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What Do The Flaps Do On An Airplane


by Elisha Coston



Welcome aboard! When it comes to flying in an airplane, there’s more to it than just the wings and engines. The intricate systems and components of an aircraft work together to ensure a safe and comfortable journey for passengers. One such component that plays a crucial role in flight is the flaps. But what exactly do the flaps do on an airplane?


In simple terms, flaps are movable surfaces located on the wings of an aircraft. They can be extended out or retracted in during different phases of flight, altering the shape and characteristics of the wing. This not only impacts the aircraft’s performance but also enhances its maneuverability, especially during takeoff and landing.


In this article, we will delve deeper into the functions and mechanics of airplane flaps. We will explore their purpose, types, working mechanisms, and the impact they have on flight performance. So fasten your seatbelts and let’s soar into the world of airplane flaps!


Overview of Airplane Flaps

Before we understand the specific functions and workings of flaps on an airplane, it is essential to have a general overview of what they are and how they are positioned on the aircraft.


Flaps are hinged surfaces attached to the trailing edge of an aircraft wing. They are typically located on the outboard sections of the wings, closer to the fuselage. These surfaces can be extended or deflected downward from the wing surface, increasing the wing’s surface area.


Unlike other control surfaces such as ailerons or elevators, which regulate roll and pitch respectively, flaps serve a specific purpose during takeoff and landing. They are designed to alter the wing’s aerodynamic characteristics, providing additional lift and increasing the aircraft’s ability to maintain steady flight at lower speeds.


Airplane flaps are not a uniform feature across all aircraft. Their design, configuration, and even the number of flaps per wing can vary depending on the specific aircraft model and its intended purpose. Some aircraft may have multiple flap sections, such as leading-edge slats in addition to the traditional trailing-edge flaps, to enhance lift and optimize performance.


It’s important to note that flaps are not permanently deployed during flight. They are only extended or retracted at key moments during takeoff, landing, and certain phases of flight requiring increased lift or maneuverability. The ability to alter flap position allows pilots to adapt to different flight conditions and optimize the aircraft’s performance at various stages of the flight.


Now that we have a basic understanding of the purpose and positioning of airplane flaps, let’s explore why they are so essential and how they contribute to the overall performance of an aircraft.


Purpose of Flaps

The primary purpose of flaps on an airplane is to increase lift and improve the aircraft’s performance during critical phases of flight, namely takeoff and landing. By adjusting the position of the flaps, pilots can manipulate the wing’s shape and characteristics, leading to several advantages.


During takeoff, when an aircraft needs to generate enough lift to become airborne, the deployment of flaps allows for a slower and safer takeoff speed. By extending the flaps, the effective wing area is increased, resulting in a higher lift coefficient. This means that the aircraft can generate more lift at lower speeds, reducing the required runway length for takeoff. The ability to take off at lower speeds is especially crucial for smaller runways or airports located in challenging geographical areas.


Similarly, during landing, flaps play a crucial role in enabling a controlled descent and ensuring a smooth touchdown. As an aircraft prepares to land, the extension of flaps increases the wing’s surface area, generating more lift at a lower airspeed. This reduces the aircraft’s stall speed and allows for a slower approach speed, giving pilots greater control over the aircraft’s descent rate.


In addition to increasing lift, flaps also enhance the aircraft’s maneuverability and control. The additional lift generated by the deployed flaps enables steeper descents, sharper turns, and a shorter landing distance. This can be particularly valuable in challenging weather conditions or when operating in congested airspace, where pilots may need to make quick adjustments in flight path or altitude.


Furthermore, flaps can also improve the aircraft’s stability during approach and landing. The extension of flaps shifts the center of pressure on the wings, reducing the nose-down tendency and creating a more balanced flight attitude. This helps pilots maintain a stable and controlled descent, ensuring a safe touchdown.


Overall, the primary purpose of flaps is to optimize lift and control during takeoff and landing, enhancing the safety, maneuverability, and efficiency of the aircraft. Their deployment is crucial in enabling safe operations on a wide range of runways and in varying flight conditions.


Types of Flaps

There are several different types of flaps that can be found on aircraft, each with its own design and functionality. The choice of flap type depends on various factors, including the aircraft’s design, intended use, and performance requirements. Let’s explore some of the most common types of flaps:

  1. Plain Flaps: Also known as the “plain” or “hinged” flaps, these are the simplest and most common type of flaps. They are hinged at the trailing edge of the wing and can be extended downward, increasing the wing’s surface area and generating additional lift.
  2. Split Flaps: Split flaps are similar to plain flaps but extend both downward and backward from the trailing edge of the wing. This type of flap increases the wing’s surface area, but it also creates significant drag. Split flaps are less common on modern aircraft due to their negative impact on overall aerodynamic efficiency.
  3. Fowler Flaps: Fowler flaps are a more complex type of flap that not only extend downward but also slide backward, increasing the wing’s surface area while maintaining the curvature of the wing profile. This design allows for a greater increase in lift and improved aerodynamic efficiency compared to plain or split flaps.
  4. Slotted Flaps: Slotted flaps are similar to plain flaps but include a slot or gap between the flap and the wing. This slot helps to improve airflow over the flap, delaying flow separation and reducing the likelihood of a stall. Slotted flaps are commonly found on larger aircraft and high-performance jets.
  5. Krueger Flaps: Krueger flaps are found on some specific aircraft designs, particularly those with swept wings. These flaps are located on the leading edge of the wing and can be extended forward to increase the wing’s surface area. Krueger flaps are typically used in combination with other flap types to optimize lift and control.

It’s important to note that not all aircraft incorporate all types of flaps. The choice of flap type depends on factors such as aircraft size, aerodynamic requirements, and performance goals. Different combinations of flap types may be used to enhance lift, minimize drag, and provide precise control during different phases of flight.


Now that we’ve explored the various types of flaps, let’s dive into the mechanics of how flaps work and the impact they have on the aircraft’s performance.


How Flaps Work

Understanding how flaps work requires delving into the mechanics of how they alter the shape and characteristics of the wings. When the flaps are extended or deployed, they change the wing’s profile and affect its aerodynamic properties. Let’s take a closer look at how flaps work:


When an aircraft is in cruising flight, the flaps are typically retracted, and the wing is in its clean or streamlined configuration. This configuration minimizes drag and allows for efficient airflow over the wing. However, during takeoff and landing, the flaps are extended to increase lift and improve the aircraft’s handling.


When the flaps are extended, several changes occur in the wing’s profile. Firstly, the extended flaps increase the wing’s surface area, effectively creating a larger wing. This larger wing generates more lift at lower speeds, allowing for a slower takeoff and landing.


The extension of the flaps also alters the wing’s camber, which refers to the curvature of the wing surface. By increasing the camber, the lift coefficient is enhanced, allowing the aircraft to generate more lift even at lower speeds. This is particularly important during landing, where a slower approach speed and a controlled descent are required.


Furthermore, the extension of flaps also changes the wing’s angle of attack. The angle of attack refers to the angle between the wing’s chord line (a straight line connecting the leading and trailing edges of the wing) and the oncoming airflow. By increasing the angle of attack, the wing can generate more lift.


It’s important to note that while flaps increase lift, they also introduce additional drag. The trade-off between increased lift and increased drag is a consideration during the design and use of flaps. However, the benefits of improved lift and maneuverability during critical flight phases outweigh the added drag.


The extension and retraction of flaps are controlled by the pilot using the aircraft’s control systems. Depending on the aircraft’s design, the flaps can be operated manually or automatically through the use of sophisticated fly-by-wire systems.


In summary, the deployment of flaps alters the wing’s shape, increasing its surface area, camber, and angle of attack. This results in enhanced lift production, allowing for safer takeoffs and landings at lower speeds. The ability to control flaps contributes to the aircraft’s overall performance and maneuverability, providing pilots with greater control during critical flight phases.


Impact of Flaps on Flight Performance

Flaps play a crucial role in enhancing the flight performance of an aircraft during specific phases of flight. By altering the wing’s shape and characteristics, flaps have a significant impact on various aspects of the aircraft’s performance. Let’s explore the key areas where flaps influence flight performance:

  1. Lift: The primary function of flaps is to increase lift. By extending the flaps, the wing’s surface area and camber are increased, allowing the aircraft to generate more lift at lower speeds. This is essential during takeoff and landing when the aircraft needs to achieve and maintain sufficient lift for a safe and smooth flight.
  2. Drag: While flaps increase lift, they also introduce additional drag. This is due to the increased surface area and the disruption of laminar airflow over the wing. The increase in drag during flap deployment helps to slow down the aircraft, allowing for a controlled descent during landing and providing the pilot with better control of the aircraft’s speed.
  3. Stall Speed: The deployment of flaps lowers the stall speed of an aircraft. The stall speed is the minimum speed at which the wings can still generate enough lift to keep the aircraft in flight. By reducing the stall speed, flaps provide a greater margin of safety and allow for slower and safer approaches to landing.
  4. Maneuverability: Flaps enhance the aircraft’s maneuverability during takeoff, landing, and other critical phases of flight. The additional lift generated by the flaps allows for steeper descents, tighter turns, and shorter landing distances. This level of maneuverability is particularly beneficial in challenging weather conditions or when operating in congested airspace.
  5. Stability: When flaps are extended, they shift the center of pressure on the wings, improving the aircraft’s stability. This reduces the nose-down tendency and helps maintain a balanced flight attitude during approach and landing.
  6. Noise Reduction: Flaps can also contribute to reducing noise during landing. By extending the flaps, the aircraft’s approach speed can be reduced, resulting in a quieter touchdown and a more comfortable experience for passengers and residents near airports.

The impact of flaps on flight performance is significant and allows pilots to achieve optimal performance based on different flight conditions and requirements. From increasing lift to improving maneuverability and stability, flaps are a crucial component in ensuring safe and efficient flight operations.


Flap Configurations in Different Phases of Flight

The optimal flap configuration for an aircraft varies depending on the phase of flight. Different flap settings are used during takeoff, climb, cruise, descent, and landing to maximize the aircraft’s performance and safety. Let’s explore the typical flap configurations for different phases of flight:

  1. Takeoff: During takeoff, the flaps are usually set at a specific angle, known as the takeoff flap setting or takeoff position. This setting provides the necessary lift to enable the aircraft to become airborne at a lower speed. The exact takeoff flap setting differs depending on the aircraft type and its weight.
  2. Climb and Cruise: Once the aircraft is airborne and climbing to its cruising altitude, the flaps are gradually retracted. The exact retraction sequence and rate may vary depending on the aircraft’s design and manufacturer’s recommendations. In general, the flaps are retracted to reduce drag, increase fuel efficiency, and allow for higher cruising speeds.
  3. Descent: As the aircraft prepares for descent, the pilot may extend the flaps partially or fully, depending on the descent profile and the desired airspeed. Extended flaps during descent help control the aircraft’s speed, reduce descent rates, and maintain a stable approach for landing.
  4. Landing: During landing, flaps are deployed to their maximum extent to provide the necessary lift and control. The specific flap setting used for landing, known as the landing flap setting, is determined based on various factors such as runway length, wind conditions, aircraft weight, and the pilot’s preferences. Landing with a higher flap setting allows for a lower approach speed, resulting in a smoother touchdown on the runway.

It’s important to note that the precise flap configurations and their corresponding settings depend on the aircraft’s design and the manufacturer’s recommendations. The pilot’s experience, operating procedures, and specific flight conditions also play a role in determining the appropriate flap settings for each phase of flight.


Understanding the optimal flap configurations for different flight phases is crucial for pilots to achieve the desired performance, ensure a safe and efficient flight, and maintain a comfortable experience for passengers.


Safety Considerations and Limitations of Flaps

While airplane flaps bring numerous benefits to flight performance, it’s important to be aware of their limitations and safety considerations. Understanding these factors is crucial for pilots to make informed decisions during flight operations. Let’s explore the key safety considerations and limitations of flaps:

  1. Aircraft Limitations: Each aircraft has specific limitations and guidelines regarding flap usage. These limitations may include maximum speeds at which the flaps can be deployed or retracted, or restrictions on flap settings during certain flight conditions or maneuvers. Pilots must be familiar with the aircraft’s limitations and operate within those parameters to ensure safe operations.
  2. Stall Speed: While flaps lower the stall speed, it’s important to note that they do not eliminate the possibility of a stall. Pilots must still be mindful of the aircraft’s speed, angle of attack, and flight characteristics to avoid an accidental stall, particularly during approach and landing.
  3. Increased Drag: While flaps provide additional lift, they also increase drag. The increased drag can affect the aircraft’s glide path and require adjustments to maintain a desired approach and landing profile. Pilots should be prepared to adjust power settings and control inputs accordingly to compensate for the increased drag.
  4. Effect on Control and Handling: The deployment of flaps can affect an aircraft’s control response and handling characteristics. Pilots must be familiar with how the aircraft behaves with different flap settings and make appropriate control inputs to maintain stable and predictable flight.
  5. Sudden Changes in Flap Position: Sudden changes in the flap position, particularly at high speeds, can result in abrupt changes in lift and aircraft attitude. Pilots should exercise caution when adjusting flap settings to ensure smooth and gradual transitions to avoid unexpected aircraft behavior.
  6. Environmental Factors: Environmental conditions, such as strong crosswinds or turbulence, can impact the performance of flaps. Pilots should consider the effects of these factors on flap effectiveness and adjust their operations accordingly for safe and stable flight.

It is essential for pilots to undergo appropriate training and adhere to standard operating procedures regarding flap usage. Regular maintenance and inspections of flap systems are also crucial to ensure their proper functioning and reliability.


By recognizing the safety considerations and limitations associated with flaps, pilots can make informed decisions in operating the aircraft, mitigate potential risks, and ensure safe and effective flight operations.



Airplane flaps are crucial components that significantly impact the performance and safety of an aircraft during takeoff, landing, and critical flight phases. By altering the wing’s shape and characteristics, flaps provide additional lift, enhance maneuverability, and optimize control.


Throughout this article, we have explored the functions, types, mechanics, and impact of flaps on flight performance. We learned that flaps increase lift, reduce stall speed, improve stability, and allow for safer takeoffs and landings. The different types of flaps, such as plain flaps, split flaps, and slotted flaps, offer varying levels of lift enhancement and aerodynamic efficiency.


Understanding the flap configurations and limitations for each phase of flight is essential for pilots to achieve optimal performance, maintain control, and ensure safe operations. The appropriate use of flaps during takeoff, climb, cruise, descent, and landing allows for the efficient utilization of runway length, increased maneuverability, and reduced noise during landing.


However, it is vital to respect the limitations and safety considerations associated with flaps. Pilots must be knowledgeable about their aircraft’s specific flap capabilities, follow operating procedures, and be aware of potential effects on control, handling, and aircraft behavior.


In conclusion, airplane flaps are essential components that enhance the safety, maneuverability, and performance of an aircraft. They enable lower takeoff and landing speeds, improve control during critical flight phases, and contribute to a smoother and more efficient flight experience. By harnessing the power of flaps, pilots ensure safe and comfortable journeys for passengers and maintain the highest standards of aviation excellence.