RC glossary
RC has a lot of jargon. Each term below has a short plain-English definition and, where there is one, a link to the guide that covers it properly. Use the filter to show terms for helicopters, planes or cars.
New to the hobby? Start with Getting started. For batteries and radios, see the Electronics hub; for the machines themselves, RC helicopters, RC planes and RC cars.
S
- 1S, 2S, 3S
- The number of LiPo cells in series in a battery pack. Each cell is 3.7V nominal, so a 3S pack is 11.1V. Read the guide
- SAFE
- Horizon Hobby's beginner stabilisation system, with self-levelling, angle limits and Panic Recovery. Read the guide
- Servo
- A small motor and gearbox that moves to a set position, used for steering, control surfaces and swashplates. Read the guide
- Short course truck
- An off-road truck modelled on desert racing trucks, with bodywork covering the wheels. Tough and stable. Read the guide
- Spur gear
- The large gear driven by the motor's pinion in a car's drivetrain. Read the guide
- Storage charge
- Taking a LiPo to about 3.8V per cell for storage, which keeps it healthy and safer. Read the guide
- Swashplate
- The mechanism under a helicopter's rotor head that changes blade pitch for collective and cyclic control. Read the guide
A
- Aileron
- A hinged surface on the trailing edge of a plane's wing that rolls the plane left or right. On a helicopter, aileron means sideways cyclic. Read the guide
- Altitude hold
- A feature, usually using a barometer, that keeps a helicopter or plane at a steady height when the throttle stick is centred. Read the guide
- ARF
- Almost Ready to Fly: a model that is mostly built but needs some assembly and usually electronics adding. Read the guide
- Article 16
- A CAA authorisation held by associations such as the BMFA, letting members follow the association's rules at club sites instead of the standard Drone Code. Read the guide
- AS3X
- Horizon Hobby's stabilisation system that smooths out gusts while leaving the model fully under the pilot's control. Read the guide
B
- Balance lead
- The small extra plug on a LiPo pack, with one wire per cell plus one, that lets a charger monitor and balance each cell. Read the guide
- BEC
- Battery Eliminator Circuit: part of a speed controller that supplies regulated power to the receiver and servos. Read the guide
- Binding
- Pairing a receiver with a transmitter so it responds only to that transmitter. Done once, then remembered. Read the guide
- BMFA
- The British Model Flying Association, the main UK body for model flying, which affiliates clubs and provides members' insurance. Read the guide
- BNF
- Bind-N-Fly: a ready-built model with a receiver but no transmitter. You bind it to your own compatible radio. Read the guide
- BRCA
- The British Radio Car Association, the governing body for RC car racing in the UK. Read the guide
- Brushless motor
- A motor with no brushes, switched electronically by the speed controller. More powerful and efficient, and needs almost no maintenance. Read the guide
- Buggy
- A light, agile off-road car with an open-wheeled design, best on dirt tracks, gravel and short grass. Read the guide
C
- C rating
- A LiPo's discharge rating. Multiply it by the capacity in amp-hours to get the maximum continuous current. Read the guide
- Centre of gravity
- The balance point of a model. On planes it must be where the manufacturer specifies, usually 25 to 33% back from the wing's leading edge. Read the guide
- Coaxial
- A helicopter with two main rotors on the same shaft spinning in opposite directions. Very stable and easy to hover, but indoor-only. Read the guide
- Collective pitch
- A helicopter that climbs and descends by changing the angle of all its main blades together, rather than the rotor speed. Read the guide
- Crawler
- A slow, high-torque RC truck designed to climb over rocks and obstacles. Read the guide
- Cyclic
- The combined forward, back and sideways control on a helicopter, which tilts the main rotor disc. Read the guide
D
- Differential
- A gearbox that lets the wheels on one axle turn at different speeds in corners. Read the guide
- Dihedral
- The upward V-angle of a plane's wings, which makes it more stable and lets 3-channel planes turn with the rudder. Read the guide
- Dual rates
- A transmitter setting that reduces how far controls move, making a model less sensitive while learning. Read the guide
E
- Elevator
- The hinged surface on a plane's tailplane that pitches the nose up or down. On a helicopter, elevator means forward and back cyclic. Read the guide
- EPO
- Expanded polyolefin foam, the tough, glue-able foam used in most ready-to-fly planes. Read the guide
- EPP
- Expanded polypropylene foam: flexible and very crash-resistant. Read the guide
- ESC
- Electronic Speed Controller: drives the motor at the speed the throttle asks for, and often powers the receiver. Read the guide
- ExpressLRS
- An open-source radio control link, often called ELRS, known for long range and low cost. Read the guide
F
- Failsafe
- What a receiver does if it loses the signal. On aircraft it should cut the throttle. Read the guide
- Fixed pitch
- A helicopter whose main blades are set at a fixed angle, climbing and descending by changing rotor speed. Read the guide
- Flight Restriction Zone
- The protected airspace around an aerodrome where model aircraft may not fly without permission. Read the guide
- Flybar
- A weighted bar across an older helicopter's rotor head that acts as a mechanical gyro to stabilise the rotor. Read the guide
- Flybarless
- A helicopter that uses an electronic three-axis gyro unit, instead of a flybar, to stabilise the main rotor. Read the guide
- Flyer ID
- A free CAA registration, obtained by passing an online test, needed to fly model aircraft of 100g or more outdoors in the UK. Read the guide
G
- Gear mesh
- How closely the motor's pinion meshes with the spur gear. Too tight overheats the motor; too loose strips the gears. Read the guide
- Glow plug
- The heated plug that ignites fuel in a nitro engine. A glow starter heats it to start the engine. Read the guide
- Governor
- A speed controller or flybarless unit function that holds a helicopter's rotor speed constant as the battery voltage falls. Read the guide
- Gyro
- A sensor that detects rotation, used to stabilise helicopters, planes and some cars. Read the guide
H
- Head speed
- How fast a helicopter's main rotor spins, in revolutions per minute. Read the guide
- Heading hold
- A tail gyro mode that returns the tail to where it was pointing after a disturbance. Read the guide
K
- kV
- A brushless motor's approximate revs per minute per volt with no load. Not kilovolts. Read the guide
L
- LiHV
- A high-voltage LiPo, fully charged at 4.35V per cell instead of 4.2V. The charger must be set to match. Read the guide
- LiPo
- Lithium polymer battery: the light, high-power rechargeable pack used in most modern RC models. Read the guide
M
- mAh
- Milliamp-hours: a battery's capacity, which decides how long a model runs. Read the guide
- Mode 2
- The most common transmitter layout: throttle and rudder on the left stick, elevator and aileron on the right. Mode 1 puts throttle on the right. Read the guide
N
- NiMH
- Nickel-metal hydride battery: heavier than LiPo but tougher and more forgiving, still common in RC cars. Read the guide
- Nitro
- A model with a small glow-fuel engine instead of an electric motor. Read the guide
O
- One-way bearing
- A bearing in a helicopter's main gear that drives the rotor in one direction and lets it spin freely in the other. Read the guide
- Operator ID
- A CAA registration for the person responsible for a model aircraft of 250g or more, or 100g or more with a camera. Costs £12.34 a year. Read the guide
P
- Panic recovery
- A switch or button that makes a stabilised helicopter or plane level itself out of trouble. Read the guide
- Pinion
- The small gear on the motor shaft that drives the larger spur or main gear. Read the guide
- PNP
- Plug-N-Play: a model with motor, ESC and servos fitted, but no receiver or transmitter. Read the guide
R
- Receiver
- The radio in the model that receives commands from the transmitter. Read the guide
- RTF
- Ready to Fly: a complete model with transmitter. Some 'RTF Basic' versions exclude the battery and charger. Read the guide
- RTR
- Ready to Run: the car equivalent of ready to fly, built and supplied with a radio. Read the guide
- Rudder
- On a plane, the hinged surface on the fin that yaws the nose. On a helicopter, the control that turns the nose using the tail rotor. Read the guide
T
- Throttle hold
- A helicopter transmitter switch that cuts the motor while leaving the other controls working. The key safety switch. Read the guide
- Tracking
- Whether a helicopter's main blades follow the same path as they spin. Out-of-track blades cause vibration. Read the guide
- Truggy
- A cross between a buggy and a truck: a buggy-style chassis with truck tyres and wider suspension. Read the guide