Geometry of the Wing-Fuselage System

For a better understanding of the aerodynamics of the wing-fuselage system to be discussed below, the geometry of such a system will be discussed first. The geometry of the wing has been described in Sec. 3-1 (Figs. 3-1 and 3-2), that of the fuselage in Sec. 5-1 (Fig. 5-1). The geometry of the wing-fuselage system is illustrated in Figs. 6-1 and 6-2. Figure 6-1 gives the plan view and the side view of a wing-fuselage system, Fig. 6-2 the rear view of two wing-fuselage systems. The position of the wing relative to the fuselage is defined by the wing rearward position e, the wing high position z0, and the angle of wing setting є0. As shown in Fig. 6-1, the wing rearward position e is the distance between the geometric neutral

point of the wing (Sec. 3-1) and the fuselage nose. According to Fig. 6-2a, the wing high position Zq is the distance between the wing and the fuselage axis. Its values are

High-wing airplanes: Mid-wing airplanes: Low-wing airplanes:

A typical mid-wing airplane with dihedral is sketched in Fig. 6-2b. The angle of wing setting є0 is, from Fig. 6-1, the angle between the chord of the wing root section and the fuselage axis. When the wing penetrates the fuselage, the portion of the wing shrouded by the fuselage requires special explanation. In the case of a swept-back trapezoidal wing, it is advantageous to replace the portion of the wing shrouded by the fuselage by a rectangular wing section. This rectangle is formed by the length of the root section /0 and by the mean fuselage width in the range of the wing Ьр0. For conventional wing-fuselage systems, bp0 is almost equal to the maximum fuselage width bpmax, according to Fig. 5-1. The wing thus defined will be termed the “substitute wing,” whereas the wing from which it has been derived will be termed the “original wing.”

Another important geometric parameter of a wing-fuselage system is the ratio of fuselage width bp0 and wing span b:

(6-1)

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