How Do Ailerons Work?
Fixed-wing aircraft facilitate controlled flight by manipulating several moving components called control surfaces. These surfaces, which include the rudder, flaps, elevators, and ailerons, help to guide the plane as it travels through the air with smoothness and safety. While each of these elements plays a critical role in aerodynamics, this blog will focus on the design, operating principle, and various types of ailerons.
The word aileron is French for "little wing," which accurately describes the component's design and function. Shortly after the Wright brothers first took flight, it was realized that while lift could be sufficiently generated using wings, lateral movement and banking would be impossible with only fixed flight surfaces. As a result, a cable system was added to early aircraft, which would initiate those movements by gently warping the wings. Although wing-warping produced favorable results, particularly in the context of coordinated turns, they quickly fell out of favor when moveable ailerons became more advanced.
Nearly all modern ailerons are found on the trailing edge of both wings and are directly connected by the actuation system. When the pilot initiates movement of one aileron, the other will move in an inverse manner. For example, if the left aileron pushes down, the one on the right will move up. The aerodynamics involved in ailerons are relatively straightforward in that a downward movement causes increased lift on that wing, while the upward-facing aileron experiences decreased lift. The result is a banked turn in the direction of the upward-facing aileron.
Most commonly, ailerons are positioned away from the center of the wing, closer to the fuselage. However, their placement is highly variable, and larger planes demand a higher surface area in order to facilitate banking. A significant technological upgrade came from the implementation of multiple ailerons, capable of moving independently from each other, on both wings. Such designs are ubiquitous among large passenger and cargo aircraft. Using an "inboard-outboard" aileron configuration is beneficial in several ways. First, it helps to ensure system redundancy in the rare event of actuation system failure since each element is controlled by a separate hydraulic control module or cable. Also, it helps to prevent incorrect net-roll torque by locking out the outboard ailerons when the aircraft reaches a high enough speed.
While ailerons play a critical role in banking and coordinated turns, they also produce the unwanted side effect of adverse yaw. Adverse yaw occurs when the nose of the aircraft begins to point in the direction opposite of the aileron-facilitated roll. This causes instability and roughness in a coordinated turn and must therefore be counteracted. To compensate for the adverse yaw produced by the ailerons, rudders are used to create an opposite sideways force to level the aircraft.
Like other flight control surfaces, ailerons contain trim tabs to aid pilots in performing continuous movements without fatigue. Additionally, trim tabs work to reduce drag, which saves on fuel efficiency and may dampen the magnitude of adverse yaw. Another, much less common, use of trim tabs is to help control the plane when controls are damaged. Although there is minimal precedent for this in general aviation, there have been several well-documented examples of military aircraft being able to operate with just trim tabs.
When inspecting the ailerons, ensure that they are free of debris and damage. As with all movable surfaces and hinged devices, it is necessary to examine the various rivets for distortion and tightness. If any maintenance is performed, it is crucial for the ailerons to be rebalanced and tested to ensure proper mechanical movement. Finally, it is important to procure replacement parts from a trusted source.
At ASAP NSN Hub, we carry millions of high-quality components for the civil and military aviation industries, including a wide selection of aileron parts. We are an AS9120B, ISO 9001:2015, and FAA AC 00-56B accredited enterprise and the only distributors to maintain a strict NO CHINA Sourcing policy. Additionally, we subject our inventory to regular inspection to help screen for any defects or issues before shipping. We invite you to browse our expansive part catalog today, keeping in mind that you may begin the purchasing process at any time using our Instant RFQ form. With account managers available 24/7x365, you will always receive a quotation within 15 minutes or less.
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