Last Updated: Nov 28, 2018 @ 11:06 pm

Common Terms, Abbreviations and Acronyms that should help new members of the community.
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General Remote Control Hobby Terms:

2.4GHz or “2.4”
The wireless frequency band primarily used for modern RC control between transmitter and receiver. Modern digital controllers use FHSS, or Frequency Hopping Spread Spectrum to use many different frequencies per second. This allows a transmitter and receiver to work around interference and not rely on a single frequency for communication. This also requires that both the transmitter and the receiver used the same FHSS technology to hop frequencies in the right order. FHSS technology allows dozens of RC models of all types to operate at once in the same area.
Short for All Up Weight. The total aircraft weight at any moment during the flight or ground operation.
American Wire Gauge
A measurement for a wire conductor’s thickness, with large numbers meaning small diameter and small numbers meaning large diameter. Common phone & ethernet wiring is 24 gauge, whereas car battery terminal wiring is often 8 or 4 gauge wiring.
Short for Battery Eliminator Circuit. Usually a part of the ESC that uses a low-voltage-cutoff to keep the motor from fully draining the battery. A BEC will allow higher voltage battery power to get to the flight controller at an appropriate voltage.
Short for Bind-N-Fly. A multicopter that is sold without a radio transmitter. You must bind the multicopter to a controller in order to fly it.
Short for Electronic Speed Controller. An electronic circuit with the purpose to vary an electric motor’s speed and its direction. ESC’s accept voltage directly from the main battery, look for a signal indicator on a servo lead, and then output power to a motor based on how much signal it receives. Multicopter ESC’s generally have different firmware for quicker reaction times than standard winged airplane ESC’s. ESC’s have an amp rating that notes how much maximum current it is designed to handle.
A type of battery connector using two spades, one of them rotated 90 degrees.
Short for First Person View. A method used to control a radio-controlled vehicle from the driver or pilot’s viewpoint via a video stream.
Short for Gimbal Control Unit. A simple computer that takes data from the gyros and responds by telling the gimbal motors which way to move.
A fancy camera mount that uses motors and gyros to smooth out multicopter motions for the camera. Gimbals are heavily used in multicopter aerial photography to reduce motion blur.
JR Module
A transmitter module that allows a transmitter to use different FHSS (frequency hopping spread spectrum) protocols. By default, many control transmitters and receivers are incompatible unless they use the same FHSS protocol. Using a JR module allows your transmitter to speak a different protocol, thus increasing compatibility and future-proofing the transmitter.
A battery connector commonly found on lower voltage batteries. JST’s are heavily used on 1 cell batteries, and often used on 2 cell batteries.
Motor rotations per volt. High kV (~2300) motors are generally for lighter quads, have very high speed and little torque. Lower kV (~750) motors are generally for heavier multicopters and have high torque but lower speeds. Generally a high kV motor is needed for smaller propellers that need to spin faster to produce lift. While a lower kV motor is used for larger and/or heavier propellers that require more torque power to spin.
Short for Line of Sight. Sometimes abbreviated as VLOS or visual line of sight. A style of flying that maintains sight between the pilot and the multicopter. Normally does not use VRx and VTx. FAA defines it as having visual contact without the aid of binoculars or other vision aid with the exception of corrective lenses.
Short for milliAmp-hour. A unit of electric charge, equal to the charge transferred by a steady current of one-thousandth of an Ampere flowing for one hour. In short, mAh directly affects the amount of time a multicopter can be flown. mAh capacity is very strongly tied to a battery’s weight.
(n)S count
Series on a LiPo battery represents the number of cells that are connected in series within the battery. For example, a 3S LiPo has 3 cells connected in series. Each cell generally has around 4V, so a 3S would have around 12V depending on its charge state.
Short for On Screen Display. A visual display on a transmitter or attached via an external screen that gives information from the sensors on the multicopter. OSD information is usually injected into a video transmission so a multicopter with FPV can transmit the camera image and important data about the copter’s status as one single video stream.
Short for Power Distribution Board. A PDB is a cleaner way to connect multiple positive wires to each other, and multiple neutral wires to each other. A PDB is optional.
Some type of landing gear that pulls up or lowers down on command. Retracts can be used on planes to reduce drag, and can be used on multicopters to allow a bottom-mounted camera to have a better view.
Short for Ready To Fly. A multicopter that is sold with a radio transmitter. It can be flown with the included transmitter right out of the box.
Short for Receiver. A radio receiver that connects to the flight controller on the multicopter. The receiver binds to a transmitter and receives the radio signal to control the multicopter.
A small motor with limited motion that can be controlled via transmitter. Servos are heavily used in model planes to adjust the angle of various control surfaces. On multicopters, they are of limited use and generally just for things such as tricopter tail motor yaw control, light duty camera pan/tilt, and bomb drop functionality.
Optional equipment that allows the multicopter to transmit status information to the ground control. Telemetry is sometimes a feature of the control transmitter and receiver, and other times it is just part of an OSD if FPV is being used. Common types of telemetry information are battery status, RX quality, and GPS position/heading. Others telemetry data options include temperature, RPM, G force, and waypoint navigation status.
The amount of force or lift that a propeller & motor combination can generate. For a multicopter, the max thrust of all props must be higher than the craft’s weight in order for it to lift off.
Short for Take Off Weight. The multicopter’s weight including everything needed for take off including batteries, receiver, frame, cables, motors, propellers, etc.
Short for Transmitter. A radio transmitter that is used to control the multicopter after binding to the receiver.
Short for Video Receiver. A video receiver that is bound to a VTx on the multicopter to provide real time video feed to the pilot or recording device. Usually transmits on the 5.8ghz frequency.
Short for Video Transmitter. A video transmitter that is bound to a VRx. It gives real time video to the pilot or recording device. Usually transmits on the 5.8ghz frequency.
A popular battery connector. Here’s a picture of the male and female XT-60 connectors.

General Drone Terms:

250 racer
A standard multicopter frame size, the “250” sized frame is 250mm diagonally from motor shaft to motor shaft. Multicopters of this size are popular for racing due to their size, weight, and speed.
450 flamewheel
A common mid sized quad, the “450” sized frame is 450mm diagonally from motor shaft to motor shaft. The original flamewheel model frame from DJI was popular enough that many other multicopter designs reuse the same arm configuration and mounting.
Short for Aerial Photography. The practice of using a multicopter to take aerial pictures and video footage.
The voltage of each cell in a pack relative to the other cells.
Balance Connector
The secondary connector on a LiPo battery that allows direct access to each cell for monitoring and individual charging.
Binding is the process of linking your transmitter to the multicopter’s receiver in order to control the multicopter.
A synchronous motor that is powered by a DC electric source via an integrated inverter/switching power supply, which produces an AC electric signal to drive the motor.
An input on the control transmitter that is communicated to the receiver. Inputs can be sticks, switches, or knobs. Transmitters commonly have between 4 and 16 channels. A minimum of 4 channels is required for any multicopter (throttle, yaw, pitch, roll) no matter the number of motors. Additional channels can optionally be used for GPS mode changes, camera pan & tilt, multiple camera switching for FPV, retractable landing gear, lights, buzzers, etc.
Flight controller board. See FCU.
FCU or just FC
Short for Flight Controller Unit. A small computer that connects the various parts of the multicopter together and is responsible for running the algorithms and calculations that keep the multicopter flying correctly. The RX outputs for throttle, rudder, elevator, and aileron are generally wired to an input side of the FC, and the ESC’s servo leads are wired to an output side.
Short for Hexacopter. A multicopter featuring six motors for redundancy and added stability.
Short for Lithium-Polymer. A rechargeable battery of lithium-ion technology in a pouch format.
A multicopter that is smaller than 20cm.
A multicopter that is typically between 20cm and 30cm.
Mode I
Mode I refers to when the pitch and roll on the multicopter are controlled by the left stick on the transmitter and the yaw and throttle are controlled by the right stick. This is much less common than Mode II in most countries, but is the 2nd most common mode.
Mode II
Mode (2) refers to when the yaw and throttle on the multicopter are controlled by the left stick on the transmitter and the pitch and roll are controlled by the right stick. This is much more common than Mode I in most countries. Different modes aren’t better… just different. Here is a video explaining the 4 different modes (turn off sound)
Short for Octocopter. A multicopter featuring eight motors for redundancy.
P’s, I’s, and D’s are the rates at which a flight controller tries to correct its stability. If PIDs are too low, the flight controller will not adjust enough and may flip if put at too much of an angle. If the PIDs are too high it will correct too much, causing a chain reaction of greater swooping motions until the multicopter eventually crashes. PID functionality and tuning is too complicated to be covered here. However, if you want to learn more about what the individual P, I, and D numbers do watch this video:
Short for Propeller. A type of fan that transmits power by converting rotational motion into thrust.
Short for Quadcopter. A multicopter featuring four motors.
A radio Receiver that connects to the flight controller on the multicopter. The receiver binds to a transmitter and receives the radio signal to control the multicopter.
Commonly called an “RC Controller” or “Remote controll” it is a Radio Transmitter that is used to control the multicopter after binding to the receiver. Transmitters have multiple channels on the 2.4ghz frequency that can be used to control different functions of the multicopter.
Short for Tricopter. A multicopter featuring three motors.
A setting that can be adjusted via the transmitter to allow multicopter to hover in place without drifting.
Short for Wide Open Throttle. Often used when talking about current draw at full throttle.

Flight Mode Terms:

Most flight controllers share the same basic set of features, but many are called by different names.

Here are Flight Modes as defined for ArduPilot Flight Controllers such as the PixHawk:

Here are Flight Modes as defined for the (DJI) Naza Flight Controller:

Acrobatic mode (a.k.a “rate mode”). The stick inputs determine the rate of rotation of the craft on a given axis. When the stick is centered again, the craft stops rotating, no matter which way it’s facing, (i.e. it is not self-levelling). This is what most acrobatic pilots and racers on.
Attitude or Atti
This mode is self-levelling when the pitch and roll sticks are near their centers, but allows flips and rolls when they’re pushed outward far enough.
Position Hold
Short for Return To Home. A feature on some multicopters that allows them to automatically return to its last known home location if they go out of range or reach a set battery level. Generally this requires GPS. It is a very important pre-flight item to check.
Return To Launch mode. The craft will use its sensors to navigate back to its takeoff point, (usually after ascending to a pre-set altitude to avoid hitting obstacles). This cane be the same location as the Home location used in RTH mode, but it is not necessarily the same spot, some flight controllers allow for setting home positions that are different than the takeoff/launch position.

Aviation Terminology:

Aircraft Communications Addressing and Reporting System
Airborne Collision Avoidance System
Aerodrome. You shouldn’t be flying within 3NM of these (5.5km)
Aircraft Flight Manual
Above Ground Level – A measurement of altitude, from your aircraft to the ground.
An aileron is the winged control surface that causes a plane to roll or strafe to the left and right. Aileron is more commonly referred to as roll in reference to multicopters. It is controlled by the left and right movements of the right control stick on a Mode II transmitter.
Control surface
A portion of a winged plane that moves on command to affect the plane’s path via aerodynamics and drag. Control surfaces include elevators, rudders, ailerons, and others.
An elevator is the winged control surface that causes a plane to pitch, or tilt up and down. Elevator is more commonly referred to as pitch in reference to multicopters. It is controlled by the up and down movements of the right control stick on a Mode II transmitter.
Short for Federal Aviation Administration. The national aviation authority of the United States.
Instrument flight rules (IFR) is one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other is visual flight rules (VFR).
Mean Sea Level – A measurement of altitude, relative to sea level (Central NY is mostly 500-1000 feet MSL).
Nautical mile – Slightly different mile sometimes used in aviation
The forward and backward strafing motion of the multicopter controlled by the up and down movement of the right control stick on a Mode II transmitter.
The side to side strafing motion of the multicopter controlled by the left and right movement of the right control stick on a Mode II transmitter.
A rudder is the winged control surface that causes a plane to yaw, or rotate to the side while remaining somewhat level. Rudder is more commonly referred to as yaw in reference to multicopters. The rudder controls the left and right rotation of the multicopter and is controlled by the left and right movement of the left control stick on a Mode II transmitter.
Statute Mile – What we commonly call “miles”.
Speed over ground – Actual ground speed, can be different than air speed.
Throttle is the controller for the speed of a multicopters motors. It is primarily used to control the altitude of the multicopter and is controlled by the up and down movement of the left control stick on a Mode II transmitter. On a plane, throttle affects the rate of forward motion.
Unmanned Aerial Vehicle/System which includes multicopters and RC planes.
The rotation of the multicopter in the z axis which is controlled by the left and right movement of the left control stick on a Mode II transmitter.
Visual flight rules, a set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going.


Automatic Position Reporting System – A way for an object’s position to be tracked with a small GPS receiver and radio transmitter which broadcasts GPS coordinates periodically. APRS devices can be placed on UAVs as trackers in the event that the UAV is lost.
A sensor that measures acceleration allowing for auto-leveling.
Barometric Pressure Sensor
A sensor that measures altitude for holding within approximately 1-2 m.
Short for Global Positioning Satellite. A sensor that receives and processes global positioning data for position holding and waypoint navigation. Includes a very rough estimate of altitude.
A sensor that measures angular velocity allowing for relative angle holding.
Short for Inertial Measurement Unit. An electronic device that measures and reports a craft’s velocity, orientation, and gravitational forces, using a combination of accelerometers and gyroscopes, sometimes also magnetometers.
A sensor that measures magnetic North allowing for orientation control.
Optical Flow Sensor
A sensor that measures optical displacement for position holding and optical navigation.
Pitot tube
A speedometer that uses air flow & pressure to measure speed.
Ultrasonic Sensor
A sensor that measures altitude for object avoidance and holding within approximately 1-2cm.

Descriptions of Motion:

A twitchy multicopter is quick on quick off. Think of a teenager first learning how to drive a car by stomping on the accelerator, panicking, and then stomping on the brake. In-flight reactions to stick movements are aggressive and allow for maximum change in direction. 250 racer quads are often tuned to be twitchy so they can make quick and hard maneuvers while totally ignoring any concern for smooth FPV video. Twitchy multicopters often have small 5 inch props and high (~2100kV) motors.
A sloshy multicopter is slow to react to input and glides smoothly. Think of piloting a canoe by paddling in such a way as to rotate the canoe. It takes a moment for the watercraft to respond, but often continues in that motion for a while after one strong paddle. Sloshy multicopters are good for smooth AP video as most reactions will be gentle and a camera gimbal has little correcting to do. Sloshy multicopters often have large 9-10 inch props and low (~750kV) motors.
Average motion is somewhere between twitchy and sloshy. It will be different for every craft based on its use. Some glide is good, and some ability to react quickly to an obstacle is good. Finding the right blend is often a matter of preference.