New technology of runway friction coefficient measurement and its towed implementation

The paper deals with the conceptual model of a towed measuring complex implementing a new runway friction coefficient measurement technology. The technology is based on the principle of controlled deceleration of the measuring wheel to simulate them in the process of measuring in anti-lock braking modes. Simulated modes are close to a real mode of braking aircraft wheels during landing formed by aviation automation systems. To improve accuracy of reproduction of electromechanical braking device characteristics, an automatic adaptive braking control system is offered. Based on the Burkhard model and additive random noise, a complex of mathematical models of distribution of friction coefficient values along the runway has been developed. A complex of mathematical models includes a variety of descriptive characteristics (snow, wet asphalt with snow, very wet asphalt and wet asphalt). Computer models of friction coefficient measurement processes have been obtained. Series of experiments depending the results of friction coefficient measurements with simulated anti-lock braking mode on variations of their shape, intensity and frequency of braking and the average values of the slip anti-lock braking mode cycles have been carried out. It is shown that at any statistically representative interval of the runway (200 m), the average value of measured friction coefficient varies depending on the change of form the anti-lock braking cycles. Design documentation has been developed; experimental model of a new towing measurement system has been designed and has passed debugging tests. Its semi-natural tests based at the test bench with a controlled drum simulator of “treadmill” and airfield tests are also planned.