Page 210 - Aerodynamics for Engineering Students

Two-dimensional wing theoly 193
y/s 1 Camberline ordinates for

CMk'O

0.2 0.4 0.6 0.8 1.0 x/c

x/c 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
y/8 0 0.324 0.577 0.765 0.894 0.970 0.999 0.988 0.943 O.St0,

x/c 0.5 0.56 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1.0
y/6 0,776 0.666 0.546 0.424 0.304 0.194 0.099 0.026 5.019 5.03 0

x/c 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
k/2nU 03 0,127 0.123 0.121 OJ18 0.1 12 0.105 0.096 0.087 0.076

x/c 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1.0
k/%U 0.Om 0.053 0.042 0.030 0.019 0.009 5.006 5.008 5.013 5.014 0

Fig. 4.20

This is the so-called Theodorsen condition, and the appropriate CL is the ideal, optimum, or
design lift coefficient, CL,,~~.

4.8.2 The NACA four-digit wing sections
According to Abbott and von Doenhoff when the NACA four-digit wing sections
were first derived in 1932, it was found that the thickness distributions of efficient