Braking, Steering, and Wear Performance of Radial-Belted and Bias-Ply Aircraft Tires 921036
Preliminary braking, steering, and tread wear performance results from testing of 26 x 6.6 and 40 x 14 radial-belted and bias-ply aircraft tires at NASA Langley's Aircraft Landing Dynamics Facility (ALDF) are reviewed. These tire tests are part of a larger, ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program involving these two different tire sizes as well as an H46 x 18-20 tire size which has not yet been evaluated. Both dry and wet surface conditions were evaluated on two different test surfaces - nongrooved Portland cement concrete and specially constructed, hexagonal-shaped concrete paver blocks. Use of paver blocks at airport facilities has been limited to ramp and taxiway areas and the industry needs a tire friction evaluation of this paving material prior to additional airport pavement installations. Concerning acceptance and use of radial-belted tires by the aviation community, early industry test results have indicated improved steering friction, greater overload capability, reduced rolling resistance, increased tread life, lower tire weight, and better tire reliability compared to similar size bias-ply tires. Some possible disadvantages in using radial-belted aircraft tires include higher initial costs, reduced retread capability, and some modification to existing equipment such as wheels, brakes, and antiskid brake system controls. NASA Langley's tests with 26 x 6.6 and 40 x 14 size radial-belted tires, however, were successfully completed using wheel and brake hardware available for similar size bias-ply tires. The purpose of this paper is to present an overview of the joint NASA/FAA/Industry START Program, describe the Langley test facility and equipment, discuss preliminary test results, and indicate future plans.