Magnificent Flying Machine
As described in the previous activities, lift is created when air flows around the airfoil (wing). Faster air above the wing has lower pressure. The relative high pressure below the airfoil pushes up the wing, creating lift.
By changing the shape of the airfoil slightly, a pilot can adjust the amount of lift on each wing. On an airplane, there are three "flight controls": the ailerons (on the wings), which control the "roll"; the rudder, which controls the "yaw"; and the elevators (on the tail fins), which control the "pitch".
Ailerons: Roll control
The ailerons are situated on the trailing edge of the wing and can be angled upward or downward.
The movement controlled by the ailerons is called "roll". When the ailerons are in neutral position, the aircraft is level. If the aileron is folded slightly downward, the curvature of the airfoil is increased, increasing the lift. If the aileron points upward, the curvature of the airfoil is decreased, reducing the lift. The wing is pushed downward. When the pilot turns the control wheel (or stick) to the left, the left aileron goes up (decreases lift) and the right aileron goes down (increases lift), causing the plane to tilt to the left.
The left and right ailerons always move in opposite directions, meaning that one wing lifts and the other drops, turning the plane.
Rudder: Yaw control
The rudder is on the trailing edge of the vertical fin and can be angled right or left.
The movement controlled by the rudder is called "yaw." When the rudder is in neutral position, the aircraft flies straight. If the rudder shifts to the right, the air pushes more against the right side of the tail, swinging the tail to the left. The rudder is NOT used to turn the plane. It helps smooth out the turn created by the ailerons.
Elevators: Pitch control
The elevators are located on the trailing edge of the horizontal stabilizer, on each side of the fin.
The movement controlled by the elevators is called "pitch." When they are in neutral position, the plane is level. When the elevators tilt downward, the curve of the stabilizer is increased. This provides extra lift at the rear of the aircraft, causing the nose to point downward. When the elevators tilt upward, the curve of the stabilizer is decreased. This causes the rear of the aircraft to drop, lifting the nose.
Using any of these controls will increase the drag force on the aircraft, slowing it down slightly (they all restrict the air flow).
Students will be able to:
- Determine which forces to adjust in order to change flight speed or height.
- Predict how flight controls will affect the direction of an aircraft.