What Makes Airplane Tires So Special?
We went to Michelin for a short course
Airplane tires are a breed unto themselves. A tire on your car has it easy compared to one on an aircraft. Your car doesn’t drive along a sun-baked, 120-degree F taxiway, then climb into sub-zero temps several miles above the Earth, hanging in a 100-mph wind, then come down and smash onto the ground at 80 miles an hour, maybe even bouncing a few times. Not just any tire is up to the mission.
The Concorde was grounded after a catastrophic tire puncture, which ultimately brought on a chain of events that led to the first and only Concorde crash. Michelin engineers looked at experiments from another division within the company that was concentrated on motorsports.
That section of the company was working with an NZG (near-zero growth) tire designed to significantly reduce tread cutting. “Regular nylon will grow when it’s inflated, and when it’s heated, it will stretch,” explains Michelin product engineer Khanh Le. “A regular tire grows about 10%, but an NZG tire only grows about 1% to 2%.” The NZG technology now has translated from racing into improved, tougher tires for general aviation in Citation and Falcon jets.
“We took this technology and got the Concorde flying again,” says Stackhouse.
From that and other research at Michelin comes the Tweel. A Tweel—a tire and wheel combination—actually puts a composite material that can be fabricated and molded on top of rubber. A Tweel isn’t inflated and requires no maintenance. You can shoot this tire, and it still performs. Understandably, Tweel technology is attractive to the military, but Michelin is looking into a variety of applications for general aviation. “This is a research project, and until it’s closer to completion, we can’t make a decision about aircraft tires,” says Le, “but we’re looking at the possibilities.”