If a manufacturer’s dry weight is available, it is better to use it rather than semi-empirical relations. In this case, the manufacturer’s dry weight is in the public domain. MDRYENG = 379 kg per engine. This gives:

(T/ Wdry engine) = 17,230/(379 × 9.81) = 4.63

The total power plant group mass can be expressed semi-empirically as

MENG per engine = 1.5 × MDRYENG per engine = 1.5 × 379 = 568.5 kg. For two engines, MENG = 1,137 kg.

8.11.8 Systems Group Mass

MTOW = 9,500 kg (use Equation 8.47),MSYS = 0.11 × 9,500 = 1,045 kg.

8.11.9 Furnishing Group Mass

MTOW = 9,500 kg (use Equation 8.50), MFU R 0.065 × 9,500 = 618 kg

8.11.10 Contingency Group Mass

MTOW = 9,500 kg (use Equation 8.52), MCONT = 0.015 × 9,500 = 143 kg

8.11.11 Crew Mass

There are two flight crew members and no cabin crew. Therefore, MCREW = 2 × 90 = 180 kg.

8.11.12 Payload Mass

There are ten passengers. Therefore, MPL = 10 × 90 = 900 kg.

8.11.13 Fuel Mass

The range requirement is 2,000 nm carrying ten passengers. From statistical data given in Table 8.1, take the highest value of 26% of MTOW, MFUEL = 0.26 × 9,500 = 2,470 ≈ 2,500 kg.

8.11.14 Weight Summary

Table 8.5 is the weight summary obtained by using the coursework example worked out thus far. The last column provides the estimation as a result of the graphical solution (in bracket –kg).

This computation requires further iterations to be fine-tuned for better accuracy. The CG position is established in the next section, when further iterations will yield a better picture.

Variant Aircraft in the Family

For simplification, linear variations are considered, which should be worked out as a coursework exercise.