ESDU 93032:2009

INTRODUCTION

This Item illustrates the practical use of those excrescence
drag Data Items, see Table 2.1, that are particularly pertinent to
the types of excrescence commonly found on wings.

In order to illustrate the application (Section 3) of the
excrescence drag Items applicable to wings the case of a subsonic
transport aircraft in the cruise condition has been chosen, and the
excrescence drag arising from a number of wing components
(controls, removable panels etc.) is calculated (Section 4).

Each component is the subject of a separate example and the
various contributions to the excrescence drag of the component are
calculated and itemised for two calculation cases. Calculation Case
(i) deals with an ideal situation in which there are no avoidable
surface mismatches or sealing problems, and Calculation Case (ii)
deals with the effects of possible surface mismatches or poor
sealing. The itemised drag contributions for each component are
used to highlight those areas of detail design and installation
that are likely to contribute most to avoidable drag. Conclusions
from the calculations are summarised in Section 5.