# Systems Group Mass

MTOW = 9,500kg (use Equation 8.47),MsYs = 0.11 x 9,500 = 1,045 kg.

8.11.5 Furnishing Group Mass

MTOW = 9,500 kg (use Equation 8.50), Mfur 0.065 x 9,500 = 618 kg

8.11.6 Contingency Group Mass

MTOW = 9,500kg (use Equation 8.52), MCoNT = 0.015 x 9,500 = 143 kg

8.11.7 Crew Mass

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

There are ten passengers. Therefore, Mpl = 10 x 90 = 900 kg.

8.11.9 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 x 9,500 = 2,470 « 2,500 kg.

8.11.10 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.

Table 8.6. Typical values of component CG locations: civil aircraft

 Component CG and typical % of component characteristic length 1. Fuselage group 45% 2. Wing group No slat-30% of MAC With slat – 25% MAC 3. H-tail group 30% 4. V-tail group 30% 5. Undercarriage group At wheel center (nose and main wheels taken separately) 6. Nacelle + pylon group 35% 7. Miscellaneous As positioned – use similarity 8. Power plant group 50% 9. Systems group As positioned – use similarity (typically 40% of fuselage) 10. Furnishing group As positioned – use similarity 11. Contingencies As positioned – use similarity MEM (do not need to compute CG) 12. Crew As positioned – use similarity OEM Compute 13. Payload As positioned (distribute around CG) 14. Fuel As positioned (distribute around CG) MTOM Compute MRM Compute

Longer Variant. Increase APayload = 400 kg, AFuselage = 300 kg, AFurnish = 200 kg, AFuel = 300 kg, and AOthers = 200 kg. Total increase = +1,400 kg; MTOMLong = 10,900 kg (no structural changes).

Smaller Variant. Decrease APayload = 500 kg, AFuselage = 350 kg, AFurnish = 250 kg, AFuel = 350 kg, and AOthers = 250 kg (lightening of the structures). Total decrease = -1,700 kg; MTOMSmall = 7,800 kg.