Abstract:

ESDU 24003 demonstrates the application of an empirical model in order to calculate the decelerating forces acting at the tyre-runway interface of undercarriage tyres that belong to an aircraft operating in abraked state on a water-covered runway. The aircraft comprises five multiple-wheel undercarriages: one nose undercarriage; two wing undercarriages; and two main fuselage undercarriages. Each type of undercarriage is initially considered in isolation.

Decelerating forces are calculated for a range of operating speeds. Subsequently, the sum of forces acting on each undercarriage is determined. These forces are compared with the sum of forces when theaircraft operates on an equivalent, but dry, runway.

Comparisons of the decelerating forces acting on all tyres from an undercarriage and the forces acting on a single tyre from the respective undercarriage operating in isolation are made for each undercarriage type. The contaminant drag forces and braking forces are compared in these cases.

Step-by-step solutions, with detailed explanations, are provided for a particular operating condition for a fuselage undercarriage.

The empirical model defined in ESDU 11004, Decelerating forces on multiple-wheel undercarriages rolling or braking on precipitate contaminated runways, is implemented in this Data Item. Additionally, the empirical model summarised in ESDU 23002, Tyre braking on dry and water-covered runways - summary of ESDU tyre-runway modelling, is used. Familiarity with the relevant methods outlined in both of those Data Items is essential before ESDU 13002 is studied.