Research and Development of a Method for Forecasting of Rollout Distance of an Aircraft

Abstract

Any aircraft mission includes a land movement phase. Such phases are carried out under control of a pilot. At this time the aircraft crew experiences high psychological stresses. Stressful conditions create prerequisites for improper or erroneous actions. Therefore, the human factor plays a decisive role in ensuring safety and accident free flights of the air transport. In order to improve the crews' situational awareness, the algorithmic methods for assessing of the current and predicting of the future movement of the aircraft were developed. The methods are based on the energy approach to the flight control. The well-known energy balance equation is generalized to the runway modes by adding a member, reflecting the absorption of energy to overcome the drag of the mechanical forces. The new member is presented in the following form: ∆ HE b= t1 t2 V kb dt , where k_b is the normalized braking coefficient equal to the ratio of the total resistance forces from the chassis to the weight of an aircraft. Here H_E (*) = E (*)/ mg is the specific energy. The extended equation ∆ HE =∆ HE eng+∆ HE D+ HE b+∆ HE w describes how to change the total energy of an aircraft throughout its trajectory, including the ahead segment. The length of this segment is calculated from the conditions of achievement of the required final energy state. In the braking mode the final state is determined by a known speed taxiing. The target braking distance is described by the following equation: Db =0,5 V t 2- Vtaksiin t 2 / gnx t . However, this forecast does not take into account the change in the braking forces on the ahead lying trajectory. Therefore, in order to improve the reliability of forecasting the method of algorithms' correction was offered. The correction coefficients are the functions of the mass, velocity and braking coefficient. These functions are approximated by the polynomials up to degree-4. The computer research stand was developed, including the mathematical model of Tupolev Tu-204. The deterministic and statistical tests within the range of the aircraft mass of 70-105 tons, approach speed of 200-220 km/h and friction coefficient of 0,3-0,75 were performed. The estimates of the accuracy of the forecast on the basis of the tests are presented.