Analysis of Known and Construction of New Mathematical Models of Forces on a Ship's Rudder in an Unbounded Flow

The forces arising on the ship's rudder at different angles of attack in an unbounded flow are investigated. The components of the resulting force on the rudder are represented in terms of the rudder lift and drag forces, as well as in terms of the normal and tangential forces on the rudder. The well-known mathematical models of hydrodynamic rudder coefficients are analyzed, and their disadvantages are found. New mathematical models of hydrodynamic coefficients have been obtained, in particular, the coefficients of rudder lift and drag, which take into account the aspect ratio of the rudder, its relative thickness and can be applied to any angle of attack of the flow on the rudder. On specific examples for rudders of the NACA series, the adequacy of the proposed models and their consistency with known experimental studies are illustrated. It is shown how the rudder lift and drag change, as well as the components of the resulting force for the maximum possible range of changes in the local drift angle and the rudder angle.