Atmospheric Flight

The ailerons are flap-like structures on the trailing edge of the wings -one on each side. When the pilot moves the control stick to the right, the right aileron will tilt up and the left aileron will tilt down. This will cause the airplane to roll to the right. When the pilot moves the control stick to the left, the left aileron tilts up, the right aileron tilts down and the airplane rolls to the left. This happens because as the aileron tilts downward (effectively increasing camber) more lift is created and the wing rises. As it tilts upward, less lift will be created and the wing will lower. If the wing of one side of the airplane rises and the other descends, the airplane will roll towards the side with the decrease in lift.

The elevators are also flap-like structures that are mounted on each side of the horizontal stabilizer. As an airplane flies in its proper orientation and level to the horizon the pilot uses the elevator to control the pitch of the nose. That means the elevator controls the nose's motion of up and down. When the pilot pushes the control stick forward, the elevators tilt downward -this is called pitching down. When the pilot pulls the control stick back, the elevators tilt upward, the tail goes down and the fuselage pitches nose-up. When the elevator tilts downward more lift is created (like the ailerons) and the tail rises. When the elevator tilts upward, less lift is created and the tail descends.

The rudder is located on the vertical fin. The rudder controls the motion of yaw. Yaw causes the airplane's nose to move sideways to the left or right. The two rudder pedals are located at the pilot's feet. When the pilot pushes on the right rudder pedal, the rudder tilts to the right and the airplane yaws nose-right. When the pilot pushes on the left rudder pedal, the rudder tilts to the left and the airplane yaws nose-left. Again this is due to lift. However, the direction of this lift force is different than the lift force that causes the airplane to ascend. When the rudder tilts to the right, more lift is created on the right, which lifts or pushes the vertical stabilizer to the left. This, in turn, causes the airplane to yaw nose-right. The opposite motion occurs when the rudder tilts to the left.

The thinner the atmosphere the slower the reaction of the airplane to its control surfaces. Airplanes flying at fast speeds in the lower atmosphere react more quickly to a change in the control surfaces than airplanes flying at extremely high altitudes at the same speed. That's because there are fewer air molecules to disturb. This becomes even more important when flying airplanes on planets with atmospheres that are less dense than Earth's atmosphere.