Please enable JavaScript.
Coggle requires JavaScript to display documents.
Scale Effect - Coggle Diagram
Scale Effect
Velocity problem
Usually in compliance
with Fr Number
Reynolds Number
Important for
Maximum lift angle
Stall evaluation
Lift Coeff increases with Reynolds
Higher Reynolds
Turbulent flow
Lower Reynolds
Laminar flow
more susceptible to separation
Tactical Diameter
Fr<0,30
Independent of speed
High speeds
increase due to wavemaking
also rudder cavitation
Shiba trials Wind Tunnel
Using NACA sections
Maximum Lift coeff
Increases with Reynolds
Due to delay of stall angle
Lift curve
varies little
With Reynolds
With section shape
Drag coeff
Decreases with
Increase in Reynolds
Roughness of surface
Decreases Max Lift Coeff
Brard
Model tests
Multiple screw
Single rudder
Overpredict tactical diameter
by around 10% to 15%
Due to failure of hull wake scale
Proximity to surface
degradation rudder performance
due to WAVE GENERATION
Small-Scale models