February 2009
Lighter planes, less fuel, longer hang time
In the coming world of composite materials and unibody aircraft construction, an occurrence like Flight 1549 out of LaGuardia Airport in New York will lack some of the drama by easily gliding back for a runway landing.
Ninety eight seconds into the US Airways flight on 15 January, an air-traffic controller radioed the jet with a routine heading change.
“Ah, this is Cactus 1549,” came the reply, using the airline’s shorthand identification and flight number. “Hit birds. We lost thrust in both engines. We’re turning back towards LaGuardia.”
Without power, their Airbus A320 was a glider weighing more than 100,000 pounds. At its peak, it was 3,200 feet in the air. The glide to the ground would be about three and a half minutes.
McGill University mechanical engineering associate professor Pascal Hubert is a member of the Structures and Composite Materials Laboratories and is helping develop the composite materials that will lay the groundwork for Aviation 2.0.
Composites are made from a resin (such as a polymer) reinforced with a fiber (such as carbon fiber). Unlike, say, steel, in which iron and carbon blend together into a homogeneous whole, we can engineer the composite constituents to achieve properties tailored for a particular application. Airframe designers can optimize their design, eliminating redundant weight and thus increasing fuel economy, flight range, and payload capacity.
Composites also have the advantage of saving manufacturing time and cost (and the added weight of fasteners) by integrating smaller pieces into one big, no-assembly-required whole.
Mitsubishi and Honda are already making all-composite business jets, but the big news is the forthcoming Boeing 787.
Dubbed the “Dreamliner,” the mid-sized wide-body will be the first major civil aircraft to have a composite fuselage and wings when it goes into service this year.
The plane will be almost 60%, by weight, composite materials. The Airbus A320, by comparison, is approximately 20% composite. The 787 will be light and consume upwards of 20% less fuel.
Lighter and less fuel probably would have allowed flight 1549 to glide home to a near routine landing last month, and probably will someday.
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