10. vibration mode: 26 hz
or 1560 rpm excitation
Propeller
Blade
Flutter
Resonance
Possible
cavitation
11. Vibration mode: 60 hz
or 3600 rpm
Propeller
Blade
possible
collision
cowl
12. Conclusions
◼ Calculated stresses agree with the
damage caused by the underwater
collision.
◼ Recommend strengthening the
support struts.
◼ Qualification testing must include
operation over the full operation speed
range to dectect propeller blade flutter
or interference with the cowl.