PREFACE TO AERODYNAMICS SERIES ESDU Data Items provide validated information in engineering design and analysis for use by@ or under the supervision of@ qualified engineers. The data are founded on an evaluation of all the relevant information@ both published and unpublished@ and are invariably supported by original work of ESDU staff engineers or consultants. The whole process is subject to independent review for which crucial support is provided by industrial companies@ government research laboratories@ universities and others from around the world through the participation of some of their leading experts on ESDU Technical Committees. This process ensures that the results of much valuable work (theoretical@ experimental and operational)@ which may not be widely available or in a readily usable form@ can be communicated concisely and accurately to the engineering community.