Lf /Df = 8.71

fuselage upsweep angle = 10 deg

fuselage closure angle = 10 deg

Wing (see Figure 9.13)

planform reference area, SW = 30 m2 (323 ft2)

span = 15 m (49.2 ft)

aspect ratio = 7.5

wing MAC = 2.132 m (7 ft)

root chord at centerline = 2.86 m (9.38 ft)

tip chord = 1.143 m (3.75 ft)

quarter-chord wing sweep = 14 deg

aerofoil: NACA 65–410 with 10% t/c ratio for design CL = 0.4

Empennage (see Figure 9.13)

V-tail: SV = 4.4 m2 (47.34 ft2)

span = m (ft)

MAC = (7 ft)

H-tail: SH = 6.063 m2 (65.3 ft2)

span = 5 m (ft)

MAC = (4.2 ft)

Nacelle (see Figure 9.13)

nacelle length = 2.62 m (8.6 ft)

nacelle diameter = 1.074 m (3.52 ft)

nacelle fineness ratio = 2.62/1.074 = 2.44

9.18.2 Computation of Wetted Areas, Re, and Basic CF

An aircraft is first dissected into isolated components, as shown in Figure 9.15. The Re, wetted area, and basic 2D flat-plate CF basic of each component are worked out herein.

Fuselage

The fuselage is conveniently sectioned into three parts:

1.Front fuselage length, LFf = 3.5 m with a uniformly varying cross-section

2.Mid-fuselage length LFm = 5.95 m with an average constant cross-section diameter = 1.75 m

3.Aft-fuselage length LFa = 5.79 m, with a uniformly varying cross-section

Wetted area

front fuselage, Aw F f (no cutout) = 110 ft2

Mid-fuselage, Aw Fm (with two sides of wing cutouts) = 352 − 2 × 6 = 340 ft2

Aft fuselage, Aw Fs (with empennage cutouts) = 180 − 10 = 170 ft2

Include additional wetted area for the wing-body fairing housing the undercarriage ≈ 50 ft2

total wetted area, Aw f = 110 + 340 + 170 + 50 = 670 ft2

fuselage Re = 50 × 1.2415272 × 106 = 6.2 × 107

from Figure 9.19b (fully turbulent) at LRC, the incompressible basic CFf = 0.0022

Wing

wing exposed reference area = 323 − 50 (area buried in the fuselage) = 273 ft2

MAC = 2.132 m (7 ft), AR = 7.5

For t/c = 10% of the wing wetted area, Aww = 2.024 × 273 = 552.3 ft2

root chord, CR = 2.86 m (9.38 ft)

tip chord, CT =1.143 m (3.75 ft)

wing Re = 7 × 1.2415272 × 106 = 8.7 × 106

from Figure 9.19b at LRC, the incompressible basic CFw = 0.003

Empennage (same procedure as for the wing)

V-tail

reference area, SV = 4.4 m2 (47.34 ft2)

exposed reference area = 47.34 − 7.34 (area buried in the fuselage) = 40 ft2

for t/c = 10% the V-tail wetted area, AwVT = 2.024 × 40 = 81 ft2

taper ratio = 0.6

MAC = 2.132 m (7 ft)

V-tail

Re = 7 × 1.2415272 × 106 = 8.7 × 106

from Figure 9.19b (fully turbulent) at LRC, the incompressible basic

CF V−tail = 0.003

H-tail

reference area, SH = 6.063 m2 (65.3 ft2); it is a T-tail and it is fully exposed

for t/c = 10%, the H-tail wetted area, Aw HT = 2.024 × 65.3 = 132.2 ft2

taper ratio = 0.5

MAC = 1.28 m (4.22 ft)

H-tail Re = 4.22 × 1.2415272 × 106 = 5.24 × 106

From Figure 9.19b (fully turbulent) at LRC, the incompressible basic CF H−tail = 0.003185.

Nacelle

length = 2.62 m (8.6 ft)

maximum diameter = 1.074 m (3.52 ft)

fineness ratio = 2.45

nacelle Re = 8.6 × 1.2415272 × 106 = 1.07 × 107

two-nacelle wetted area, Awn = 2 × 3.14 × 3.1(Dave) × 8.6 − 2 × 5 (two pylon cutouts) = 158 ft2

from Figure 9.19b (fully turbulent) at LRC, the incompressible basic CFnac = 0.0029

Pylon

each pylon exposed reference area = 14 ft2

length = 2.28 m (7.5 ft)