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Construction Details - Unsteady Forces - Coggle Diagram
Construction Details - Unsteady Forces
Due to
Operation in wake field
Depends on
Harmonic content of wake field
Amount of Skew
Propeller vibrations
Natural Frequency of the blade
Conventional Propellers
Usually higher primary excitation freq
High Skewed (Cumming)
Decreases Natural Freq
Boswell strain measurement
2 bladed propeller
60° Skew
Max Stress
Near Trailing edge
Backing
Normal
Lower stress
Crash Stop
High Stress
Elastic deflection
Static Divergence
Instability leads to damage
Luttmer
Influence of screw on backing
Max Stress
Tip
Worsens
as increases skew