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RC Flying Glossary

This RC flying glossary contains some of the more common words and terms that you'll hear now and again when you're reading about rc airplanes, or when you're down at the flying field.


The glossary is as non-technical and lighthearted as possible...

  • 2.4GHz - the frequency band of the newest, interference-free 'spread spectrum' digital rc systems that have all but replaced the traditional MHz ones.

  • 2 stroke - the most common type of glow plug engine for rc airplanes. The fuel/air mixture is drawn in, ignited and spat out with one single revolution of the piston inside the engine.

  • 4 stroke - the 2nd most common type of glow plug engine, much more suitable for larger and scale planes because they sound more realistic. 4 stroke engines take 2 revolutions to do what a 2 stroke does in one, but this doesn't make them twice as lazy.

  • 3D - a complex form of advanced aerobatic flying. 3D airplanes have over-sized control surfaces, exaggerated control surface deflection and excess power for maximum performance and sensitivity. Many 3D maneuvers are performed at very slow speeds, often with the plane at the point of stall.

  • Aerobatic - any maneuver or series of maneuvers that involve stunts of any kind, such as loops, rolls and spins. An airplane that is capable of performing such stunts is said to be "fully aerobatic".

  • Aeromodelling - the general term used to describe the hobby of building and flying model airplanes and aircraft. Aeromodellers are the guys and gals that do it.

  • Ailerons - the moving section of the trailing edge (TE) of the wing, located towards the outer end, or they can be the whole length of the TE. Ailerons come in pairs, (left and right) and always work in opposite directions to each other (one up, one down). When used, they cause the airplane to roll to the left or right.

  • Aileron Differential - 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. More details here.

  • Air brakes - often found on, but not limited to, larger gliders. An air brake is a small panel that pops up vertically from the top surface of the wing (or fuselage). The sudden extra drag slows the plane.

  • Airfoil - the cross-section shape of a wing. Airfoils can be flat-bottomed, under-cambered, semi-symmetrical or symmetrical, depending on the style of airplane and what it needs to do. Also written as aerofoil, depending on which country you are in. Different shape airfoils have different lift generating properties.

  • Altitude - the vertical distance between your rc airplane and the ground, usually expressed in feet ('). Just the fancy way of saying height.

  • Angle of Attack - the angle of the wing (when viewed from the end) in relation to the horizontal airflow when the airplane is flying. Nothing to do with your incoming trajectory when trying to cut the tail off your friend's plane in aerial combat games.

  • ARC - Almost Ready to Crash. An rc aircraft that knows something that the pilot is just about to find out.

  • ARF / ARTF - Almost Ready To Fly. This one's a legitimate abbreviation. An ARF airplane needs a few small finishing touches and you have to install the engine/motor and radio gear yourself. They vary in degrees of completeness, from manufacturer to manufacturer.

  • Attitude - not the obvious meaning, but in the flying world 'attitude' refers to the angle of the plane in relation to the horizontal eg "My plane had a very nose-down attitude, from which it would not recover..."
    Well, in this case you could say that your plane had a 'very bad attitude'!

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

  • BEC - Battery Eliminating Circuit. A common feature of ESCs, whereby the ESC supplies a regulated 5V to the radio control gear (receiver and servos) from the flight battery pack. BECs can be of the linear variety (constant current flow) or the switching variety, whereby they turn the power on and off thousands of times per second.

  • 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. A DSM2/DSMX compatible receiver is included though so you just, er, bind and fly.

  • Binding - a 2.4GHz receiver needs to be 'bound' to the transmitter before it can receive signals from it. The process involves the Rx identifying a unique code being emitted from the Tx, and then the two components lock together on an available frequency. The process usually only takes a few seconds.

  • Brushless motor - type of electric motor used in rc electric aircraft. Brushless motors are much more powerful than traditional brushed motors, and have become the norm. They can be inrunner or outrunner motors.

  • Buddy Box - one of the best training aids, where the student's transmitter is attached via cable to the instructor's. The student has complete control over the airplane, but at the flick of a switch the instructor can take control if the student gets into difficulties. Or just to be mean, funny or annoying.

  • Bulkhead - the foremost former of your airplane, on to which the engine is mounted. Also called a firewall.

  • Bungee launch - a popular method of launching rc gliders. More details here.

  • Butterfly - not a cute little flying insect, but the name given to a type of air-braking method on rc gliders, whereby the flaps go down and the ailerons go up simultaneously. The lowered flaps create high drag, while the raised ailerons reduce lift, this combination makes landing a fast glider easy.

Centre of Gravity / CG - the airplane's point of fore-aft balance, or the point at which all gravitational forces act on the plane. 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 and is built in during the design stage.

  • Centre of Lift / CL - the point at which all forces of lift act on the plane. Typically the CG needs to be in front of the CL for a plane to be stable and flyable.

  • Channel - 2 meanings for this in the rc world. First, it can be the number of channels that the model has, eg a 1 channel model may have just motor or rudder control while a 2 channel model will have motor and rudder, etc etc. Second, the channel number refers to the radio frequency which you're using, when using a MHz system. 2.4GHz systems don't utilise the same frequency channels.

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

  • Control horn - plastic or metal piece that is attached to a control surface, onto which the servo linkage is connected to.

  • Control surface - the term used to describe the moving part of any flying surface i.e. 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.

  • Channel mixing - when two or more channels are made to operate together with one transmitter stick movement eg rudder can be mixed with aileron, so that the rudder automatically deflects when the ailerons are moved. More details here.

  • Crosswind - when the wind is blowing at, or approximately, 90 degrees to your line of flight, take off or landing.

  • Crow - just another (more common) name for rc glider Butterfly braking.

  • Crystal - the small component that determines which channel number you fly on, when using a MHz rc system. 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.

  • Dead stick - when your airplane's motor cuts out unexpectedly in mid-air. With any luck you'll have enough altitude to glide safely in for a nice landing, otherwise you may need to use your plastic bag.

  • Dihedral - the upward angle of the wings when viewed from the front. An airplane with dihedral is more stable in the air than one without.

  • Disorientation - when you lose sight of which way up your rc airplane is and what it's doing, either because it's too far away to see properly or because of low light levels, or you've just flown it directly over your head and momentarily lost all visual reference to everything. Not much fun when it gets you.

  • Drag - the force that is created by the movement of the airplane through the air, on the air immediately surrounding the plane. Higher drag means that the plane has to work harder to cut through the air. Low drag, oddly enough, means the opposite.
    A real drag is the term used to describe your flying day when it's not going to plan.

  • DSM/DSM2/DSMX - a type of technology developed by Spektrum for their spread spectrum 2.4GHz rc systems. Stands for Digital Spectrum Modulation, the '2' and the 'X' just being the updated versions of the original. Just one of many branded abbreviations for particular 2.4GHz rc technology names.

  • Dual rates - a feature of many rc systems, whereby the control surface deflection can be reduced while still maintaining full movement of the transmitter sticks. With dual rates enabled, the airplane is less (or more) sensitive to control inputs. Typically dual rates are activated by flicking a toggle switch on the transmitter.

  • Electric starter - a glorified 12 volt electric motor with a special end cup that you place over the spinner to turn an IC engine over until it starts, hopefully. You can see one here.

  • Elevator - the moving section at the rear of the horizontal stabiliser, or tailplane, that controls the pitch attitude of the airplane i.e. whether the nose of the plane points up or down.

  • Elevons - when elevator and aileron control is made by the same control surface, this surface is called an elevon(s). Only possible with a channel mixing facility on the rc set.

  • EP - Electric Power. The alternative to IC.

  • ESC - Electronic Speed Controller - the small unit that delivers the appropriate amount of power from the motor battery pack to the motor, depending on your input at the transmitter. It also supplies power to the receiver and servos, via the BEC.

FASST - Futaba's answer to Spektrum's DSM technology. Stands for Futaba Advanced Spread Spectrum Technology and uses warp-speed frequency hopping to ensure no breakdown of signal. I think FASST has probably been updated to a new name by now; things don't stay still for long in this hobby.

  • Field box - a box that you take to the field. It contains all your flying accessories and tools, except the one thing that you need on the day when nobody else is at the field to help you out. You can see one here. Also often called a flight box, particularly when it gets kicked through the air just after you've written off your airplane.

  • Field equipment - accessories and equipment that you take to the field in your field box. Apart from that one crucial thing... More details here.

  • Fin - also called the vertical stabiliser, it's the vertical surface at the rear of the airplane used to stabilise the plane in flight.

  • 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, flaps are usually only found on rc airplanes with 5 or more channels.

  • Flaperons - a single control surface on the trailing edge of each wing that does the job of flaps and ailerons. An rc system with control mixing capability is needed to have flaperons.

  • Flare - the action taken in the last few seconds of the landing approach, to reduce the approach angle and slow the rate of descent. Forgetting this crucial action may result in you needing your plastic bag.

  • Frequency - all radio control gear works on frequencies. Best explained here.

  • 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, and if you're starting the engine by hand you really know about it.

  • Fuselage - the main body of an airplane, excluding wings, tail and everything else. Flying wing type planes, oddly enough, don't have much in the way of a fuselage.

  • 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 plugs have an uncanny habit of burning out on the one day that you've run out of spare ones, and no-one else is at the flying field.

  • Glow plug igniter / starter - used to ignite the glow plug. Obviously.

  • Gravity - the force that every rc airplane is trying to beat. RC pilots are often caught out when gravity decides to have some fun and suddenly increases its strength without warning. This common phenomenon is also known as pilot error or radio failure.

  • Hand launch - the way to launch any flying aircraft without an undercarriage. The model should be held level at head-height and launched into wind. A hefty shove is needed, but don't throw the model like a ball. Alternatively an underarm lob gets the job done with a low wing plane, if you're feeling confident.

  • High winger - a plane that has the wing sitting on top of the fuselage. Trainers are typically high wingers, and the high wing position gives good stability in the air.

  • Horizontal stabiliser - also called the tailplane. The horizontal surface at the back of the fuselage, to which the elevators are attached. It's a tailplane's job to generate a downward force, to counteract the natural tendency for a plane to want to nose-dive into the ground.

  • IC - internal combustion, the general term given to engines that are fuel powered - glow plug, petrol, diesel... The alternative to EP.

  • Inrunner - a type of brushless motor where the permanent magnets and motor shaft rotates within the fixed stator, as in a normal brushed motor. Inrunners don't provide a lot of torque and often need to be geared. If ungeared (direct drive) they are good for turning small props at high RPM.

Landing - the action of bringing your rc airplane safely back down to earth, hopefully keeping it in one piece. A good landing negates the use of the plastic bag.

  • 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', usually only found on planes with 5 channels or more).

  • Leading edge (L.E.) - the front edge of the wing, tailplane or rudder.

  • Lift - the force created by the forward motion of the airplane's wing. Air pressure over the wing is less than the pressure below the wing and so the wing, along with the rest of the plane, is pushed upwards. Lift generation is actually a complex subject.

  • Li-Po - stands for lithium ion polymer battery. These are the most modern kind of battery pack being used in electric aircraft. They provide enormous amounts of power for their size, especially when used in conjunction with a brushless motor.

  • Loop - an aerobatic maneuver whereby the airplane flies a vertical circle in the air. The easiest stunt of all to pull off, and any airplane with an elevator can do them. Just make sure you're not flying too close to the ground first...

  • Mid-air - term used to describe the unfortunate incident of two or more aircraft making physical contact with each other while in flight. A mid-air collision can be very spectacular given the correct speeds and trajectories of each model, and all models involved in such a crowd-pleasing incident almost always end up going home in the plastic bag.

  • Mixing - the ability to combine two different rc functions into one. See control surface mixing and channel mixing above.

  • 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. More details
  • here.

  • 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. The most common transmitter mode. More details here.

  • 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 successors to NiCDs with much better performance and up to 3 times the capacity for an equally sized battery.

  • Nitro - short for nitro methane, or nitromethane, depending on who you believe. It's a principle ingredient of glow fuel and, while not essential, helps to keep the fuel/air mixture burning inside the oxygen-starved combustion chamber of the engine. A 10% nitro mix is a common one for general rc glow plug plane flying.

  • Non-scale - any model aircraft that is not modelled from a real-life airplane, helicopter or whatever, i.e. a completely made up design.

  • 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, so they are more powerful than inrunners and are rarely geared.

  • "Oh nooo" - hearing this term from an rc pilot usually indicates that his/her airplane isn't doing what he/she wants it to do. 'Oh nooo' soon changes into mixed swear words if the airplane's situation deteriorates.

Park Flyer - the general name given to any electric rc airplane that can be safely flown in a public park / school yard / parking lot / sports field etc.

  • Peg board - the most common form of frequency control used at rc flying clubs. Pilots must notify other pilots of which channel they are using by pushing a peg into a hole. Not necessary with 2.4GHz systems.

  • Pilot error - any mistake, particularly one that ends in a crash, made by the pilot for whatever reasons. Pilot error is never admitted to by the pilot in question. Instead, the incident is traditionally put down to radio failure, radio interference, unexplained gusts of wind, extra fast-growing trees, the strange phenomenon of the ground suddenly lifting upwards and getting in the way without warning, or gravity having some fun and suddenly increasing its strength.

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

  • Pitch - the angle of a wing, propeller blade or helicopter rotor in relation to the airflow over it. The pitch angle of a moving wing or blade is known as the Angle of Attack.

  • Plastic bag - the thing used to take home the pieces that was once your beloved model aircraft, before you failed to keep it airborne at the wrong moment, or didn't manage to pull off the best of landings, or tried to perform an aerobatic maneuver too close to the ground...
    RC pilots who have used plastic bags can be laughed at here.

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

  • Power panel - a small central control box for all your electrical field equipment items, typically powered by a 12V battery. Used by flyers who fly IC powered planes to power their electric starter, glow plug igniter, fuel pump etc. You can see one here.

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

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

  • Propeller - the thing at the front of the airplane. It spins round very fast when the motor is running. Propellers have been known to eat the fingers of careless rc pilots who hand start their motor without the use of a chicken stick. Props will fly off at an alarming speed, if the securing nut hasn't been tightened properly.

  • Prop - abbreviation for propeller.

  • Prop-hanging - a 3D maneuver whereby the plane is put into a vertical attitude but is held at the same altitude i.e. it doesn't climb or fall, very close to the ground. RC pilots who prop-hang over the club patch often frustrate other rc pilots who actually want to fly their planes.

  • Radio failure - very occasionally this happens, but the uncontrollable actions of the aircraft are usually down to pilot error, not that they'd ever 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 aircraft'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 aircraft what to do.

  • Range check - an essential pre-flight check to test the operation and signal strength of your rc gear.

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

  • RC 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, but equally great for flyers of any age and experience.

  • Receiver - part of the radio control gear that lives inside the aircraft and picks up the radio signals being emitted by the transmitter.

  • Retracts - abbreviation for 'retractable undercarriage', which is an undercarriage that folds up into the airplane's wings or fuselage after take off. They work most of the time, but sometimes they decide not to re-appear just when you need them the most.

  • Roll - the rotational movement of an airplane about its longitudinal axis. Also an aerobatic maneuver whereby the airplane is rolled about its longitudinal axis through 360 degrees, while trying to keep the thing in a straight line.

  • RTC - Ready To Crash. RTC aircraft that are in the throws of making unplanned air to ground contact, and nothing can be done to prevent it. Usually a result of pilot error, but never admitted to.

  • RTF - Ready To Fly. RTF aircraft that can be assembled in minutes, usually it's a case of
  • just strapping on the wing. RTFs are very popular these days.

  • Rudder - the moving section on the back half of the fin. Used to control the airplane's yaw.

  • Rx - abbreviation for receiver.

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

  • Semi-scale - any model aircraft 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.

  • Servo arm or horn - the plastic or metal piece fixed to the servo output shaft, onto which the linkage connects.

  • Servo linkage - the piece of metal or plastic rod (or thread/cable) that connects a servo arm to its control surface or function. Clevises are commonly used at the ends of the linkages, to clip to the servo/control horns.

  • Servo reverse - a feature on rc systems whereby the direction of the servo horn movement can be reversed, if the builder has been daft enough to install the servo the wrong way round.

  • Slow Flyer - different name for Park Flyer. Or an rc aircraft that is experiencing engine problems, or a very strong headwind.

  • Spin - an aerobatic maneuver whereby the airplane is flown vertically down towards the ground, while being made to rotate about its longitudinal axis (i.e. roll). Easy to get into one but not always so easy to get out of, especially when the airplane-to-ground distance has been badly judged. In this instance, you will need to use the plastic bag, and I speak from experience!

  • Spinner - the plastic or aluminium cone-shaped piece that covers the centre of the propeller. Planes without spinners never quite look complete...

  • Sport airplanes - a general term for model airplanes that can be used for training on but are also capable of aerobatic maneuvers, whether intentional or not.

  • Spread spectrum - the latest technology for radio control systems. Based on the 2.4GHz frequency band, spread spectrum radio systems are virtually interference-proof, although it's now realised that 2.4GHz rc systems are not as infallible as first thought. 2.4 gig systems have all but replaced the traditional MHz ones.

  • Stall - any flying airplane will stall when the wing's Angle of Attack increases beyond the critical point of maximum lift generation, or the flying speed gets too low. When either of these things happen, the necessary amount of lift needed to hold the aircraft in the air is lost. Getting to know your rc plane's stalling speed by reducing throttle and applying up elevator at the same time is a very good idea, but don't practice too close to the ground if you want to avoid using the plastic bag.

  • Stall turn - an aerobatic maneuver whereby the airplane is put into a short vertical climb. At the top of the climb, power is reduced and full rudder is applied. The airplane should stop and turn through 180 degrees, pivoting on its tail in whichever direction rudder was applied. Then you need to pull out of the ensuing dive.

  • Straight and level - when your rc airplane is flying in a straight line, with no fluctuation in altitude. A well trimmed airplane should fly straight and level with the Tx control surface sticks in their central positions.

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

  • Taildragger - an airplane that has 2 main wheels and a small tail wheel. Taildraggers have a habit of going round in circles on the ground when you're learning how to take off.

  • Tailplane - see horizontal stabiliser.

  • Tail wind - when the wind is blowing in the same direction as your plane is flying, taking off or landing. Flying with a tail wind not only increases the plane's airspeed, but also its stalling speed, and that's never good. You should never take off or land with the wind.

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

  • Trailing edge (T.E.) - the rear edge of the wing, tailplane or rudder.

  • Trainer - any rc airplane that has been designed for learning to fly on. 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 trying to control your rc airplane.

  • Trimming - the action of getting your plane to fly straight and level, with the transmitter sticks in their neutral positions and no input from you.

  • Tricycle undercarriage - a fixed undercarriage that consists of 2 main wheels and a nose wheel, which is sometimes connected to the rudder servo for easier ground handling. Often abbreviated to 'trike'.

  • Tx - common abbreviation for transmitter.

UBEC - Universal Battery Eliminating Circuit, a common brand name that's come to be used for standalone BECs, in the same way that the name Hoover is often used to describe a vacuum cleaner. When an ESC's built-in BEC isn't man enough to do the job (for example, if your plane has high current servos) then a more powerful standalone UBEC can be used instead, perhaps along with a separate battery pack if needs be. Common in larger rc planes.

  • Undercarriage - see landing gear.

  • Vertical stabiliser - see fin.

  • Windsock - a large material cone-shaped tube, horizontally mounted on a tall pole at the flying field, that indicates the direction of the wind. Important because rc airplanes need to be taken off and landed into wind where possible, so the pilot needs to know the wind direction.

  • Wing - come on, seriously??

  • 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 airplane 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 for rc planes are commonly given in Oz/sq.ft (ounces per square foot), or less commonly the decimal equivalent.

  • Wingspan - the overall length of the wing, from tip to tip. Wingspan is the primary measurement when referring to an airplane's size, and it's commonly stated in inches (") or millimeters (mm).

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