The reason why airplane tires don’t explode on touchdown

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Landing Plane

Whenever an airplane lands, there’s always a landing gear that nails it no matter how big or how fast it goes. Considering the weight of the airplane, most likely it’s comparable to an office building that is descending 170 miles per hour plus the gravity pull. You’d probably think of it right now: What makes the airplane tires so special? Their secret is they are all pumped! Yes, you read that right. A typical airliner’s tire can hold 38 tons of load. Airplane tires touch the ground 500 times before scheduled for a re-tread. A re-tread happens seven times in its lifespan.

Structure

Russia’s behemoth Antonov has 32 tires, followed by Airbus A380 which carries 22, while the Boing 777 has 14. The secret to the amazing durability of airplane’s tires is the optimization of their air pressure. According to Lee Bartholomew, a lead engineer for Michelin aircraft tires, a typical aircraft tire has a pressurized air of 200 psi – that’s 6 times the pressure that is inflated to a car’s tire. “It’s really pressurized air, that’s so strong,” he says. An F-16 fighter plane requires a 320 psi tire to complement its speed and weight on landing.

Plane Tire

Would you believe us if we’ll tell you that aircraft tires are not that big? A Boing 737 has a 27×7.75 R15 tire meaning the tire is 27 inches in Diameter, 7.75 inches wide and 15 inches thick. The sidewalls are not that thick. Below the tread is the core strength of the tire. The materials used on the tire are primarily made of a variety of nylon called aramid. Each layer of the tire contributes to its capacity to handle air pressure and to hold tons of load. But, that doesn’t mean that they are indestructible. The aircraft tires will fail if the airplane is overloaded or it doesn’t have enough pressurized air on it. When this happen, treads will come off then the casing will blow.

The moment the plane touches down, the tires will skid, not roll. Because of the aircraft’s speed descent, the airplane drags the tire in the runway until it reaches the rolling velocity that should also match the velocity of the plane. That is the moment when the tires hit the runway causing smoke upon landing. Aircraft tires use grooves pattern to let it skid, unlike the block pattern that is used on the car (which would break off). Most of the aircraft tires are rated to handle up to 288 mph of speed.

In order to develop a new generation of airplane tires, Michelin undergoes the same steps as with any product design: they will test the new design in a computer simulation, which will be followed by drafting the prototype and then, the real testing, which includes pushing the tire’s limits in a scenario where the plane is taxiing, landing, and taking off. During this phase, tires will undergo a series of verifications. For example, the tires should withstand air pressure that is four times to its limitation and should hold for at least three seconds.

It is almost impossible to blow out a tire by over inflating it,” – Bartholomew added. In case the tires were over-inflated, the wheel will fail first, and then the tire.

Michelin is known as leader in tire technology. They have a mindset focused on improvement and innovation.

Michelin Tires

Michelin tires have a special rubber mixture which ensure a longer life with a low-cost per landing. An exquisite production mechanism, designed to balance the landing struggle, offers a longer life and a smoother taxiing. Plus, they make a really strong nylon casing, which keeps weight at minimum.

You have to remember that tires are not the only ones which count. The inner tubes are also very important. A bad quality inner tube can bring an excellent landing to a total disaster.

Inner tubes are designed to deliver a good fit between the tube and tire cavity. Their roles are to reduce the potential of dimples, curves, dissipate heat and air loss. One thing that you have to know is that “size really matters”. Inner tubes do not have to be stretched to fit design. They have to be full size, in order to have less air diffusion. This also means a longer life.

Michelin Inner Tube

Why airplane tires are filled with nitrogen?

Nitrogen gas is in a great measure inert. What does this means? Nitrogen (Ni2) is a diatomic molecule who has a triple bond between the atoms. Because the triple bond is really strong, it requires lot of energy to destroy the bonds and to participate in the reaction. Nitrogen reacts in pretty harsh conditions. This is significant because at high temperatures, oxygen might start to react with the rubber, oxidizing it and making it weaker, which is not good. Nitrogen diffuses with oxygen pretty slow. This means that a tire filled with 95% nitrogen will keep the pressure for a longer period of time. In conclusion, filling tires with nitrogen means saving money.

How to extend the life of the tires?

Operators often check tire pressure. Every landing stress the tires. If the temperature is extreme, the tires are more stressed. The environment temperature also contributes to wear. Airport pavement is also important. If the airport field has cracks or stones, it reduces the life of the tires. Another thing to consider is the applied load when the plane is parked. If the plain remains idle for a long period of time, it has to be moved every 72 hours.

Of course, the tires are rigorously checked by the airline’s engineers, by the manufacturer, and other specialists. All this work is undergone to be sure that you have safe flights.

Please tell us, what do you think about airplane tires and the tech behind them?

I'm an avid tech consumer. Whether it is news, gadgets or movies, I like to stay in touch with everything that's new and cool.

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