Principles of Flight

• If lift is greater than weight, the airplane will rise or climb.
• Air flowing on the top of a standard wing speeds up.
• Four forces act on an aircraft in flight: lift, weight, thrust, and drag.

Low Pressure Area

• The area identified by the center arrow is a low-pressure area.
• Aircraft axes are imaginary lines that pass through the aircraft's center of gravity, used to describe its orientation.
• The three axes are: Longitudinal (roll), Lateral (pitch), and Vertical (yaw).
• Two types of drag encountered by an aircraft are parasite drag and induced drag.
• Thrust is the force in flight that opposes drag on a fixed-wing aircraft.
• Lateral stability in a low-wing aircraft is designed by angling the wings upward (dihedral).
• Factors that can lead to a stall of the airfoil include exceeding the critical angle of attack, airspeed too low for the angle of attack, and abrupt control movements.
• If the angle between the chord line and relative wind becomes too high, airflow over the top of the wing separates, causing a stall.
• The angle between the chord line and the relative wind approaching an airfoil is called the angle of attack.
• The angle between the chord line and the line at the trailing edge parallel to the longitudinal axis is called the angle of incidence.
• If one wing is more stalled than the other, the aircraft can experience a roll or spin towards the stalled wing.
• The chord of an airfoil is the straight line connecting the leading edge and trailing edge.
• Thrust opposes drag on a fixed-wing aircraft.
• Roll (lateral) stability can be improved by designing a wing with dihedral.
• Yaw (longitudinal) stability is maintained through the vertical stabilizer (fin) and rudder.
• Pitch stability is maintained through the horizontal stabilizer and elevator.
• A straight line through the wings of an airplane passing through the center of gravity is called the wing axis.
• Bank or Roll is the motion around the longitudinal axis, controlled by ailerons.
• Yaw is the motion around the vertical axis, controlled by the rudder.
• Pitch is the motion around the lateral axis, controlled by the elevators.
• The combined flight control surfaces on the V-Tail of an aircraft are called ruddervators; they work by deflecting together for pitch control and differentially for yaw control.
• When the pilot pulls the control wheel (stick) aft (backwards), the plane goes up (nose up), achieved by using the elevator, this increases the angle of attack
• When the pilot moves the control wheel (stick) turns, or moves the stick left, the plane banks left; this is achieved by using the ailerons.
• Small movable portions of the trailing edge of the control surface controlled from the cockpit are called trim tabs.
• The purpose of the slot on a wing is to delay stall by directing high-energy air to the upper surface of the wing.
• Methods to counteract adverse yaw include using differential ailerons, frise ailerons, or a yaw damper system.
• The Motion of Bank or Roll is controlled by the Ailerons.
• One purpose of the spoiler on a wing is to reduce lift, increase drag, and assist with roll control.
• To relieve pilot input force in a "Nose Up" attitude, the trailing edge of the trim tab on the elevator should be positioned down.
• The type of trailing edge flap generates increased lift and drag by extending both back and down is the Fowler flap.
• The motion of Yaw is controlled by the Rudder.
• The motion of Pitch is controlled by the Elevators.
• The Flap in picture 35 is a Slotted Flap.
• The Flap in picture 36 is a Split Flap.
• The Flap in picture 37 is a Fowler Flap.
• The Flap in picture 38 is a Krueger Flap.
• The Flap in picture 39 is a Plain Flap.
• Two movable leading-edge lift augmenting devices are slats and leading-edge flaps.
• The trailing edge tab that is used to move the flight control surface is called a trim tab.
• The trailing edge device that counteracts the nose-up or nose-down tendency of the stabilator assembly is called an anti-servo tab or a balance tab.
• The device in picture 43 is a stabilator trim system.
• The device identified on the trailing edge of the rudder in picture 44 is a trim tab.
• The Auxiliary Device circled in the picture 45 is an air brake or speed brake, used to increase drag and slow the aircraft.
• The Auxiliary Device circled in the picture is a winglet which reduces induced drag by diffusing wingtip vortices.
• The Auxiliary Device identified with the arrows is Vortex Generators; to energize the boundary layer of air on top of the wing to prevent flow separation.
• The device circled is an angle of attack sensor, it measures the angle between the wing and oncoming air..
• This type of Auxiliary Device is a Yaw Vane, used to measure the angle of yaw.