Every aircraft is built and maintained with a specific job in mind. It isn't possible for one aircraft to cover every characteristic a plane can have. For example, a fighter aircraft is made for defense and attack functionality. Thus, it has an extremely strong structure and is extremely powerful. Each characteristic is selected to coincide with one another, so the aircraft is built into a cohesive machine.
A fixed-wing aircraft is used for commercial purposes, one of its most important characteristics is to be comfortable for the passengers as well as the pilot. There are nine components to a fixed-wing, or conventional, aircraft: the fuselage, engine mount, nacelle, wings, stabilizers, flight control surfaces, landing gear, arresting gear, and catapult equipment. In this article we will be focusing on the fuselage.
The fuselage is the heart of the aircraft and where every other structure connects to. Usually composed of all metal, most fuselages are modified in a monocoque design. This design is structured in a way that relies on the strength of the shell (exterior) to carry various loads. Shell or skin thickness depends on what the aircraft's purpose is and what stresses it will have to encounter. To distribute these forces a cross sectional shape is composed and made up of bulkheads, station webs, and rings. Longitudinal members, such as longerons, formers, and stringers, take the brunt force of bending tension.
There is also a semimonocoque fuselage made up of aluminum alloy or graphite epoxy. In this design, longerons are used in conjunction with stringers, which are lighter and used more commonly. Vertical members, known as bulkheads, frames, and formers, are used to support concentrated loads and attach parts such as wings, engines, and control stabilizers. This design is more streamlined and sturdier as compared to the monocoque design since all structural components aid the structure. This configuration is most likely used in fighter jets to protect the structure from the damage it may contract.
Fuselages may be constructed in as little as two sections to as many as six sections for larger aircrafts. Each aircraft will have differing maintenance and inspection manuals depending on where the access doors and inspection panels are located.