The main purpose of the tail is to provide stability. If tilted by a gust of wind, a stable airplane tends to recover, just as a ball lying at the bottom of a bowl will roll back to the center after being disturbed.
What Is an Airplane’s “Tail Fin” For?
A vertical stabilizer, or tail fin, keeps the airplane lined up with its direction of motion. Air presses against both its surfaces with equal force when the airplane is moving straight ahead. But if the airplane pivots to the right or left, air pressure increases on one side of the stabilizer and decreases on the other. This imbalance in pressure pushes the tail back into line.
What Is an Airplane’s “Rear Wing” For?
Like the vertical stabilizer, the horizontal stabilizer helps keep the airplane aligned with its direction of motion. If the airplane tilts up or down, air pressure increases on one side of the stabilizer and decreases on the other, pushing it back to its original position. The stabilizer also holds the tail down, countering the tendency of the nose to tilt downward—a result of the airplane’s center of gravity being forward of the wing’s center of lift.