Drone Building Glossary: 60 Terms Every Builder Should Know

Drone build guides are full of shorthand. This glossary explains the terms you’ll see most, in plain English, grouped by system. Bookmark it and come back whenever a parts list stops making sense.

Power and propulsion

• AUW (all-up weight): the drone’s weight with battery, ready to fly.
• Brushless motor: the type of motor all modern drones use. No brushes to wear out.
• KV: motor RPM per volt, with no load. A 1750 KV motor on a 25 V battery spins about 43,750 RPM unloaded. See motors explained.
• Stator size (e.g. 2207): the motor’s stator is 22 mm wide and 7 mm tall. Bigger stators make more torque.
• Prop size (e.g. 5.1×3.6×3): 5.1-inch diameter, 3.6-inch pitch, 3 blades.
• Pitch: how far a prop would move forward in one rotation through a solid. Higher pitch means more top speed and more current draw.
• Thrust-to-weight ratio: total motor thrust divided by drone weight.

Batteries

• LiPo: lithium polymer battery, the standard for FPV.
• Li-ion: lithium-ion cells such as 18650 or 21700. Lower power, longer flight time; used for long range.
• S count (4S, 6S): the number of cells in series. Each LiPo cell is 3.7 V nominal and 4.2 V full.
• mAh: capacity. A 1300 mAh pack stores 1.3 amp-hours.
• C-rating: the advertised maximum discharge rate. Often exaggerated. See the LiPo guide.
• XT60 / XT30: common battery connectors.
• Storage voltage: 3.80–3.85 V per cell, the safe level for storing LiPos.

Electronics

• FC (flight controller): the drone’s brain.
• ESC (electronic speed controller): converts FC commands into motor power. A 4-in-1 ESC controls all four motors on one board.
• Stack: an FC and 4-in-1 ESC mounted together, usually 20×20 or 30.5×30.5 mm.
• AIO (all-in-one): FC, ESC and sometimes receiver on one board. Common on whoops.
• IMU / gyro: the motion sensor that measures rotation.
• UART: a serial port on the FC for connecting receivers, GPS and VTX control.
• BEC: a voltage regulator that powers 5 V or 9 V accessories.
• DShot: the digital protocol the FC uses to talk to the ESC.

Radio and video

• TX / RX: transmitter (the radio in your hands) and receiver (on the drone).
• ELRS (ExpressLRS): a popular open-source radio link. See radio links.
• Failsafe: what the drone does if it loses signal.
• VTX: video transmitter.
• FPV: first-person view, flying through a live camera feed.
• OSD: on-screen display. Battery voltage, timer and warnings overlaid on your video.
• Latency: delay between the camera seeing something and you seeing it.

Flight and tuning

• Acro / Rate mode: manual mode with no self-leveling.
• Angle mode: self-leveling mode.
• PID: the control math that keeps the drone stable. See PID tuning.
• Rates: how fast the drone rotates for a given stick movement.
• Propwash: shaking when the drone falls through its own dirty air.
• Blackbox: flight data logging used for tuning.
• Turtle mode: reverses motors to flip a crashed drone back over.
• Arming: enabling the motors before flight.

Autonomy

• ArduPilot / PX4: open-source autopilots for GPS and autonomous drones.
• MAVLink: the messaging protocol between autopilots, ground stations and companion computers.
• Companion computer: an onboard computer such as a Raspberry Pi that runs AI or mission code. See companion computers.
• SITL: software-in-the-loop simulation.
• RTH / RTL: return to home / return to launch.
• Geofence: a virtual boundary the drone won’t cross.

Video and image terms

• Air unit: a digital camera and transmitter combined for HD FPV.
• DVR: digital video recorder in the goggles that records the received feed.
• Field of view (FOV): how much of the scene the camera or goggles show.
• Uptilt: the angle the FPV camera points above horizontal.
• Jello: wobbly distortion in video caused by vibration.
• Polarization (RHCP / LHCP): the twist of an antenna’s signal. Matching antennas on the drone and goggles is essential.

Build and hardware terms

• Standoff: the metal or plastic spacers between frame plates.
• Grommet: a rubber mount that isolates a board from vibration.
• TPU: a flexible 3D-printing plastic used for mounts and bumpers.
• Pad: a copper soldering point on a circuit board.
• Smoke stopper: a current limiter used on first power-up.
• Conformal coating: a protective film for boards against moisture.

Racing and freestyle terms

• Gate: the frame racers fly through.
• Heat: one race between a small group of pilots.
• Spec class: a racing class with equipment limits.
• Power loop, split-S, dive: common freestyle maneuvers. See freestyle tricks.
• Punch-out: full-throttle climb.

Navigation terms

• HDOP: a number that describes GPS accuracy; lower is better.
• EKF: the extended Kalman filter ArduPilot uses to estimate position and attitude from all sensors.
• Loiter: ArduPilot’s GPS position-hold mode.
• Offboard / Guided: modes where a companion computer sends movement commands.
• Waypoint: a point in a planned mission.

Rule and safety terms

• TRUST: the FAA’s free recreational safety test.
• Part 107: the FAA rule for commercial small drone operations.
• Remote ID: a broadcast that identifies a drone in flight.
• FRIA: an FAA-recognized area where drones without Remote ID may fly.
• VLOS: visual line of sight.