Abstract:

The accumulation of water on a runway surface can adversely impact aircraft performance during take-off and landing operations. As the surface becomes damp there is a loss of adhesion between aircraft tyres and the runway surface, due to a masking of the sharpness of the runway material micro-texture. As the rainfall intensity increases, water accumulations arise which inhibit the drainage provided by the runway macro-texture. This results in seriously diminished braking action and can ultimately cause planing of aircraft tyres, with an associated loss of braking action and aircraft directional control. Additionally, the accumulation of water in troughs and tyre-tracks on the runway may lead to the impingement of spray on airframes which, when combined with the potential ingestion of spray by aircraft engine intakes, can result in an unacceptable loss of take-off performance.

This Data Item comprises a mathematical model that predicts the level of water accumulation on an ungrooved runway surface. The empirical model was derived from the analysis of data obtained from experiments conducted on a variety of surfaces which are representative of runway surfaces. Additionally, a range of rainfall intensities were simulated by the researchers.

The empirical correlation is shown to model accurately the accumulation of water on surfaces similar to those likely to be found on operational runways.

This document can be used in conjunction with a series of ESDU Data Items related to the modelling of aircraft tyre performance on water-covered runway surfaces, the primary documents being ESDU 10015 and ESDU 05011.