Aileron

An aileron is a special part of a plane's wing that helps the aircraft turn. It is usually found at the back edge of each wing and can move up and down. When pilots want the plane to roll or tilt to one side, they use the ailerons. One aileron goes up while the other goes down, which makes the plane turn.

There has been some debate about who first invented the aileron. The Wright brothers and another pilot named Glenn Curtiss had a long legal fight over who owned the idea. The Wright brothers won in court, but later during the First World War, the government had to make a decision to end the fight. Even before that, a scientist named Matthew Piers Watt Boulton had written about a similar idea many years earlier.

History

The word "aileron" comes from French and means "little wing." It refers to parts on the edges of a bird's wings that help control flight. The term was first used in English in 1877 and became common in airplane discussions around 1908. Before ailerons, pilots used other methods to control rolling, such as changing the shape of the entire wing.

Ailerons were invented by a British scientist named Matthew Piers Watt Boulton in 1864, but they weren’t used on real airplanes until 1904. They slowly replaced older methods because they were easier to use and didn’t weaken the airplane’s wings. By 1911, most airplanes had ailerons.

Many people claimed to have invented the aileron, but it’s clear that Boulton was the first to describe and patent the idea. Other early designers, like John J. Montgomery and Richard Pearse, also experimented with similar controls, but their work was either not well documented or not as effective.

The Wright brothers used a different method called wing warping for a while, but later switched to ailerons. Their patent on flight control caused many legal fights, slowing down airplane development in the United States until the government stepped in during World War I. Even today, there is debate about who truly invented the aileron first.

Flight dynamics

Pairs of ailerons are connected so that when one moves down, the other moves up. The down aileron increases lift on its wing, while the up aileron decreases lift on its wing. This creates a rolling or banking movement around the airplane's long axis, from nose to tail. Ailerons are often placed near the end of the wing, but sometimes closer to the middle.

When using ailerons, an unwanted side effect called adverse yaw can happen. This means the airplane turns slightly in the opposite direction of the roll. For example, rolling right causes a slight left turn. This happens because of changes in drag between the two wings. To fix this, pilots use the rudder to balance the turn, or special ailerons called differential ailerons that move differently to help cancel out the yaw.

Aileron components

Main article: Trim tab

Ailerons on airplanes have several important parts that help pilots control the plane. One of these parts is called a horn. Horns are small extensions on the front of the aileron that help make it easier for pilots to move the controls. They were first used during World War I on planes like the Handley Page Type O, Sopwith Snipe, Fokker Dr.I, and Fokker D.VII.

Another important part is the trim tab. Trim tabs are tiny sections at the back of the aileron that help adjust how much force a pilot needs to control the plane. They can be fixed, bent by hand, or adjustable from the cockpit to make flying easier.

Spades are flat metal plates attached to the bottom of the aileron. They help reduce the force needed to move the aileron and are often used on planes that perform stunts in the air.

To keep the ailerons steady and reduce shaking during fast flight, some planes have balance weights added to the front of the aileron. These weights help keep control smooth and reduce the force needed to move the controls.

Types of ailerons

Single acting ailerons

During the early days of flying and into the first years of World War I, these ailerons were controlled by a single cable that pulled them up. When the plane was on the ground, the ailerons hung straight down. This type was used on planes like the Farman III in 1909 and the Short 166. Later, some planes used springs to bring the ailerons back to their normal position when the control stick was let go.

Wingtip ailerons

The very first airplane to have modern-style controls used wingtip ailerons, where the whole wingtip moved to control rolling. Planes like the Blériot VIII in 1908 and the AEA June Bug used this method. However, this type could be risky if used too hard, especially if the plane was already struggling to fly, so it was mostly used in early test planes.

Frise ailerons

An engineer named Leslie George Frise created a special aileron shape in the 1930s to make controlling faster planes easier. His design made the aileron stick out slightly under the wing when moved up, which helped reduce the force needed to control the plane. This design was used in popular planes like the Canadian Fleet Model 2 and the American Piper J-3 Cub.

Differential ailerons

By designing the controls carefully, engineers made it so that one aileron moved more than the other. This helped prevent problems when flying at high angles and reduced unwanted twisting motions. The classic British de Havilland Tiger Moth biplane was one of the first to use this improved design.

Roll control without ailerons

Wing warping

Main article: Wing warping

The very first airplanes, like the Wright Flyer and the Blériot XI, used a method called wing warping to control rolling. This meant twisting part of the wing to change how much lift it created. But this made the plane harder to fly and could cause problems, so most planes later switched to using ailerons instead. Scientists are now studying wing warping again with new technology.

Differential spoilers

Main article: Spoileron

Some modern airplanes, especially jets like the F4 Phantom II, use devices called spoilers to help control rolling. When spoilers pop up on the wing, they break the airflow and reduce lift, helping the plane turn.

Roll induced by rudder

Planes with a certain wing shape can sometimes use the rudder alone to roll. In some cases, like the Boeing 737, the rudder can control rolling better than the ailerons in certain situations.

Other methods

• Weight-shift control is used in small planes like hang gliders.
• Flight with disabled controls has worked in a few special situations.
• Reaction control valves are used in military planes like the Harrier.
• The British Army Aeroplane No 1 used a special fin above the wing to roll the plane.

Combinations with other control surfaces

Some aircraft have special parts that help them turn and move. One example is called a flaperon, which works as both an aileron and a flap. When used to turn, the flaperons move differently on each wing. When used as a flap, they both move down.

Other planes use parts called spoilers or spoilerons to help turn instead of regular ailerons. This lets the whole back edge of the wing be used for flaps, which helps the plane fly slowly. Some planes like the Northrop P-61 Black Widow and modern airliners use this method.

On planes with delta wings, ailerons are combined with elevators to make something called an elevon. Some fighter planes don’t have ailerons at all. Instead, they use moving parts on the tail to turn, called "tailerons" or "rolling tails". This also allows for bigger flaps on the wings.