Practical Ship Hydrodynamics

188 Practical Ship Hydrodynamics
C p = P dyn /q
1.0
0.8
0.6
0.4
0.2
0
−0.2
−0.4
−0.6
−0.8
−1.0
−1.2
−1.4
−1.6
−1.8
1.25
1.0
0.75
0.5
0.25
0
0.75
0.25
0.5
1.0
1.25
C Ll as parameter
0.5 1.0
−2.5
−3.0
−3.5
0.1
0.75
1.0
1.25
X / C
Figure 5.17 Distribution of the non-dimensional dynamic pressure along a NACA0021 profile
as a function of the local lift coefficient CLl (Riegels (1958))
sides, respectively. For profiles with a curved mean line, an additional velocity
component has to be added. It may be taken from Abbott and Doenhoff (1959),
pp. 77ff and App. II, or it may be determined by a two-dimensional potentialflow
calculation for which various methods and codes are available. Brix
(1993), p. 84, gives a sample calculation for the NACA643-018 profile for
˛ D 15°.
5.4.3 Rudder types
Various rudder types have been developed over the years (Fig. 5.18):
Simplex rudder Spade rudder Semi-balanced
rudder
Figure 5.18 Various rudder types
Flap rudder