Fuselage

fuselage wetted area = Aw f = 1,474 ft2

fuselage Re = 69 × 1.381 × 106 = 9.53 × 107 (length trimmed to what is pertinent for Re)

use Figure 9.19b to obtain basic CF f = 0.0021

Wing

wing wetted area = Aww = 1,144.08 ft2

wing Re = 15.19 × 1.381 × 106 = 2.1 × 107

use Figure 9.19b to obtain basic CFw = 0.00257

Empennage (same procedure as for the wing)

V-tail wetted area = AwVT = 235.33 ft2

V-tail Re = 8.35 × 1.381 × 106 = 1.2 × 107

use Figure 9.19b to obtain basic CF V−tail = 0.00277

H-tail wetted area = Aw HT = 388.72 ft2

H-tail Re = 9.73 × 1.381 × 106 = 1.344 × 107

use Figure 9.19b to obtain basic CFH−tail = 0.002705

9.19.3 Computation of 3D and Other Effects to Estimate Component CDpmin

A component-by-component example follows.

Fuselage

From the previous section, at Mach 0.6, the basic CFf = 0.0021.

3D effects (Equations 9.9, 9.10, and 9.11):

Wrapping:

CFf = CFf × 0.025 × (length/diameter) × Re−0.2

=0.025 × 0.0021 × (9.66) × (9.53 × 107)−0.2

=0.000507 × 0.0254

=0.0000129 (0.6% of basic CF f )

Supervelocity:

CFf = CFf × (diameter/length)1.5 = 0.0021 × (1/9.66)1.5

= 0.0021 × 0.033 = 0.0000693 (3.3% of basic CFf )

Pressure:

CFf = CFf × 7 × (diameter/length)3 = 0.0021 × 7 × (0.1035)3

=0.0147 × 0.00111 = 0.0000163 (0.8% of basic CF f )

Other effects on the fuselage (intake included – see Section 9.18):

Reference [3] suggests applying a factor of 1.284 to include most other effects

except intake. Therefore, unlike the civil aircraft example, it is simplified to only the following:

Intake (little spillage – remainder taken in 3D effects): 2%

The total CFf increment is provided in Table 9.11. Table 9.18 lists the components of the Vigilante fuselage CFf.

Therefore, in terms of the equivalent flat-plate area, f, it becomes = CFf × Aw F :

f = 1.067 × 0.0021 × 1,474 = 3.3 ft2

Add the canopy drag, CDл = 0.08 (approximated from Figure 9.4).

Therefore, canopy = 0.08 × 4.5 = 0.4 ft2; f f = 3.3 + 0.36 = 3.66 ft2

Wing

From the previous section, at Mach 0.06, the basic CF = 0.00257.

3D effects (Equations 9.14, 9.15, and 9.16):

Supervelocity:

CFw = CFw × 1.4 × (aerofoil t/c ratio)

= 0.00257 × 1.4 × 0.05 = 0.00018 (7% of basic CFw )

Table 9.18 gives the components of the Vigilante fuselage CF f .Pressure:

CFw = CFw × 60 × (aerofoil t/c ratio)4 × 6 0.125 AR

=0.00257 × 60 × (0.05)4 × (6/3.73)0.125

=0.1542 × 0.00000625 × 1.06 = 0.00000102 (0.04 % of basic CFw )

Interference: Fw for a thin high wing, use 3% of CFw

Other effects:

Excrescence (nonmanufacturing; e.g., control surface gaps):

flap and slat gaps: 2%

others (increased later): 0%

total CFw increment: 12.04%

Table 9.19 lists the components of the Vigilante wing CFw .

Therefore, in terms of the equivalent flat-plate area, f, it becomes =

CFw × Aww :

f w = 1.12 × 0.00257 × 1,144.08 = 3.3 ft2