Semi-Monocoque Fuselage Construction

Semi-Monocoque Fuselage Construction (Figure 2.6)

To overcome the problems encountered in the true monocoque construction, designers thought of a substructure to be placed beneath the stressed skin so that the sub-structure carries a large share of the total load. Hence, semi-monocoque construction came into practice. The substructure is made of vertical members (rings/formers, bulkheads) connected by horizontal members (longerons and stringers)

There is wooden semi-monocoque fuselage as well as all-metal semi-monocoque fuselage.

Today, majority of aircraft fuselage is all-metal semi-monocoque in design.

Figure 2.6 shows structural members/elements that are used in the internal framework to which a relatively thin skin is attached to produce semi-monocoque fuselage construction.

Figure 2.6: Semi-Monocoque Fuselage Construction 

2 Structural Members of Fuselage

Following are the names of the most important structural members used in the fuselage structure:

a)                 Formers/Rings/Frames : Vertical members to take load, give cross-sectional ‘form’

b)                 Bulkheads: Vertical members with no central apertures to isolate one section from another, taking end loads.

c)                  Longerons: Principal horizontal structural members.

d)                 Stringers: Lighter horizontal members to be used as fill-ins between longerons