Glossary of RC Terms

Browsing through the manuals, specifications and forums relating to RC hobby products can be a confusing experience sometimes. It’s all going fine until someone throws in that one word that leaves you blinking and going…“What?”. It can happen to the best of us, and that’s why we’ve put together this list of definitions to help you out with those “What?” moments. Fill in those gaps in your knowledge with our comprehensive rc glossary of terms and never get caught out again.

If you have comments, suggestions or requests for additions to this RC glossary please leave us a reply at the bottom of this page!

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ABC Engine

Stands for ‘aluminium/brass/copper or composite’ engine. This type of engine (also known as ‘Non-Ringed’ due to the lack of a piston ring) uses an aluminium piston and a brass cylinder within a copper or copper composite (for example, nickel) sleeve. It is technically a higher-performing engine than most, forgoing the piston ring and relying simply on a perfect tight fit of parts. It can, however, be more difficult to run.

Activating/Arming Switch

A safety feature included in some electric models, this is an external switch that needs to be flipped before the motor will start. It helps prevent the motor from starting unintentionally, which could be very dangerous if fast-spinning propellers are involved.

Adjustable Function Rate (AFR)

A feature that allows you more control over the movement of the servos; you can set limits on their travel distance to either side to suit your needs. This feature is not affected by exponential or dual rate settings, and is effectively another name for Adjustable Travel Volume or End Point Adjustment.

Adjustable Travel Volume (ATV)

The ability to set limits on the travel distance of a servo to either side of its neutral position. These limits can be different for either side, which can help to balance a tilting or listing aircraft. See also: Adjustable Function Rate and End Point Adjustment.

Adverse Yaw

A trait in an aircraft that sees it oppose the desired roll or bank, and yaw in a way that hinders it. It is most common in planes using flat-bottomed training wings and poorly designed ailerons, or when flying at steep angles and low speeds. Setting up differential throw or using the rudder and ailerons at the same time can limit this effect, which is often a cause of poor take-offs and landings as well as problems in the air. High-wing planes are also prone to it, especially when in combination with one of the above factors.


An adjustable ‘control surface’ on the trailing edge a plane wing that can be raised or lowered to cause rolling to the left and right. Raising the aileron on one wing and lowering the one on the other whilst in forwards motion will cause a bank to the side of the raised aileron in a roll or turn. See also: Strip Aileron and Barn-Door Aileron.

Aileron Extension

A length of cable which connects the normal servo cable to the receiver when the supplied cable cannot reach. Primary use is to allow the aileron servo to be positioned further away from the receiver, for example mounted on the wing. Such positioning allows for easier removal of the wing, although the longer the extension cable/electrical distance from the receiver, the more potential there is for radio interference.

Aileron/Rudder Mixing

Linking an aileron servo to the rudder servo/control in such a way that the rudder also moves when the aileron receives a command.

Air Bleed Screw

A component of the carburetor that allows for the manual alteration of the amount of air entering the idling careburetor. This alteration is made by tightening or loosening the screw.

Airborne Pack

See ‘Flight Pack’. This is not a similar thing to the flight box, rather it refers to all the radio equipment that is used in an RC aircraft during flight. This includes most importantly the receiver, but also the servos/ESC, flight pack battery/BEC and the harness. The transmitter is outwith the craft and so not considered part of the flight pack, despite its involvement.


Refers to the shape of the wing, of which there are three common designs: flat-bottomed, semi-symmetrical and fully symmetrical. As a general rule, though, the front of the airfoil will be rounded while the back tapers to a blunt point, and the upper surface is curved in order to help achieve smooth airflow and lift.


Stands for ‘The Academy of Model Aeronautics’, which is a US national body that runs model competitions and creates official model flight records.


Amps and Milliamps are units of electricity, much in the same way that Litres and Millilitres are units of volume. They measure capacity (how much electricity your battery pack can hold), and when spoken of in relation to hours, this indicates ‘flow’, i.e. how many of those units are used per hour, how fast the electricity is coming out.

Amplitude Modulation (AM)

Used to be the most common type of radio modulation, but has now been overtaken by more sophisticated systems. It works by varying the transmission signal’s amplitude.


A signal transmission aid that is to be found on most control units. It is an extendable telescopic tube that can be folded away again after use.

Angle of Attack (AOA)

The angle at which the wing of a plane meets the oncoming air, i.e. whether it is head-on, or tilted up or down. A high angle of attack is when the wing is tilted strongly upwards and providing a wide surface area for resistance, which creates lift but also drag. There is no relation to the angle of the ground or the horizon, however, only the relative wind. This makes calculating AOA more complicated, as the wind may not be running parallel to the ground. See also: Relative Wind


Stands for ‘Almost Ready to Fly’, and indicates when a product is mostly pre-assembled, but may need extra parts gluing together/fitting/buying. Often there is a transmitter or motor missing, so be sure to check what is included in the kit. If you already compatible transmitters etc., this can be a great money-saver.


Stands for ‘Almost Ready to Run’. This is used to describe vehicles that come mostly pre-assembled, but require some extra work doing before you can start to drive them. They cost a little more than a self-build kit (especially if you have to buy your own batteries/engine/transmitter as well), and give you less of an easy familiarity with how your vehicle works, but do save time and minimise the opportunity for beginners to put their car together wrong.

Automatic Tail System

A type of radio mixing that includes a measure of tail rotor movement with throttle or pitch variations.


Either a) When rotors (usually on helicopters) turn without input from the motor/engine. This occurs during downward flight, with air from below the blades being pushed up and through them and turning them, as opposed to the deliberate movement of the blades sucking air down through them from above. This can only occur with certain blade shapes, but allows a safe landing even if the engine fails. Or b) When an engine is idling, having been deactivated by a “hold” switch.


An imaginary line around which an object rotates, for example the ‘axis’ between the Earth’s North and South Poles.




When referring to RC engines, this is the covering protecting the rear of the engine’s crankcase. See also: Crankcase, Engine.


Deliberately added weight in an air- or water-borne craft that helps it to remain steady and manageable in rougher conditions. It can also help to increase speed. It can be positioned in a variety of places, depending on the crafts, but ensuring that the craft is evenly ballasted on either side of the main axes is important.


The lateral inclination of an aircraft in flight. In practise this looks like the craft is tilted to one side, and causes it to turn in the direction of the lower wingtip. This is a method of turning more commonly used by gliders, operating around the roll axis rather than using yaw, although in complex stunts both may be employed at the same time.

Barn-Door Aileron

A chunky aileron that usually only extends part-way from the wingtip to the body of the plane. It is positioned predominantly on the trailing edge. See also: Strip Aileron.

Battery Cycling

Fully charging and discharging a battery (sometimes multiple times) to erase its built-up ‘memory’. This is used on nickel-based batteries, and depending on the frequency of their use should be done every month or so. See also: Battery Memory.

Battery Memory

A quirk of nickel-based batteries whereby they apparently ‘remember’ how much they have been discharged, and begin to reduce their maximum capacity towards their habitual discharge level. This can be combated by battery cycling.

Battery Meter

Monitors the remaining capacity of connected batteries. Most commonly used for transmitter batteries where the live result can be displayed on the unit screen.


This doesn’t stand for a ‘Buddy Box’, but rather the inclusion of ball bearings in the crankshaft support system. If that doesn’t mean anything to you, it is a feature that allows for a smoother-running engine, and usually extends the life of an engine.


Stands for ‘Battery Eliminator Circuit’, which is a circuit that reduces the number of separate batteries required to run an electric device. There is no need for a separate receiver battery to supply the different voltage it requires, as this circuit does the conversion. A BEC can be a standalone unit or part of an ESC system. See also: Electronic Speed Control.

Brushed Motor

A common electric motor type that uses brushes when producing power. The running process involves more friction than a brushless motor, which reduces performance and efficiency in comparison, but brushed motors are considerably cheaper to buy.


A component of ‘brushed motors’, they are used both to convey current and control the magnets which cause the rotating element (the armature) of a brushed electric motor to turn. They also create friction, however, which leads to reduced motor power/efficiency in comparison to brushless motors.

Brushless Motor

Always specified as an advertising point (i.e. if a company doesn’t tell you it’s a brushless motor, it’s not), these electric motors produce the fastest speeds recorded in RC hobby racing. They are faster and stronger but also more expensive and less common than brushed motors. They achieve their greater efficiency by avoiding the use of mechanical sliding contact, and so lessening friction; this also makes them longer-lasting than their brushed counterparts.

Buddy Box

This is effectively a system of dual control for the one aircraft/boat/car, where two people are able to send commands to the receiver through linked transmitters. Rather like the passenger set of pedals in a specially adapted driving instructor’s car, it is a great beginner training tool – or a way to let less experienced friends try your model out without so much danger crashing!




Stands for ‘Cyanoacrylate’, a common ingredient in quick-setting hobby glue. While suitable for woods and most plastics, CA glues will eat away at Styrofoam, so are never to be used when constructing foam gliders. The glue can be bought in a variety of thicknesses depending on your needs.


Used in reference to batteries, this is the maximum ‘volume’ of energy that the battery in question can hold.


The engine component that controls speed/throttle. It can also be used to control the balance between lean/rich settings through adjusting the needle valve.

CCPM Mixing

Stands for Cyclic Collective Pitch Mixing, a type of mixing used for helicopters in which three servos are mounted below the swash plate, linked to it at intervals of 120 degrees. The mixing is then set electronically, through programming, instead of mechanically, which simplifies the physical mechanism used to support it. This allows for quicker building, less maintenance and less mechanical know-how on the part of the owner.

Centre Line

An imagined line that runs from the front edge to the back edge of a given craft/vehicle, e.g. from the nose to the tail of a helicopter or plane.


Stands for ‘Centre of Gravity’ a.k.a. balance point. It is the point where the horizontal and vertical axes meet. Models can be deemed ‘unbalanced’ when the centre of gravity is not in an optimal place, for example being too far towards an aircraft’s nose (‘nose-heavy’) and causing the nose to drop when hovering, landing or moving slowly.


Lines of communication between an RC transmitter and craft or vehicle that control particular mechanical functions in the craft/vehicle itself. A particular channel might control left/right spin, for example. The more ‘channels’ a hobby product has, the more different types of movement it can perform.

Charge Jack

The socket into which a charging system is plugged to allow charging of the airborne battery. Sometimes this socket can also be used to connect an expanded scale voltmeter or ‘ESV’ between flights. In well designed models the charge jack will be in an easily accessible part of the fuselage. It is a part of the switch harness. See also: Switch Harness, ESV.


Gadget for recharging batteries. There are a number of different kinds used for RC hobby products, from so-called dumb chargers or wall socket chargers to specialist units with in-built cell balancers and programming options.

Chicken Stick

A handheld stick used for starting the engine of a model plane or similar device.


A component that attaches a pushrod to a control horn/servo arm, also known as a ‘link’. It is an alternative to the z-bend attachment that eliminates its use. Typically it attaches to a control horn using a non-adjustable clip, and the pushrod using a screw fitting, which allows the length of the pushrod to be ‘altered’ depending on how tightly the clevis is screwed on. This is a manual way of altering ‘throw’.


A weighted device used in the fuel tank of a nitro- or petrol-powered vehicle to ensure that the intake line always has a fuel supply. The inclusion of this in a vehicles working parts can improve run times and fuel efficiency.

Collective Pitch

A system for controlling RC helicopters whereby the blades are able to rotate at a constant speed throughout, and climb/dive is controlled by the angle of the blades.

Computer Radio

A transmitter that uses an inbuilt computer, allowing the operator to program very complex types of mixing among other specialist applications.

Constant Drive Tail

A clutch that ensures that the tail rotor remains active even if the main engine is in autorotation, in “hold”, or even off.

Control Horn

A lever or moving part attached directly to the control surface of a craft, and also connected to the pushrod. Instructions for the movement of the control surface are passed from the receiver through a variety of electrical and moving parts, finishing with the final pushrod and control horn, which pushes/pulls the control surface directly and executes the command.

Control Surface

An external aircraft component that can be controlled by the operator to affect the movement of the craft. Examples include the ailerons, rudder, spoilers or elevator, which help adjust a plane’s flight path and speed. Using more than one at once is often most effective.

Conventional Tail

The tail of an aircraft which sees the stabiliser(s) attached directly to the fuselage. It is known as the ‘conventional’ tail because it is the most common setup.


See: Mixing


The main/outer body of an engine.

Critical Angle of Attack

The angle of attack (AOA) at which the airflow over and around the wings becomes too violent/smooth flow stops.

Crow Mixing

A combination whereby the ailerons go up as the flaps go down. Used to enhance spoiler action.

Crucifix Tail

This is a type of tail in which the stabiliser is located partway between the conventional tail and T-tail positions, forming the shape of a crucifix by crossing the fin near – but not at – the top.


The component of transmitters and receivers that set the frequency of the radio transmission.


The part of the engine where combustion occurs.



Dead Stick

Also known as ‘glide’ or ‘un-powered flight’, this is when the engine of an aircraft fails or is stopped and the craft is moved by the interaction between the control surfaces and the air currents alone.

Differential Ailerons

A form of mixing which allows the ailerons to be controlled on separate channels or, through programming, together but with different travel volumes. Each aileron requires its own servo.

Differential Throw

This is a setting for the ailerons on an RC plane that is used to counteract adverse yaw. It involves deflecting upwards more strongly than downwards, and so counteracting the contrary response created by the undesired yaw.


This is the ‘bow’ of the wings of an RC plane, which appears like a wide V shape when viewed head-on. Having this upward-pointing angle creates greater stability, making obvious dihedral angles a common feature of training planes. It limits the plane’s ability to perform stunts, however.


Refers to a small bit of damage to the body or working parts of an RC hobby product, which can be more or less serious depending on where has been damaged. Some ‘dinged’ components, such as props, must be replaced, whereas others can continue being used indefinitely.

Direct Servo Control (DSC)

A radio feature that allows a cable to be connected between the transmitter and receiver in order to perform on-the-ground tests without sending out a radio signal.


A new 2.4GHz transmission system from Japan Remote Control which claims to offer the best of both from the DSSS and FHSS systems. The acronym stands for ‘Dual Modulation Spread Spectrum’. The system used a wider signal (3MHz vs. <1MHz), apparently avoiding the added interference this could entail by frequency hopping.

Down Thrust

A feature that helps prevent excessive altitude gain in RC aircraft. Planes with flat-bottomed wings are especially prone to excessive climbing, but a downward angled engine producing down thrust can counteract this.


The aerodynamic resistance presented by the air to an object moving through it.


Stands for ‘Direct Sequence Spread Spectrum’. This is a type of radio control system whereby one or at most two available frequencies are chosen, and commands are transmitted only via those. It is less flexible and interference-resistant than FHSS, but in the absence of any interference it is a more responsive system.

Dual Aileron Extension

See: Y-Harness.

Dual Conversion

The preferred method of processing incoming signals in the receiver, as it is less vulnerable to interference.

Dual Rates (DR)

A feature that offers two levels of control sensitivity with regards to servo throw. When “off” is selected, throw is uninhibited and can be controlled up to 100%. When the feature is “on”, servo throw is limited, which is also referred to as having less sensitive controls. The limits added by the “on” setting are usually adjustable, allowing for the preferences of the operator.



Electric Starter

A type of engine starter that uses a small external electric motor, which is applied to the engine by hand. The most common type of power is a 12V battery, which the Starter unit requires to run. This is the most common type of ‘starter’ for fuel-powered aircraft.


A liquid or gel containing ions that can conduct electricity; a material used in batteries.

Electronic Speed Control (ESC)

A higher-performing alternative to mechanical speed control (servo/servo arm throttle control) that operates by altering the battery power delivered to the motor. Either a built-in part of the receiver or a separate unit plugged into the receiver’s throttle control channels that connects to the main battery and motor, it is most often used with brushless motors to create highly functional products. This system is also lighter, which is often an advantage, and usually includes a battery eliminator circuit for the receiver. See also: BEC.


A movable control surface that affects an RC aircraft’s pitch, i.e. whether it is climbing, diving or level. It is most commonly found on the rear edge of the craft’s horizontal stabiliser. When using a standard transmitter, pulling the control stick towards the operator will cause the elevators to rise and the craft to climb, whereas pushing it away will initiate a dive.

Elevator/Flap Mixing

Mixes the elevator and flaps so that whichever direction the elevators are instructed to move in, the flaps move the opposite way. This is most often used on stunt planes, as is helps in the execution of tight manoeuvres, but has few other uses.

Elevon Mixing

Used on models where the elevator and ailerons are in fact the same control surfaces, it allows the operator to instruct the transmitter as though they were separate surfaces. When instructions are sent requiring the elevators, they move in sync like elevators; when instructions are sent for turns, they move separately like ailerons.

Endpoint Adjustment

This is a way of ironing out the various quirks of an individual RC product to make it easier to control. The ‘endpoint’ described is the maximum reach of the servo arm on any given channel, which, when adjusted, limits servo arm travel in a particular direction. This can be helpful when, for example, rebalancing an aircraft that rolls more readily in one direction that the other. Different from Adjustable Travel Volume in that movement is limited on one side of neutral only. See also: Adjustable Travel Volume.


A machine that converts energy (e.g. heat or electrical energy) into motion. Although technically the terms ‘engine’ and ‘motor’ are interchangeable, ‘engine’ is more commonly used to describe fuel-powered types that electricity-powered variants.

Engine Mount

The supporting structure that secures the engine in an RC vehicle/craft. Many engine manufacturers also make custom engine mounts; generic engine mounts can also be effective within their specified dimension ranges.

Exponential Rate

A type of servo control that allows for more precise control in the smaller movements without limiting overall travel/endpoint. When moving the control stick up to 50% of its maximum reach, the servo is less responsive, and will move by a smaller degree than the control stick. Beyond 50% however, the movement of the servo catches up, so that when the control stick is in the 100% position, the servo is also at 100% of its travel volume. Exponential rate is useful for allowing more controlled movements in smooth flight without disabling the servo reach required for stunts or emergencies.


Ultra-durable RC hobby glue or resin. Available with a variety of drying times, it is a two-part fixer for areas that will have to deal with high levels of resistance, for example RC plane wings.

Expanded Scale Voltmeter (ESV)

Hand-held device for taking voltage readings from battery packs quickly and easily. A handy product and great safety tool for the more volatile varieties of battery.




A pre-programmed feature that helps limit problems caused by radio interference. The system dictates a set position that the servos should return to (usually neutral) in the event of prolonged radio interference. This can help to prevent crashes by preventing temporary commands from being continued, and is included in most PCM radio systems.


Stands for ‘Frequency Hopping Spread Spectrum’, which is one of the two main 2.4GHz radio systems. It involves jumping between available frequencies at a rapid rate, the changes only milliseconds apart. This limits interference due to the small amount of time spent on the ‘hampered’ frequency before switching to another. This is more flexible than the DMSS.

Field Charger

A fast battery charger for use while out and about with your RC hobby product. Designed to run from a 12V power source such as those found in car batteries, these let you recharge on the go. They are not as safe or reliable as home charging units, however.


A.k.a. Vertical Stabiliser or Yaw Stabiliser. Fins are vertical surfaces attached to an aircraft’s tail that can help to counteract yaw and roll.

Fixed Landing Gear

Non-retractable landing gear (skids/wheels etc.) that remain in a set position. While retractable landing gear is preferable, as this provides the aircraft with a more aerodynamic shape while in flight, it is not always practical in RC products.

Fixed Pitch

A type of helicopter blade setup in which the angle or pitch of the rotating blades cannot be altered, and height is controlled at least partially by the speed of blade rotation.


These are aircraft control surfaces not often used on entry-level models, but which can be a great help in producing or resisting lift, especially during takeoff and landing. They are located closer to the body of the plane (fuselage) than their sister control surfaces, the ailerons, but are also found on the trailing edge of the wing. Their use aids lift in a similar way to an under-camber airfoil without the shape being a permanent feature.

Flaperon Mixing

Couples the flaps and ailerons to allow both surfaces to act as either ailerons or flaps. This is achieved by connecting the ailerons to separate servos, one of which is controlled through the designated aileron channel, and one through the flap channel.

Flap/Elevator Mixing

Mixing the flaps and elevator so that when the flaps are adjusted the elevator automatically adjusts to complement the movement e.g. acting to resist pitching when the flaps are lowered.


A technique used when landing an aircraft to ensure a gentler and more elegant touchdown. It involves increasing the up elevator when about three feet from the ground (depending on aircraft size) and so landing with the nose a little up, which, when done properly, elicits only the smallest of bumps upon touchdown.

Flat Bottom Wing

A type of plane wing commonly seen on training models due to its suitability for lift. Its name is self-explanatory, referring to the wing’s flat underside.

Flex Cable

A highly flexible variation on the standard pushrod, a flex cable is capable of even more pronounced bends than a ‘flexible pushrod’. It is described as a cable due to the plastic sheath that protects its metal core. Although it has a number of advantages, it is unsuitable for many applications as it will bend under heavy pressure.

Flight Box

The container for the protection and transport of all the flight equipment to be used in the field.

Flight Pack/Airborne Pack

This is not a similar thing to the flight box, rather it refers to all the radio equipment that is used in an RC aircraft during flight. This includes most importantly the receiver, but also the servos/ESC, flight pack battery/BEC and the harness. The transmitter is outwith the craft and so not considered part of the flight pack, despite its involvement.

Flight Modes

A transmitter’s memory can often store different types of control i.e. different sets of functions for each control stick. The ‘mode’ used by an operator is purely a matter of preference. See also: Mode 1, Mode 2, Mode 3, Mode 4.


This is when the elevator or aileron begins to ‘flutter’ during flight, i.e. flapping in a violent and uncontrolled way when travelling through the air. From the ground, the first sign that you usually get is a low pitched buzz sounding from the plane, and when hearing this you should cut the throttle and land right away to avoid the affected control surface snapping off and/or a crash. Common causes of ‘flutter’ include too great a hinge gap or dysfunction in the control horns.

Flying Stabliser/Stab

A combined stabiliser and elevator, i.e. the elevator is not attached to the trailing edge of the stabiliser, rather both are a single larger unit.

Foam Rubber

A material used to prevent the flight pack (receiver, receiver battery etc.) of a plane from being affected by engine vibrations. While not 100% effective, it can provide some protection.

Four Way Wrench

A wrench with four different sizes, each suited to a particular component of the RC product e.g. prop nut or glow plug.

Frequency Control

This is when the operator of an RC hobby product is able to manually select a frequency within their band using a frequency module. This is useful where there is area-specific interference (for example from pagers, which are no problem in some areas but worse in others), and local hobby enthusiasts are often able to find preferred frequencies for their area. This is not necessary when using 2.4GHz technology, however, and especially not when employing frequency hopping.

Frequency Flag

A visible marker attached to your transmitter that alerts other modellers in the vicinity as to the frequency you are using. This allows them to ensure they select a different frequency (when manual selection is possible/required), ensuring less interference for both of you.

Frequency Module

A unit that attaches to the transmitter that allows the operator to manually select a broadcast channel or frequency. See also: Frequency Control.

Frequency Modulation (FM)

Anyone who as ever used an old radio will be familiar with the FM and AM terms as different methods of broadcasting. FM is now considered the superior system of encoding commands, as it is less vulnerable to interference. The information is transmitted through altering the frequency in a particular pattern.


Stands for ‘First Person View’. This is when the operator of an RC device is able to see the world as a real-life pilot/driver of the device would. This is usually achieved through the use of a live-streaming camera fitted to the front of the vehicle/craft, facing in the direction of travel and transmitting to a video screen or goggles.

Fuel Bulb

A rubber tool resembling a flower bulb that helps in transferring fuel to the tank of an RC vehicle/craft. It is one method of solving the problem of transferring fuel from a large-mouthed container to a small opening.

Fuel Overflow Line

An escape route for excess fuel. A good comparison is the hole at the top of a kitchen sink that prevents it from overflowing when a tap is left running. Fuel can change in volume when subjected to pressure changes (which are caused by both altitude changes and custom-built pressurising systems designed to aid fuel flow to the engine), so an overflow line is an excellent safety feature.

Fuel Pick-Up Line

The connection between the fuel tank and carburettor through which fuel travels in order to power the engine. It is usually a flexible tube, and can also be used to top-up the tank. A clunk is usually attached to the tank end to keep the end of the line submersed in fuel regardless of sloshing. See also: Clunk.


This is the term used to describe the main body of an aircraft (i.e. excluding wings/blades).




Allowing air currents and control surface adjustments alone to carry and airborne craft i.e. not using the engine/motor/throttle. This can be done on purpose or due to engine failure.

Glide Ratio

The distance travelled forwards compared to the distance dropped when gliding. For example a 12:1 glide ratio would mean that the craft in question could travel 12 feet for every 1 foot of lost altitude. Glide ratios can be expressed metrically or imperially.


Brief or seemingly minor problem with an RC device or transmitter. Usually harmless, but depending on the nature of the problem can become serious.

Glow Fuel

More commonly known as Nitro fuel, it has earned this alias as a result of the need for a glow plug to start the engine, as opposed to the spark plug equipment used in petrol-powered engines. See also: Glow Plug.

Glow Plug

A device used to start an engine by using a heat source to ignite the fuel/air mixture. A wire filament inside the plug is heated up by converting electrical power from a connected battery into heat energy, which leads to the engine starting. Once the engine is started it will maintain the heat of the filament itself, and the battery can be removed.

Glow Plug Clip/Battery

The power source used to heat up the wire filament in a glow plug in order to start the engine. Usual voltage is 1.2V. See also: Glow Plug.


A highly professional landing with no bounce or jolt to be observed whatsoever.




Also known as a Stall Turn, this is an aircraft stunt that involves a directly vertical climb, followed by a 180 degree rotation on the yaw axis alone and a directly vertical dive. This requires a ‘stall’ at the top of the upwards movement so that the plane is able to perform its standalone rotation, hence the alternative name. The merit of the move is judged on the proximity of the upward and downward flight paths; ideally they should be no more than a wingspan apart.


A device containing wires and plugs that connects different electrical components within an RC craft or vehicle.


A part of the compression chamber in a fuel-powered engine.

High Wing

A design of aeroplane that involves affixing the wings to the top of the fuselage as opposed to attaching them to the sides.


The component of a control surface that attaches it to the aircraft, generally along one of its edges, whilst still allowing the surface to change in angle. Different types of hinges used in RC hobbies include pinned hinges, “living” hinges and hinge points, all of which perform the same function with slight variations.


Noun or verb referring to the sudden onset of radio interference that hampers the responsiveness of an RC vehicle/craft (to be hit or to take a hit). Symptoms include sudden lack of control and erratic movements from the vehicle/craft. A hit can be caused by anything from another RC user nearby to radio transmissions from miles off.

Horizontal Stabiliser/Stab

The horizontal surface located at the very rear of a plane of helicopter (on the end of its tail) that helps the craft resists pitching movements. This helps limit unwanted pitching (forwards/backwards movement on the horizontal axis) while not providing enough resistance to prevent it altogether. Elevators can be located on the horizontal stab.

Hovering Pitch

A certain amount of pitch is required to hover a helicopter successfully; if none is applied it will not remain static. Many transmitters can be programmed or manually adjusted to take this into account however, so that neutral control stick positions result in an even hover.

Hovering Throttle

Like hovering pitch, a certain amount of throttle is required to allow a helicopter to remain static. The average amount required is about half throttle, though this varies depending on the craft.



Idle Bar Plug

A type of glow plug that includes a ‘bar’ device to limit the amount of raw fuel that can touch the glow element directly. Idle bar glow plugs are more efficient than other varieties as they prevent the cold raw fuel from cooling the heating filament, and so cut the amount of time it takes for the glow plug to start the engine. They are also useful after ignition, helping to prevent splashing onto the plug and to maintain its heat in ‘idle’ engine states, hence its name.

Idle Up

A function for collective pitch helicopters that brings the throttle and rotor to the correct speed before adding the collective pitch function.

Inverted Flight

Generally a fancy term for upside-down flight. This is only possible with RC aircraft that can accommodate 6 channel control and above.




A set of parts that will allow the hobbyist to built a specific RC hobby model almost from scratch. All of the building and finishing must be done by the customer, who may also need to hunt down independently parts that are not included in the kit (for example a radio system or batteries). This is the least pre-assembled of all RC product types (apart from entirely custom vehicles), but see also: ARF, ARR, RTF, RTR, BNF and PNP.


The symbol/shorthand for ‘kilovolt’, which is essentially a unit of 1000 volts (think grams and kilograms). In terms of RC hobbies, it is used to refer to the number of revolutions per minute (RPM) a motor will do with different voltages applied, e.g. kV=860. Different motors will list different response levels depending on how they have been produced, and more is not always better. A lower kV rating means more torque, for example, which is more important for larger propellers and stunt aircraft. kV ratings are also helpful when choosing batteries.



Landing Gear

The equipment used by an aircraft to ensure a safe and upright landing. This commonly takes the form of skids or wheels (tricycle or tail-dragger gear) attached to the underside of the fuselage, and can be retractable, like on commercial aircraft, or non-retractable, like on most RC hobby aircraft.

Lateral Balance

This refers to how straight an aircraft/boat sits in the air/water, i.e. whether it lists to one side or not. An aircraft that does not lean more readily to one side or the other is referred to as being ‘laterally balanced’, whereas one that does has poor lateral balance. Well balanced aircraft are better stunt models, while well balanced boats flip less readily.

Leading Edge

This is the front edge of the wing or stab on an aircraft. It can help to think about it as the ‘cutting edge’, as it is the side that cuts through the air like the sharp edge of a knife. See also: Trailing Edge.


A lithium based battery type evolved from Lithium Ion batteries, LiFe batteries have dropped from popularity since the development of their LiPo sister-batteries, which are similar but safer, and boast a higher energy density to boot. LiFes are still available, though, and still used in a number of RC hobby products.


The aerodynamic force that – generally – causes an aircraft to gain height. Scientifically, however, lift bears no relation to the direction of gravity, rather the direction of the various air currents involved.

Lift:Drag Ratio (LD)

See: Glide Ratio.


Stands for ‘Lithium Ion’, which is a medium-efficiency class of battery. Lighter and offering longer run-times than NiCd and NiMH batteries, it has been overtaken as a type by the development of saleable LiPo and LiFe batteries.


Currently the most common type of ‘expertise upgrade’ battery, these are more powerful and efficient than the entry-level NiCd and NiMH batteries, but also more complicated and dangerous to run. They pack more power into a smaller space, thus making them more attractive but also more volatile. They are marginally safer and lighter than their LiFe predecessors, however, with a higher energy density.

Long Stroke

‘Stroke’ is a term used to describe the total travel distance of the piston in a fuel-powered engine. In an engine described as ‘long stroke’, this means that this distance is proportionally longer than it would be in a standard engine. The advantages of a long stroke engine include more torque, so they can be useful for monster trucks, but the disadvantages include reduced RPM, making them less popular among speed racers, especially on-road.


An aerobatic stunt that involves beginning from a level flight path, climbing until the craft is vertical and then moving into inverted (upside-down) flight back in the other direction, before diving while inverted until vertical once more (this time pointing downwards) and then levelling out to resume the original flight path.




Stands for the ‘Model Aircraft Association of Canada’, which is the go-between organisation for hobbyists/manufacturers and the Canadian government. This ensures that hobby flight commands are broadcast on safe and legal frequencies. The organisation also offers membership, which has a number of benefits, and presents international competitors from Canada to the Fédération Aéronautique International (FAI).


Shorthand for Milliamp Hour, this denotes the total capacity of a battery. In many cases, it can also be used to predict how long a battery will last and thus compare batteries; if the same power demands are made upon two batteries with different mAh, the one with the higher capacity will last longer.

Main Gear (Mains)

These two ‘legs’ positioned beneath an aircraft’s wings that are part of its landing gear.

Minimum Sink

The speed at which an aircraft looses the least height per minute. An alternative measure to glide ratio, this is a popular comparison feature in sail planes.


Also known as ‘Coupling’, this is when two RC channels are joined i.e. one command movement will operate them both. This ‘joining’ takes place electronically at the transmitter, not at the receiver or mechanically. Useful in advanced RC aircraft, where there are many command options available, wise mixing can make the craft easier to fly. Common types of mixing include Flaperon and Elevon setups.

Mode 1

‘Mode’ refers to the arrangement of a transmitter’s controls. Mode 1, when used to discuss RC transmitters for aircraft, means that the aileron and throttle are operated via the right hand control stick, and the rudder and elevator are operated via the left. This mode is more common in Europe and Asia.

Mode 2

‘Mode’ refers to the arrangement of a transmitter’s controls. Mode 2, when used to discuss RC transmitters for aircraft, means that the elevator and aileron are operated via the right hand control stick, and the rudder and throttle are operated via the left. This mode is the standard mode throughout the Americas.

Mode 3

A direct opposite to Mode 1, Mode 3 is set up so that the ailerons and throttle are commanded using the left stick, and the rudder and elevator using the right. This is not a particularly common flight mode, but is sometimes considered better for stunt planes.

Mode 4

The same as Mode 3; the numbers are used interchangeably in many corners of the web.

Model Memory

Allows specific settings for more than one RC model to be stored on the one transmitter and toggled between when the different models are used. Especially useful when each of your models has a variety of complex settings such as mixing or ATV.


The pattern of radio waves that is used to send commands from the transmitter to the receiver.

Monster Truck

These RC trucks focus on torque and sheer strength rather than speed, making them good for even the most difficult surfaces and obstacles. Petrol-fuelled models are the strongest (although not necessarily the best), and they are popular in large scales.

Mounting Lug

Similar to a built-in engine mount, this is the part of the crankcase that attaches to the body or fuselage of the RC vehicle or craft, securing the engine in place.


As the name would suggest, attaching this to your RC vehicle/craft will reduce the noise it emits. It also aids performance when driving or flying at low speeds. It is positioned on the exhaust stack, and for many models is an optional add-on, although for 2-stroke engines many would consider it a vital purchase.

Muffler Baffle

This is the component in a muffler that helps to reduce the noise an engine emits, which is known in technical spheres as a ‘restrictor plate’. Although it is optional and can in fact inhibit engine performance, many areas have noise restrictions that will spoil your fun if you try to do without.



Needle Valve

A valve on a carburetor that is adjusted to alter the fuel/air mixture in the engine, making the fuel mix ‘leaner’ or ‘richer’. Different valves are adjusted in different ways, so always consult the instructions from the manufacturers of your product.


Short for Nickel-Cadmium, this is a type of rechargeable battery that can be used to power RC hobby motors, but is these days more commonly used as a ‘support’ battery. Main RC uses therefore include powering transmitters, receivers, servos and engine-starters. These batteries are heavier, bulkier and less powerful than newer LiPo and LiFe types by some 50%, but they are safer and easier to maintain.

NiCd Starter

A NiCd battery and glow plug clip joined together as one unit. Glow plug clips are used to power glow plugs and start engines. See also: Glow Plug and Glow Plug Clip/Battery.


Another battery type that has been overtaken in many areas by LiPos and the like, but is still used for beginner-level products and more basic/less demanding functions such as powering transmitters and receivers. The acronym stands for ‘Nickel-Metal Hydride’. While lighter, more environmentally friendly and longer-lasting than NiCd batteries, they are still larger, heavier, less powerful and yet safer than LiPo-a-likes.


While it is commonly used to describe the type of hobby fuel it is found in, ‘nitro’ is in fact shorthand for ‘nitromethane’, a component of that fuel. The fuel is not composed entirely of nitromethane (it also contains lubricants, for one), but ‘nitro’ is the term it has come to be known by. Percentages of nitromethane content in nitro fuel vary, making it more or less suitable for different engine designs. Occasionally the term is meant to describe the nitromethane component alone (e.g. the ‘nitro’ content of ‘nitro’ fuel), but this is less common.

Noise Traps

An electronic device used to reduce radio interference, especially in the case of long servo extensions. It can also boost the control signal received by the servo.

Non-Ringed Engine

Also known as an ABC engine due to the metals commonly used to make it (aluminium, brass and copper), this is a type of engine that does not use a piston ring. Instead, it simply uses a very tight-fitting design to create the piston/cylinder seal. These can be more difficult engines to get started with and run, but ultimately deliver higher levels of performance than ringed varieties.


Stands for the ‘National Organization for Racing Radio Controlled Autos’, which is – or was – an RC vehicle racing organisation. It is no longer a major force in the RC vehicle racing world, however, due to a lack of regulation and leadership.

Nose Gear

Landing gear attached to the nose of an RC aircraft. Wheeled nose gear is usually link to the rudder servo, meaning that operating the rudder will help to steer the craft after it has touched down.



Off-Road Vehicle

This is a type of RC car, buggy or truck that is designed for driving on rougher surfaces than plain tarmac or concrete. Some of the more robust sub-types, such as monster trucks, are able to handle almost anything, including mud, sand, gravel, ice, long grass and some types of snow. Off-road buggies are the most popular kind of radio control vehicle on the market today. Features than make a vehicle suitable for off-road use include strong suspension, high ground clearance and high-grip tyres; vehicles described as ‘off-road’ should have all of these.

One-Point Landing

Just about the opposite of the desirable three-point landing (where all three wheels or landing gear parts touch the ground simultaneously). When only one point touches the ground first, this can throw the craft so badly that it is effectively a crash. A move to be avoided.

On-Road Car

A type of vehicle that is designed to be driven on firm, smooth surfaces only. It might be able to cope with some small unevenness depending on its size, but should really only be driven on tarmac or concrete. The same level of suspension and stability as off-road vehicles is therefore not required, and the design emphasis can be put on appearance and speed.



Peak Charger

A charger with an in-built safety mechanism that stops it from continuing to charge when the battery has reached capacity. This can prevent explosions and fires with the more volatile battery types, such as LiPo, and will generally help to extend the life of your rechargeable battery; even if you forget to switch it off, your battery will never get over-charged.

Peak Detection

In RC hobby terms, this is a feature of a battery charger that enables it to tell when a battery is fully charged. It does this by detecting the small drop in voltage that occurs when the battery reaches capacity. Usually connected to a mechanism that automatically shuts off charging when the battery is fully charged.

Pitch/Pitch Axis

The horizontal axis of an aircraft upon which it rotates to raise or lower the nose i.e. angle upwards, downwards or fly parallel to the ground. This determines whether it will fly straight, climb or dive. Pitch movement is initiated/controlled by the elevator and limited by the horizontal stabiliser.

Pitch Curve

This is a way of adjusting the sensitivity of the pitch controls on collective pitch helicopters at different command strengths. The more ‘pitch curve points’ a radio allows the operator to adjust, the more tailored control for a particular craft can be.


A type of dihedral wing where at a particular point on the wing’s length the angle of dihedral increases further. Polyhedral wings therefore have multiple panels per wing.

Power Panel

A panel powered by a 12V battery and often attached to a field box that can supply the right amount of power to a number of different field gadgets such as fuel pumps and glow plug clips or battery-powered engine-starters.

Programmable Radio

An expert-level control unit and transmitter that includes a small computer and allows to operator to input very specific settings for a number of RC aircraft. It is also possible to program particular stunts or moves, so that one touch of a button initiates the sequence. These only come with helis and planes that receive commands on a high number of channels – usually 7 or more – and require expert knowledge. Also known as a computer radio due to the inbuilt computer.


This is a component of aircraft and speedboats that spins in order to create thrust and therefore (usually) forward motion. They are attached to the craft’s engine/motor and usually resemble a set of curved blades. They can be made of a wide range of materials, each of which have their own strengths and weaknesses for various applications, for example plastic is very light but too weak to power many heavier craft. The size of a propeller is described by two numbers, e.g. 9×6, which is the diameter times the pitch expressed in inches. In this case pitch refers to how far the craft will move ahead with one turn of the propeller in optimum conditions.

Prop Pitch

The angle of the blades on the propeller, which is referred to officially as ‘pitch’. In the shorthand for describing propellers, where they are described by two numbers (e.g. 9-5), the amount of pitch is denoted by the second number.

Prop Shaft

The crankshaft used to power a propeller, transferring the movement produced by the engine to the propeller hub.

Pulse Code Modulation (PCM)

A particular kind of FM radio transmission that is encoded differently from standard transmissions. It can help to protect the transmission from various kinds of interference.


A part of the system of moving parts that translates movement of the servos into movements by the control surfaces. Pushrods are usually rigid, made of balsa or fiberglass, but flexible variations such as ‘flexible pushrods’ and flex cables are available. They are connected to other moving parts by clevises or z-bend wires.

Pushrod Connectors

The small devices that connect the pushrods to the servos, enabling movement to be transmitted from the servo arm to the pushrod.



Radio Transmitter

The part of the control unit (the – usually – handheld device used by the operator to control their RC hobby product) that sends a radio signal to the vehicle/craft containing the commands given. This term is also used to refer to the control unit as a whole. Every wireless transmitter is a radio transmitter.


Stands for ‘remote control’, ‘radio control’ or both, as RC vehicles, boats and aircraft are remotely control devices for which the method of control is radio signals. ‘Remote control’ simply means controlling the device from a distance rather than having anyone inside it or manipulating it manually, so pedants might point out that ‘remote control’ could involve wires connecting the control unit and the device for relaying commands. The terms are used interchangeably, however, and ‘RC’ can mean whichever you want it to mean.


The component of an RC vehicle, aircraft or boat that picks up the commands sent by the transmitter and delivers them to the servo. Often these require a different level/type of power from the motor, and so rely on separate batteries. This need can be eliminated, however, using a battery eliminator circuit. See also: BEC.

Receiver Battery

The battery that supplies the receiver with the correct voltage etc. for its needs. This is a different battery from the one powering the motor, and is often a lesser type such as a NiCd or NiMH battery. It works in place of a more costly battery eliminator circuit, which would have enabled the receiver to use the power from the main battery.


Reducing an RC hobby product to its kit form i.e. taking it apart until all the component parts are disconnected. This is usually done to salvage parts from a crashed or crippled device.

Relative Wind

The direction of the airflow ‘relative’ to the leading edge of a wing/airfoil. As air does not always flow parallel to the ground, this is an important term for calculating stunts and aerobatic manoeuvres.

Retractable Landing Gear/Retracts

Landing gear that can be folded away during flight to improve the aerodynamic shape of an aircraft. Many also feel that this improves an aircraft’s appearance and realism. See also: Landing Gear and Fixed Landing Gear.


The side-to-side pitching movement of an aircraft or boat, which is called ‘roll’ to differentiate it from forwards/backwards pitch. It can either be a planned manoeuvre (for example a corkscrew motion whilst in flight) or an undesirable characteristic that needs to be combated with vertical stabilisers and competent handling. It is controlled using the ailerons or, in their absence, the rudder in combination with stronger dihedral, although without ailerons a roll cannot be executed as a full manoeuvre.

Roll Axis

The horizontal axis running from the nose to the tail of the plane (or in an unbalanced craft, slightly to the left or right of that) upon which the plane tilts to the left or right. The axis is the middle line that remains in the same altitudinal position while one side raises and the other side falls. Roll can be adjusted using the ailerons, tipping one of the wingtips deliberately below the roll axis. See also: Bank.

ROAR (Remotely Operated Auto Racers)

A US national organisation for the moderation and certification of RC car, buggy and truck races. It also selects and sends qualifiers to the IFMAR (International Federation of Model Auto Racing) World Championships, where it holds one of four board votes, and is the only body in the US and Canada that can do so.


Stands for ‘Rotations Per Minute’ and refers to the number of times that a propeller can turn 360 degrees in one minute when powered by a particular motor or engine. The number of RPM an engine can produce is a measure of its speed.


Stands for ‘Ready to Fly’, and is used to describe RC model aircraft that arrive fully pre-assembled and with all the parts needed to fly them straight away including pre-installed radio equipment and a transmitter. Sometimes these kits require a battery charge, or independently sourced batteries for the transmitter, but any less than this and they should be called ‘ARF’ or ‘Almost Ready to Fly’. See also: ARF.


Stands for ‘Ready to Run’, and is used to describe RC model vehicles or boats that arrive fully pre-assembled and with all the parts needed to drive them straight away. Sometimes these kits require a battery charge, or independently sourced batteries for the transmitter, but any less than this and they should be called ‘ARR’ or ‘Almost Ready to Run’. Most vehicles come in kit form, however. See also: ARR, Kit.


Movable control surface at the very rear of an RC boat or aircraft which controls yaw or left/right spin. Moving the rudder to the left or right causes the plane/helicopter or boat to turn or yaw on its vertical axis, so that while remaining level its nose swings to point in an altered direction. It is usually attached to the trailing edge of the craft’s vertical stab.




A term that has dual meanings, ‘scale’ is most commonly used to refer to the original:model size ratio, for example a 1/8 scale buggy being one eighth of the size of a real racing buggy. The other meaning relates to exactitude of the scale copy, and is not measured in numbers, but by the precision of the model’s loyalty to the original’s design features. There is usually a lot of compromise involved in reducing a model’s size, and exact scale models are rare.

Semi-Symmetrical Wings

This is an airfoil type that is almost symmetrical above and below, but in which the underside of the wing has less of a curve than the top surface. This makes it a good compromise between the flat-bottomed and fully symmetrical types. These wings are popular for sport planes.


A small motor connected to an RC product’s receiver unit that moves on command, so operating the control arm it is connected to, which in turn operates other working parts. Each servo is mechanically connected a particular function of the vehicle/craft through this system, so that the movement of the servo causes a desired movement elsewhere in the machine. This is how the control surfaces of an aircraft are operated. The servos of an RC product are usually found in a small cuboid case adjacent to the receiver.

Servo Arm/Servo Horn

These are the small working parts connected directly to an RC hobby product’s servos that pass on the commands of the operator from the servo to the pushrod. They are moved by the movements of the output shaft of the servo, and pass on movement, so are an essential part of converting radio commands into mechanical functions. There are usually a range of sizes and shapes that can be fitted, suitable to different applications. Also known as control arms.

Servo Extension

See: Aileron Extension.

Servo Reversing

A mechanical alteration that changes the direction a particular servo turns in. This can be done either by purchasing a specialist connection cable or manually modifying the servo’s wiring. Where this modification is already provided for, it can also be commanded at the flick of a switch. Reversing a servo is useful when it cannot be mounted in a way that accommodates its preset turn direction.

Servo Torque

The power of a servo, described as the number of ounces it can push relative to the length of its control arm (when the weight is expressed in ounces the length will be expressed in inches).

Servo Tray

A component that makes mounting a model’s servos easier. The tray grips the servos securely, and is itself easier to fasten to various surfaces than a naked servo. Servo trays can be made to secure anything between one and four servos in a variety of positions.

Shot Down

When taking a ‘hit’ causes a crash landing. See also: Hit.

Slipper Clutch

A specialist unit connected to a craft’s autorotation clutch that allows continued functioning of the tail rotor even when the engine is off or set to “hold”. Similar to a constant drive clutch, but ‘slips’ to prevent the movement of the tail rotor loading the main rotors.


Non-requested or free movement of the various control surfaces of an aircraft. This includes serious malfunctions such as flutter, but can also simple be an inconvenience that interferes with the execution of your flight commands. Slop is often caused by poorly matched/fitting servo arms, pushrods wires, clevis pins etc.

Snap Roll Button

A function of more complex radios whereby pressing the button causes a series of pre-programmed commands to be sent – usually a combination of rudder, aileron and elevator movements – that result in the aircraft executing a roll.


Usually short for ‘wingspan’, although where specified could refer to the width of other objects.


Some will know spin as the jargon-free description of yaw (the movement of an aircraft or speedboat around its vertical axis leading to the nose pointing in an altered direction), as it is commonly used to explain the movements of such craft to RC rookies. However a ‘spin’ is also an aerobatic stunt that involves a stall and then a yaw rotation so that the aircraft turns on the spot. It is the move used at the top of a hammerhead or stall turn. See also: Hammerhead, Stall Turn.


The conical cap that covers the central part (a.k.a. hub) of a propeller, protecting where the blades meet the central point and aiding aerodynamic efficiency.


A less common control surface that can help to decrease lift and slow an aircraft. Although not often a requirement, this can be helpful for gliders and jet aircraft, where they are attached to the centre of the wings, either above or below.

Sport Airplane

The most versatile type of RC plane, these aircraft have a number of the characteristics of specialist models (for example ailerons or elevators), making them more manoeuvrable than entry-level models, and are intended for fun rather than to be exact scale replicas.


A component on an aircraft that helps it resist unwanted rolling and pitching motions. This is especially helpful for beginners who may initiate these moves accidentally and will not want to use them for stunts. There are two types of stabilisers used to resist these two moves, which are known as horizontal and vertical stabilisers. See also: Roll, Pitch, Horizontal Stab, Vertical Stab.

Stadium Truck

Often considered to be another name for a monster truck, these are super-tough vehicles designed to race on the most difficult terrain. See also: Monster Trucks.


What happens to a aircraft when too little lift is produced to hold it in the sky, and it begins to drop. This usually happens when too severe an angle of attack has been taken, and so much resistance is met that the craft can no longer maintain the speed required to fly. It is a common cause of crashes for beginners, as they tend to fly too close to the ground to allow recovery from a stall.

Stall Turn

Another name for a Hammerhead or Spin stunt manoeuvre, although the upwards/downwards vertical component required in a Hammerhead is not necessary for a Spin or Stall Turn. See also: Hammerhead, Spin.

Strip Aileron

A narrow ‘strip’ of an aileron that runs along the entire/majority of the trailing edge of a wing. See also: Barn Door Aileron.

Symmetrical Wings/Airfoil

Wings which are the same shape above and below their imagined centre-line i.e. have the same degree of curve, so that the shape of the top half is mirrored in the bottom half. See also: Semi-Symmetrical Wings, Flat-Bottomed Wings.

Synthesised Frequency

An alternative to using crystals for setting radio frequency when transmitting. Considered to be more advanced that crystals, this system is also more expensive. It offers the advantage of being able to select from a variety of frequencies rather than being ‘locked in’ by the frequency of the crystal, which may be hampered by interference.




A device for measuring the RPM of a motor/engine and propeller. It operates by being placed behind the propeller so that whatever light source is available is interrupted by the turning of the propeller. The tachometer then detects the number of changes or ‘pulses’ in the light is receives and counts them to determine the propeller’s speed.


The section of an aircraft located at the rear of the fuselage, beginning where the aircraft’s body thins out suddenly and ending at the very rear tip of the craft. The tip of the tail is the location of a number of essential stabilisers and control surfaces, namely the vertical stab/rudder and horizontal stab/elevator.

Tail Dragger (Gear)

A type of aircraft landing gear that is pretty much the reverse of tricycle gear; instead of having two parallel main gears and another leading wheel descending from near the nose, the third wheel is located to the rear of the aircraft. The term ‘tail dragger’ is also uses to describe an aircraft that uses this type of landing gear. See also: Landing Gear, Tricycle Landing Gear.


A body of rising hot air that, if caught, can carry an aircraft quickly to high altitudes.

Thread Locker

A liquid similar to oobleck that solidifies when subject to pressure or vibration. It is used around the screws in RC hobby products to prevent them being loosened by constant vibration.


A device that regulates the flow of fuel or power to an engine. In practise this is generally used to control forward movement and speed.

Throttle Stop Screw

A mechanical device in the body of an RC vehicle or craft that allows a lower limit for throttle functioning to be set.


The force provided by a motor/propeller set that powers an aircraft or speedboat forwards. Speed also provides lift in aircraft such as planes and helicopters. It is measured using weight (metric or imperial) and used to determine a craft’s top speed, as well as how heavy it can afford to be. Higher thrust potential denotes a higher performance craft, although the body needs to be durable enough to withstand it.

Tip Stall

This is when only one wingtip of a model plane stalls while the other continues to provide lift, the combination of which causes the plane to tilt suddenly and drastically (roll) towards the ground on the side of the stalled wing.


Technically, torque is described as a rotational force of varying strengths. In practise however, it is used to assess how strong an engine is, and how much weight and resistance it can withstand. This is different from power, which refers to the engine’s speed (although of course resistance/weak torque will slow it down).


A precision manoeuvre for aircraft that involves landing smoothly and then taking off again straight away, so that the aircraft briefly touches the ground before taking to the air again. This is not the same as a bounce, as there is little or no jolt delivered to the aircraft.

Tow Hook

A small catch or hook attached to the bottom as an aircraft’s fuselage to which a hi-start or winch can be linked. Ideally, it should be as close to the craft’s centre of gravity as possible.

Trailing Edge

The rear edge of a wing or control surface on an aircraft. Opposite of the leading edge. See also: Leading Edge.

Trainer Aircraft

RC helicopters and planes designed specially to provide high levels of stability and low levels of speed. This offsets the mistakes that a beginner might make as they familiarise themselves with piloting an RC craft and so make learning quickly rewarding.

Trainer System

Also known as a ‘Buddy Box’ system, this is where two transmitters are connected via a cable running between them, so that both are able to issue commands to the one vehicle/craft. This can allow beginners to get used to more advanced models with a friend or instructor able to step in quickly if things go wrong. The ‘instructor’ has a switch on their transmitter that allows them to toggle control between the two transmitters.


This is the device which relays the commands of the operator to the RC product being operated. It converts the manual movements of the control sticks and/or computer-programmed sequences initiated into radio signals, which are then picked up by the vehicle or craft’s receiver and re-converted via the servos into the applicable movements. The entire control unit is often referred to as the transmitter.

Tricycle Landing Gear

A type of landing gear that involves using three wheels to make contact with the ground, as with commercial aircraft. A single, often steerable, wheel is positioned beneath the nose, with two more (the main gears) sitting parallel at the same distance from the tip, further back along the fuselage – just like the arrangement on a kid’s tricycle. This set-up makes a plane very simple to handle on the ground.


Can either refer to a vehicle/craft’s appearance or the adjustment/modification of an aircraft to elicit smoother flight. The former use is more common, where the term describes the finishing touches of the model’s appearance such as go-faster stripes or coloured mud-guards.

Trim Scheme

A set of additional decorative features that match or compliment each other. They serve no function and are purely to improve the model’s appearance.


A type of tail design where the stabiliser is attached to the very top of the tail fin, creating a T shape. This distances the stab from the turbulence created by the wings passing through the air, which can increase the sensitivity of pitch control. This setup is more fragile, however, and less suitable for beginners.



Undercamber Airfoil

A specialist airfoil shape in which the lower wing surface curves up in the centre, towards the upper surface, rather than down. This can produce impressive lift, but can be difficult to handle.


See: Landing Gear.



Vertical Fin/Stabiliser/Stab

This is a non-movable surface located at the end of the tail that stabilises an aircraft by resisting rolling and yawing movements. A rudder is often attached to its trailing edge (although some would consider the rudder a movable component of a more advanced vertical fin).


A tail design that eliminates the need for a vertical stabiliser fin by including two ‘horizontal’ stabilisers in a V-shape, each angled upwards to a particular degree, usually between 30-45 degrees. Thus both pitch and yaw are partially stabilised, and both are also partially affected by the ‘elevator/rudder’ control surfaces attached.

V-Tail Mixing

A type of mixing that accommodates the unconventional V-tail structure and its combination elevator/rudder control. The two control surfaces are connected to different servos, so that when the elevator stick is used they operate in tandem, but when the rudder stick is used they can move in opposing directions to aid turning.


Stands for ‘Vertical Take-Off and Landing’, which is when an aircraft is able to take off and land whilst remaining entirely upright i.e. no tilt or pitching is required to loose or gain height. VTOL is used to refer to the aircraft that are capable of this move as well as the move itself.




A method of preventing tip stalls, performing a washout involves ensuring that the leading edges of the wing tips are lower than the trailing edges, so that they have a lower angle of attack than the wing root. See also: Tip Stalls.


A measure of electrical energy calculated by multiplying amps by volts (current by voltage). This gives a good overall impression of power.

Wheel Collars

Small nut-like devices positioned either side of a wheel on its axle to prevent it from sliding or slipping off the end.


The large, horizontal surface that extends to either side of a plane’s fuselage and provides it with its main source of lift. In general, the higher the wings are placed on the craft, the more stable it will be, the fuselage resembling a pendulum.

Wing Area

The total surface area of both wings on an aircraft (when discussing a single wing, this should be specified). This is expressed either metrically (square centimetres) or imperially (square inches) depending on your location. It is generally safe to assume that the larger a wing area is, the more lift the wings will produce, although wing shape also has a part to play in this. Wing area can be calculated simply as the wingspan multiplied by the wing chord.

Wing Chord

This is the wing’s depth, i.e. the distance between the leading edge and the trailing edge at any given point.

Wing Loading

This refers to the amount of weight that the wings must carry (including their own weight) when attempting to gain lift. It is calculated by dividing the total weight of an aircraft (in ounces) by the total wing area (in square feet). Planes with greater wing loading need to fly faster (i.e. have more air flowing around the wing) in order to stay in the air, however it is easier for them to fly at speed. On the other hand, gliders and training craft tend to have low wing loading, and so fly more slowly, but more predictably.

Wing Root

The section of the wing that bears the highest bending force during takeoff, flight and landing. It is usually located adjacent to the fuselage (hence the name ‘root’).

Wing Seating Tape

A kind of tape used to insulate the roots of removable aircraft wings from vibrations, as well as providing protection against the re-entry of exhaust gases, if these are produced. It is applied to the join at the wing root.


This refers to the total width of the plane, and is measured from the tip of one wing to the tip of the other.

Wing Tip

The outermost point of the wing, commonly described as the furthest end from the fuselage. Wing tips are usually tapered at the very end.




The connecting device used to plug two servos into the same channel. This is essential for a number of types of mixing, but can also be used to provide double the power to a single movement. Also known as Dual Aileron Extension.

Yaw/Yaw Axis

Yaw is movement in any direction on a craft’s vertical axis. This causes the nose of the aircraft to swing to the left or right. Also described as ‘spin’, it can either be a command used to steer the aircraft, or an undesirable characteristic should it happen un-requested.




A connection between a control rod/pushrod and a servo output arm that incorporates two ninety degree bends. This gives it an appearance not unlike the letter Z, hence its name.

Z-Bend Pliers

A specialist but inexpensive tool that will allow you to make perfect Z-bends every time, crimping the wire into shape.



2 Channel

A type of RC product that can only receive commands concerning two functions. In RC helicopters, for example, the only functions that can be controlled remotely are up/down and left/right spin. Many consider this too few channels, as it allows not control over speed and means that hovering is impossible, to name but a few problems.


A type of radio control band also known as ‘Spread Spectrum’. It is very popular among RC hobby product owners, as it [quality/functions]. As such, it is almost always used as an advertising point, so if not explicitly identified as a feature, it is probably not included. See also: FHSS and DMSS.

2 Wheel Drive

This term denotes a car (RC or full-sized) which drives by supplying power only to the back wheels rather than all four. These cars are cheaper than their 4 Wheel Drive counterparts, and less complicated and time-consuming to maintain, but they are not so easy to steer, especially when turning.

3 Channel

A type of RC product that can receive commands concerning only three functions. In RC helicopters, for example, a 3 channel model will be able to fly forwards/backwards, up/down and spin left/right on its yaw axis. This is a common number of channels for an entry-level product.

4 Channel

A type of RC product that can process commands concerning four different functions. Also considered suitable for committed beginners, the four channels of control on a 4 channel RC helicopter are usually up/down, forwards/backwards, left/right spin and direct movement from side to side.

4 Stroke Engine

The less powerful sister of the 2-stroke engine type, this is a quieter, more fuel-efficient aircraft engine suited to large stunt models. With no need for a muffler (they are quieter than muffled 2-strokes even when unmuffled), they also run bigger propellers, though not as fast.

4 Wheel Drive

These cars get their wheels turning by supplying power to all of the wheels as opposed to just the back two. They are more functional than their 2 Wheel Drive counterparts, with especial benefits when it comes to turning, but require more maintenance and cost more to purchase to begin with.

6 Channel

Only applicable to RC aircraft, this is a product that can be manoeuvred in six different ways: directly up/down, forwards/backwards, directly side-to-side, spun left/right, pitched up/down and tail adjusted left/right. A more expensive and complicated type of craft, it flies much better in the right hands than those with fewer channels.

So there you have it. We hope you’ve found out everything you wanted to know. If you didn’t understand some of the terms in a definition, make sure to check for them else where in the glossary, they’re probably there! Otherwise if you have requests or suggestions please leave us a reply here. Happy hobbying!

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