buttcock lines

The term "buttock lines," also known as "buttock plies" or "diagonals," refers to a series of parallel lines drawn on the exterior skin of an airplane or helicopter in a vertical plane that extends from the forward edge of the aircraft to the rear edge. These lines are used to indicate the position of the centerline of the aircraft and are an essential tool in the construction of aviation vehicles.

Buttock Line Meaning

Buttcock lines are essentially vertical lines on the aircraft's centerline, drawn perpendicularly to the longitudinal axis of the aircraft. These lines play a crucial role in defining the aircraft's geometric shape and are utilized as a reference point for measurements such as length, width, and height. In essence, the position and shape of the buttock lines are critical to designing and building an aviation vehicle that is both safe and efficient to operate.

Buttock Line Definitions

Buttcock lines can also refer to the center lines of the aircraft's main wings and fuselage, which are typically identified by a letter or number and placed next to the corresponding body part, such as the "nose" or "center section." These are the lines that help to locate the center of gravity, balance, and center of pressure of the aircraft, which are essential factors in flight stability. Additionally, "water lines" or reference lines, drawn on the aircraft's skin, represent the level of water that exists at various points along the aircraft's water line. These lines are particularly important for determining the aircraft's stability and capacity to carry load.

Buttock Line Applications

Buttcock lines are essential in the construction of aircraft, where they serve as a navigational aid by providing a fixed reference point against which structural elements and systems can be aligned. They are also used in the design and construction of aircraft components, such as the发动机, landing gear, and interior furnishings, to ensure that they are correctly oriented and aligned with the aircraft's centerline.

Discussion On Buttock Line

Buttcock lines, also known as "side plies" or "transom sterns," serve a significant purpose in the construction of modern aircraft. These aircraft feature a pronounced 'tail' or 'fin' that extends downward from the back of the plane. The position of the centerline, however, can be difficult to accurately determine, particularly when the aircraft's design contains complex curves or changes in cross-section.

This difficulty can lead to alignment issues throughout the aircraft, including the aircraft's engines, landing gear, and propellers. To address this, aircraft builders use diagonal lines or other reference marks to help align these components with the centerline. By carefully locating and marking these points, builders can ensure that all of the飞机's systems are aligned and functioning as intended.


Buttock lines are a fundamental concept in aviation that play a crucial role in the design, construction, and maintenance of modern aircraft. These lines provide a consistent and repeatable reference point against which the airplane's many components can be aligned, ensuring that the aircraft functions safely and effectively in all phases of flight.

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