Welcome to our new glossary, designed for beginners or anyone seeking clarity or the meaning of the many abbreviations used in connection with model flying. 

If there are others you feel we can add to the database then please use the forum thread link below to make your suggestions and we'll make sure they're included. 



35 MHz (35 Meg) - see frequency

2.4GHz / 2.4 Gig - see frequency

3D - a type of extreme aerobatics often involving manoeuvres impossible in full size aeroplanes. Essentially this is flying off the propeller and involves prop-hanging and high angles of attack. 


AMT - see all-moving tail

Aerobatic - manoeuvres that involve stunts of any kind, like loops and rolls.

A-Cert - A Certificate. The first stage of the BMFA achievement scheme. A basic test of ability to fly a model solo. The A-certificate can be obtained for powered/non-powered fixed wing and helicopter models. See BMFA website for more info on this and the B and C certificates. 

AC - alternating current.

Adverse yaw - the situation when, on rolling into a bank prior to a turn, the UPgoing WING yaws aft in the opposite direction to the turn. i.e. the plane is rolling and turning one way but yawing the other.  Caused by severe increase in drag brought about by the downgoing aileron.  Can be counteracted with Frise ailerons or by adding relatively more "up" than "down", or by adding rudder at the same time as roll.  See also Differential Aileron.

Aerofoil - the cross-section shape of a wing. Aerofoils can be flat-bottomed, semi-symmetrical or symmetrical, depending on the style of aeroplane and what it needs to do. 

Air speed - the speed of the aeroplane relative to the incident airflow. Everything the plane does is relative to airspeed. See also ground speed. 

Ailerons - moving section of the trailing edge of the wing, in pairs, (left and right) and work in opposite directions to each other (one up, one down). They roll the model to the left or right.

Aliphatic resin - type of wood glue. Chemically similar to PVA but stronger, more waterproof and quicker drying. It also sands better than ordinary PVA/white glue. See PVA for comparison.

Altitude - The height of the model in relation to sea level.

All-moving tail - as implied, where the whole tailplane (horizontal stabiliser) is movable by servo rather than just the elevator part.

AM - Amplitude Modulation

Anhedral - where the wings on an aircraft are angled downwards - the opposite of dihedral.

AOA /Angle of Attack - the angle at which air hits the wing.

AOI /Angle of Incidence - the angle at which the wing or horizontal tail of an aeroplane is installed on the fuselage, measured relative to the axis of the fuselage

ARTF - Almost Ready To Fly.

Aspect Ratio - the wing's length compared to the chord. A glider wing has a high aspect ratio whereas a low aspect ratio wing has a small span in relation to the wing area. Often calculated simply as the span divided by the chord, most wings taper so a better definition is the ratio of the span squared to the wing area or AR = b2/S where b is the wingspan and S is the area of the wing when viewed from directly above (planform).)

Attitude - refers to the angle of the plane in relation to the horizontal.

Avalanche - loop with a flick roll at the top.


Balsa basher - slang term for someone who builds from plans or traditional kits and hence spends a lot of time cutting and shaping balsa wood. 

Barrel roll - an aerobatic manoeuvre that involves the plane following the twist of a large imaginary corkscrew (horizontal) through the air.

Base - The leg of the circuit immediately before turning onto finals. 

BEC – Battery Eliminator Circuit – built into most ESCs (see below) this device - in electric models - supplies power to the radio, and eliminates the need for a separate battery.

Binding - a process that ensures the 2.4GHz receiver is recognised by the transmitter so the two can operate together. The actual process varies from brand to brand.  

Bind-N-Fly (BNF) - a trademark name for a range of Horizon Hobby distributed aircraft (namely ParkZone & E-flite) whereby the model is sold in RTF form but lacks the transmitter. 

Bipe -  slang abbreviation for biplane.

BMFA – British Model Flying Association, previously known as SMAE - Society of Model Aeronautical Engineers.  

Brown Out - a  momentary loss of operation of a receiver due to a drop in supply voltage below a minimum threshold. Normally a momentary effect only, and affects 2.4Ghz equipment rather than the older 35MHz radio.

Brushless motor - Brushless motors are more powerful than older brushed motors, and are now the norm. They can be inrunner or outrunner . See below.

Buddy Box - a term used to denote a training aid whee the student's transmitter is attached via cable to the instructor's - 'buddied'. The student has control over the model, but at the flick of a switch the instructor takes control.

Bulkhead - the foremost former of your airplane, on to which the engine / motor is mounted.

Bungee launch - a method of launching gliders. Normally a long cable some of which is elastic cord.

Butterfly braking - see under Crow braking


C  or C rating - capacity of a battery seen on the label of a LiPo usually preceeded by a number e.g 20C as an indication of the maximum continuous discharge rate of the battery i.e 20 times the battery capacity. Also in battery specification as the maximum charge rate that can be applied to the battery e.g. 1C (up to 5C on some batteries).

C/G / Center of Gravity / COG - the plane's point of fore-aft balance. As a very general rule of thumb it's found approximately 1/4 to 1/3 of the way back from the leading edge of the wing.

Cabane - the struts on a biplane used to support the upper wing over the fuselage.

Camber - when activated the flaps and ailerons all drop down a few millimeters, all together and by the same amount. The result of dropping the entire trailing edge of the wing slightly is to increase lift without increasing drag too much.

Canard - horizontal surface in front of and smaller than the main wing. Can be fixed or have a moving element. (From the French for Duck).

Captive nut - a nut which is fixed in place on the model, the bolt being removable. The nut can either be glued in place or sometimes is made with a set of spikes which are drawn into the wood by the bolt. 

Castor oil - the oil found in model engine glow fuels. Historically the oil was castor, characterised by a wonderful aroma when passed through the engine or left to dry inside the car / workshop. In modern times this has been superceded by synthetic oils because castor leaves an horrendous gummy mess over the model and eventually can gum up the engine. 

Channel - The number of channels that the model has, eg a 1 x channel model may have just motor or rudder control while a 2 x channel model will have motor and rudder and so on. Can Also refer to the frequency in use ie. 35MHz, 2.4GHz.  

Chord – the width of the wing from leading edge to trailing edge.

Chicken stick - a tough rubber sleeve that you put on your finger if starting an engine by hand to give essential protection from the propeller. It can also be a wooden/plastic stick with a rubber coating on one half that you use to flick over the prop, instead of using your finger.

Choke - valve in a carburettor which controls the amount of air combining with fuel.

Clampmeter - device consisting of a pair of pincer-like jaws and a readout which when clamped around a wire will measure the current flowing through that wire - useful aid to preventing damage through overload and provides reading without breaking any connections.

Clevis - U-shaped fastener and pin used for connecting servo push rods to horns on control surfaces.

Closed-loop - type of control system in which two tensioned wires are used to connect between the servo and its control surface. Movement is achieved by pulling the surface with one wire whilst the other is relaxed.

Clunk - a small nozzle, usually made from brass, attached to the end of the feed pipe in a fuel tank. 

Collet - see wheel collet

Compression bar(tommy bar) model diesel engines have an adjustable contra-piston inside the cylinder which allows the operator to adjust the volume of the engine.  The Compression screw comes out of the top of the cylinder and ends in a "T" bar allowing finger adjustment.  Typically the volume is reduced by unwinding the Tommy bar for starting, then increased by screwing in the Tommy bar once running to achieve peak power.

Contra piston - model diesel engines have two pistons -  the main one fastened to the crank shaft by the connecting rod and the second, contra piston, fastened to and adjusted by the Tommy bar.

Control check The last thing a pilot should do before take off.  Stand behind the plane and move all the controls, one at a time, to ensure that ALL the operated surfaces move as designed and in the correct sense.  Rudder stick left / right, rudder left / right. Elevator stick up / down, TE of elevator up / down. Aileron stick left , left aileron up , right aileron down. Aileron stick right, left aileron down, right aileron up.  Blip the throttle -  forward stick faster. Flaps, equal movement.  NB just waggling the sticks to see some movement is a useless activity and does NOT comprise a control check.

Control surface - the term used to describe the moving part of any flying surface ie rudder, elevator and ailerons are all control surfaces. 

Control surface mixing - when two control surface operations are performed by one pair of surfaces eg when aileron and elevator movement is combined into elevons ( see below).

Co-ordinated turn - a turn in which the lift and centrifugal forces on the aircraft are exactly balanced and so there is no inward or outward slip during the turn. Such turns often require the simultaineous use of ailerons and rudder working in co-operation. Such turns often look better and lower the chance of stalling in slow turns.

Cotter key - a pin (mostly metal) inserted into a hole in another part to prevent undesired movement of the part.

Coupling, as in 'short-coupled' - used to refer to the distance between the wing and the tail section.

Cowl - the part of an aircraft that covers the engine. Often a one-piece plastic or fibre-glass moulding.

Channel Mixing - the process by which movement in one control channel results in an associated movement in a other channel automatically without further pilot input. For example some co-ordinated  rudder movement can be automatically added to any aileron input the pilot makes to aid turns.

Crosswind - (1) is the component of the wind vector blowing at 90 degrees to  your line of flight, take off or landing. (2) The leg of a circuit pattern at 90 degrees to the runway before turning to downwind.

Crow braking - also called 'Butterfly braking', this wing function is used when landing. When Crow is activated the flaps drop down and both ailerons deflect upwards, all at the same time. This gives a very effective combination of drag from the flaps and reduced lift from the up ailerons, now acting as spoilers

Crystal - the small component that determines which channel number you fly on. Both tx and rx need to have an identically matching crystal for the radio set to function. 2.4GHz spread spectrum sets don't require crystals.

Cuban eight - a very nice manoeuvre to fly. A= 3/4s of a loop then half roll and do another 3/4 loop to form a figure eight lying on its side. Could also be described as a horizontal eight with half rolls at the intersection. 

Cyano - short for cyanoacrylate. A generic term for fast acting adhesives. Sometimes called 'super glue' or 'instant adhesives'.


DC - direct current. 

Dead stick - when your plane's motor cuts out unexpectedly in mid-air. 

Decalage - term used to describe the relationship or angle between the main wing and the rear horizontal control surface. Commercial measuring devices are available from model shops to gauge this.

Depron - commercial name for a type of styrofoam made originally in the Netherlands. Depron has advantages over some other types of foam such as EPP (q.v.) in that it is quite rigid and can be easily worked - i.e. cuts cleanly, glues and sands well. 

Diesel - generic term for compression ignition. A diesel engine is one that runs on any fuel ignited by compression. "Dieseling" is a term for the act of compression ignition, usually (only?) in a spark ingnition engine where it continues to run after the spark has been removed.

Diesel fuel - model engine fuel consisting  (roughly and usually) of - Castor oil 20 - 25%, Ether30%, Paraffin45 - 50%, IPN(qv) 2 - 3 %  The oil lubes and cools the engine, the ether allows ignition and the paraffin provides the energy.  IPN modifies the ease with which the fuel ignites and the speed of the flame front (i.e. smoothness of running). 

Differential aileron - when the ailerons are set up to move upwards more than downwards, to counteract any adverse yaw during a turn caused by extra drag on the outer wing from the down aileron.

Dihedral - the upward angle of the wings when viewed from the front.

Disorientation - when you lose sight of which way up your plane is and what it's doing, either because it's too far away to see properly or because you've just flown it directly through the sun or over your head and momentarily lost all visual reference. 

Dolly - a wheeled cradle/set of self-detaching wheels used to help models aloft.  

Dope - a type of paint or sealer used while covering aircraft, there are two types - Nitrate (not fuel proof) and Butyrate (fuel proof). Nitrate dope can be painted over Butyrate dope, but Butyrate can not cover over Nitrate.

Down wind - (1) Flying the model in the direction of the wind. (2) General description of a direction relative to the wind. (3) the part of an aerodrome / airfield circuit , opposite the runway, that takes the plane in a downwind direction.

Drag - the force that is created by the movement of the plane through the air, on the air immediately surrounding the plane. High drag means that the model has to work harder to cut through the air.

DSM / DSM2 - a type of technology developed by Spektrum for their spread spectrum 2.4GHz R/C systems. Stands for Digital Spectrum Modulation, the '2' just being the newer updated version of the original. Also used by JR 2.4GHz radios. 

Dual rates - a feature of many R/C systems, whereby the control surface deflection can be increased or reduced while still maintaining full movement of the transmitter sticks.

Ducted fan - where an engine is used to drive a small fan at high RPM in a shroud or tube to simulate a jet engine in a model. Most i.c. DF set ups have now been superseded by EDF. 

Duplex - the proprietory name for Jeti's 2.4GHz R/C system.

DuralDuralumin, Duraluminium - a type of aluminium alloy often used for making sheet metal undercarriages and engine mounting plates.

Dynamic soaring / DS - slope soaring off the back of the hill. Models move in a tight cicruit gaining energy with every revolution to reach speeds commonly in excess of 200mph.


EP - Electric powered.

EDF – Electric Ducted Fan – an electrically driven fan housed in a duct, ie. a short diameter propeller in a tube.

Elapor - the name given by Multiplex to the moulded EPO foam used for its models and one that has almost become a generic term for the material.  

Electric starter – A hand held electric motor with a special end cup that you place over the spinner to turn the motor over until it starts.

Elevator - the moving section at the rear of the horizontal stabilizer, or tailplane, that controls the pitch attitude of the airplane.

Elevons - when elevator and aileron control is made by the same control surface, this surface is called an elevon(s). usually done with a mixing facility on the rc set, or mechanical mixer fitted to the model (rare these days).

EPO - Expanded Polyolefin - a larger cell moulded foam commonly used for in preference to the more brittle EPS. Can be moulded in differing densities and has a waxy, softer feel. Also named Elapor, Z-Foam, Solidpor etc. by different model manufacturers. 

EPP - Expanded Polypropylene. A foam used in making some foam planes. Strong and very flexible but characterised by a rougher feel to the surface than EPS and EPO.

EPS - Expanded Polystyrene - the traditional polystryrene foam. More brittle then EPO and EPS and more liable to dents etc. Note - cyano glue melts this foam.  

ESC - Electronic Speed Controller - the small unit that delivers power from the motor battery pack to the motor, depending on your input at the transmitter.

Expo/Exponential - A system provided on most computer transmitters which allows for a non-linear relationship between stick movement and control surface movement. Often used on 'twitchy' models to de-sensitise the effect of stick movement around the centre or neutral position. 


FAI - Federation Aeronautique Internationale - world air sports governing body to which the BMFA is affiliated.

Fan swept area - the internal area of an EDF shroud, less the spinner area. The EDF influx area should equal the FSA and the efflux area should be around 85% of the FSA.

FASST - Futaba's 2.4GHz system brand name. Stands for Futaba Advanced Spread Spectrum Technology and uses warp-speed frequency hopping to ensure no breakdown of signal.

Field/ Flight box - a box that you take to the field. It contains all your flying accessories and tools etc. Normally also holds your fuel container etc.

Film / Iron-on films - a generic term/s for an iron-on self adhesive coloured plastic film that can be used to cover models. The film is backed by a heat-sensitive adhesive that adheres to the model when heated by an iron. After application the film can be shrunk by a further application of heat from an iron or heat gun. 

Fin - also called the vertical stabilizer, it's the vertical surface at the rear of the aeroplane used to stabilize the plane in flight.

Final/Finals - the leg of the circuit from which leads the plane to the runway and from which the plane will land. 

Firewall - the fuselage former to which the engine or motor is attached. 

Fishtailing - an intended or unintended flying trait where the aircraft tail waggles along the yaw axis slightly. It can be a cause of instability. There are several causes but a cure can be found by enlarging the fin area or thickening the fin trailing edge. 

Flaps - moving sections of the trailing edge of the wing, usually found between the ailerons and fuselage. Used to create more lift at slower flying speeds and also to slow the plane on landing approach.

Flapperons - a single control surface on the trailing edge of each wing that does the job of flaps and ailerons. An R/C system with control mixing capability is needed for flapperons.

Flare - the action taken in the last few seconds of the landing approach, to reduce the approach angle and slow the rate of descent.

Flick / flicking - the act of hand starting a model diesel engine. So named because of the nature of hitting the prop in a rapidly repeated flicking action. 

Flight simulator - a home computer based training aid that lets you practice flying radio control from the safety and comfort of your house. Excellent for novice rc pilots, particularly those looking at flying rc helicopters.

FM - Frequency Modulation

Foamie - a type of model aeroplane - usually small - made entirely from some type of expanded foam - sheet or moulded. Very light and often aerobatic. Very popular for indoor flying. 

FOD - foreign object damage, a term from the full size aviation world usually relating to items on the runway being ingested into turbine engines.

FPV - First Person View. A system of R/C model flying where a camera is fitted to the model along with a device that transmits real time video back to the ground station. The pilot wears a pair of video goggles and flies the model using the on board view received from the camera. 

Freestyle aerobatics - a style that combines 3D, F3A (precision) and just about anything else that'll impress the judges.  

Frequency - all radio control gear works on frequencies. UK most popular are 35 Megahertz and 2.4 Gigahertz. Note that only 27MHz, 35MHz and 2.4GHz can be used for model flying in the UK with 40MHz reserved for surface vehicles such as cars and boats. In practice 27MHz is no longer used for model flying and beginners would be advised to opt for the new 2.4GHz. 

Frequency hopping - A system whereby some 2.4GHz radios hop from 2.4GHz band to band many times per second. 

Fuel lock - when your glow engine gets flooded and the excess fuel inside the engine prevents you from being able to flick over the prop. It usually happens if you've over-primed the engine.

Full chat - slang for 'full throttle'. 

Fuselage - the main body of a aeroplane, excluding wings, tail etc.


Glitch - a slang term which generally means a momentary failure of radio control or sometimes the ESC on an electric model.

Glow Fuel - The fuel mix used in i.c. two and four-stroke engines.

Glow engine - refers to any engine that uses glow fuel (above).

Glow plug - sits in the top of the engine's cylinder head and contains an electrical filament that glows red hot to ignite the fuel/air mixture in the combustion chamber. 

Glow plug igniter / Glo-stick used to ignite the glow plug at start up.

Go around - where the pilot decides to abort the landing, adds power and flies away. 

Ground speed - Speed of an aeroplane relative to the ground or observer. The pilot of a model can only see ground speed and this needs to be borne in mind when flying down wind on a windy day. 

Grubscrew - a small headless screw having a slot cut for a screwdriver or a socket for a hexagon key and used to secure a sliding component in a determined position


Hack - a slang term for a general sport model. Perhaps a model that the owner will care less about and fly in poorer weather conditions. 

Hand launch - the way to launch any flying model without an undercarriage. The model should normally be held level at head-height and launched into wind.

Hangar rash - superficial damage to the surface of the plane caused by clumsy handling of the plane in transit from base to flying field and back.

High alpha - a high angle of attack, a term often used to denote 3D or freestyle manouevers.

HLG - hand launch glider

Horn - Static connector fixed to servo head or control surface to act as a lever.

Horizontal stabilizer - also called the 'stab' or tailplane. The horizontal surface at the back of the fuselage, to which the elevators are attached.


I.C. - internal combustion. Usually refers to any engine that uses liquid fuel such as a two-stroke, four-stroke or petrol engines.

Idling - a state in which the engine is turning over slowly without providing enough power to move the aircraft.   

Incidence - the difference between a surface (wing) being parallel to the center line of the aircraft and a wing offset from the center line. If the front of the wing is up, its positive, if down its negative.

Inrunner - a type of brushless motor where the permanent magnets and motor shaft rotates within the fixed stator, as in a normal brushed motor.


Jig - a structure or device built, usually on a bench or board, to ensure the correct alignment or fitting of other parts and assemblies.  A fuselage Jig for example, made strong and ridgid, allows the builder to produce very accurate fuselages, or many fuselages that are exactly alike.

Junction box - electrical unit where a number of wires can be connected together.


Knife-edge - Flying the aeroplane on its side for an extended duration so that the wings are pointing up and down. 

Kv - The theoretical number of RPM  per volt of electricity applied to an electric motor. EG: An unloaded 2000 Kv motor, supplied with 10 volts, will spin at  20,000RPM.

Landing gear - also called the undercarriage. Refers to all wheels and associated bits. Landing gear can be fixed or retractable up into the underside of the wing or fuselage (called 'retracts'). 

L/E or Leading edge - the front edge of the wing, tailplane or rudder.

Lift - the force created by the forward motion of the plane's wing or helicopter's rotor blades. Air pressure over the wing is less than the pressure below the wing and so the wing, along with the rest of the model, is pushed upwards.

Li-Ion - Lithium Ion/cell Similar to Li-Po but in hard case, often cylindrical. Lower power to weight ratio with slightly lower nominal voltage of 3.6V The battery of choice for most protable devices such as mobile phones etc. More rugged than Lipo, but far less widely available and more costly.

Li-Po - Lithium Polymer battery /cell. Ususally soft "pouch" rectangular shaped construction, with excellent power to weight ratio. Nominal voltage 3.7V per cell. Most popular of the lithium flavours, available in a very wide range of sizes at reasonable prices, but needs to be charged and used with some care to avoid potential fire risk.

Li-Fe PO4 - Lithium Phosphate/cell. Another lithium based cell the most popular and efficient of which are manufactured in the US by the A123 company and also known as M1 cells. Hard cylindrical casing, can be fast charged in under 15 minutes, and with nano-particle technology, very low internal resistance meaning huge discharge current potential. Also very long overall useable lifespan compared to LiPo - but available in only 2 sizes for us aeromodellers.

LMS / LHS - Local Model Shop / Local Hobby Store.

Loop - an aerobatic manoeuvre whereby the airplane flies a vertical circle in the air. The easiest stunt of all to pull off, and almost any airplane with an elevator can do them. 

LVC / PCO = Low Voltage Cut-off  / Power Cut-off – The electronic circuit within an ESC ( see above ) that cuts power to the motor should the main battery fall below a certain voltage.


Mains - an abbreviation of 'main' retract or undercarriage legs. 

Methanol - One constituent of glow fuel. Methanol is a flamable alcohol and when mixed (typically but varies 70 - 90 % to 30 - 10% oil) with oil and carburetted into an engine in the correct ratio it burns. (C6:1 fuel to air.)

Mid-air - as in mid-air collision, a term used to describe the unfortunate incident of two or more aircraft making physical contact with each other while in flight. 

Mixing - (see also channel mixing) the ability to combine two different R/C functions into one. See control surface mixing and channel mixing above.

M-Link - the proprietary name for Multiplex's 2.4GHz system.

Mode 1 - refers to the set-up of the transmitter whereby the left stick operates the elevator and rudder, and the right stick operates the throttle and ailerons.

Mode 2 - refers to the set-up of the transmitter whereby the left stick operates the throttle and rudder, and the right stick operates the elevator and ailerons. Mode 3 and 4 also exist but are very rare in the UK.

Mode 3 - refers to the set-up of the transmitter whereby the left stick operates the elevator and ailerons, and the right stick operates the throttle and rudder.

Mode 4  - refers to the set-up of the transmitter whereby the left stick operates the throttle and ailerons, and the right stick operates the elevator and rudder.


NiCd - abbreviation for 'nickel cadmium', a type of metal used in rechargeable battery cell production. Also written as 'nicads', they are a form of rechargeable battery cell used in radio control gear as well as motor battery packs. NiCDs are being used less and less these days, as NiMH and Li-Po batteries take over.

NiMh - abbreviation for 'nickel metal hydride', the other type of material used in rechargeable batteries. They are the nickel based successors to NiCDs. 

Nitro - short for nitromethane, An additive to methanol based fuels. Added to increase power output, ease starting in cold weather, and  also flattens the response to the needle valve making adjustments less sensitive. Nitro also has the benefit of cooling the burn, thus making life easier for glow plugs (qv). 

Non-scale - any model that is not modelled from a real-life airplane, helicopter or whatever.

Old timer - refers to vintage models (see vintage) but also a affectionate term for older flyers.

Oily hand brigade - an operator of model diesel engines is said to be a member of the oily hand brigade because of the fact that such engines historically spewed large quantities of pleasant smelling oil over his hand as he held the model prior to launch.

Oleo - a sprung undercarriage leg often used for larger, heavier models

Over shoot - to overrun the landing strip and end up in the long grass or outfield.

Outrunner - the other type of brushless motor, where the outer casing, or 'can', of the motor rotates with the shaft and permanent magnets, which are attached to the inside of the can. Outrunners produce more torque than inrunners and are the most common type of brushless motor.



PCM - Pulse Code Modulation
PPM - Pulse Width Modulation

PVA - Polyvinyl Acetate, type of wood glue often used in model construction. Also known as 'white glue'. 

Park flyer - (1) the general name given to any model that can be flown in a small space such as a park. (2) increasingly a generic term for small and electric models although in mnay cases the model may be too fast for the park.

Pattern ship - type of model aeroplane specifically designed for competition or precision aerobatics (F3A). 

Peg board - a form of frequency control or monitoring used by some clubs. Pilots either put a peg onto the board to claim a channel (peg 'on' system) or they take a peg off a slot (peg 'off' system). Either way only the pilot with the peg, or whose peg is on the slot, may switch on a Tx on that (35Mhz) channel. The advent of 2.4GHz has left this system redundant though some clubs retain a blanket system to allow others to see how many sets are being operated at the site. 

Piano wire - a type of tough steel wire with a high degree of springyness. Often used to fabricate undercarriage.

Pitch attitude - the upward or downward angle of the airplane in relation to the horizontal, when viewed from the side. Pitch is controlled by the elevators.

Pitch - (1) the twist of a propellor that gives it efficiency in the air. (2) The axis of an aeroplane in the plane perpendicular to the aircraft centreline. The pitch angle of a moving wing or blade is known as the Angle of Attack.

Pitcheron - wing type where a model uses a separate servo for each wing (both of which are fully moving) using a delta/elevon mix. Both wings are driven together for pitch (there is no elevator) and in the opposite directions for roll.

Polyhedral - a particular wing shape where the outward ends of the wing panels are at a different angle to the main panels.

Plug-N-Play (PNP) - Ready To Fly models that are missing just the transmitter and receiver, allowing the pilot to use his/her own.

Poly-C - Polycyclic (water based) covering solution used as a friendly alternative to Epoxy (with F-glass cloth, tissue etc), also known in the trade as "Ronseal Floorseal XL".

Power panel - a small instrument panel usually mounted on the side of a flight box (q.v.) which contains useful facilities such as; a fuel pump, power outlets for an electric starter and glow plug etc.

Pusher - A model which fitted with the propellor or other motive force at the rear which then "pushes" the model through the air.

Push rod - a tough metal wire (or a wooden rod with metal wire ends) that usually links the servo to a control horn so as to activate a control surface.

Pre-flight checks - essential checks that you need to carry out immediately before flight. 

Priming - the action of introducing fuel in to the engine prior to starting it. Over-priming often causes fuel lock.

Prop - abbreviation for propeller.

PSS - Power Scale Soaring. Unpowered slope soaring scale model, of
either piston + prop or jet powered, full size aircraft.

PSSA - Power Scale Soaring Association.


Q, Q Feel - Artificial feedback provided into a powered control system in an aeroplane. Historically this was by springs but modern aircraft have servo motors and other specialist devices.  Technically the springs on a radio Tx stick provide rudimentary Q Feel but it is likely that as M Link (qv) and FPV (qv) develop then proper feedback will be sent from the aeroplane to the sticks.


Radio failure - very occasionally this happens, but the uncontrollable actions of the model are usually down to pilot error, not that they'd usually admit to it.

Radio interference - when two (or more) identical, or close, frequencies are being used at the same time the radio signals will mix together, so your model's receiver won't know which ones to respond to. Radio interference is also a good cover-up for pilot error. 2.4GHz rc systems pretty much eliminate radio interference altogether.

Radio signals - the invisible messages that pass from transmitter to receiver, telling the model what to do.

Range check - an essential pre-flight check to test the operation of your R/C gear.

RC or R/C - abbreviation for Radio Control. Often you'll see 'remote control', but 'radio control' is the technically correct term.

Rx / Receiver - part of the radio control gear that lives inside the model and picks up the radio signals sent out by the transmitter.

Reflex - this is the opposite to camber and when activated the flaps and ailerons all move upwards slightly, in unison. Changing the airfoil in this way results in the model becoming more 'slippery' through the air, hence you get a slight increase in speed.

Retracts - abbreviation for 'retractable undercarriage', which is an undercarriage that folds up into the airplane's wings or fuselage after take off. 

ROG – Rise Off Ground –where a model can taxi along the ground, and increase speed and 'rotate' to commence flying.

Roll - the rotational movement of an airplane about its longitudinal axis. Also an aerobatic manoeuvre whereby the airplane is rolled about its longitudinal axis through 360 degrees.

Rotate - the motion of pulling back on the control wheel to lift the nose during takeoff.

RTF - Ready To Fly. RTF models can be assembled in minutes, usually it's a case of just strapping on the wing.

Rudder - the moving section on the back half of the fin. Used to control yaw.


Scale - any model that has been modelled from a real aircraft, such as a Piper Cub or P-51 Mustang for example.

Stand –off / Semi-scale - any model that is loosely based on a real aircraft, with maybe a few details left out or proportions changed.

Servo - the part of the radio control gear that converts the radio signal into movement of the control surfaces. 

Servo reverse - a feature on R/C systems whereby the direction of the servo horn movement can be reversed.

Servo-slowera device which is usually located between the receiver and one or more servos which causes the servos to move to their new command position in a much slower manner than normal. Often used for scale effect on undercarriage retract servos and on flap servos to make re-trimming with flaps deployed easier. 

Shockie / Shockflyer- type of model, often small and made from foam, used to fly 3D style manoeuvres indoors.

Side/Down thrust - a deliberately built in offset to the thrust line of the engine or motor intended to compensate for the torque effects and other forces which could pull the model off track. 

Sideslipping - a mode of flight in which the model's nose is yawed away from its direction of motion and so the aircraft "crabs" partially sideways through the air. This mode of flight considerably increases drag on the model and thus can lead to a dangerous loss of airspeed. It can occur unintentionally in badly co-ordinated turns, but also may be used intentionally by pilots as a way of loosing altitude without gaining speed when a model is not fitted with flaps.

SIM – see flight simulator above.

    Slope soaring - flying gliders   from a hill or higher ground so as to use the wind blowing off the slope as a means to get and stay airborne.

Slow Flyer - different name for Park Flyer/ Indoor flyer.

SMAE - see BMFA.

SMARTuseful mnemonic to help pre-flight checks - should be carried out immediately before lining up for take-off. The items are: 

S - Switched on transmitter
M - Meter showing good tranny voltage, correct Model selected
A - Aerial fully extended (35MHz), or aerial aligned correctly (2.4 MHz)
R - Rates selected correctly. Range check was OK
T - Trims set correctly

Snake - type of control rod connecting the sevo to the control surface - e.g. rudder etc. - in which a flexible inner plastic rod slides in an outer sleeve or tube.

Spackle - a proprietory name in the USA for a lightweight filler that can be used in foam modelling. Also 'to spackle' means 'to fill'. Polycell No Sanding Polyfilla is the equivalent UK brand.  

Spars - wooden (normally) beams that run roughly parallel to the leading/trailing edge. Main spars add strength while minor spars add rigidity. 

Spat - a streamlined covering for a wheel fitted on aircraft to reduce drag. Also called a 'wheel pant' in the USA.

Spin - the state of an aircraft that is both stalled and rotating in all three axis. My be erect or inverted. Most spins descend though some aerobatic pilots with the right plane can spin upwards too. 

Spinner - the cone-shaped piece that covers the center of the propeller.

Spiral dive - Similar to a spin but the wing is not stalled and rotation is about an axis removed by some way from the plane. Characterised by high and increasing forward speed and rapoid rate of descent. Recovery should be done gently to avoid over stressing the wing. 

Spoiler - a movable part of the wing surface which reduces lift and increases drag. Used to make a glider lose height in a controlled way.

Spoilerons - a control surface that performs the dual function of ailerons and spoilers. Like flaperons, spoilerons are on the trailing edge of the wing, but move upwards to 'spoil' the lift to assist with landing. They are activated by a switch on the transmitter and require an elevator mix to keep the model stable in pitch.

Sport Flyer - (1) a general term for model aeroplanes that can be used for general flying and capable of general aerobatic manoeuvres but rarely 3D. Sometimes also called a 'hack' model. (2) Also used to denote a non-competitive model flyer, someone who flies just for fun, also called a Sunday flyer.  

Spread spectrum - the latest technology for radio control systems. Based on the 2.4GHz frequency band, spread spectrum radio systems are virtually interference-proof, and require no frequency control by the users.

Stall - when the angle of attack for any wing is exceeded the wing starts producing more drag than lift and the airflow over the wing becomes disturbed and lift decreases.

Stall turn - an aerobatic maneouver whereby the aeroplane is put into a vertical climb, power is reduced and full rudder is applied. The model should stop in mid-air and turn through 180 degrees, thus facing the ground, in the direction that the rudder was applied.

Straight and level - when the model is flying in a straight line, with no fluctuation in altitude. A well trimmed airplane should fly straight and level with the tx sticks in their central positions.

Static marginFor an aircraft to be stable in pitch, its CG must be forward of the Neutral Point NP by a safety factor called the Static Margin, which is a percentage of the MAC (Mean Aerodynamic Chord). Static Margin should be between 5% and 15% for a good stability

STOL - short take off landing. 

Swapmeet - an informal gathering for the barter or sale of new/used articles.

Sunday flyer - see sport flyer

SX - servo mechanism.

Synthetic oil - The modern replacement for Castor oil. Commercially sold as EDL, Klotz and others they all do the same thing - lube and cool the engine but leave no messy residue. The modern modeller need know none of this: just buy fresh fuel from a reputable dealer and you'll be fine.



Take-off - the action of accelerating your aeroplane along the ground until flying speed is reached, and the thing gets airborne. Only suitable for models with an undercarriage, otherwise you're limited to hand launching.

Tail dragger - an aeroplane that has two main wheels and a small tailwheel. 

Tailerons - in this set up (which is often used in jet type airframes) the model is controlled by two all moving horizontal stabilisers. These are also referred to as stabilators and are set up with an elevon mix and provide pitch and roll control. The main wing on the model can be set up with or without ailerons.

Tailplane - see horizontal stabilizer.

Tail wind - when the wind is blowing in the same direction as your plane is flying, taking off or landing.

Telemetry - a feature of some 2.4GHz radio systems that allows real-time data from sensors in the model to be sent back to transmitter and reflected on the Tx screen or a separate add-on screen/box. 

Threshold - the beginning of that portion of the runway usable for landing.

Thrust - the force that is generated by the spinning propeller or fan/turbine of the airplane, and pushes/pulls the model through the air.

Torque is the turning effect of a Force.
If using a spanner on a prop-nut the nut is tighter if you increase either the force used or the length of the spanner, or both.
So we get..............Torque = Force X Distance (from the nut!)
The metric units are Newtons X metres, or Nm, said 'Newton metres'.
We tend to use the force to lift either a pound or a kilogram so torque wrenches use ftlb or kgm and for servos we use kgcm.

Torque or Torque effect -  the result of the torque effect is a tendency of the plane to want to turn upwards and left in response to the propeller wanting to turn (bank) the plane in the opposite direction of the propeller spin.

T/E or Trailing edge - the rear edge of the wing, tailplane or rudder.

Tractor - A model where the propellor or other motive force is fitted at the front and pulls the model through the air.              

Trainer - any R/C plane that has been designed for learning to fly with. Usually trainers are high wing, with plenty of dihedral.

Transmitter - the main part of the radio control system that you hold in your hands while controlling your model.

Trim - can mean either control surface trim (see below) or the covering or decoration of your aircraft

Trimming - Adjusting the trim settings to correct unwanted tendancies. The action of getting your model to fly straight and level, with the transmitter sticks in their neutral positions and no input from you.  

Tricycle undercarriage/ Trike - a fixed undercarriage that consists of two main wheels and a nose wheel, which is sometimes connected to the rudder servo for easier ground handling. 

Turbine (Gas turbine) - a small jet engine used to power a model.

Tx - abbreviation for transmitter.


UBEC – a standalone regulator which functions as a BEC (see above).

Up wind - (1) Flying the model against the wind. (2) General description of a direction against the wind.

U/C or Undercarriage - see landing gear.

VPP - Variable Pitch Prop

Vertical stabilizer - see fin.

Vintage - usually refers to older designs, often pre-war but increasingly up and including the 1970s.

V-Tail - often used on gliders where the model has two rear stabilisation surfaces in the shape of a V. These work together by way of a movable airfoil at the trailing edge to give both elevator and rudder response - often referred to as a ruddervator. When setting up the rudder movements, the surfaces must move in the opposite direction to the ailerons. The elevator function works in the conventional way.

VTPR - Voltige Tres Pres du Relief - a French slope soaring term that has gained worldwide use and translates as "aerobatics very close to the ground". Models have been designed specifically for this part of the hobby and world champs have been held.

Washout - the twisting of the wing with leading edge down and trailing edge up, so the wing tip is in a negative angle in compare with the root of the wing.

Wattmeterdevice inserted between battery and ESC to provide an indication of the load being produced by the motor and propeller combination - a useful aid to preventing damage through overload.

Wheel Collet - A retention device, normally a thick metal ring with threaded hole for grubscrew that'll clamp the ring onto lenth of wire. Often used to secure wheels to piano wire undercarriage but sometimes in other applications too.

Windsock - a large material cone-shaped tube, mounted on a tall pole at the flying field, that indicates the direction of the wind and to a lesser degree, strength. Important because airplanes need to be taken off and landed into wind where possible.

Wing Bandage - a strip of material , usually glass fibre matting, fitted over the join between two wing halves and thus, on being coated with resin, offering strengthening reinforcement in this area. 

Wing loading - a calculation that is useful when determining certain flight performance characteristics of a plane, the figure is obtained by dividing the flying weight of the plane by the total wing area. A plane with large wings relative to its weight will have a lower wing loading, which means better lifting capacity but not so great high speed performance, and vice versa. Wing loading values are given in oz/sq.ft (ounces per square foot).

Wingspan - the overall length of the wing, from tip to tip. Wingspan is the primary measurement when referring to an plane's size.

Wing rib - a normally wooden and aerofoil shaped piece that gives the wing it's cross sectional shape and runs parallel to the cord and held by spars running perpendicular. 

Wing section - The shape seen if a slice were taken through a wing cutting down vertically from the top. 

WOT - wide open throttle.


Xtal - an abbreviation of crystal (see Crystal)


Y-lead - a wire harness designed to allow two servos to be connected to a single channel on the receiver - for example to connect two aileron servos to the aileron channel.

Yaw - the rotational movement of an aircraft about its vertical axis, controlled by the rudder.


Z-bend - double right angle bend made on the end of a control rod (wire) to attach to hole in servo arm or control horn. Z-bend pliers are a tool used to achieve just such a shape.