# Fuselage Group Mass

Consider a 5% weight reduction due to composite usage in nonload-bearing struc­tures (e. g., floorboards). Use Equation 8.15:

L = 15.24 m, Dave = 1.75 m, VD = 380KEAS = 703.76 kmph = 195.5 m/s and Cfus = 0.04, ke = 1.04, kp = 1.09, kuc = 1.06, and kmat = (0.9 + 0.9 x 0.1) = 0.99

 Semi-empirical Mass Graphical Component (kg) fraction % solution – lb (kg) 1. Fuselage group 930 10 ^2,050 (932) 2. Wing group 864 9.2 ^2,100 (94б) 3. H-tail group 124 1.32 H-Tail+V-Tail^460 (209) 4. V-tail group 63 0.67 5. Undercarriage group 380 4 ^900 (409) 6. Nacelle + pylon group 212 2.245 ^410 (18б) 7. Miscellaneous Structures group total 2,591 27.56 8. Power plant group 1,060 11.28 9. Systems group 1,045 11.12 10. Furnishing group 618 6.57 11. Contingencies MEM 143 5,457 0.7 58.05 12. Crew 180 1.92 13. Consumables OEM ^ 119 5,800 1.73 61.7 13. Payload (as positioned) 1,100 11.7 14. Fuel (as positioned) MTOM 2,500 9,400 26.6 100 MRM 9,450 100.53
 Table 8.5. Bizjet mass (weight) summary

fuselage

horizonta tail

Then:

MFcivil = cfus X ke X kp X kuc X kdoor X; (MTOM X nult) X (2 X L X Dave X

For civil aircraft, (MTOM x nult)x = 1; therefore:

M-Fcivii = 0.04 X 1.04 X 1.09 X 1.06 x 1 x 1 x (2 x 15.24 x 1.75 x 195.50’5)1’5 = 0.048 x (2 x 15.24 x 1.75 x 195.50’5)1’5 = 0.048 x (53.35 x 13.98)15 = 0.048 x (745.95)15 = 0.048 x 20,373.3 = 978 kg

There is a 5% reduction of mass due to the use of composites:

MFcivil = °.95 MFcivil-all metal ^ 930 kg

This is checked using Torenbeek’s method (Equation 8.13); refer to Chap­ters 6 and 9 for dimensions:

WFcivil = 0.021 Kf {VdLht/ (W + D)}05 (f s-gross _area )

Kf = 1.08, L = 50 ft, W = 5.68 ft, D = 5.83 ft, Lht = 25 ft, Vd = 380 KEAS,

Sfus „gross – area = 687 ft

Therefore,

WFcivil = 0.021 X 1.08 X 1.07 X {380 x 25/(5.68 + 5.83)}0 5 x (687)12

= 0.0243 x (825.4)0 5 x 2,537.2 = 0.0243 x 28.73 x 2,537.2 = 1,770 lb (805 kg)

The higher value of the two (i. e., 930 kg) is retained, which gives a safer approach initially.