Aluminum alloys continue to be the most prevalent material in aircraft structure. Table 15.6 is a conservative presentation of typical percentages of composite use for the coursework project. The table reflects the typical current practice, although there are some newer designs that perform better than what is listed.
The introductory coursework exercise may use the following strategy. The weight equations provided in Chapter 8 are valid.
Civil Aircraft Design
For civil aircraft, the design is all-metal construction. If nonmetals (i. e., composites) are introduced, they may be limited to secondary and tertiary structures up to only approximately 25% of the OEW. Typical nonmetal structures include the floorboards, control surfaces, complex fairings, and empennage.
Military Aircraft Design
For military aircraft design, the same philosophy about nonmetal (i. e., composites) components is maintained, with weights increased to 40% of the OEW. Typical nonmetal structures include the floorboards, control surfaces, complex fairings (e. g., intake ducting and wing-body junction), and empennage.