Fuel – Civil Aircraft

The fuel load is mission-specific. For civil aircraft, required fuel is what is needed to meet the design range (i. e., market specification) plus mandatory reserve fuel. It can be determined by the proper performance estimation described in Chapter 13. At this design stage, statistical data are the only means to estimate fuel load, which is then revised in Chapter 13.

The payload and fuel mass are traded for off-design ranges; that is, a higher payload (if accommodated) for less range and vice versa.

8.11 Worked-Out Example – Civil Aircraft

The semi-empirical relations described in Section 8.10 are now applied to obtain an example of the configuration worked out in Chapters 6 and 7 in the preliminary configuration layout. This chapter more accurately estimates component and air­craft mass along with the CG locations (Figure 8.4). Therefore, the preliminary con­figuration needs to be refined through an iterative process with more accurate data. The iteration process may require the repositioning of aircraft components (see Sec­tion 8.13). The aircraft configuration is finalized in Chapter 11. From Chapter 6, the following specifications are obtained for the baseline-aircraft preliminary configura­tion. They are required to estimate aircraft component mass, as shown here:

MTOM = 9,500 kg (refined in this exercise)

Two turbofans (i. e., Honeywell TFE731), each having TSLS = 17,235 N (3,800 lbs), BPR < 4 and dry weight of 379 kg (836 lbs)

The results from this section are compared with the graphical solutions in Figure 8.3 and in Table 8.5.