Chapter 6: Tires

OVERVIEW

This chapter discusses tires from the landing gear designer's standpoint and does not, therefore, attempt to become involved with the science of tire design. The gear designer is interested in the following characteristics: 1) load-deflection, 2) size and weight, 3) loaded radius, 4) flat tire radius, 5) rolling radius, 6) tire life (sometimes), and 7) crush load capability (sometimes). Other features, such as radius of gyration, effects of temperature, effects of centrifugal forces, friction, side forces, and hydroplaning are all evaluated where appropriate.

Aircraft tires are subjected to a wide variety of high dynamic and thermal loads and their failure can have disastrous consequences. Even with all of today's safety factors and recent advances in tire design, there are still instances such as the Pan Am DC-10-30 accident on Sept. 30, 1980. While taking off from London, a tire on the right-hand gear burst. The pilot rejected his takeoff and passengers were evacuated. One passenger suffered a broken leg while using the escape slide, there were two localized fires on the center and right-hand gears, and there was considerable aircraft damage. All of the tires on the right-hand gear were destroyed and the braking system damaged. Pieces of the tires made holes in the wing, engine nacelle, and horizontal tail all of this from the failure of one main gear tire! Touchdown speeds are creeping upward in some cases and the associated spin-up loads can have very severe effects on the tires. The Space Shuttle, touching down at 220 knots,...