | url=http://www.nytimes.com/2006/05/07/business/yourmoney/07boeing.html ] These airframes are designed to transport 220-300 passengers, while chief competitor Airbushas designed its A380 flagship airframes to transport 550-850 passengers. The A380 is also built with a large proportion of composite material.
Airframe production has become an exacting process. Manufacturers operate under strict quality control and government regulations. Departures from established standards become objects of major concern. [cite web | author=Florence Graves and Sara K. Goo | title=Boeing Parts and Rules Bent, Whistle-Blowers Say | publisher=Washington Post | year=Apr 17 2006 | url=http://www.washingtonpost.com/wp-dyn/content/article/2006/04/16/AR2006041600803.html U.S. "whistleblower" lawsuit.] The crash on takeoff of an
Airbus A300in 2001, after its tail assembly broke away from the fuselage, called attention to operation, maintenance and design issues involving composite materials that are used in many recent airframes. [cite web | author=Todd Curtis | title=Investigation of the Crash of American Airlines Flight 587 | publisher=AirSafe.com | year=2002 | url=http://www.airsafe.com/events/aa587.htm ] [cite web | author=James H. Williams, Jr. | title=Flight 587 | publisher=Massachusetts Institute of Technology | year=2002 | url=http://web.mit.edu/jhwill/www/Flight587.html ] [cite web | author=Sara Kehaulani Goo | title=NTSB Cites Pilot Error in 2001 N.Y. Crash | publisher=Washington Post | year=Oct 27 2004 | url=http://www.washingtonpost.com/wp-dyn/articles/A63850-2004Oct26.html ] The A300 had experienced other structural problems but none of this magnitude. The incident bears comparison with the 1959 Lockheed L-188 crash in showing difficulties that the airframe industry and its airlinecustomers can experience when adopting new technology.
Notes and references
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