Glossary

Helpful RC Terms and Definitions

3D. A style of flying fixed-wing RC aircraft that involves many maneuvers where the plane hovers and flies below its minimum stalling speed, depending on the power of its motor rather than on lift from its wings to keep it in the air.

Academy of Model Aeronautics. Commonly called the "AMA", it is the leading and largest organization for model aircraft builders and fliers in the United States. It represents the United States to international flying organizations and it lobbies for model aircraft interests with local, state, and federal governments and agencies. It also operates a model airplane museum, oversees contest regulations, produces and distributes a magazine, and provides insurance protection for most model-airplane-related risks.

Aerodynamics. (1) The study of how things move through the air. It is a branch of physics. (2) The flying qualities of an aircraft, as in "That model has good aerodynamics."

Aileron. A control surface, usually attached to or part of the trailing edge of the wing, used to cause the plane to roll. With standard ailerons, raising the left aileron and simultaneously lowering the right aileron will give a bank to the left.

Airfoil. A vertical cross-section of the wing, what you would see if the wing were cut by a vertical knife while the plane was flying straight and level and you looked at the wing from where the wing tip used to be. The shape of the airfoil can have significant influence on the flying qualities of an airplane.

Angle of attack. If you picture a wing as a flat sheet of material, the angle between that sheet and a line parallel to the oncoming wind. See Angle of incidence, with which this is often confused.

Angle of incidence. If you picture the wing as a flat sheet of material, the angle between the wing and the centerline of the fuselage. See Angle of attack, with which this is often confused.

ARF. Almost Ready To Fly. A model airplane kit that requires only a few hours of assembly before it is ready to fly. Typically, some preparation of the parts is required, glue may have to be used, radio equipment must be installed, and the motor or engine may or may not be installed by the manufacturer. All accessories needed for flight such as wheels and propellers are included. The transmitter is usually not included as part of the kit.

Attitude. (1) The orientation of an aircraft. See pitch, roll, and yaw. (2) Something that the editor says this author has too much of.

BEC (Battery Eliminator Circuit). This is either a stand-alone electronic circuit or is part of an ESC; in either case, it eliminates the need for a separate battery (in electric-powered models) to power the receiver and servos by producing the right voltage to operate them.

Brushed motor. The most common and least expensive form of electric motor used in model airplane propulsion. If an electric motor is not designated "brushless" then it is almost certainly a brushed motor. See Brushes. Also see Brushless.

Brushes. A part of brushed electric motors, they convey current to the rotating element (the armature) and mechanically affect the switching on and off of these magnets which, in turn, cause the armature to rotate.

Brushless motor. A form of electric motor which does not contain brushes. They are favored because of their greater power-to-weight ratio, longevity, and higher efficiency than electric motors that have brushes.

CA. An abbreviation for "cyanoacrylate," it is the principle ingredient in a kind of fast-setting glue widely used in building model planes.

Clevis. A small part made of plastic or metal, which is used to attach a pushrod to a control horn or to a servo arm. Typically, it screws onto the pushrod and clips onto the control horn so that at the field, the position of the control surface can be easily adjusted by unclipping the clevis from the horn and screwing or unscrewing it to adjust the length of the pushrod assembly.

Control horn. A lever firmly attached to a control surface and usually perpendicular to it that allows a pushrod or cable to move the surface.

Control surface. Any external moveable part of an aircraft designed to help it change orientation or speed, not including the propeller. The most commonly used control surfaces are ailerons, elevator, rudder, flaps, and spoilers. They are each defined separately.

ESC (Electronic Speed Control). Used in electric-powered models, this plugs into your receiver, and connects to both the battery and the motor, allowing you to control motor speed from your transmitter. An ESC often includes a BEC.

Flare. A maneuver executed just before touching down, where the elevator is used to slow the rate of descent. Timing is critical; if done too late, the plane lands hard; if done too soon, the plane may "float" and land far down the runway; if done too enthusiastically, the plane may stall and crash, To know just when and how much to flare is a key indicator of an experienced pilot, and nobody gets it right every time.

FM (Frequency modulation). A method of encoding control signals in a radio transmission. Considered superior to AM in some applications.

Hammerhead. An aerobatic maneuver in which the aircraft begins by ascending vertically. At the top of its ascent it rotates only on its yaw axis until it is heading vertically downward. The upward and downward lines must be within a wingspan, and the closer the better. This maneuver is also called a "stall turn."

Inverted. The proper term to use when describing that regime of flight where pulling on the elevator stick causes the plane's nose to move toward the ground. Airplane speak for "upside down.”

Lithium battery. A kind of battery that, for a given capacity, weighs significantly less than NiMH or NiCd batteries. However, for a given capacity, they generally have a lower maximum current rating than other rechargeable batteries.

Lithium-Polymer batteries (Li-Poly). A kind of rechargeable lithium battery that is lighter and sometimes can supply higher currents than other lithium-based batteries.

Minimal flying area. The smallest space in which a flyer can operate a particular model airplane safely and enjoyably. The pilot is assumed to be one for whom the airplane was designed as a beginning pilot needs more room to fly a given model than an expert. Flying areas are given by example rather than measurements: dining room, gymnasium, baseball infield, dirigible hangar, soccer field, model airplane club flying field, Kansas.

Nickel-Cadmium batteries (NiCd). A kind of rechargeable battery often used to power transmitters, receiver packs in RC airplanes, and as motor batteries. They are becoming obsolete and are being replaced by the lighter NiMH batteries (which see) and by still lighter Lithium batteries. Nickel-cadmium batteries contain toxic metals and must be disposed of as hazardous waste.

Nickel-Metal Hydride batteries (NiMH). A kind of rechargeable battery often used to power transmitters, receiver packs in RC airplanes, and as motor batteries.

RTF. Ready To Fly. A model airplane kit that requires only minimal assembly before it can be flown. To be classified RTF, the motor (if there is a motor), radio equipment, and all accessories should be installed by the manufacturer. It should require only attaching the wing and possibly the empennage with fasteners that take only a few minutes to install, such as bolts or rubber bands. RTF kits usually include the transmitter. You may have to charge any rechargeable batteries prior to flight. See ARF.

Stall. A condition of flight where a lifting surface, such as a wing, stops producing a useful amount of lift and the aircraft starts to fall. Stalls are always due to attempting to operate the flying surface (usually the wing) at too high an angle of attack. This, in turn, is always caused by overuse of the elevator control.

Tachometer. A device for measuring the number of times a shaft rotates, usually calibrated in "revolutions per minute," abbreviated "rpm." The most common use of this in modeling is to measure motor speed. Most model tachometers operate optically, by being pointed at the rotating propeller.

Wheel collar. A small, cylindrical part that can be fixed in place on a shaft by means of a setscrew that bears on the shaft. It is often used to keep wheels from coming off the ends of landing gear wires (hence the name) and can be removed by loosening the setscrew. They are also useful for many other purposes, which includes limiting the depth of drilling on small bits.

—Compiled by Jef Raskin

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