Influence of the Propeller on Other Parts of the Airplane Structure

The ideal presented by the more general treatment of wing and airplane theory contemplates an airplane or airfoil moving relative to a body of undisturbed air. In the actual case with the usual disposition of the propeller, a part of the wings and most or all of the control surfaces will be under the influence of an additional velocity, more or less turbulent in character, and formed by the wake of the propeller. Moreover even outside the wake proper the action of the propeller will be accompanied by a change of the flow and hence of the forces acting on a part of the airplane. Obviously no complete theory, including in detail the effects of a turbulent wake, can at present be hoped for and in order to secure any approach to a theoretical discussion of the influence of the propeller on the remainder of the structure, various simplifying assumptions must be made.