Aircraft Tire Construction
Introduction
An aircraft wheel must be constructed or manufactured in a way to withstand a variety of operational conditions. For instance, when an aircraft is on the ground it must be able to support the weight of the entire load. The tire should also be able to provide a cushioned ride, resisting heat generations and provide stability during taxi. The craft should also be able to endure forces produced at high angular velocities and load at take-off. During landing the aircraft requires high dynamic breaking loads transmitted to the ground and also absorbs shocks during impact. All this should be achieved while manufacturing an aircraft tire that is reliable, dependable and has a long service life.
These demands require a tire that is precisely manufactured and highly engineered. Tires of this kind are therefore designed as compounds of various products such as steel, fabric, and rubber. Each component serves a specific purpose to enhance the high performance of the aircraft tire. Tire manufacturers today generate and design two distinct and different tire constructions. These are the radial tire and the bias or cross-ply tire. The technologies utilized in the two designs are distinct involving different compounds, materials, and design parameters.
Some of the principal elements required in an aircraft tire during manufacturing are:
The Under Tread
This is a layer of rubber specifically designed to improve the bond between the carcass body and the tread reinforcement. Tires designed to be replaced have a rubber layer that is of adequate thickness to connect the old tread assembly and the liaison with new re-tread products.
The Tread
This refers to the crown region of the tire that comes into contact with the ground. The majority of the Michelin tires are specifically designed with circumferential grooves shaped in the tread region. This helps improve ground adhesion by providing a mechanism of channeling water between the tire and the runway surface area. The tread component is designed to resist cutting, cracking, abrasion, heat build-up and wear. Protects the underneath carcass ply thus prolonging the life of the casing.
The Liner
Liners in tubeless tires are formulated to resist the penetration of moisture and nitrogen through to the carcass. It replaces the inner tube common in the tube type tires and its vulcanized in the inside. The tube-type tires have a different liner material for protecting the carcass ply from tube chafing and moisture. However, this is inadequate to maintain and sustain air retention.
Elements in the Radial Tire
The Protector Ply
This is placed in the crown region under the tread rubber. It protects against a cut to the carcass plies and the underlying belts.
Belt Plies
These are laid between the top carcass ply and the tread area. They control the outer diameter of the tire thus providing a flat tread surface with great resistance to wear, squirm and cornering stiffness.
Elements in the Bias Tire
Fabric Tread
This is a unique element developed for high-speed military aircraft. Multiple nylon cord plies are laid throughout the tread stock reducing distortion of rubber under high speeds and loads. This reduces the heat generated by flexing.
The Tread Ply
This consists of multiple layers of rubber and nylon fabric laid in the midpoint beneath the top carcass ply and the tread grooves. These plies help to stabilize and strengthen the crown area thus increasing resistance to tread puncture and enhance high-speed stability.