Subsonic Unsteady Aerodynamics for General Configurations. Part 1. Volume I. Direct Application of the Nonplanar Doublet-Lattice Method
Final technical rept. Dec 1969-Sep 1970
DOUGLAS AIRCRAFT CO LONG BEACH CA
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Two methods of accounting for body-lifting surface interference in unsteady flow are considered. The first method is a direct application of nonplanar lifting surface elements to both the lifting surfaces and the body surfaces. This type of idealization must be used with an axial doublet introduced to account for body incidence effects. The undesirable effects of the annular wing representation are then reduced. The second approach uses an image system and an axial singularity system to account for the effects of the bodies. The methods described are intended to be used by airplane designers to calculate with improved accuracy, the unsteady aerodynamic pressures that act on a lifting surface being propelled at subsonic speeds. The new feature of these calculations is that the effects on the pressure field induced by interference between the fuselage, for example, and the wing or the wing, pyon and nacelle, are taken into account. These calculations are an essential ingredient of flutter analyses and will improve the confidence level of such calculations in preventing wing-store flutter and flutter of advanced vehicles where fuselages are relatively large, provide some lifting capability and cause noticeable interference effects.
- Fluid Mechanics