📖 RC glossary

1/10 scale

The most common car size, around 40 cm. Ideal for getting started, on-road as well as off-road.

1/8 scale

Larger, more powerful cars, around 50 cm. The benchmark in off-road competition, in nitro as well as electric.

1/5 scale

The largest RC cars, often powered by a 2-stroke gasoline engine. Spectacular, but expensive and bulky.

Off-road

A discipline run on dirt, grass or astroturf, with jumps and bumps. The opposite of on-road.

On-road

A discipline run on smooth surfaces, asphalt or carpet. High speeds, fine-tuned setups, streamlined bodyshells.

Buggy

A low, lightweight off-road car with exposed wheels. The premier class in off-road competition, in 1/8 as well as 1/10.

Truggy

A widened 1/8 buggy fitted with large truck wheels. More stable and forgiving, slightly less agile.

Short course

An off-road car inspired by American racing pickups, with a wraparound bodyshell. Very playful, and it forgives contact.

Crawler

A slow crawling car for rocks and obstacles. Here the goal is control and grip, not speed.

Touring

A 1/10 four-wheel-drive on-road car with a sedan-style bodyshell. The flagship class on carpet and asphalt.

Carpet

A very high-grip indoor track surface. It calls for specific tires and setups.

Astroturf

Synthetic grass laid on off-road tracks, mostly indoor ones. Consistent grip and reduced tire wear.

Tarmac

Another word for asphalt. Refers to outdoor asphalt tracks.

Brushless motor

An electric motor with no brushes, powerful and nearly maintenance-free. Today's standard, from hobby to competition.

Brushed motor

An electric motor with brushes, simple and inexpensive. Common on entry-level models, it wears out over time.

ESC

An electronic unit that meters motor power according to the trigger. It also handles braking and reverse.

Servo

A small servo motor that actuates the steering. On a nitro car, a second servo controls throttle and brake.

Receiver

The unit that picks up commands from the radio. It relays them to the servo and the ESC.

2.4 GHz radio

A modern transmitter, with no crystals and no frequency conflicts. Each radio is paired to its own receiver.

BEC

The circuit that powers the receiver and servo from the main battery. Built into the ESC, or separate (UBEC) on bigger setups.

Sensored / sensorless

A sensored motor carries position sensors: smooth, precise control at low RPM. Sensorless motors are simpler and fine for casual driving.

KV

The RPM per volt of a brushless motor. The higher the KV, the faster the motor spins.

Motor turns (17.5T, 13.5T…)

The number of wire turns in the motor winding, shown in T. The lower the number, the more powerful the motor. 17.5T is the benchmark in stock classes.

LiPo

Lithium-polymer battery, light and powerful. The RC standard, but it demands a suitable charger and careful handling.

NiMH

Nickel-metal hydride battery, sturdy and easy to charge. Less powerful than a LiPo, common in beginner packs.

LiFe

Lithium-iron battery, very stable and long-lasting. Often used to power the receiver or the transmitter.

HV (LiHV, high voltage)

A high-voltage LiPo, charged to 4.35 V per cell instead of 4.20 V. A bit more punch, where the rules allow it.

2S, 3S, 4S

The number of cells in series in the pack. 2S = 7.4 V, 3S = 11.1 V, 4S = 14.8 V. The more cells, the more power.

mAh

Battery capacity, in milliamp-hours. The higher the value, the longer the run time.

Discharge rate (C)

The maximum current the pack can deliver, expressed as a multiple of its capacity. Example: 5000 mAh 50C = a theoretical 250 A.

Internal resistance (IR)

A health indicator for a cell, measured in milliohms. Rising IR gives away a tired battery.

Balance charge

A charge that equalizes the voltage of each cell through the balance lead. This is the normal way to charge a LiPo.

Storage

A charger mode that brings each cell back to around 3.8 V. Use it whenever the LiPo will sit unused for several days.

Hardcase

A LiPo with a rigid case that protects the cells in a crash. Mandatory in competition.

Nitro engine

A miniature 2-stroke combustion engine running on nitro fuel. Fast and loud, it demands tuning and maintenance.

Nitromethane

A key fuel component, blended with methanol and oil. Common percentages range from 16 to 25%.

Glow plug

An incandescent plug that ignites the fuel mixture. Its color and filament give clues about the carburetion.

Glow igniter

Battery-powered accessory that heats the glow plug red-hot for starting. A must-have in every nitro driver's pit box.

Break-in

The first tanks through a new engine, run at low RPM on a rich mixture. A good break-in determines performance and longevity.

Carburetor

The part that meters the air-fuel mixture. Its needles adjust the mixture at high and low RPM.

Fuel mixture

The proportion of fuel in the mixture. Too rich: the engine smokes and lacks RPM. Too lean: overheating and risk of engine damage.

Exhaust / tuned pipe

A tuned pipe that affects power and fuel consumption. In racing, the pipe must be EFRA homologated.

3-shoe clutch

A centrifugal clutch with three shoes, between the engine and the drivetrain. It slips at idle: the car stays still with the engine running.

Chassis

The plate or tub that carries all the car's components. Aluminum, carbon or composite depending on the range.

Camber

The vertical tilt of the wheel, in negative degrees. It determines cornering grip.

Toe (toe-in / toe-out)

The angle of the wheels seen from above. Toe-in at the rear adds stability, toe-out at the front makes the steering more responsive.

Caster

The angle of the steering axis, seen from the side. More caster stabilizes the car in a straight line.

Ride height

The height of the chassis above the ground. Low on-road, more generous off-road.

Shock absorber

A spring and oil unit that soaks up bumps and weight transfer. One of the most influential settings on the car.

Silicone oil (WT)

Calibrated oil for shocks and differentials, graded in WT or cSt. The higher the number, the thicker the oil.

Anti-roll bar

A rod that limits body roll in corners. Fitted at the front, the rear, or both.

Differential

A mechanism that lets the wheels spin at different speeds. A 4WD 1/8 car has three: front, center and rear.

Slipper clutch

A friction clutch mounted on the spur gear of 2WD cars. It protects the drivetrain and smooths out acceleration.

Driveshaft

An articulated shaft that transfers rotation from the differential to the wheel. A wear item to inspect regularly.

Pinion and spur gear

The pair of gears between the motor and the drivetrain. Changing their sizes alters acceleration and top speed.

Final drive ratio (FDR)

The final ratio between the motor and the wheels. Shorter favors acceleration; taller favors top speed.

Compound

The hardness of the tire rubber. Soft for grip, hard for longevity: choose according to the track and temperature.

Insert

Foam fitted inside the tire in place of air. Its density changes the car's handling.

Tire gluing

Attaching the tire to the rim with cyanoacrylate glue. A poorly glued tire pops off the rim mid-race.

Transponder (chip)

A small onboard device that identifies the car on every pass. Personally owned or loaned by the club.

Timing loop

A wire laid across or buried under the track. It detects transponders passing over it for timing.

Lap

One complete pass around the track, counted at the loop. A heat result combines laps and time.

Lap time

The time it takes to complete one full lap. Consistency counts as much as raw speed.

Best lap

The fastest lap time of a heat or a day. It often serves as a tie-breaker.

Qualifiers

Timed heats that rank drivers before the finals. They determine the groups and starting grids.

Heat (run)

A race session of fixed length, often 5 to 8 minutes. Drivers run in groups of similar skill level.

Final

The race that decides the final standings of the day. In 1/8 nitro it can last 30 to 45 minutes.

Main (A-main…)

The level of a final: the A-main gathers the fastest drivers, followed by the B-main, C-main, and so on.

Starting grid

The starting order of a final, inherited from qualifying. The best qualifier starts up front.

TQ (Top Qualifier)

The fastest driver in qualifying. They start at the front of the A-main.

Marshal

A track official who puts crashed cars back on their wheels. Each driver usually marshals the heat after their own.

Pit

The area where mechanics work during the race. Repairs, tire changes and refueling all happen there.

Refueling

A pit stop to refuel a nitro car. One tank covers roughly 5 to 8 minutes of racing.

Race direction

The team that enforces the rules during the race: starts, penalties, disputes.

FFVRC

The French radio-controlled car federation. It issues racing licenses and oversees official competitions in France.

League

The regional tier of the FFVRC. League races serve as qualifiers for the French Championships.

French Championship (CF)

A national competition run per class, over several rounds during the year. The goal for licensed racers.

EFRA

The European RC car federation. It organizes the European Championships and homologates racing equipment.

IFMAR

The international federation. It oversees the World Championships, organized per class.

MyLaps / SpeedHive

The most widespread timing system and its results app. Practice and race times can be viewed online.

MyRCM

A race management platform widely used in Europe. Entries, heat orders and live results.

Lexan

The thin, tough polycarbonate used for bodyshells. It is painted on the inside, with special paints.

Setup / setup sheet

The complete set of the car's settings, recorded on a sheet. It lets you get back to a configuration that works.

Shakedown

The very first run of a new or freshly rebuilt car. You check that everything works before fine-tuning the setup.

Warm-up

Free practice held before qualifying on race day. Final adjustments to setup and tires.

RTR (Ready To Run)

A car sold ready to drive, radio installed. Often all that's missing is the battery and charger.

Kit

A car you assemble yourself, supplied without electronics. The choice of racers, who hand-pick every component.

Option parts

Upgrade parts sold separately: aluminum, carbon fiber, extra tuning options.

Droop

Downward suspension travel with the wheel hanging. More droop = more traction and weight transfer. Less = a flatter, more responsive car.

Anti-squat

Angle of the rear suspension mounts viewed from the side. More anti-squat limits squat under acceleration and helps traction out of corners.

Kick-up / anti-dive

Angle of the front end viewed from the side. Kick-up softens landings over bumps; anti-dive limits diving under braking.

Ackermann

Steering angle difference between the inside and outside wheel. Changes agility at corner entry and behavior at the apex.

Bump steer

Toe variation as the suspension moves. Adjusted with the shims under the steering ball studs. Almost always to be minimized.

Roll center

Point around which the chassis leans in a corner. Moved via shims and link positions. It drives how much each end of the car rolls.

Camber link

Upper link that holds the camber. Its length and position change camber gain through the suspension travel.

Turnbuckle (link)

Threaded rod with opposite threads. A quarter turn adjusts toe, camber or Ackermann without disassembly.

Preload

Initial spring compression, set with collars or clips. Used to set ride height, not stiffness.

Shock pistons

Drilled discs the oil flows through. Number and diameter of the holes change the damping: small holes = firmer damping.

Rebound

Speed at which the shock re-extends. An emulsion shock or a different air volume changes the rebound.

Shock positions

Holes used on the shock tower and the suspension arm. A more laid-down shock = softer and more progressive; a more upright one = more direct.

Differential oil

Thick silicone oil (1000 to 500000 cst) in the differentials. Thicker = ends more locked together; the center diff manages the front/rear split.

Downstop / upstop

Stop screws that limit the downward (droop) and upward travel of each arm. Measured with a dedicated gauge.

Wheelbase

Distance between the front and rear axles. Long = stable; short = agile. Often adjustable with shims on the rear hubs.

Track width

Total width of one end of the car, set with the hexes or shims. Wider = more stable but less responsive.

Wheel hex (offset)

Hex drive adapter between the axle and the rim. Its thickness changes the track width of that end of the car.

Weight distribution

Position of the heavy components (battery, servo) on the chassis. Changing the front/rear balance changes traction and steering.

Chassis stiffness (flex)

Deliberate flexibility of the chassis and decks. More flex = more grip on a slippery track; stiffer = more precise on high grip.

Blinky (stock mode)

Mode with no software timing: the ESC LED blinks. Mandatory in stock classes to guarantee equal power.

Timing (advance)

Electronic timing advance given to the brushless motor. More timing = more RPM and more speed. Motor heat increases too.

Boost

Progressive timing advance added according to motor RPM. Wakes up the mid-corner. Set in degrees, with a start RPM.

Turbo

Extra timing applied at full throttle only, after a delay. Delivers top speed on the straight. Use with care: it generates a lot of heat.

Drag brake

Small automatic brake as soon as you release the throttle. Mimics the engine braking of a nitro car. Very popular in off-road and crawling.

Brake force

Maximum brake power when you pull the trigger fully. Set as a percentage. Too strong = wheel lock-up.

Initial brake

Force applied at the very first touch of the brake. A soft initial brake makes braking more progressive.

Punch

Aggressiveness of the power delivery at launch. Low punch = smooth acceleration, useful on a slippery track. High punch = explosive start.

Neutral range

Dead zone around the trigger neutral. Wider = fewer unwanted reactions. Narrower = immediate response.

LiPo cutoff

Voltage floor below which the ESC cuts the power. Protects the LiPo battery from deep discharge. Always enable it.

PWM frequency

Switching frequency of the power sent to the motor. A high frequency smooths the response. A low one gives more low-end punch.

Trim

Small offset of a channel's neutral. Used to make the car run perfectly straight without touching the linkages.

Sub-trim

Fine offset of the servo neutral, set before everything else. Center the servo first, then adjust the linkage.

Dual rate (D/R)

Reduces the total steering travel from the radio. Car too twitchy = lower the dual rate. Adjustable while driving on most radios.

EPA (end point adjustment)

Maximum servo travel on each side. Set so the steering stops just before mechanical binding. Protects the servo and the linkages.

Expo (exponential)

Response curve around neutral. Negative expo = softer steering around center, more forgiving. Positive expo = more aggressive.

Servo reverse

Reverses the operating direction of a channel. First setting to check: the car must turn the same way you steer.

Fail-safe

Safe position taken by the servos if the radio signal is lost. Set it with the brake applied, especially on nitro.

ABS (radio)

Pulsed braking managed by the radio, like on a real car. Prevents wheel lock-up under hard braking.

Throttle curve

Changes how progressive the trigger is. Softening the start of the travel helps on a slippery track or with a powerful motor.

Servo speed

Deliberately slows down the steering servo movement. Makes the car less twitchy, especially in fast 1/8 scale.

Model memory

Each car has its own settings profile in the radio. Switch models in two clicks instead of redoing every setting.

Gyro (gain)

Assist that counters deviations from the driving line, adjusted via the gain. Common in drift and speed runs; banned in most competitions.