HERE鈥橲 that worrying statistic again: in 2002 airlines carried more than 1.3 billion passengers, and the figure is rising by about 5 per cent a year. By 2030 airlines expect to be transporting almost 4 billion passengers each year. With airports and runways already packed to bursting, the airline industry needs to work out how it will achieve this.
So far two main strategies have emerged. A clue to the first can be found at London鈥檚 Heathrow, the world鈥檚 busiest international airport, where construction has begun on a new terminal. Heathrow is expecting a big increase in passenger numbers, yet there is little chance of a new runway. Instead Heathrow anticipates a new generation of huge aircraft to bear the burden. These giants will fly long-haul routes between major airports.
So who is building these behemoths? NASA and Boeing are looking at plans for a giant flying wing that could carry up to 800 passengers. But even if it gets the go-ahead, it is not expected to fly for at least a decade.
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The first of the giants off the drawing board is Airbus Industrie鈥檚 four-engined, 80-metre wingspan A380, the world鈥檚 biggest double-deckered passenger jet. It will seat between 555 and 800 passengers, and is due to fly its first test flights in late 2004, possibly heading for an airport near you by 2006.
The key to building this giant is keeping its weight down, says Daniel Deviller, former chief engineer at Airbus Industrie. More than 20 per cent of the A380 is made of composite materials, mainly carbon-fibre-reinforced plastic. The design is also the first large-scale use of glass-fibre-reinforced aluminium, a new composite that is 25 per cent stronger than conventional airframe aluminium, but 20 per cent lighter.
Even so, the A380 will be the heaviest aircraft ever built, preventing it operating from most airports. Airbus believes that airlines will still want the A380 because carrying more passengers in greater comfort means they can offer cheaper, more tempting long-haul flights. The plan could work 鈥� as long as profit-hungry airlines don鈥檛 cram in too many seats. 鈥淲e have taken a gamble,鈥� admits Phillipe Camus, chief executive of the European Aeronautic Defence and Space Company (EADS), based in The Netherlands, which owns Airbus.
The second strategy is almost the exact opposite. Instead of trying to push more passengers through the same large airports, researchers at NASA, Boeing and Embry-Riddle Aeronautical University in Florida are banking on a revolutionary change in the way flight networks operate.
In 2001, 75 per cent of passengers in the US flew through just 29 airports, yet 98 per cent of Americans live less than 40 kilometres from a small local airport. Instead of flying between a few large hubs that act as feeders to smaller regional airports, the idea is to build a network that allows aircraft to fly easily from any airport to any other. This switch from hub-and-spoke operation to point-to-point travel (see Diagram) could triple the capacity of air traffic control systems, as well as making air travel four times faster than using roads alone, according to a US government study.
Such a revolution would require a new generation of smaller, quieter airliners, hence Boeing鈥檚 proposed investment in a new low-cost, 200-seater twin-engine plane, the 7E7 Dreamliner. The 7E7鈥檚 engine and airframe design will, if built, reduce fuel consumption 鈥� and emissions 鈥� by as much as 20 per cent, which is vital if the plane is to fly into airports in city centres. Meanwhile, Eclipse Aviation of Albuquerque, New Mexico, has taken this idea one step further and built the Eclipse 500, a low-cost, high-speed jet 鈥渢axi鈥� that can carry five passengers and has a range of more than 1500 kilometres.
One of the factors that will make a point-to-point network possible is 鈥渇ree flight鈥�, the idea of giving pilots control over where they fly rather than using air traffic control. Free flight relies on computers aboard each aircraft, linked to computers on the ground, to wrap a plane in a virtual 鈥渂ubble鈥� extending forward up to 300 kilometres, into which no other aircraft can stray (see Diagram, below right).
On-board software uses data from aircraft radar and ground-based sensors to give aircraft advance warning of any possible collision, so planes should be able to fly direct, more fuel-efficient routes (快猫短视频, 13 July 2002, p 12). Tests of a free-flight control system developed by NASA and Embry-Riddle have already begun at small airports in Florida, and the experiment should expand to other US states in 2004.
Automated air traffic control will be essential, too, if true personal flight is ever to succeed. Flying cars that you can land in your backyard have been promised many times, but Boeing believes they are finally coming. 鈥淥ur job is to look into the future, to the extreme version of point-to-point air transport,鈥� says Pam Drew, engineering vice-president at the firm鈥檚 Phantom Works R&D lab in Seattle, 鈥渁nd that would be personal transportation vehicles where you can have this thing take off and land from your driveway.鈥�
Until now, the idea of a flying car has only been pursued by small outfits building vehicles such as the Moller Skycar (快猫短视频, 14 June, p 40). These cost a whopping $500,000, but the economies of scale in a company with Boeing鈥檚 manufacturing capacity could send that price crashing. But the barrier to launching a successful flying car is not so much the flight hardware as the collision-avoidance software, says Drew. So she and her team are exploring the technologies and automated software necessary for personal flight. Much of the latter is derived from Boeing鈥檚 work on software that allows military unmanned aerial vehicles to fly in formation (see below). With Boeing backing the idea, personal flight could become viable more quickly than anyone imagined.
