ESDU 90020:2009

INTRODUCTION

This Item provides a simple theoretically-based method for
predicting the airframe-induced upwash at any point in the
flowfield ahead of the wing at subsonic speeds. The airframe can be
considered to consist of "wing-like", essentially planar, lifting
components, and "body-like", essentially non-lifting, components.
The method, detailed in Section 3, consists of a means of
predicting the upwash due to these two classes of airframe
component in isolation, together with an approximate means whereby
account is taken of interference effects between the various
components. The method is therefore capable of application to a
wide range of airframe configurations.

The method, commonly called the "Yaggy-Rogallo" method, although
originally developed for application to the propeller vibration and
flutter problem (Derivation 4), is applicable to any area requiring
a knowledge of upwash flow fields. Such areas could include jet
engine inlet flows, the local flow around canards, boom-mounted
sensors and fuselage-mounted or underwing-mounted stores, for
example.

The applicability and accuracy of the method are discussed in
Section 4. In particular, Section 4.2.3 describes two extremes of
application for which the method has already been used. The
Derivation and References are given in Section 5 and worked
examples illustrating two of the many possible uses of the method
are provided in Section 6. Material supporting the implementation
of the method is given in Appendices A, B and D. Details of a
computer program for the method, ESDUpac A9020, are given in
Appendix C.