ESDU 05011:2015

$62.40

Summary of the Model for Performance of an Aircraft Tire Rolling or Braking on Dry or Precipitate Contaminated Runways

Published By	Publication Date	Number of Pages
ESDU	2015-07	24

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Category: ESDU

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Description

This Data Item summarises the empirical model defined in ESDU
10015, Model for performance of a single aircraft tyre rolling or
braking on dry and precipitate contaminated runways, which
describes the decelerating forces acting on an aircraft type tyre
when rolling or braking on hard surfaces typical of runways and
taxiways. The model is valid for runways contaminated with water,
slush, snow and ice but can also be applied to runways that are
free from any contaminant. In order to calculate decelerating
forces, in addition to an approximation to the operating slip ratio
for the braking system, it is necessary to know values of nine
variables, all of which are used in customary calculations of
aircraft performance. These are

• depth of macro-texture of runway surface

• depth of contaminant (where applicable)

• density of contaminant (where applicable)

• ground speed

• tyre inflation pressure

• normal (to runway) load on tyre

• nominal tyre width

• nominal tyre diameter

• runway surface temperature.

The model is founded on experiments with aircraft type tyres
analysed in the context of observations based in rubber technology.
It has been substantiated over a range of experimental data so that
aircraft and ground-test machine performance can be predicted for a
wide range of operational envelopes. Where values are known for all
the variables listed above, the model provides estimates of the
decelerating forces due to rolling or braking. However, in cases
where, say, runway conditions are unknown, the model can be used to
deduce those conditions from ground-test machine measurements.
Subsequently, those conditions can be re-applied to the model to
predict aircraft performance. In the particular case of winter
precipitation, the model includes the statistical variation of the
mechanical properties of snows and the frictional characteristics
for runways that are completely covered with ice or snow.

Application of the method to multiple-wheel undercarriages is
also considered.

Additional information