Tyres reinforced with a tough new material could help the supersonic passenger jet Concorde to fly again.
All Concorde aircraft have been grounded since a crash in July 2000 killed 113 passengers. Investigations indicate that a piece of metal punctured one of the plane鈥檚 tyres, throwing large chunks of rubber into the aircraft鈥檚 fuel tanks and causing a catastrophic fire.
Michelin has now developed new tyres using what it calls Near Zero Growth (NZG) technology. This involves replacing nylon threads, which strengthen the tyre, with a new unnamed but even stronger material.
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The designers claim this material reduces stretching of the tyre鈥檚 rubber when it is inflated. This would lower the tension on the rubber and make it less likely to puncture and produce debris when damaged.
Michelin says that the new tyre expands by just three percent when inflated -conventional radial aircraft tyres expand by six percent. Michelin has applied to patent the material used to build the new tyre.
鈥淭his has given us performance that was unknown until now,鈥� said John Couratier, technical director of Michelin鈥檚 aircraft tyre division. 鈥淚t will certainly improve the design of tyres and hopefully make for safer transportation.鈥� Couratier said that he expects to see the other aircraft use tyres built with NZG technology by 2002.
Puncture tests
Aircraft tyres experience much more stress than automobile tyres. They must cope with quick acceleration to high speeds, large and variable loads and extreme heat. One of Concorde鈥檚 operators, Air France, has tested the NZG-built tyre. The test, running the tyre over a 30 centimetre metal rod at various speeds, was designed to simulate the impact of runway debris on a Concorde tyre during take-off or landing.
At the maximum runway speed of 384 kilometres per hour, the tyre did not loose pressure or spread debris, said Couratier. Even at over 400 km/h, only small pieces of rubber debris were projected from the tyre, he said.
Concorde鈥檚 fuel tanks have also been redesigned to make the aircraft safer. New tanks lined with Kevlar panels have been built to prevent punctures.
The future of the jet still depends on it receiving a certificate of airworthiness from the British Civil Aviation Authority and France鈥檚 Direction Generale De L鈥橝viation Civile.
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