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Rudder

technology Maturity 9-11 Next article →

A rudder is a key tool used to steer many kinds of vehicles. It works on ships, boats, and even submarines. You can also find rudders on hovercraft and airships. On an airplane, the rudder helps control the side-to-side motion. This motion is called yaw. While it helps with yaw, it is not the main way a pilot turns the plane.

Olympic stern and rudder
Olympic stern and rudder

How does a rudder actually work? It works by redirecting fluid, which can be water or air. The rudder is usually a flat sheet of material. It is attached to the back of a craft using hinges. When the rudder moves, it changes how the fluid flows past the hull or fuselage. This change in flow creates a force. This force causes the craft to turn or yaw.

Aileron yaw
Aileron yaw

Long ago, people used different ways to steer. In ancient Egypt, boats used many steering oars. During the Old Kingdom, between 2686 and 2134 BC, some boats had five oars on each side. People also used a tiller, which is a small pin or lever. The Greek historian Herodotus wrote about these rudders in Egypt. In ancient Rome, sailors used quarter-rudders on the sides of their ships.

Maler der Grabkammer des Menna 013
Maler der Grabkammer des Menna 013
Rudder of a Roman Boat (RG Museum Koeln, Germany)
Rudder of a Roman Boat (RG Museum Koeln, Germany)

A new kind of rudder appeared in China during the 1st century AD. This was a stern-mounted rudder, which means it was at the very back. This design was much better for traveling on the big ocean. It did not disturb the sails like an oar did. Some Chinese ships even used fenestrated rudders. These are rudders with holes in them to help with control.

Pottery boat from Eastern Han Dynasty showing rudder
Pottery boat from Eastern Han Dynasty showing rudder
Guo Zhongshu-Traveling on the River in Snow
Guo Zhongshu-Traveling on the River in Snow

Today, we use many clever ways to move a rudder. On small boats, a person might use a tiller. This is a simple stick that acts as a lever. On much larger ships, people use cables or pushrods. Many modern vessels even use hydraulics. Hydraulics are systems that use liquid to move parts. In a typical airplane, a pilot uses pedals to move the rudder.

MM00756-4
MM00756-4
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🖼️ Images & Media (11)
File:Brosen propelersterntychy.jpg
Brosen propelersterntychy.jpg
File:Olympic stern and rudder.jpg
Olympic stern and rudder.jpg
File:Maler der Grabkammer des Menna 013.jpg
Maler der Grabkammer des Menna 013.jpg
File:Rudder of a Roman Boat (RG Museum Koeln, Germany).JPG
Rudder of a Roman Boat (RG Museum Koeln,...
File:Eastern Han pottery boat.JPG
Eastern Han pottery boat.JPG
File:Guo Zhongshu-Traveling on the River in Snow.jpg
Guo Zhongshu-Traveling on the River in Snow.jpg
File:Pottery boat from Eastern Han Dynasty showing rudder.jpg
Pottery boat from Eastern Han Dynasty...
File:Adler von Lübeck. Model ship 05.jpg
Adler von Lübeck. Model ship 05.jpg
File:RudderBereFerrersBenchEnd.jpg
RudderBereFerrersBenchEnd.jpg
File:Aileron yaw.gif
Aileron yaw.gif
File:MM00756-4.jpg
MM00756-4.jpg
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