New Technology Tyre For Concorde From Michelin
Following the tragic Concorde crash in July 2000, the European Aeronautic Defence and Space Co. (EADS) approached tyre manufacturers to see if any research was on-going to improve the resistance of tyres to damage by fo reign objects. In September, Michelin unveiled its response to EADS; the new NZG (Near Zero Growth) Technology.
EADS asked Michelin to come up with a tyre that could meet stringent new test requirements and, after witnessing prototype testing at Michelin’s Almeria test centre, EADS asked Michelin to go ahead with development of a tyre for Concorde. The result was revealed today in Paris, 16 months after the development of NZG and 8 months after first contact with EADS. Aircraft are subject to extreme load and temperature conditions; takeoff speed for a supersonic plane is 0 to 440 km/hr in 45 seconds.
Landing acceleration is 0 to 290 km/hr in one second. The tyre may have to bear a weight more than 266 times its own mass and the temperature on landing rises from -50oC in the hold to +150oC on the crown. Both bias-ply and radial tyres are produced, with 72% of all aircraft tyres made by Michelin being bias-ply, but the new NZG technology is described by Michelin as “a technical breakthrough [that will] revolutionise tyre design as, in its time, did the radial.
” This being Michelin, no-one should expect any secrets to be given away, but the company has revealed a few details. Previously, the only way of increasing damage resistance was to make the tyre thicker, but this adds weight and could lead to heat build up. NZG is based on the use of “high-modulus” materials which reduce structural deformation.
Carcass growth is limited when the tyre is inflated (half that of a nylon-reinforced tyre) which means the tread rubber is under less tension and less vulnerable to damage. The number of layers in the tyre has been halved, reducing the weight of the NZG tyre by 20% compared to a Michelin bias-ply Concorde tyre. Testing was severe, with the tyre required to run over a 30cm steel blade without deflating or throwing off debris.
The tyre was loaded to its Concorde working weight of nearly 23 tonnes and the tests were carried out at low and high speeds (20 km/hr and 324 and 382 km/hr). The traditional bias tyre burst, while the NZG was unaffected. The damaged tyres were then required to undergo a residual test assessment by being subjected to a series of three complete cycles (taxiing – take-off – landing – taxiing) and the NZG tyre damaged at the speeds mentioned above came through with no loss of pressure and no shedding of debris.
The bias tyres were too damaged to take part in this test. Michelin NZG tyres, like all Michelin radial aircraft tyres, are manufactured at the plant in Bourges, where 250 employees produce 45 different radial aircraft tyres..