Glossary of Terms

Sep 17

Glossary of Terms


             Glossary of Terms

 Below is a list of terms commonly used in aeromodeling. This is not an exhaustive list so please feel free to send me your input.



Adverse yaw. When turning an airplane using only ailerons, the drag of the lowered aileron is greater than that of the raised aileron; this extra drag tends to yaw the airplane in a direction that’s the opposite of what the pilot intends.

Aerobatics. Maneuvers that involve bank and pitch angles in excess of 60 degrees. 

Aerodynamics. The dynamics of bodies relative to gases’ especially the interaction of solid objects moving within the atmosphere.

Aileron. A hinged or movable portion of an airplane’swing (usually at the trailing edge); primarily used to induce a roll.


Airfoil. A part or surface, e.g., wing, prop blade, aileron or rudder, that’s designed (shape, orientation, etc.) to control aircraft stability, direction, lift, thrust, or propulsion.

Angle of attack. (AoA). The acute angle between the wing chord line and the relative airflow.

Auxiliary channel. Any radio-channel function other than one of the four basic channels’ aileron, rudder, elevator and throttle.

Base leg. The part of the landing pattern that’s at 90 degrees to the final approach.


Bulkhead. A solid, vertical piece of wood inside a fuselage that helps to give it shape and rigidity.

Center of gravity (CG). A model airplane’s balance point.

Climb out. To gain altitude after takeoff.

Control linkage. Metal rods or plastic tubes that connect servos to control surfaces.

Control surface. A movable airfoil that can be controlled by the pilot to change the aircraft’s attitude.

Crab. To point the model’s nose into a crosswind by using the rudder to move the model sideways and prevent it from being blown off-course.

Crosswind. Wind blowing across the takeoff run or the model’s flight path. 

Crosswind leg. Portion of the traffic pattern at 90 degrees to either the upwind or downwind legs; directly opposite the base leg.

Dead-stick landing. A landing with the engine stopped.

Doubler. A section of balsa or plywood added to the inside of a fuselage side to strengthen it.

Drag. Air resistance that slows the airplane.

Elevator. A movable control surface usually on the horizontal stabilizer that’s used to control the model’s pitch attitude.

Final approach. The portion of the landing pattern that starts from the 90-degree turn from the base leg and is followed by the landing.

Flare. A slow, smooth transition from a normal approach attitude to a landing attitude.


Former. An open, vertical piece of wood inside the fuselage that helps to give it shape and rigidity.

Fuel mixture. The mixture of air and fuel drawn into the engine through the carburetor.

Fuselage. The main body of the airplane.

Ground effect. A reduction of induced drag’s downwash caused by the downwash hitting the ground sooner than expected; it allows the plane to gain a little extra lift. 


Headwind. Wind blowing straight at a model (parallel to its line of flight).

Heading. The direction the model travels over the ground. Not the direction the model is pointing.

Horizontal stabilizer. Flight surface that supports the elevator; also stabilizes the model in pitch.

Induced drag. The drag that is a direct result of the production of lift.

Landing gear (conventional). An airplane’s wheels, axles and supporting structure. Conventional landing gear is a tail-dragger configuration.

Leading edge (LE). The foremost edge of an airfoil or prop blade.

Lean mixture. An air/fuel mixture setting that contains more air 
than the engine requires to run 

Lift. A created aerodynamic force that is equal to or greater than the weight of the airplane and acts in opposition to the force of gravity. 

Longeron. A long, square or triangular balsa stick that runs from nose to tail to strengthen the fuselage.

Longitudinal axis. An imaginary straight line that runs through the fuselage from nose to tail and through the model’s CG on the same plane. 

Moment (nose moment, tail moment). Refers to a distance on a model forward or aft of the balance point.

Nose-heavy. A condition in which a model’s CG (balance point) is too far 

Over-control. Excessive control inputs that overcompensate for unwanted model movement. 

Parasite drag. The sum of pressure and skin-friction drag.

Pressurized fuel system. A fuel-tank setup in which the vent tube is connected to the pressure nipple on the muffler. The pressure from the muffler pressurizes the fuel tank and helps pump the fuel to the carb.

Receiver (RX). The part of the radio system that receives the radio signal sent by the transmitter. 

Ribs. Vertical portions of the wing’s structure that give it its contour.

Rich mixture. An air/fuel mixture that contains more fuel than the engine requires to run efficiently.

Rudder. Vertical, hinged control surface that controls yaw. 

Servo. Electromechanical device that moves the control surfaces.

Positive stability. The natural tendency of a model to return to a straight and level condition.

Stall. The point at which the wing experiences a loss of lift; the aircraft will tend to drop. 

Stringer. A thin, stick-like length of wood that supports a model’s covering. Similar to a longeron but does not significantly contribute to the model’s strength.

Symmetrical airfoil. An airfoil that has the same curve on its top and bottom surfaces.

Tail-heavy. A condition in which the model’s CG (balance point) is too far aft.

Taxi. To move the model along on the ground under its own power.

Thrust. A generated force that is required to overcome the natural resistance of drag.

Torque. The force created by the engine spinning the propeller; it will turn an airplane to its left.

Trailing edge (TE). The aft edge of an airfoil or prop blade.

Transmitter (TX ). The part of the radio system that sends the radio signal to the RX. 

Trike (tricycle landing gear). Landing gear that includes a nose gear and two main gear.

Trim. To adjust a model’s control surfaces to obtain the balanced flight performance you want. 

Upwind leg. First portion of the landing pattern directly opposite the downwind leg and 90 degrees to the crosswind leg.


Vertical fin. A fixed vertical airfoil that gives directional stability, i.e., it reduces the tendency to yaw about the vertical axis.

Wing spar. Runs from wingtip to wingtip; the wing’s main horizontal member; gives the wing its strength. 

Yaw. The left and right movement of the aircraft’s nose about the vertical axis.

Y-harness. A Y-shaped wire with one input connection and two output connections. 

The simplest way to connect the pushrod to a controlhorn or servo arm. Shaped like a Z.


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