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Encyclopedia > Rudder
Stern-mounted steering oar of an Egyptian riverboat depicted in the Tomb of Menna (c. 1422-1411 BC)
Stern-mounted steering oar of an Egyptian riverboat depicted in the Tomb of Menna (c. 1422-1411 BC)
Stern-mounted steering oar of a Roman boat, 1st century AD (RG-Museum, Cologne).

A rudder is a device used to steer ships, boats, submarines, aircraft, hovercraft or other conveyances that move through air or water. Rudders operate by re-directing the flow of air or water past the hull or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft's stern, tail or after end. Often rudders are shaped so as to minimize hydrodynamic or aerodynamic drag. On simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be steered by a helmsman. In larger vessels, cables, pushrods and hydraulics may be used to link rudders to steering wheels. In typical aircraft, pedals operate rudders via mechanical linkages. Image File history File links Download high-resolution version (2048x1197, 222 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Rudder ... Image File history File links Download high-resolution version (2048x1197, 222 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Rudder ... Image File history File links Download high-resolution version (511x681, 46 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Rudder ... Image File history File links Download high-resolution version (511x681, 46 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Rudder ... For online phenomenon of shipping, see Shipping (fandom). ... A boat, like a ship, is a buoyant vessel designed for the purpose of transporting people and possibly goods across water. ... USS Los Angeles A submarine is a specialized watercraft that can operate underwater. ... An Airbus A380, currently the worlds largest passenger airliner An aircraft is any vehicle or craft capable of atmospheric flight. ... BHC SR-N4 The worlds largest car and passenger carrying hovercraft A hovercraft, or air-cushion vehicle (ACV), is a vehicle or craft that can be supported by a cushion of air ejected downwards against a surface close below it, and can in principle travel over any relatively smooth... A hinge is a mechanical device that connects two solid objects, allowing rotation between them. ... A tiller or till is a lever attached to a rudder post (American terminology) or rudder stock (English terminology) of a boat in order to provide the leverage for the helmsman to turn the rudder. ...

Contents

History of the rudder

Early history

Oars mounted on the side of ships for steering are documented from the 3rd millennium BCE in Ancient Egypt in artwork, wooden models, and even remnants of actual boats. An early example of an oar mounted on the stern is found in the Egyptian tomb of Menna (1422-1411 BC). Stern mounted oars were also quite common in Roman times as proved from contemporary depictions. Khafres Pyramid (4th dynasty) and Great Sphinx of Giza (c. ...


China

The world's oldest depiction of a stern rudder. Pottery model of a junk, 1st century AD. Kuangchow National Museum (drawing).
The world's oldest depiction of a stern rudder. Pottery model of a junk, 1st century AD. Kuangchow National Museum (drawing).

The world's oldest known depiction of a stern-mounted rudder can be seen on a pottery model of a Chinese junk dating from the 1st century CE, predating their appearance in the West by a thousand years. The Chinese stern-mounted rudder is hung from the stern, held in place and controlled with a rope mechanism. Also, many junks incorporated "fenestrated rudders" (rudders with holes in them, allowing for better control), an innovation adopted in the West in 1901 to increase the manoeuvrability of torpedo boats. Detailed descriptions of Chinese junks during the Middle Ages are known from various travellers to China, such as Ibn Battuta and Marco Polo. ImageMetadata File history File links Download high resolution version (373x640, 132 KB) Pottery model of a junk, with the worlds first known depiction of a rudder. ... ImageMetadata File history File links Download high resolution version (373x640, 132 KB) Pottery model of a junk, with the worlds first known depiction of a rudder. ... Unfired green ware pottery on a traditional drying rack at Conner Prairie living history museum. ... A four-masted junk. ... A torpedo boat is a relatively small and fast naval ship designed to launch torpedoes at larger surface ships. ... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... Abu Abdullah Muhammad Ibn Battuta (Arabic: أبو عبد الله محمد ابن بطوطة) (born February 24, 1304; year of death uncertain, possibly 1368 or 1377) was a Moroccan Arab Sunni Islamic scholar and jurisprudent from the Maliki Madhhab (a school of Fiqh, or Sunni Islamic law), and at times a Qadi or judge. ... Marco Polo (September 15, 1254 – January 8, 1324) was a Venetian trader and explorer who, together with his father Niccolò and his uncle Maffeo, was one of the first Westerners to travel the Silk Road to China (which was then called Cathay) and visited the Great Khan of the Mongol...


Europe

Oars mounted on the side of ships evolved into quarter rudders, which were used in Antiquity until the end of the Middle Ages in Europe. As the size of ships and the height of the freeboards increased, quarter-rudders became unwieldy and were replaced in Europe by the more sturdy stern-mounted rudders with pintle and gudgeon attachment from the 12th century. The West's oldest known depiction of a stern-mounted rudder can be found on church carvings dating to around 1180. Classical antiquity is a broad term for a long period of cultural history centered on the Mediterranean Sea, which begins roughly with the earliest-recorded Greek poetry of Homer (7th century BC), and continues through the rise of Christianity and the fall of the Western Roman Empire (5th century AD... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... World map showing Europe A satellite composite image of Europe Europe is one of the seven traditional continents of the Earth. ... Used with light machine guns, the pintle is the mounting hardware that mates the machine gun to a tripod. ... In general, a gudgeon is a circular fitting, often made of metal, which is fixed onto some surface. ... (11th century - 12th century - 13th century - other centuries) As a means of recording the passage of time, the 12th century was that century which lasted from 1101 to 1200. ...


All evidence indicates that the European stern-mounted rudder, whose technical specifications considerably differ from the Chinese one, was invented independently:

The only actual concept which can be claimed to have been transmitted from the Chinese is the idea of a stern-mounted rudder, and not its method of attachment nor the manner in which it was controlled. Since that idea of putting a rudder on the stern can be traced back to the models found in Egyptian tombs, the need to have the concept brought into the Middle East is questionable at best. There is no evidence to support the contention that the sternpost-mounted rudder came from China, and no need to call on exterior sources for its introduction into the Mediterranean.[1]

Arabs

The Arabs also used a sternpost-mounted rudder which differed technically from both its European and Chinese counterparts. On their ships "the rudder is controlled by two lines, each attached to a crosspiece mounted on the rudder head perpendicular to the plane of the rudder blade."[2] The earliest evidence comes from the Ahsan al-Taqasim fi Marifat al-Aqalim ('The Best Divisions for the Classification of Regions') written by al-Muqaddasi in 985:

The captain from the crow's nest carefully observes the sea. When a rock is espied, he shouts: "Starboard!" or 'Port!" Two youths, posted there, repeat the cry. The helmsman, with two ropes in his hand, when he hears the calls tugs one or the other to the right or left. If great care is not taken, the ship strikes the rocks and is wrecked.[3]

Technical details

Boat rudders may be either outboard or inboard. Outboard rudders are hung on the stern or transom. Inboard rudders are hung from a keel or skeg and are thus fully submerged beneath the hull, connected to the steering mechanism by a rudder post which comes up through the hull to deck level, often into a cockpit.


Some sailors use rudder post and mast placement to define the difference between a ketch and a yawl, similar two-masted vessels. Yawls are defined as having the mizzen mast abaft (ie. "aft of") the rudder post; ketches are defined as having the mizzen mast forward of the rudder post.


Small boat rudders that can be steered more or less perpendicular to the hull's longitudinal axis make effective brakes when pushed "hard over." However, terms such as "hard over," "hard to starboard," etc. signify a maximum-rate turn for larger vessels.


Aircraft rudders

The tail of a KC135 Stratotanker, with the rudder marked
The tail of a KC135 Stratotanker, with the rudder marked

On an aircraft, the rudder is called a "control surface" along with the rudder-like elevator (attached to horizontal tail structure) and ailerons (attached to the wings) that control pitch and roll. The rudder is usually attached to the fin (or vertical stabilizer) which allows the pilot to control yaw in the horizontal axis, ie change the horizontal direction in which the nose is pointing. The rudder's direction is manipulated with the movement of foot pedals by the pilot. Download high resolution version (750x630, 82 KB)The tail of a KC135 Stratotanker, with the rudder labelled. ... Download high resolution version (750x630, 82 KB)The tail of a KC135 Stratotanker, with the rudder labelled. ... Aircraft flight controls allow a pilot to adjust and control the aircrafts flight attitude. ... Aileron location on a Piper PA-28. ... A fin is a surface used to produce lift and thrust or to steer while traveling in water, air, or other fluid media. ... The vertical stabilizer or fin of an aircraft is found on its tail, generally pointing straight upward. ... Flight dynamics is the study of orientation of air and space vehicles and how to control the critical flight parameters, typically named pitch, roll and yaw. ...


In practice, both aileron and rudder control input are used together to turn an aircraft, the ailerons imparting roll, the rudder imparting yaw, and also compensating for a phenomenon called adverse yaw. Adverse yaw is readily seen if the ailerons alone are used for a turn. The downward moving aileron acts like a flap, generating more lift for one wing, and therefore more drag. Initially, this drag yaws the aircraft in the direction opposite to the desired course. A rudder alone will turn a conventional fixed wing aircraft, but much more slowly than if ailerons are also used in conjunction. Use of rudder and ailerons together produces co-ordinated turns, in which the longitudinal axis of the aircraft is in line with the arc of the turn, neither slipping (under-ruddered), nor skidding (over-ruddered). Improperly ruddered turns at low speed can precipitate a spin which can be dangerous at low altitudes. A slip is an aerodynamic state where an aircraft is moving sideways as well as forward relative to the oncoming wind. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


Sometimes pilots may intentionally operate the rudder and ailerons in opposite directions in a maneuver called a forward slip. This may be done to overcome crosswinds and keep the fuselage in line with the runway, or to more rapidly lose altitude by increasing drag, or both. A slip is an aerodynamic state where an aircraft is moving sideways as well as forward relative to the oncoming airflow. ...


Foot notes

  1. ^ Lawrence V. Mott, p.92
  2. ^ Lawrence V. Mott, p.93
  3. ^ Lawrence V. Mott, p.92f.

Literature

See also

Aircraft flight controls allow a pilot to adjust and control the aircrafts flight attitude. ... Wheel of the French carrier Clémenceau. ...

Conventional ship and boat rudders

  • Fully balanced rudder
  • Semi-balanced rudder
  • Spade rudder

Specialist ship and boat rudders

  • Jet flap rudder
  • Kitchen rudder
  • Pleuger rudder
  • Rotating cylinder rudder
  • Schilling Rudder
  • Voith Schneider Propeller (a combination propulsion and steering unit}

  Results from FactBites:
 
Rudder - Yaw (691 words)
The rudder is the small moving section at the rear of the stabilizer that is attached to the fixed sections by hinges.
Because the rudder moves, it varies the amount of force generated by the tail surface and is used to generate and control the yawing motion of the aircraft.
The rudder input insures that the aircraft is properly aligned to the curved flight path during the maneuver.
  More results at FactBites »

 
 

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