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Aerodynamics: A section of physics dealing with fluids (both liquids and gases).

Airfoil: The cross-section of a wing.

Ailerons: Movable hinged sections on the trailing edge of each wing that are used to control roll.

Angle of attack: The angle that is required to generate lift. It is the angle between the airspeed vector and the chord of the wing.

Bank: The angle between a line drawn through the wing tips and the ground; when a plane rolls, it changes its bank. An aircraft makes a banked turn by dropping the inside wing and raising the outside wing.

Camber: The amount of curvature in the centerline of an airfoil, usually expressed as a percentage of the length of the airfoil's chord.

Center of gravity: The point where the plane will balance.

Chord: A straight line that connects the front edge to the trailing edge of an airfoil.

Control surfaces: Ailerons, elevators, and rudders. These surfaces control rotation in roll, pitch and yaw respectively.

Dihedral angle: The upward angle of the wings that is formed where the wings connect to the fuselage.

Drag: The retarding force parallel to the direction of movement.

Elevators: Control surfaces on the horizontal part of the tail that are used to allow the airplane to control pitch. Raising the elevators will cause the airplane to increase the angle of attack.

Equilibrium: When two or more forces act and cancel the effects of each other. The end result is that there is no change in speed.

Fin: Another word for the vertical portion of the tail, also called the vertical stabilizer.

Flaps: Movable parts of the trailing edge of a wing that are used to increase lift (and drag) at slower air speeds. When a plane lands, the flaps are extended to increase lift and drag, to fly at a slower speed. Flaps increase lift by changing the shape of the airfoil.

Force: A push or a pull in a certain direction. Force is measured in Newtons.

Force (Net) = a net force occurs when forces are unbalanced. For example, if a plane reduces its thrust, then drag because the net force. In the example below, drag has a net force of 15 Newtons. This net force is capable of accelerating (slowing down) the plane. Net force is also known as a resultant force.

Force (Unbalanced) = an unbalanced force means resultant or net force. See Force (Net). An unbalanced force is capable of accelerating a mass.

Gravity: An attractive force between all objects. We feel the pull of gravity toward the center of our planet. We experience gravity as weight. An airplane must generate enough lift to counteract its own weight.

Horizontal stabilizer: The horizontal portion of the airplane tail.

Inertia: Property of matter that resists any change in motion.

Kinetic energy: The work an object can do because of its motion. It is the energy of a moving object.

Leading edge: The front edge of a wing.

Lift: When a plane flies level, lift equals weight. Lift is perpendicular to the direction of motion.

Pitch: The angle between the fore and aft axis of the plane and the ground. A change in pitch points the nose of the plane up or down. Elevators control pitch. Your head moves in pitch when you make a "yes" motion.

Roll: Rotation about the centerline of the plane. Describes the tilting motion of the plane when one wing rises or falls in relation to the other. Ailerons control roll. Your head moves in roll when it moves "side-to-side."

Rudder: Control surface on the trailing edge of the vertical part of the tail. The rudder controls yaw.

Stabilizer: A surface that helps to provide longitudinal stability for an aircraft, stability in pitch.

Stall: A breakdown of the smooth flow of air over a wing. Flying a plane at a large angle of attack can cause a stall, which increases drag and often results in a decrease in lift as well. Stall generally occurs at an angle of attack between 10 and 15 degrees. A stall can also occur if a plane flies too slowly.

Streamline: To smooth an object's shape so that it creates less drag.

Three-Axis Control: Control of the rotation of an aircraft about all three axes is necessary for stable flight. (Pitch, Roll, Yaw)

Thrust: A force created by the engines that push or pull an aircraft through the air. Thrust acts against the force of drag.

Trailing edge: The back part or rear edge of a wing. The trailing edge is normally thin and sharp.

Turbulence: Airflow that is not smooth and steady.

Unbalanced Force: An unbalanced force is capable of accelerating a mass. See net force.

Vertical stabilizer: The fin, the vertical part of the tail.

Weight: Weight pulls an aircraft toward the earth. In steady flight, lift equals weight.

Wind tunnel: A wind tunnel is an enclosure in which a model of an airplane or part of an airplane is placed. Air is passed by the model at a known velocity, so that the model experiences the forces as if it were actually flying.

Wing: A surface that produces lift.

Wing Area: The surface area of one side on the wing.

Yaw: The sideways angle between the direction of movement and the center axis of the plane. Yaw occurs when the nose of the plane turns left or right to the direction of its motion. Rudders control yaw. Your head moves in yaw when you make the "no" motion.

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