Karen Walker/LANGLEY

A NASA TESTBED developed to simulate Space Shuttle takeoffs and landings has been used to assess the durability of radial tyres for wide body commercial aircraft. The successful tests are expected to speed up US Federal Aviation Administration certification of the tyres.

NASA's Langley Research Center, in Hampton Virginia, has completed a project with Michelin Aircraft Tire to test the tyres, which are under consideration for the Boeing 777. The programme has been made possible by the US Space Act Agreement, which encourages US industry to use NASA equipment and expertise.

Michelin needed to test the radial tyres to determine their mechanical properties at various loads. The company, which is based in Charlotte, North Carolina, approached NASA at the beginning of 1995 to see whether it could use Langley's unique Aircraft Landing Dynamics Facility (ALDF). Testing has just been completed. Although it was not part of the original agreement, NASA says that the partnership has worked so well that its engineers are now also helping Michelin to assess the data gathered.

"This is a perfect example of a US industry benefiting from NASA-invested capital and helping keep our country ahead of the competition," says Robert Daugherty, project engineer at the ALDF. Radial-ply tyres are widely used in Europe, but are used only on smaller aircraft in the USA. Daugherty says that the tests were successful and NASA and Michelin are considering further joint work on radial tyres.

The testbed consists of an 800m (2,650ft) set of rails along which a large carriage equipped with a test tyre can be propelled by a jet of water, reaching speeds up to 220kt (400km/h) in 1.5s. The tyres were tested repeatedly for their ability to function under various loads, including a double-overload condition, to ensure that all remaining tyres would perform fully should one blow. In addition, tyre relaxation lengths and side forces were measured, on a test platform, which allowed the tyre to be pulled sideways over a simulated steel runway.

Source: Flight International