Parts of an Airplane
Airplane Parts
Aileron
The ailerons are hinged control surfaces along the trailing outboard edges of each wing used to operate the "rolling" movement of the aircraft. They are the primary control used for turning the aircraft, and they move opposite to each other. To turn right, the pilot turns the yoke or joy stick to the right. The aileron on the left moves down (increasing lift on that side) and the aileron on the right moves up (decreasing lift on that side). As a result of differential lift, the aircraft rotates (rolls) about the fuselage (longitudinal) axis. When a bank angle of about 5 or 10 degrees is achieved, the pilot neutralizes the controls to hold the bank at that angle. With the aircraft banked to the right, it is pulled around the corner by the wing's lift, who's lift vector is also tilted to the right. To complete the turn, the pilot turns the yoke or stick to the left, causing the aircraft to roll in that direction. Once the wings are level again, the pilot neutralizes the controls and straight flight continues.

The ailerons have limited application to control line model planes because the models are constrained to fly in the semi-sphere around the pilot by the control lines. Some models are fitted with a ground-adjustable "tab" where the right aileron would be. This tab is used to trim the model's flight so that the wings stay aligned with the control lines coming from the model's left wing tip..
Elevator
The elevator is the horizontal hinged control surface at the back of the tail used to operate the "pitching" movement of the aircraft. When the pilot pushes forward on the yoke or stick, the elevator deflects downward increasing lift on the tail. As a results, the tail flies up, levering the airplane into a nose-down attitude for descent. Pulling on the yoke or stick results in a climb.

The elevator is the only in-flight-controllable surface on a control line model plane. Tilting the control-line handle down deflects the elevator down and vice versa.
Flap
The flaps are hinged control surfaces along the trailing inboard edges of each wing. They are used to increase a wing's lift by operating together in a downward direction. In a "real" aircraft, a separate control is used to operate the flaps for take-off and landing, otherwise the flaps remain stowed.

In control line model aircraft, flaps are often fitted the entire length of the wings. They control is tied to the elevator, but flaps operate opposite to the elevator. When the elevator moves down (increasing the lift on the tail), the flaps move up (decreasing the lift on the wing). Using flaps in this way creates a more pronounced "pivot" when pitching the aircraft into a climb or descent, which is very handy for aerobatic manoeuvres.
Fuselage
This is the longitudinal structure that holds the plane together. In large pressurized aircraft, this is a tube-like structure who's cross-section is almost a perfect circle. This is where the passengers and cargo sit.

In control line model aircraft, the fuselage may be "built up" to resemble a real aircraft, or it may be a more two dimensional "profile" that only resembles a real aircraft when viewed from the side. The advantage of profile models is that they are more aerodynamic and easier to build. The built up models look nicer.
Horizontal Stabilizer
The horizontal stabilizer is the "fixed" horizontal portion of the tail. It is used to move the aircraft's "centre of pressure" about its lateral axis aft resulting in stable "pitch" behaviour. In large airliners, the horizontal stabilizer is not actually "fixed"; it is hinged so that pitch attitude can be "trimmed" by small adjustments.

In control line model aircraft, the horizontal stabilizer is fixed. Some models have a larger elevator and no horizontal stabilizer.
Landing Gear
The landing gear is the aircraft's wheels, skis, or floats and supporting structures used for takeoff and landing. Large aircraft are almost always fitted with stowable (retractable) landing gear. Stowing the gear greatly improves aerodynamic performance and gas mileage.

In control line model aircraft, landing gear is not usually retractable, except on "scale" models where retractable gear is common.
Propeller
The propeller is shaped like the blades of a fan. It is fitted to the front of the engine. When it turns, it produces the thrust necessary to move the aircraft forward. In "real" aircraft, the propeller is often a "constant speed" arrangement, where the pitch of the propeller changes automatically to keep the engine running at the most effective RPM.

In control line model aircraft, the propeller almost always turns clockwise (right, when viewed from the pilot seat). Less common is the "pusher" prop which turns in the opposite direction. The propeller has fixed pitch.
Rudder
The rudder is the vertical hinged control surface at the back of the tail used to operate the "yawing" movement of the aircraft. It is operated by the pilots foot pedals. Pressing the right foot pedal deflects the rudder to the right causing the aircraft to rotate about it's vertical axis. This control alone would result in an "uncoordinated" (skidding) right turn. This kind of turn is very uncomfortable for pilot and passengers as sideways forces are felt throughout the turn. Under normal circumstances, rudder is used sparingly and in cooperation with the ailerons to achieve a "coordinated" turn, where the tail follows the path of the wings rather than skidding and slipping about behind them.

The rudder has limited application to control line model planes because the models are constrained to fly in the semi-sphere around the pilot by the control lines. Since control lines come out of the model's left wing tip, the rudder is often permanently deflected to the right to keep the lines tight. Some models are equipped with a ground-adjustable rudder which can be deflected to suit the weather conditions of the flight.
Spinner
The spinner acts as a fairing and protection for the parts that hold the propeller to the engine. It also conceals the "constant speed" mechanism of the propeller.

In control line model aircraft, the spinner may or may not be fitted. Often the spinner replaces the nut holding the propeller to the engine.
Vertical Fin
The vertical fin (or vertical stabilizer) is the "fixed" vertical portion of the tail. It is used to move the aircraft's "centre of pressure" about its vertical axis aft resulting in stable "yaw" behaviour.

In control line model aircraft, the vertical fin has the same purpose. It may be aligned down the aircraft's longitudinal axis, or it may be deflected to the right with the rudder to help keep the control lines tight. It is often the first part of the model to break off when the aircraft noses over in a hard landing.
Wing
The wing is the device that holds the airplane aloft be creating lift. It does this by making the path over the wing longer than the path under the wing. As air molecules pass by the wing, greater air pressure exists along the shorter path under the wing. This differential air pressure pushes the airplane up.

In control line model aircraft, the profile of the wing is often symmetrical. To change the length of the path "over" or "under" the wing, the wing is tilted into an "angle of attack" that achieves the desired lift. The advantage of the symmetrical profile is that the aircraft behaves the same in inverted flight as in regular flight.