Example: Civil Aircraft
Figure 11.4 shows the final configuration of the family of variants; the baseline aircraft is in the middle (see Figure 6.1 for the plug sizes).
Section 6.10 proposes one smaller (i. e., four to six passengers) and one larger (i. e., fourteen to sixteen passengers) variant from the baseline design that carries ten to twelve passengers by subtracting and adding fuselage plugs from the front and aft
of the wing box. The baseline and variant details are worked out in Chapter 6 as the preliminary configuration, followed by the undercarriage design in Chapter 7. Aircraft mass is calculated in Chapter 8. After obtaining the aircraft drag, this chapter finalizes the size of the baseline along with the two variants.
The final sized aircraft came very close to the preliminary baseline aircraft configuration suggested in Section 6.10. Therefore, iterations to fine-tune the aircraft mass, drag, and so forth have been avoided. It is unlikely for a coursework exercise to be that fortunate. It is highly recommended that any exercise should make at least one iteration in order to get a sense of the task. Setting up a spreadsheet is part of the learning process; all equations in this book are provided to set up the required spreadsheet.