Table 1 δ-Optimal propellers.

Comparison of optimal (geometric) propulsion efficiency, δmax, obtained using GA search for propellers with two mutually perpendicular symmetry planes, skew-symmetric propellers, and unconstrained shapes upon varying the filament aspect ratio/slenderness (width to length).

Aspect ratioOne symmetry
plane*
Skew-symmetryUnconstrained
1:60.1290.1530.154
1:70.1440.1760.177
1:80.1560.1950.196
1:90.1670.2120.212
1:100.1750.2250.224
1:110.1830.2380.238
1:120.1890.2460.246

*The resulting shapes have twofold reflection symmetry.

†This shape is shown in Fig. 3.