AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

Understanding Aircraft Flaps and Their Functionality

For aircraft to achieve heavier-than-air flight and provide the benefits of rapid global travel, they harness the forces of aerodynamics. By manipulating airflow with various structures and surfaces, a sufficient amount of lift can be created under the wings to allow the aircraft to ascend and glide. With flight control surfaces known as flaps, pilots can further manipulate the aerodynamic forces exerted on the aircraft, allowing them to increase lift as needed. While the use of flaps may vary by aircraft, they typically allow for operations to be conducted at lower speeds and distances than would be needed without them.

Installed on the trailing-edge of an aircraft wing, airplane flaps extend into the air when deployed with a flap actuator. With their extension, the flap can reduce the stalling speed of a wing, and thus allow for an aircraft to lessen the speed and distance needed to conduct landing procedures. For certain high-speed aircraft, flaps may also be used for takeoff as well. As such units tend to have low profile wings, the extension of flaps can create the extra lift needed to conduct a slower takeoff efficiently. Despite this, flaps also create more drag the further they are deployed, and thus most aircraft will avoid using them altogether during takeoff or will ensure that they are only slightly extended. When landing, however, airplane flaps serve to make the descent process quick, all while ensuring that airspeed does not reach an unsafe level. As such, pilots can conduct a steep landing at a safer and slower airspeed.

Depending on the aircraft and its design, a number of common flap types may be implemented on the wings. The plain flap is one of the most simplistic types, and it consists of a hinged airfoil that can pivot downwards from the wing when using the flap actuator. While not as effective or efficient at manipulating lift as some of its alternatives, plain flaps are still highly useful when there is a need for simplicity in assembly.

For aircraft that feature split flap assemblies, the flap will rotate downwards while the upper surface remains still. As such, only the bottom section of the flap will be extended into the airflow. With this type of operation, the flap will exhibit effects similar to an aircraft spoiler. Generally, split flap assemblies are most often reserved for aircraft that cannot facilitate plain or slotted flaps due to their construction.

The fowler flap is similar to a split flap, albeit the lower portion of the surface slides backwards before it is rotated downwards. As such, the wingspan of the aircraft is slightly extended, causing more lift to be generated. With the fowler flap design, aircraft that have large differences in speed between their cruise and terminal operational state will benefit.

Regardless of what type of flap may be present on an aircraft, almost all are controlled from levers within the cockpit. Often shaped like a flap to make distinguishing the control easier, the flap actuator can be deployed by the pilot as needed. As aircraft will vary in their method of flap deployment, pilots should always make themselves aware of the aircraft’s control system to ensure proper deployment. In some aircraft, flaps may be operated separately, so having an understanding of the system can help the pilot avoid unwanted rolls or movements.

At Internet for Aviation, we can help customers procure the airplane flaps and flight surface components that they need with competitive pricing and rapid lead-times. Explore our expansive part and manufacturer catalogs at your leisure, and you may send us a Request for Quote form at any time to begin the purchasing process. If you have any questions or concerns regarding our offered services or part procurement process, our team members are available 24/7x365 and may be reached via phone or email.


September 23, 2022
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