Barrel roll

A barrel roll is an aerial maneuver in which an airplane makes a complete rotation on both its longitudinal and lateral axes, causing it to follow a helical path, approximately maintaining its original direction. It is sometimes described as a "combination of a loop and a roll." The g-force is kept positive (but not constant) on the object throughout the maneuver, commonly between 2–3 g, and no less than 0.5 g. The barrel roll is commonly confused with an aileron roll.

The barrel roll is so named because an aircraft executing this maneuver looks as though it were flying with its wheels running around the inside wall of a cylinder, or an imaginary barrel lying on its side. A more common modern visualization is to imagine an airplane trying to fly in a horizontal corkscrew around the line of the direction of travel. Although the maneuver predates the name, the term was first used in 1917, gaining popularity during the early 1930s.

In aviation, the barrel roll is an aerobatic maneuver in which an aircraft performs a helical roll around its relative forward motion, with the nose ending up pointed along the original flightpath. It is performed by doing a combination of a roll and a loop. The maneuver includes a constant variation of aircraft attitude (nose orientation) in two or perhaps all three axes. It consists of a rotation along the pitch axis (nose rotates upward, in a direction perpendicular to the wings) through the application of elevator input, followed by aileron input to rotate the aircraft along its roll axis. Sometimes rudder input is applied to help assist the roll through the yaw axis (nose rotates sideways), by swinging the tail over the top. At the midpoint (top) of the roll, the aircraft should be flying inverted, with the nose pointing at roughly a right angle to the general flightpath. The aircraft will have also gained altitude and travelled a short distance from the original flightpath. Flying inverted, the plane continues through the roll, descending in altitude and returning to the original flightpath. Upon completing the roll, the airplane should end up flying along the same flightpath, and at roughly the same altitude at which the maneuver began.

The term "barrel roll" is frequently used, incorrectly, to refer to any roll by an airplane (see aileron roll, slow roll or snap roll).

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