MODEL EXPERIMENTS TO DETERMINE THE ANGLE OF HEEL WHEN TURNING AND THE RADIUS OF THE TURNING CIRCLE FOR U.S. DESTROYER 'FARRAGUT'.
DAVID TAYLOR MODEL BASIN WASHINGTON D C
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Throughout the series of tests one fact stood out prominently, viz, that at speeds above 4.5 knots a sudden lengthening of the radius of the turning path occurred with all the rudders when they were located in the normal position. As a consequence of this lengthening of the radius of the turning circle the maximum angle of outward heel which normally would increase steadily with an increase in speed, remained practically constant at speeds above this critical speed, as is clearly shown. Futhermore, at 4.50 knots speed it was found that when the rudder was lowered from its normal position successively by equal amounts the maximum angle of outward heel decreased immediately, while at 6.50 knots speed it remained constant or even increased for the first inch of drop and then decreased. This peculiarity indicates that the breakdown of the rudders was due to air being sucked down from the surface, or what may be termed rudder cavitation, which ceased when the head of water above the top edge of the rudder was increased one inch for the 10 ft. model. It appears that for all the rudders the lengthening of the radius of the turning circle due to rudder cavitation is very marked. Author
- Marine Engineering