Page 119 - Aeronautical Engineer Data Book

Basic fluid mechanics 95

Shape Dimensional Datum Approximate
ratio area, A drag
coefficient, C D
Cylinder (flow direction) I/d = 1 0.91
2 0.85
d π
4 0.87
– d 2
U 7 4 0.99
l
Cylinder (right angles to flow) I/d = 1 0.63
2 0.68
5 0.74
U l 10 dl 0.82
40 0.98
∞ 1.20
d
Hemisphere (bottomless) I 0.34
π
– d 2
4
d II 1.33
U
I II
Cone a = 60˚ π 0.51
– d 2
4
d a = 30˚ 0.34
U
π
– d 2 1.2
4
U d
Bluff bodies
6
Rough Sphere (Re = 10 ) 0.40
6
Smooth Sphere (Re = 10 ) 0.10
Hollow semi-sphere opposite stream 1.42
Hollow semi-sphere facing stream 0.38
Hollow semi-cylinder opposite stream 1.20
Hollow semi-cylinder facing stream 2.30
Squared flat plate at 90° 1.17
Long flat plate at 90° 1.98
Open wheel, rotating, h/D = 0.28 0.58
Streamlined bodies
Laminar flat plate (Re = 10 ) 0.001
6
6
Turbulent flat plate ( Re = 10 ) 0.005
Airfoil section, minimum 0.006
Airfoil section, at stall 0.025
2-element airfoil 0.025
4-element airfoil 0.05
Subsonic aircraft wing, minimum 0.05
Subsonic aircraft wing, at stall 0.16
Subsonic aircraft wing, minimum 0.005
Subsonic aircraft wing, at stall 0.09
Aircraft wing (supersonic) n.a.
Aircraft -general
Subsonic transport aircraft 0.012
Supersonic fighter, M = 2.5 0.016
Airship 0.020–0.025
Helicopter download 0.4–1.2
Fig. 5.13(b) Drag coefficients for standard shapes