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.

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