Farther, Faster, Safer
THE MAGAZINE DEVOTED TO NICKEL AND ITS APPLICATIONS
|
 |
EXTENSIVE RENNOVATIONS are being made at major airports around the world to accommodate the new Airbus
A380 aircraft.
|
 |
THE MAIDEN FLIGHT of the A380 in 2005 was a triumph of years of engineering work that relied heavily on
nickel alloys to succeed.
|
 |
THE GP72000 ENGINE, developed by Engine Alliance, has lower fuel burn emissions and far less noise than
other aircraft engines. These improvements are designed to meet tougher noise restrictions at European
airports.
|
 |
NICKEL ALLOYS enable engineers to lower engine weights, even as they develop more thrust at higher
operating temperatures.
|
 |
ADVANCED NICKEL ALLOYS enable the disks inside the GP72000 to operate for long periods of time at
temperatures 38 °C hotter than the previous generation of disk alloys.
|
|
Making air travel cleaner, quieter and more fuel efficient By Carroll
McCormick
Nickel Magazine, May 2006 -- Every year, nickel makes it possible for roughly two billion people and 34 million tonnes of cargo to take to the skies.
Aluminium, because of its low density, is normally associated with aircraft. However, it is the unique properties of nickel alloys, such as resistance to heat and corrosion in some alloys, and nearly zero expansion and contraction across temperature swings of hundreds of degrees in other alloys, on which the airline industry is highly dependent. That’s because aircraft are becoming larger and aerospace engineers are striving to reduce airframe weight, engine noise and emissions.
For an example of nickel’s vital contribution to modern aviation, consider the Airbus A380, the largest passenger aircraft built to date. History was made on April 27, 2005, when a gargantuan A380 began its four-hour maiden flight from Toulouse, France. The aircraft is manufactured by the French joint stock company Airbus S.A.S., which is 80% owned by the European Aeronautic Defense & Space Company and 20% by BAE Systems.
In its standard passenger configuration, the A380 will have 555 seats, weigh 560 tonnes on takeoff, and be capable of flying 15,000 kilometres at 85% of the speed of sound (Mach 0.85). Yet despite these record-setting figures, the A380 will burn 12% less fuel per seat than any other passenger aircraft – less than 3 litres per 100 passenger kilometres.
Today, skyrocketing fuel prices pose the single greatest threat to commercial aviation, and international transport in general. In 2005, 2.08 trillion litres of jet fuel were burned worldwide at a cost of €120 billion, more than double the cost reported for 2003.
Aside from improving airframe aerodynamics, there are two ways to reduce fuel consumption: create lighter aircraft and build more efficient engines. Since it takes about three kilograms of fuel per hour for an aircraft to carry 100 kilograms, weight reduction has become key.
Designers of the A380 minimised weight by using lightweight composite materials made of layers of carbon fibre cloth impregnated with resin (the same materials used to make lightweight sporting equipment). About 23% of the total airframe weight of the A380 consists of composites, including the centre wing box (the roughly-box-shaped section of the fuselage between the two wing roots), the rear pressure bulkhead, wing and tail ribs, trailing edges, and landing gear doors. Composite parts have bettered Airbus weight goals by as much as 25%.
A composite part is fabricated, or "laid up", layer by layer, on a nickel alloy mould milled to give the part a precise shape. Then the mould and part, impregnated with a resin (such as epoxy) are wheeled into an oven where the part is cured by heating it to temperatures ranging from 375 to 425 °C.
This alloy, known as Invar®, contains 36% nickel and has a particular property that’s essential in the creation of composite components: a near-zero coefficient of thermal expansion, meaning it does not expand as it’s heated or contract as it cools. As a result of this high stability, composite parts can be fabricated to the required tolerances measured in mere fractions of a millimetre.
Less weight means less fuel consumption, and that in turn means aircraft can carry more cargo and passengers. Our skies are vast, but capacity at many airports is strained to the point where runways are incapable of accepting any more aircraft. Gate space is often at a premium, and some airports have slot restrictions that make it impossible for airlines to add flights to their schedules. One solution to this exceedingly difficult problem is to put more passengers on fewer aircraft.
"Runway capacity ultimately determines airport capacity," says Robert Hornblower, assistant director of airport development with the International Air Transport Association. "It's expected the A380 will increase passenger throughput at airports with severe runway limitations."
By February 2006, Airbus had received 159 orders for A380s, including both passenger and cargo versions. Emirates, an airline headquartered in Dubai, has ordered 45, to be used primarily on its main trunk routes from Dubai to New York, Europe and Australia.
"Since the A380 is an aircraft with great passenger capacity, we’ll use it on routes where we have slot restrictions," says an Emirates representative. "As things stand, Emirates serves a great many cities where we could offer more daily services; if we can’t get these, then using an A380 on the route offers greater capacity."
Singapore Airlines will be the first to use the A380; its initial flight is scheduled for later in 2006. European customers include Air France, Lufthansa and Virgin Atlantic Airways, with combined orders totalling thirty-one A380s. Already more than 60 airports worldwide have made improvements to accommodate the aircraft, and in a few years it will be a common sight for international travelers.
The Evolution Continues
Nickel alloys have advanced the performance of aircraft engines since the 1930s, when new alloys were
developed that could withstand the extreme temperatures and pressures of new engines.
This process continues today with the engines that have been developed for the A380. The GP72000 for example, developed by Engine Alliance, will have lower fuel burn emissions and far less noise than other aircraft. These improvements are designed to meet tougher noise restrictions at European airports.
Nickel alloys allow lower engine weights, even as they develop more thrust, and higher operating temperatures. Engine Alliance uses advanced nickel-base alloys such as Rene 104®. "This advanced alloy allows the disks to operate for long periods of time at temperatures 38 °C hotter than previous generation disk alloys," says Ken Bain, leader of the materials application engineering team for the GP7200 engine at GE – Aviation. "This improvement in temperature capability, to more than 704 °C, enables significantly more efficient engine cycles and improved fuel economy."
Carroll McCormick is a Montreal-based freelance writer.
PHOTOS:
Mary Anne Greczyn |
