Balanced rudder
Encyclopedia
The balanced rudder was an innovation in warship construction used as early as 1862 in the USS Monitor
, one of the Union
's first ironclads during the American Civil War
. It was also used in , which was launched in 1865.
The balanced rudder was also adopted by the aircraft industry.
that was a simple flat piece of wood or metal, situated at the after end of the hull and hinged at the forward end, which could be angled to one side or the other to deflect the water passing it and hence provide an impulse to turn the ship. This required the exertion of significant force, as the passage of the water past the rudder tended to force it into a straight line in conformity with the flow.
The concept of a balanced rudder involved the shifting of the centre of rotation of the rudder to a point approximately 1/2 of the way from the forward end to the after end. This meant that when the rudder was turned, the flow of water past the ship actively worked on the forward part to increase the angle of deflection, whereas the same flow acted on the after part to reduce the angle. A degree of semi-balance is normal to avoid rudder instability i.e. the area in front of the pivot is kept less than that behind.
The mechanics of fluid dynamics
produced a solution in which the turning force applied in one direction on the rudder by the passing fluid was balanced by the turning force applied in the other direction, allowing the rudder to be moved with only limited mechanical resistance.
The balanced rudder was soon adopted by the fledgling aircraft industry in the early 20th century, which often made use of the horn balance, in which a section of the rudder, usually at the top of the vertical stabiliser, projected into the airstream. Two illustrations of aircraft rudders published by Flight Magazine in 1920, illustrate both the conventional balanced rudder (at lower left on the Short Swallow) and with a large 'horn' (at left centre, in this case in the form of a semicircle, on the 'Short Sporting Type').
USS Monitor
USS Monitor was the first ironclad warship commissioned by the United States Navy during the American Civil War. She is most famous for her participation in the Battle of Hampton Roads on March 9, 1862, the first-ever battle fought between two ironclads...
, one of the Union
Union Navy
The Union Navy is the label applied to the United States Navy during the American Civil War, to contrast it from its direct opponent, the Confederate States Navy...
's first ironclads during the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...
. It was also used in , which was launched in 1865.
The balanced rudder was also adopted by the aircraft industry.
Description
Before the balanced rudder, all ships employed a rudderRudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...
that was a simple flat piece of wood or metal, situated at the after end of the hull and hinged at the forward end, which could be angled to one side or the other to deflect the water passing it and hence provide an impulse to turn the ship. This required the exertion of significant force, as the passage of the water past the rudder tended to force it into a straight line in conformity with the flow.
The concept of a balanced rudder involved the shifting of the centre of rotation of the rudder to a point approximately 1/2 of the way from the forward end to the after end. This meant that when the rudder was turned, the flow of water past the ship actively worked on the forward part to increase the angle of deflection, whereas the same flow acted on the after part to reduce the angle. A degree of semi-balance is normal to avoid rudder instability i.e. the area in front of the pivot is kept less than that behind.
The mechanics of fluid dynamics
Fluid dynamics
In physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...
produced a solution in which the turning force applied in one direction on the rudder by the passing fluid was balanced by the turning force applied in the other direction, allowing the rudder to be moved with only limited mechanical resistance.
The balanced rudder was soon adopted by the fledgling aircraft industry in the early 20th century, which often made use of the horn balance, in which a section of the rudder, usually at the top of the vertical stabiliser, projected into the airstream. Two illustrations of aircraft rudders published by Flight Magazine in 1920, illustrate both the conventional balanced rudder (at lower left on the Short Swallow) and with a large 'horn' (at left centre, in this case in the form of a semicircle, on the 'Short Sporting Type').