Table 3: Theoretical and experimental values of mass moment of inertia and torsional natural frequencies.

Mass moment of inertia for platform, kg·m2 Mass moment of inertia for platform with propeller, kg·m2 Mass moment of inertia for propeller, kg·m2 Total mass moment of inertia (propeller + plate* + shaft**), kg·m2 Torsional natural frequency for uncracked shaft , Hz Theoretical Experimental Experimental Experimental Theoretical and experimental Theoretical Experimental (a) (b) (c) (d) = (c) − (b) 7.746 × 10−3 7.571 × 10−3 1.163 × 10−2 4.057 × 10−3 5.639 × 10−3 43.04 43.72

* = 1.5232 × 10−3 kg·m2 (by experimental measurements); ** = 1.5232 × 10−3 kg·m2 (by theory).