Reference

Glossary

Every term the book defines, and the chapter that introduces it. Free and complete — useful on its own when a forum post or a product listing loses you.

180-degree shutter rule: An optional motion-blur convention: exposure time t = 1/(2f) seconds for frame rate f in frames per second (fps), such as 1/120 s at 60 fps or 1/240 s at 120 fps. It is not a universal FPV setting; shorter exposure times may suit stronger electronic stabilization.Chapter 13 · Capture and Share — Filming What You Watched
4-in-1 ESC: An electronic speed controller board containing four motor ESCs in one board, commonly mounted in a 5-inch stack.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
5-inch freestyle quad: An FPV quad using approximately five-inch propellers and configured for freestyle manoeuvres. The label does not establish an exact compatible build, pilot readiness or permission for a location.Chapter 1 · What FPV Actually Is
5-inch race quad: An FPV quad using approximately five-inch propellers and configured for an event's racing rules. Racing also has other size classes; the label alone does not establish durability, repairability or recording capability.Chapter 1 · What FPV Actually Is
65 mm class: A nominal tinywhoop wheelbase class, commonly measured diagonally between motor centres. Verify the maker's drawing; the class alone establishes neither prop clearance, installed mass, lift, fit nor handling.Chapter 1 · What FPV Actually Is
7-inch long-range quad: An FPV design using approximately seven-inch propellers and marketed or configured for cruising and endurance. The label establishes neither efficiency nor permission to fly beyond visual line of sight.Chapter 1 · What FPV Actually Is
75 mm class: A nominal tinywhoop wheelbase class, not a guaranteed propeller size or payload capacity. Qualify the exact frame, prop/motor combination and installed camera/board stack rather than inferring HD suitability from the class number.Chapter 1 · What FPV Actually Is
A30: A small connector used on some 1S and 2S micro packs and builds. The exact connector must match the AIO pigtail and charger leads.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
accelerometer: A sensor of specific force, or support/push relative to free fall. Quiet supported rest normally gives about 1 g magnitude; ideal free fall gives about zero. Under quiet conditions the estimator can infer gravity's direction, but maneuvers complicate that inference. Axis signs depend on convention.Chapter 2 · The Physics in Plain English
Acro mode: A flight mode where roll, pitch and yaw input commands rotational rate. Centering commands zero rate, so existing rotation tends to stop with finite response time and available motor authority; it does not command level or hold position. It is the standard mode for freestyle and racing.Chapter 2 · The Physics in Plain English
action camera: A self-contained camera carried as a separate recording payload. Compare the exact model, supported mode and complete installation; the class name does not establish an image-quality advantage over another recording route.Chapter 1 · What FPV Actually Is
AETR / TAER: Channel order conventions describing which radio channel carries aileron, elevator, throttle, and rudder; the radio and Betaflight must agree.Chapter 11 · Betaflight Deep-Dive
air unit: A manufacturer's name for airborne video-system hardware. A kit may contain a separate camera, transmission module, antenna and connecting cables; some systems also record onboard. The name does not imply one enclosure or interchangeable cameras. Use the exact model's camera, cable and module compatibility information, as explained in Chapter 3.Chapter 1 · What FPV Actually Is
air-unit recording: A file recorded on a suitably equipped video transmitter/air unit aboard the aircraft, distinct from the receiver/goggle DVR file. DJI O3/O4 and selected Walksnail kits offer this feature with model-specific modes and storage. Do not infer onboard recording from HD video support; the listed HDZero Whoop V2 route uses ground-side recording instead.Chapter 13 · Capture and Share — Filming What You Watched
all-in-one board (AIO): A compact board that combines the flight controller and electronic speed controllers, and sometimes the receiver or video transmitter, into one board. At whoop size, AIOs save weight, wiring, and stack height.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
all-up weight (AUW) cost: The total weight penalty added to the aircraft by a camera, mount, screws, filters, and accessories, considered against the build's thrust, handling, battery life, and legal weight category. Chapter 9 uses it to compare build and payload choices; Chapter 13 applies it to the complete recording setup.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
AM32: An open-source ESC firmware family for supported 32-bit ESC hardware. It is not interchangeable with Bluejay. Configuration and direction-setting depend on the exact ESC hardware, installed firmware and supported tool; identify these before following an equipment-specific procedure.Chapter 1 · What FPV Actually Is
analog 5.8 GHz video: An FPV video path carrying an analog camera signal on a selected 5.8 GHz channel. The camera format and channel must be supported by the receiver and display; cost, image quality and loss-of-signal behavior depend on the complete system.Chapter 3 · The Radio Link, the Video Link, and the Goggles
analog AIO: An all-in-one analog video assembly, such as a combined camera and video transmitter. AIO can also describe a flight-controller board with an integrated VTX, so identify what the actual product combines. Compare mass, cost and image characteristics using the complete selected systems, not the abbreviation alone.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
Angle mode: A mode where roll and pitch input command a limited tilt angle; a held input asks for that bank, and centering asks for level. Yaw remains rate-based. Leveling needs a valid attitude estimate and motor authority, and is not position or altitude hold.Chapter 2 · The Physics in Plain English
ARM channel: The radio channel carrying the pilot's arming request. In the book's standard ELRS Arm using CH5 route, this is CH5 / AUX1, low off and high requested on. The FC must still satisfy its other arming checks; an active switch range alone does not mean the aircraft is armed.Chapter 11 · Betaflight Deep-Dive
arming: Enabling normal flight motor control. Disarming disables that normal flight-control state, but a separate bench motor-test override can still command motors. Low throttle is not disarm; disarmed is not isolated. Disconnect battery, USB and other supplies before hands-on motor/prop/wiring work.Chapter 8 · First Flights — Indoor to Park
AUW (all-up weight): The complete flying mass of the aircraft, including battery, payload, props and all carried hardware, normally recorded in grams. Despite the customary name, a scale's gram reading is mass; its weight is the gravitational force W = mg.Chapter 1 · What FPV Actually Is
balance charging: Charging a pack with more than one series position while monitoring and balancing the series-cell or parallel-group voltages through the connections specified by its charger. A balance tap does not measure each cell within a parallel group independently. A 1S pack has only one series position and does not require an invented separate balance lead.Chapter 3 · The Radio Link, the Video Link, and the Goggles
battery buzzer: A pack-voltage alarm, often connected to a supported multi-cell balance connector. Check its supported cell count and power requirements; it is not automatically suitable for 1S. A bench checker, pack alarm, FC-driven beeper and independently powered lost-model finder have different roles. Continued sound after a crash or battery ejection is not guaranteed.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
BEC (battery eliminator circuit)BEC: A regulated supply for onboard electronics, often integrated into the FC or ESC. Depending on its design it can reduce or raise the battery voltage; the book's Matrix 1S board, for example, provides a regulated 5 V rail from a 1S pack. Match the specified output voltage and total load to the exact board's ratings.Chapter 3 · The Radio Link, the Video Link, and the Goggles
Betaflight: The flight-controller firmware this book uses on every build. It runs the gyro/PID loop, motor mix, OSD, blackbox logging, and configuration interface. Chapter 11 distinguishes the browser/PWA Betaflight App baseline from the legacy Configurator 10.10.0 tasks retained for original Matrix firmware. Use the tool specified for the exact task and firmware. Other firmwares exist (INAV, EmuFlight, KISS) but Betaflight is the default.Chapter 1 · What FPV Actually Is
Betaflight Configurator: Betaflight's earlier configuration application. Chapter 11 retains Configurator 10.10.0 for specified tasks on original Matrix 4.5.0/4.5.1 firmware and separately uses Betaflight App 2025.12.2 for the documented supported tasks. The App is a browser-based progressive web app (PWA), not the legacy native installer. Neither its version nor a PWA installation identifies or freezes the flight-controller firmware. Follow the exact task's tool, firmware and board requirements rather than mixing walkthroughs.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
Betaflight passthrough: A connection method in which flight-controller firmware forwards communication between a compatible configuration tool and a connected ESC or receiver. Supported routes depend on the exact hardware, wiring and firmware; it is not a universal flashing recipe. Only one serial tool may use the port at a time. Follow the exact tool and board's power and connection instructions.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
bidirectional DShot: A DShot mode where ESCs send motor RPM telemetry back to the flight controller, enabling RPM filtering.Chapter 11 · Betaflight Deep-Dive
bill of materials (BOM): A structured parts and inventory record for a build, which can remain provisional. Record exact identity, sources and unresolved compatibility, plus purchase packages and quantities separately from the physical quantities carried on one aircraft. Prices and listed or measured masses keep their evidence status; a filled list or numeric subtotal is not purchase or flight approval.Chapter 1 · What FPV Actually Is
bind phrase: Text from which ELRS derives a pairing UID for a transmitter module and receiver. Use exactly the same phrase on both through their supported configuration routes; flashing is not inherently required. It reduces accidental pairing collisions, not a password or authentication scheme. In the reviewed 4.1 firmware, a stored phrase does not by itself prevent manual binding; receiver binding-storage policy also matters. See Chapter 8.Chapter 3 · The Radio Link, the Video Link, and the Goggles
bind-and-fly (BNF)BNF: An assembled aircraft sold for use with a compatible radio system, usually with its receiver installed. Check the exact receiver, video system, supplied equipment and manufacturer instructions. Binding alone does not complete configuration, inspection, failsafe or first-flight checks. Chapter 1 explains the BNF entry and where it rejoins the book's learning route.Chapter 1 · What FPV Actually Is
Blackbox: Betaflight’s flight data logging system, stored to flash memory or microSD, used for troubleshooting and tuning.Chapter 2 · The Physics in Plain English
BLHeli_32: Closed-source 32-bit ESC firmware family, distinct from BLHeli_S, AM32 and OX32. Exact ESC/version and applicable tooling, support and recovery need checking; a dated release alone does not establish an end-of-life date.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
BLHeli_S: Older ESC firmware family for 8-bit ESCs; often updated with Bluejay for current Betaflight features.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
Bluejay: An open-source ESC firmware family for supported BLHeli_S-class hardware. It is not a universal motor-reversal requirement or a substitute for AM32. Use the supported tool for the firmware actually installed; Chapter 7 distinguishes direction-setting from remapping and firmware flashing.Chapter 1 · What FPV Actually Is
bolt-together frame: Separate arms fastened to center plates. An individually supported arm may be replaced when damage is confined to it; exact parts, hardware, access and damage assessment govern. No automatic mass or cost advantage.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
bounce-back: A rebound after a sharp stick input or snap move, where the quad overshoots or springs back instead of stopping cleanly.Chapter 12 · Tuning — From Stock to Smooth
brushed motor: An older motor type that uses physical brushes to switch current. Brushed whoops are treated as legacy context in this chapter, not as a recommended Build One path.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
brushless motor: A motor driven electronically by an ESC rather than by brushes rubbing on a commutator. The book's reference builds use brushless motors. Their voltage, KV, propeller and ESC requirements belong to the exact selected combination.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
BT2.0: A low-resistance connector commonly used on modern 1S whoop packs. It is preferred over older PH2.0 connectors when the build and charger support it.Chapter 3 · The Radio Link, the Video Link, and the Goggles
Build Two: The reader's second quad in the book: either the 5-inch freestyle quad used as the spine build or the alternate cruising-4S toothpick. The toothpick targets a lower flying mass; weigh the complete aircraft rather than assuming a sub-250 g result or regulatory exemption.Chapter 1 · What FPV Actually Is
C-rating: A claimed current-to-capacity multiplier. Multiply the stated C value by capacity in amp-hours to obtain amperes. Charge and discharge ratings are separate, as are continuous and burst conditions. The label alone does not establish usable current in a particular aircraft or a like-for-like comparison between packs. Chapter 4 works through an identified pack's ratings.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
capacity: The amount of charge a pack can deliver, labeled in milliamp-hours (mAh). A 1500 mAh pack is 1.5 amp-hours.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
CE mode: A label used for some regional radio configurations, not the CE conformity marking or proof of permission to transmit. Identify the actual band, firmware domain and equipment; check applicable conformity and national spectrum-use requirements rather than assuming a universal power/LBT rule.Chapter 3 · The Radio Link, the Video Link, and the Goggles
cell: One lithium battery unit inside a pack. FPV voltage rules are stated per cell because 1S, 4S, and 6S packs have different total voltages.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
center of gravity: The balance point of the complete flying quad, including the battery in its recorded position. Moving payload changes motor lever arms, hover thrust distribution and available pitch headroom as well as rotational inertia.Chapter 2 · The Physics in Plain English
channel order: The mapping between radio stick/switch outputs and Betaflight inputs, commonly AETR or TAER; incorrect channel order makes the quad respond to the wrong control.Chapter 8 · First Flights — Indoor to Park
charger: The bench device used to charge flight packs. It is shared gear bought once and reused across builds when compatible with the packs.Chapter 1 · What FPV Actually Is
cinelifter: An FPV platform configured to carry a cinema-camera payload. Its exact mass and capability depend on the build; it is outside this book's practical route.Chapter 1 · What FPV Actually Is
cinematic prop: An informal use or marketing label, not a standardized propeller specification or demonstrated smoother-footage result. Identify the exact manufacturer, part, diameter, pitch, blade count, hub and matched set. T-mount describes an attachment interface, not vibration performance; changing props requires compatibility review and affected configuration acceptance.Chapter 13 · Capture and Share — Filming What You Watched
cinewhoop: A ducted FPV quad configured for filming with an onboard recording system or separate camera payload. Ducts do not make flight near people safe; the name does not establish size, mass or wind limits.Chapter 1 · What FPV Actually Is
CLI: command-line interface (Betaflight's text console). Command-line interface accessed through the Betaflight App where configuration can be read and changed as text commands.Chapter 8 · First Flights — Indoor to Park
CLI diff: A Betaflight export of settings different from defaults. The complete `diff all` belongs to one recorded configuration state; the newest file may be rejected or untested. A restore needs exact compatibility, error checking, persisted readback and renewed affected acceptance, not merely a pasted file.Chapter 11 · Betaflight Deep-Dive
clockwise (CW) prop: A prop intended to spin clockwise when viewed from above the quad.Chapter 2 · The Physics in Plain English
cold joint: A weak solder joint formed when the pad, wire, or solder did not reach a suitable working condition or was moved while cooling; it may be lumpy, cracked, peaked, visibly separated, or poorly wetted. Uniform dullness alone is normal for some lead-free alloys such as SAC305 and does not establish a cold joint.Chapter 7 · Building the Whoop
community contribution: A useful, bounded action such as a private sourced note, documented question or substantiated correction. Practical help depends on demonstrated competence, appropriate procedure and supervision; submission is not acceptance.Chapter 15 · Your First Year as an FPV Pilot
conformal coating: A thin protective coating applied to electronics to reduce damage from moisture, dust, grass clippings, and conductive debris.Chapter 3 · The Radio Link, the Video Link, and the Goggles
continuity check: A meter-dependent low-resistance indication, not a universal short-circuit verdict. Use only after battery, USB and other supplies are isolated and relevant stored-energy instructions followed. Windings, components and charging capacitors can affect the result; use the exact meter/board procedure and polarity checks.Chapter 7 · Building the Whoop
control link: The radio connection carrying stick, switch, and arming commands from the handheld radio transmitter to the receiver on the quad.Chapter 1 · What FPV Actually Is
counterclockwise (CCW) prop: A prop intended to spin counterclockwise when viewed from above the quad.Chapter 2 · The Physics in Plain English
Crossfire: A control-link family from Team BlackSheep (TBS) using the 868/915 MHz family. It is a separate RF system from ELRS; exact transmitter, receiver, firmware, interfaces and permitted use need their own checks. The book's worked configuration follows ELRS, not a Crossfire setup procedure.Chapter 1 · What FPV Actually Is
crosshair antenna: A directional antenna style used on goggles or ground stations to focus reception in one direction rather than equally around the pilot.Chapter 3 · The Radio Link, the Video Link, and the Goggles
CRSF (Crossfire serial protocol)CRSF: A serial protocol originally created for TBS Crossfire and also used by UART ExpressLRS receivers for control and telemetry communication with the flight controller. Configure the exact receiver's UART and protocol; SPI ELRS is a separate route. Ghost's native GHST protocol is not another name for CRSF.Chapter 3 · The Radio Link, the Video Link, and the Goggles
D term: The derivative term. In the pinned Betaflight rate controller, D is based on negative change in filtered gyro rate, not the derivative of rate error. It supplies damping, but noise on this path can produce motor activity and heat.Chapter 12 · Tuning — From Stock to Smooth
deadband: A small region around stick center in which input changes are ignored. The radio, simulator and flight controller can apply different controls; do not add deadband at every layer by default. Diagnose mapping, calibration and actual center jitter first. Chapters 5 and 11 explain the relevant setup checks.Chapter 5 · Sim Before Sky
deadcat frame: A layout with different front/rear motor placement, commonly intended to help camera clearance. Exact positions and camera/prop geometry govern; the name does not guarantee prop-free images or handling.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
DFU mode: Device Firmware Update mode, a bootloader state used to receive compatible firmware on supported hardware. The exact board supplies the entry procedure. DFU enumeration does not prove board health or require a flash; failure to enumerate does not uniquely diagnose a damaged regulator or USB port.Chapter 14 · Maintenance, Troubleshooting, and Crash Repair
diagnostic flowchart: A structured investigation from observations through possible causes and discriminating evidence. It may end with an unresolved grounded outcome; a flowchart does not guarantee a diagnosis or verified repair.Chapter 12 · Tuning — From Stock to Smooth
diff: A shorter CLI export showing settings that differ from the firmware defaults. A complete, unmodified `diff all` includes all profiles and restore context in the referenced firmware. Keep it with exact board/firmware/build identity and acceptance records; it is not portable to another target and does not back up ESC, radio or peripheral settings.Chapter 8 · First Flights — Indoor to Park
dipole antenna: An antenna with two radiating elements whose orientation affects signal strength and link reliability; placement and polarization matter for video performance.Chapter 10 · Building the Quad
DJI O3/O4: DJI digital FPV air unit generations that combine high image quality, onboard recording options, and an ecosystem tied to compatible DJI goggles.Chapter 1 · What FPV Actually Is
double-elimination bracket: A race format where pilots remain in contention until they lose twice, creating a winners bracket and a lower bracket.Chapter 15 · Your First Year as an FPV Pilot
DShot: A digital ESC protocol family. Betaflight 2025.12.5 names DShot150, DShot300 and DShot600. Chapter 11's reference candidate is DShot300; the actual FC, ESC, firmware and loop configuration must support the selected setup.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
ducted whoop frame: A small quad frame with circular guards around the propellers. Guards can limit contact from some directions but do not enclose every moving part or make contact with people, pets or furnishings safe. Use the clear practice area and flight precautions in Chapter 8.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
dump: A fuller text export including default-valued settings. Use `dump all` for all profiles in the referenced firmware and keep the complete raw output alongside `diff all`. Neither file is a board-independent setup or evidence of physical acceptance.Chapter 11 · Betaflight Deep-Dive
DVR: digital video recorder. Digital video recorder. In this book, goggle DVR means a recording made at the receiving end of the video link. It is distinct from a file recorded on the aircraft and may retain link breakup or different overlays and timing. Check the exact recorder, mode and storage medium; a DVR file is not an exact measurement of the image reaching the pilot's eyes.Chapter 3 · The Radio Link, the Video Link, and the Goggles
dynamic notch filter: A filter that tracks selected peaks in the gyro signal and attenuates narrow frequency bands. A detected peak alone does not identify its physical cause.Chapter 12 · Tuning — From Stock to Smooth
EdgeTX: Open-source radio firmware providing model setup, mixers, telemetry and USB joystick functions. The book's supported radio route uses EdgeTX; Chapter 5 teaches the selected simulator setup. Check the exact radio and firmware version rather than assuming that every radio has the same controls.Chapter 1 · What FPV Actually Is
error: Commanded value minus measured value in the controller discussed here. For Betaflight's rate loop this is rate setpoint minus gyro rate, not an error in ground position.Chapter 2 · The Physics in Plain English
ESC (electronic speed controller)ESC: The board that drives a brushless motor by switching its three phases in the right sequence. Modern FPV builds usually run a 4-in-1 ESC stacked under the flight controller, or an all-in-one (AIO) board that combines the FC and ESCs on one PCB. Build chapters cover wiring, sizing, and firmware.Chapter 1 · What FPV Actually Is
ESC current rating: The current an ESC is designed to handle. For whoop AIOs, the rating must fit the motor, prop, and battery cell count so hard throttle does not burn the ESC.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
ESC desync: A loss of synchronization between an electronic speed controller's commutation and motor position. Stutter, lost thrust or unusual sound can prompt investigation but do not uniquely identify desync. Previewed as a crash-mode symptom in Chapter 2; full diagnostic flow in Chapter 14.Chapter 14 · Maintenance, Troubleshooting, and Crash Repair
EU Open A1: An EASA Open Category operating subcategory. A privately built aircraft qualifies for the below-250 g path only when its maximum take-off mass including payload is below 250 g and maximum operating speed is below 19 m/s, with all other applicable Open Category and national conditions still in force. Verify current requirements locally in the year of flight.Chapter 1 · What FPV Actually Is
expo: A parameter that changes the shape of a stick-response curve. Its effect depends on the named rate model; do not copy a value between models as though it had the same meaning. Throttle expo shapes a separate input curve and is not automatic altitude hold.Chapter 5 · Sim Before Sky
ExpressLRS (ELRS)ELRS: An open-source radio control-link project with hardware from multiple manufacturers. This book follows a 2.4 GHz route for consistent examples; that is not a universal performance or purchasing ranking. Other bands depend on exact hardware and firmware. Chapter 3 separates compatibility, supported configuration and local RF permission.Chapter 1 · What FPV Actually Is
F411: An STM32F4 microcontroller identifier used on some flight controllers. It is not the board's firmware target. Check the exact board, gyro, release and required features rather than treating the family as accepted or obsolete.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
F722: An STM32F7 microcontroller identifier used on some flight controllers. It is not a board target or an automatic upgrade recommendation. Firmware support and usable features depend on the exact board, gyro and release.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
failsafe: The configured flight-controller response to missing or invalid receiver control data. Detection, fallback and final action are distinct. DROP disarms when reached; the falling aircraft remains hazardous. AUTO-LAND and separately qualified GPS Rescue are different procedures, not guaranteed hover or safe landing. Validate the exact normal-radio route props-off, USB/serial disconnected and on qualified power before any first flight, indoors or outdoors; repeat affected checks after changes/repair. Record actual observations and low-throttle-path limits.Chapter 1 · What FPV Actually Is
failsafe stage 1: Betaflight's channel-fallback stage. It can hold previous values or apply configured values when receiver control data is missing or invalid. Low throttle is not disarm; fallback does not guarantee a hover.Chapter 3 · The Radio Link, the Video Link, and the Goggles
failsafe stage 2: Betaflight's configured failsafe procedure, such as DROP, AUTO-LAND or separately qualified GPS Rescue. Entry and recovery depend on the trigger, configuration and received data, not one universal timed sequence.Chapter 3 · The Radio Link, the Video Link, and the Goggles
FCC mode: A label used for some regional radio configurations, not an FCC equipment authorization. Identify the exact band, firmware domain, hardware, antennas and operating conditions; a menu setting does not establish permitted use.Chapter 3 · The Radio Link, the Video Link, and the Goggles
feedforward: A setpoint-driven Betaflight control contribution, separate from gyro feedback. On normal Acro axes in pinned 2025.12.5 it responds to processed setpoint change without waiting for a matching rate error; it does not bypass the mixer, output limits or the aircraft's response time.Chapter 12 · Tuning — From Stock to Smooth
field of view (FOV): In a goggle specification, the apparent angular size of its displayed image; in a camera specification, the scene angle captured by the lens/sensor combination. These are different quantities. Compare the same horizontal, vertical or diagonal convention, aspect ratio and mode before comparing values.Chapter 3 · The Radio Link, the Video Link, and the Goggles
filter: A signal-processing step that changes selected signal components. Attenuation and timing depend on type, configuration and frequency; a cleaner trace does not establish acceptable hardware or motor temperature.Chapter 12 · Tuning — From Stock to Smooth
flight controller (FC): The onboard computer that reads the radio command and sensors, computes the control response, and sends commands to the electronic speed controllers.Chapter 2 · The Physics in Plain English
flight log: A written record of session/pack/flight IDs, actual airborne duration with timing source and precision, configuration/acceptance references, actual mode/profile, conditions, observations, crashes including zero, repair holds and one intended practice change. Distinct from optional raw Blackbox recordings; examples and missing observations do not count as performed practice.Chapter 8 · First Flights — Indoor to Park
flux: A chemical cleaner that helps molten solder flow by removing surface oxidation from metal.Chapter 7 · Building the Whoop
FPV (first-person view): A way of flying where the pilot sees a live video feed from the aircraft, usually through goggles, and controls the quad as if seated inside it.Chapter 1 · What FPV Actually Is
framerate: The number of video frames recorded per second, commonly 30, 60, or 120 fps for FPV capture.Chapter 13 · Capture and Share — Filming What You Watched
full-charge voltage: The normal maximum charge voltage for a standard LiPo cell: 4.2 V per cell unless the manufacturer specifies a different chemistry or high-voltage mode.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
fume extractor: Equipment that captures solder/flux fumes near the joint and controls the extracted air. Select, position, maintain and check it for the actual solder/flux and workstation; a fan or carbon-filter pad alone does not establish adequate protection. Chapter 7 explains the workbench requirements.Chapter 7 · Building the Whoop
Gemini: An ELRS mode that sends packets on two RF channels simultaneously. It requires compatible transmitter and true-diversity receiver hardware, firmware and antenna-mode settings at both ends. Single-band Gemini and dual-band GemX have different requirements. Two receiver antennas alone do not establish Gemini operation or guarantee range.Chapter 3 · The Radio Link, the Video Link, and the Goggles
Ghost: An ImmersionRC control-link family. The Ghost 2G4 system discussed here uses 2.4 GHz and needs its own compatible transmitter/receiver and setup route. It is not interchangeable with ELRS merely because both use that band. The comparison makes no current stock, support or performance ranking.Chapter 3 · The Radio Link, the Video Link, and the Goggles
GNB27: A small whoop pack connector used on some Gaoneng (GNB) 1S packs. Less common than BT2.0; the BOM must match the connector to both the AIO pigtail and the charger lead.Chapter 3 · The Radio Link, the Video Link, and the Goggles
goggle perspective: The first-person camera view from the simulated quad, matching the visual frame used in real FPV flight. Used as a noun ("from the goggle perspective"), and hyphenated when attributive ("a goggle-perspective replay").Chapter 5 · Sim Before Sky
goggles: The display worn by the pilot to view the live video feed from the quad. This book uses 'goggles,' not 'headset.'Chapter 1 · What FPV Actually Is
GPS Rescue: A Betaflight emergency mode (UI label capitalized as "GPS Rescue") that attempts to climb and fly the quad back toward the recorded home point; it is not full autonomous return-to-home. The book matches Betaflight's capitalization.Chapter 8 · First Flights — Indoor to Park
graduation criteria: The book's recorded progression checks. Chapter 5 owns the simulator practice gate before Chapter 8's separate real-aircraft checks; Chapter 8 owns the full indoor/outdoor whoop progression before the Build Two route. Reading, hours or quiz answers alone do not establish practical readiness.Chapter 5 · Sim Before Sky
gravity: Earth's gravitational attraction. The quad's weight is W = mg, directed downward; m is mass in kilograms and g is gravitational acceleration. Weight is balanced in steady level hover, not eliminated.Chapter 2 · The Physics in Plain English
ground-return routing: Considering the paths by which supply and signal currents return to their source or reference. It is not a specified filter circuit or permission to move connections between ground pads; follow the exact equipment wiring. Three switched motor phases are not a positive/negative supply pair.Chapter 10 · Building the Quad
gyro: The inertial sensor that measures rotational rate around the roll, pitch, and yaw axes.Chapter 2 · The Physics in Plain English
gyro lowpass filter: Attenuates higher-frequency gyro-signal components. Enabled stages, types and static or dynamic cutoff settings depend on exact firmware and saved configuration. A clean-build label does not justify disabling a stage.Chapter 12 · Tuning — From Stock to Smooth
gyro stabilization: Post-processing that uses recorded camera motion to adjust video framing. A supported workflow needs usable motion data matched to the footage, lens information and synchronization; it is optional and does not repair a mechanical fault.Chapter 13 · Capture and Share — Filming What You Watched
gyro trace: The rotation rate the FC measured from the gyro. Comparing gyro to setpoint shows whether the quad followed the command cleanly or lagged, overshot, or oscillated.Chapter 12 · Tuning — From Stock to Smooth
Gyroflow: Free, open-source post-stabilization software requiring supported camera/mode footage, usable motion data, a matching lens profile and accurate synchronization. Motion data may be embedded or supplied by a separately supported external log. Use is optional; missing inputs do not enable a gyro-free optical-flow fallback.Chapter 13 · Capture and Share — Filming What You Watched
HD digital video: The umbrella category for modern non-analog FPV video systems that deliver high-resolution color video over a digital link. The three families this book covers are DJI O3/O4, Walksnail Avatar, and HDZero. Distinct from analog 5.8 GHz, which is the legacy alternative. Chapter 3 covers the choice between HD digital and analog in full.Chapter 3 · The Radio Link, the Video Link, and the Goggles
HD VTX: A high-definition video transmitter system such as DJI O4/O3, Walksnail Avatar, or HDZero that sends digital video to compatible goggles.Chapter 1 · What FPV Actually Is
HDZero: A digital FPV video ecosystem with matched cameras, transmitters and receivers. Exact camera, video mode and goggle or external display determine the available features. A sub-frame or display-delay claim is not a universal complete-frame latency measurement.Chapter 1 · What FPV Actually Is
HDZero whoop module: An HD digital FPV VTX option designed for lightweight whoop builds and low-latency digital video.Chapter 1 · What FPV Actually Is
heat: A scheduled race group where several pilots fly the course at the same time on coordinated video channels.Chapter 15 · Your First Year as an FPV Pilot
heat shrink: Plastic tubing that shrinks when heated and is used to insulate exposed solder joints or reinforce wires.Chapter 7 · Building the Whoop
Horizon mode: A hybrid rate/leveling mode whose assistance depends on both stick deflection and attitude. In the book's pinned Betaflight 2025.12.5 source, the default inclination limit is 135 degrees and leveling strength falls to zero at or beyond that limit. It is not a general emergency-recovery switch.Chapter 2 · The Physics in Plain English
I term: The integral term accumulates rate error with limits and can counter persistent rotational disturbances while motor authority remains. It does not measure or hold ground position; translation in wind is not by itself an I fault.Chapter 12 · Tuning — From Stock to Smooth
inrush current: The brief surge of current that flows when a battery is plugged into electronics and input capacitors charge.Chapter 10 · Building the Quad
internal resistance: Electrical resistance inside a cell or pack, often reported in milliohms. Compare readings only with a consistent method and connections, and comparable temperature, state of charge and rest conditions. Trends can inform assessment, but a charger reading alone neither diagnoses damage nor proves a pack safe.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
interpupillary distance (IPD): The distance between the centers of the pilot's pupils. For binocular goggles, check that the optical adjustment accommodates that distance and that both images are clear. Single-screen box designs have different fit constraints; an IPD range alone does not establish comfortable vision or spectacle clearance.Chapter 3 · The Radio Link, the Video Link, and the Goggles
jello: Wavy image distortion that can arise when camera motion interacts with rolling-shutter readout. It is a symptom, not proof of one damaged part or a required PID/filter change. Inspect the exact mount, retention and aircraft safely, then review camera mode and actual footage; neither TPU, a heavier camera nor post-stabilization guarantees its removal.Chapter 7 · Building the Whoop
JST-XH: A connector family used for balance leads on many packs with multiple series positions. The exact charger connection, series count and pinout must match; the name alone does not establish compatibility. Balance readings show a series cell or parallel group's voltage, not each physical cell within a parallel group.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
Kapton tape: Polyimide insulating tape used around electronics. Check the actual tape and adhesive's temperature limits; heat resistance does not mean immunity to an iron tip. Chapter 7 explains its limited protective role during soldering.Chapter 7 · Building the Whoop
KV: motor velocity constant, in RPM per volt unloaded. A motor rating that approximates revolutions per minute per volt with no load. On whoops, KV must be matched to cell count, prop size, and frame class so the motor has enough punch without overheating or draining packs too fast.Chapter 1 · What FPV Actually Is
latency budget: An accounting of delay between explicitly named endpoints. Add only nonoverlapping stages measured under compatible conditions; do not add a whole path's delay to one of its already-included stages. Packet period, video transmission minimum, full-frame camera-to-display time and human response are different quantities. An unmeasured stage is unknown, not zero.Chapter 3 · The Radio Link, the Video Link, and the Goggles
LBT: listen before talk. Listen Before Talk, a channel-access mechanism that checks activity before allowing transmission when enabled. Its behavior and applicability depend on the system, band and configuration. The label alone does not prove compliance or guarantee interference-free operation.Chapter 3 · The Radio Link, the Video Link, and the Goggles
LHCP: Left-hand circular polarization, the opposite circular polarization from RHCP. Where a video system uses circular antennas, match the required hand within each intended link. Opposite hands between links may add isolation, but do not guarantee non-interference or permit channel sharing.Chapter 3 · The Radio Link, the Video Link, and the Goggles
liability insurance: Insurance addressing specified legal liabilities, such as third-party injury or property damage, subject to the actual policy's terms, limits and exclusions. It is distinct from cover for damage to the insured's own aircraft and does not itself authorize flight.Chapter 15 · Your First Year as an FPV Pilot
lift: In this chapter, informal shorthand for the world-vertical component of rotor thrust. Thrust is body-relative, so tilting the aircraft changes that component; it is not a separate always-upward prop force.Chapter 2 · The Physics in Plain English
lifted pad: A copper solder pad that has separated from the circuit board substrate because of heat, force, crash damage, or repeated rework.Chapter 7 · Building the Whoop
LiHV (high-voltage LiPo)LiHV: A high-voltage LiPo variant, commonly specified for a 4.35 V per-cell charge limit instead of regular LiPo's 4.20 V. The selected Build One LAVA pack is LiHV. Use its exact manufacturer instructions and a compatible charger program; the regular-LiPo example is not its default charging recipe.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
link quality (LQ)LQ: For the book's ELRS 4.1.0 2.4 GHz LoRa 250 Hz route, the percentage of recent receive periods with a valid uplink packet, including sync/data, not only RC commands. Repetition modes can account differently. Downlink telemetry has its own quality measurement. High uplink LQ alone proves neither valid FC control delivery nor signal margin or safe range. Read it with RSSI dBm and the exact RF mode's sensitivity limit.Chapter 3 · The Radio Link, the Video Link, and the Goggles
LiPo batteryLiPo: A lithium-polymer flight pack. FPV LiPos are optimised for high power delivery rather than energy density, which is why hard flights last only a few minutes. Cell counts are written nS (1S, 2S, 4S, 6S) where each cell is roughly 3.7 V nominal. Capacity is given in mAh. LiPos are flammable when damaged or over-discharged; safe handling and storage are non-skippable. Chapter 4 is the full safety treatment.Chapter 1 · What FPV Actually Is
lollipop antenna: A rounded-housing style commonly used for small omnidirectional antennas. The name does not specify compatibility; check the exact model's band, polarization, connector and dimensions.Chapter 3 · The Radio Link, the Video Link, and the Goggles
long-range build: An FPV build marketed or configured for cruising and endurance. The label alone establishes neither actual range or efficiency nor a universal pack, navigation system or operating permission.Chapter 1 · What FPV Actually Is
loop frequency: How often the FC runs the PID calculation, commonly 2 kHz, 4 kHz, or 8 kHz depending on board processor, gyro, firmware settings, and DShot mode.Chapter 12 · Tuning — From Stock to Smooth
lost-quad finder: A recovery aid, not a guarantee. An active FC sounder needs suitable power and drive; motor beeping uses a separate ESC-dependent route. A backup finder has model-specific charging, enable, trigger and stop behavior. The outdoor route needs a qualified physical device, not just an output pad.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
Low-ESR capacitor: A capacitor with low equivalent series resistance, used across the battery input to absorb voltage spikes and reduce electrical noise on the power rail.Chapter 10 · Building the Quad
LUT: A look-up table that maps color values for a specified technical conversion or creative look. It is one tool, not all color management; match its expected input/output and avoid repeating a conversion already applied.Chapter 13 · Capture and Share — Filming What You Watched
Matty flip: An outside or inverted power loop associated with MattyStuntz, using forward pitch around a horizontal obstacle and exiting upright; not an inverted yaw rotation. Optional simulator-only practice here, not a universal recovery or first-flight requirement.Chapter 5 · Sim Before Sky
minimum safe voltage: A manufacturer-specific lower operating limit, not a universal 3.0 V-per-cell permission to keep flying. Loaded and resting voltage differ. Landing warnings must be qualified for the exact pack and aircraft; a suspect low-voltage pack is taken out of service for advice, not automatically recharged.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
model match: An optional ELRS identity check. When enabled, the receiver's stored Model Match ID must match the selected radio model's Receiver ID. A mismatch can leave the RF link connected but withhold control frames from the FC. It is not an FC arming command or a substitute for checking the selected model.Chapter 3 · The Radio Link, the Video Link, and the Goggles
modes: Flight-control states and switch-assigned functions such as ARM, ANGLE, BEEPER and Flip Over After Crash. Ordinary Acro is the default rate-control state when overriding flight modes are inactive, not an ACRO selection box. ACRO TRAINER and AIRMODE are different functions. Chapters 8 and 11 teach the selected switch setup.Chapter 8 · First Flights — Indoor to Park
moment of inertia: Resistance to angular acceleration about a specified axis. Moving mass farther from that axis increases its inertia contribution, so the same angular acceleration needs more torque. This is distinct from CG-related trim changes.Chapter 2 · The Physics in Plain English
motion blur: Image streaking caused by motion during a frame's exposure. Its appearance depends on exposure time and scene/camera motion. Longer exposures may suit a chosen look but can leave objectionable blur after electronic stabilization; blur is not a cure for vibration or rolling-shutter distortion.Chapter 13 · Capture and Share — Filming What You Watched
motor direction: The clockwise or counterclockwise spin direction of each motor as expected by Betaflight and matched by prop orientation.Chapter 1 · What FPV Actually Is
motor mix: The flight controller’s calculation that turns desired roll, pitch, yaw, and throttle into four separate motor outputs.Chapter 2 · The Physics in Plain English
MSP DisplayPort: An MSP-based transport for Betaflight on-screen-display drawing commands to a supported video system, normally over an FC UART. The receiving video system renders the overlay; the exact renderer, supported character canvas and control settings depend on its hardware and firmware. This is distinct from the camera cable, power supply and native system warnings.Chapter 7 · Building the Whoop
MultiGP: An FPV racing organization with local chapter and event listings. The actual event's current rules determine participation, classes and operating arrangements; a listing is not clearance to attend or fly.Chapter 1 · What FPV Actually Is
Naked GoPro: A conversion that removes or replaces parts of a stock GoPro for a particular installation. Complete carried mass, power, cooling, controls and protection depend on the exact donor camera and conversion; a generic weight allowance or stock-camera rating does not qualify the conversion.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
ND filter: An optional neutral-density filter that reduces light entering the camera. Its strength depends on actual light, supported exposure controls and intended motion/stabilization. It does not repair vibration, rolling-shutter distortion or a missing gyro-data workflow.Chapter 13 · Capture and Share — Filming What You Watched
nominal voltage: The middle-of-use label voltage, commonly 3.7 V per LiPo cell, used for pack naming rather than a precise charge target.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
open class: A racing class allowing broader equipment choices within stated limits. The actual event's rules still determine eligibility; Open does not mean any aircraft or pilot is accepted.Chapter 15 · Your First Year as an FPV Pilot
oscillation: Unwanted repeated movement caused by the control loop or vibration system feeding energy back into itself. In flight it can look like shaking, buzzing, or rapid wobble.Chapter 12 · Tuning — From Stock to Smooth
OSD (on-screen display)OSD: A live overlay of telemetry — battery voltage, link quality, flight timer, warnings — drawn over the FPV video feed so the pilot can read it without looking away from the goggles. Driven by the flight controller and configured in Betaflight; the build chapters cover layout. Used throughout the book.Chapter 3 · The Radio Link, the Video Link, and the Goggles
P notation: Parallel cell grouping inside a pack. FPV flight packs are usually described mainly by S count; P count matters when cells are paralleled to increase capacity or current capability.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
P term: The proportional term. In practical tuning language, P is stiffness: its contribution responds to the current commanded minus measured rotation rate.Chapter 12 · Tuning — From Stock to Smooth
pack: A flight battery selected for an exact aircraft configuration. Its label does not establish endurance or a safe flight duration; use the applicable battery checks, landing margin and measured results rather than a generic runtime.Chapter 1 · What FPV Actually Is
pad: An exposed copper area on a circuit board designed for soldering a wire or component lead.Chapter 7 · Building the Whoop
pagoda antenna: A compact circularly polarized antenna style common in FPV, often used on goggles or quads where size and durability matter.Chapter 3 · The Radio Link, the Video Link, and the Goggles
parallel charging: Connecting multiple packs in parallel to a charging circuit. Pack mismatch can cause uncontrolled equalization current; similar voltage alone does not establish a safe setup. This book covers the hazards, not a parallel charging procedure or permission to proceed.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
Part 107: The U.S. FAA rule framework for most non-recreational civil small-UAS operations. Payment alone does not determine applicability; some operations use other authorities, and a pilot certificate does not authorize every operation.Chapter 3 · The Radio Link, the Video Link, and the Goggles
PH2.0: A name commonly used for the small two-pin JST PH-family connector on some whoop batteries. Check the exact connector, polarity, lead and ratings; a matching-looking plug does not establish battery compatibility. Chapter 4 separates those checks from chemistry and cell count.Chapter 3 · The Radio Link, the Video Link, and the Goggles
PID: proportional-integral-derivative (the flight controller's control loop). Proportional, integral and derivative feedback terms. In the pinned Betaflight rate controller, P responds to commanded minus measured rotation rate, I accumulates that rate error with limits, and D damps changes in filtered gyro rate. Setpoint-driven feedforward is separate. Chapter 12 handles tuning depth.Chapter 1 · What FPV Actually Is
PID loop: The flight controller's rate-feedback calculation, using the latest available command and gyro data. P and I use rate error; the pinned Betaflight D path uses filtered gyro-rate change. Radio frames and PID updates have different clocks. Rate tracking is not position or altitude hold.Chapter 2 · The Physics in Plain English
pit mode: A device-specific low-output or RF-suppression state intended to reduce interference while preparing a VTX. Its controls and behavior depend on the model and firmware; it is not a universal SmartAudio/Tramp switch, proof of zero RF, or a guarantee that other pilots will not be affected. Agree permission and the system-specific RF plan before power-up; follow the documented antenna, cooling and power requirements. A mode that suppresses RF may show no picture. Do not arm or increase power to diagnose an unexplained fault.Chapter 3 · The Radio Link, the Video Link, and the Goggles
plug-and-play (PNP)PNP: A retail quad that ships pre-built but without a receiver, so the buyer installs and binds their own receiver before flying. Less common than BNF and RTF (ready-to-fly) but still a recognized retail tier.Chapter 1 · What FPV Actually Is
power loop: A vertical loop using coordinated pitch and throttle to climb, pass through an inverted segment and return to upright forward flight. Entry speed, space and throttle timing matter; full speed or one fixed throttle recipe is not the definition. Chapter 5 uses simulator-only exposure and controlled recovery, not a requirement to master a real obstacle maneuver.Chapter 2 · The Physics in Plain English
pre-flight check: A repeatable inspection and readiness check before every flight, confirming that the actual aircraft and session still meet their accepted conditions. It does not replace first-use or post-repair acceptance.Chapter 14 · Maintenance, Troubleshooting, and Crash Repair
prearm: An optional additional Betaflight arming condition, operated by a separate deliberately configured control. Verify its channel output and the full PREARM-to-ARM sequence on the actual setup. It does not replace the other arming checks or make a momentary button automatically suitable.Chapter 11 · Betaflight Deep-Dive
Presets: Betaflight App tab offering optional setting bundles that can change many CLI values at once. Eligibility depends on the exact preset revision, options, firmware and hardware, not just a build-class label. Preview changes, preserve the last accepted state and recheck the saved result.Chapter 8 · First Flights — Indoor to Park
prop direction: The prop maker's CW/CCW type and installation orientation, matched to the verified motor rotation and selected mixer. Motor numbering, spin direction and prop installation are separate checks; Chapter 8 owns the later isolated installation.Chapter 7 · Building the Whoop
prop pitch: A prop geometry measure, conventionally its theoretical advance per revolution without slip. Actual thrust, current and efficiency depend on the exact motor, prop and operating conditions. More pitch can increase load; it is not a cure for an overloaded or undersized motor/ESC/pack combination.Chapter 2 · The Physics in Plain English
propeller (prop)prop: The plastic blade(s) that move air down so the quad goes up. This book uses "prop" as the house term after first mention. In an inch-based FPV naming convention, diameter × pitch × blade-count makes 5×4.3×3 a 5-inch tri-blade with 4.3 inches of nominal pitch. Check the exact manufacturer specifications and units; naming conventions do not prove performance or compatibility. Chapter 2 covers prop pitch; build chapters cover prop choice.Chapter 1 · What FPV Actually Is
propwash: Disturbed rotor wake that the props can encounter again during a descent or direction change, varying their airflow and thrust. Resulting shaking is not a unique diagnosis; damage or control problems can overlap. This airflow is not the propeller's swept volume, the space occupied by its rotating blades; that separate geometry governs strike clearance.Chapter 2 · The Physics in Plain English
quad: A multirotor aircraft with four motors. In this book, 'quad' refers to the FPV aircraft the reader builds or flies.Chapter 1 · What FPV Actually Is
radio: The handheld transmitter used to send stick commands from the pilot to the quad.Chapter 1 · What FPV Actually Is
radio transmitter (TX): The handheld radio used by the pilot to send control commands. In this book, radio means the transmitter, not the video transmitter.Chapter 3 · The Radio Link, the Video Link, and the Goggles
rates: In Acro, settings that map roll, pitch and yaw stick positions to commanded rotational speeds. Record the rate model as well as every axis value; Actual and legacy Betaflight models use different parameters. Matching the curve does not make simulator and real-aircraft dynamics identical.Chapter 5 · Sim Before Sky
ready-to-fly (RTF): A sales-package label for an aircraft kit intended to need little assembly, not a flight-control mode. Check exact included equipment, required accessories and remaining setup/preflight requirements; an RTF package may itself be FPV.Chapter 1 · What FPV Actually Is
Rec. 709: Common shorthand for the ITU BT.709 HDTV color/signal specification, used in SDR workflows. It is not every camera profile or the only web/display output; converting to it requires an identified input and supported color path.Chapter 13 · Capture and Share — Filming What You Watched
receiver (RX)RX: The small board on the quad that receives stick commands from the radio and hands them to the flight controller. Receiver protocol must match the radio's protocol family (ELRS, Crossfire, Ghost). Chapter 3 covers the radio link in full.Chapter 1 · What FPV Actually Is
ReelSteady: The older name of GoPro's post-stabilization feature, now marketed as HyperSmooth Pro in GoPro Player. Use the exact app version, its requirements and supported GoPro camera/mode; in-camera HyperSmooth is not a universal motion-data-recording switch.Chapter 13 · Capture and Share — Filming What You Watched
Remote ID: A regulatory identification broadcast requirement for many drones in the United States under FAA Part 89; applicability depends on aircraft, use, and current rules.Chapter 1 · What FPV Actually Is
repair journal: A running record of inspections or incidents, configuration, observations, possible or established causes, evidence, unknowns, actual action or referral, parts and time, with separate acceptance outcomes.Chapter 14 · Maintenance, Troubleshooting, and Crash Repair
replace-vs-repair decision: A practical judgment about whether a damaged part is safe and economical to fix, or whether replacement is faster, safer, and more reliable.Chapter 14 · Maintenance, Troubleshooting, and Crash Repair
resource map: Betaflight assignments of processor pins to firmware functions such as motor outputs, UARTs and LEDs. Related timer/DMA allocations also constrain some protocols; a resource list is not the whole allocation map. Chapter 14 supplies the diagnostic and FC-swap context.Chapter 14 · Maintenance, Troubleshooting, and Crash Repair
RHCP: Right-hand circular polarization, the opposite circular polarization from LHCP. It is not a universal FPV default; check the exact system and antenna specifications, including whether they use linear polarization.Chapter 3 · The Radio Link, the Video Link, and the Goggles
RPM filter: Uses qualified motor-speed telemetry and the correct motor pole-count conversion to place configured notches near motor-frequency estimates and harmonics. RPM use is conditional; an accepted non-RPM setup may remain unchanged.Chapter 11 · Betaflight Deep-Dive
RSSI: received signal strength indicator. Received Signal Strength Indicator. Use the identified dBm reading for received radio power; an unlabelled RSSI percentage may use a different scale. Margin above the exact RF mode's sensitivity limit is measured in dB. RSSI and decoded-packet LQ describe different things; neither a low LQ value nor its relationship to RSSI uniquely diagnoses interference.Chapter 3 · The Radio Link, the Video Link, and the Goggles
S notation: Number of series positions in a pack. With one cell per position (1P), 1S, 4S and 6S contain one, four and six cells respectively. Parallel groups can increase the physical cell count without changing S. Series positions add voltage; P describes the parallel grouping.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
setpoint: The target rotation rate or attitude the FC is trying to achieve based on pilot stick input and flight mode.Chapter 2 · The Physics in Plain English
simulator: Desktop software used to practice FPV flying with the radio before risking a real quad.Chapter 1 · What FPV Actually Is
SmartAudio: A serial protocol used between a flight controller and a VTX to set supported channel, band, power and pit-mode options. Use only the protocol and version supported by the exact VTX. It is not interchangeable with Tramp or MSP, and does not carry the Betaflight DisplayPort overlay.Chapter 3 · The Radio Link, the Video Link, and the Goggles
smoke stopper: A current-limiting or cutoff device whose exact design/rating must suit the documented bench source's actual voltage and charge state, polarity, connectors and test load. A storage-state bench route does not authorize a fully charged pack on the same device. It may reduce some fault damage but does not guarantee reverse-polarity or complete protection. A trip can be overload or a fault; an untripped device is not a safety verdict.Chapter 10 · Building the Quad
smoke test: An informal name for a qualified first-power check after isolated inspection, with props removed and documented voltage, polarity, protection/load and abort conditions. Smoke is a failure, never an intended stimulus. Tones, no smoke or an untripped limiter do not establish electrical or flight acceptance.Chapter 7 · Building the Whoop
solder wick: Braided copper used to absorb excess solder from a pad or bridge.Chapter 7 · Building the Whoop
spec class: A racing class with specified equipment or performance constraints. Check the particular event's exact rules; Spec does not mean novice eligibility.Chapter 15 · Your First Year as an FPV Pilot
Split-S: A freestyle maneuver consisting of a half-roll to inverted followed by a pitch-back half-loop that exits lower and in the opposite direction. It needs sufficient height and a clear lower exit corridor; it is not a universal recovery from an inverted attitude. Optional simulator-only practice in Chapter 5, not a first-flight requirement.Chapter 2 · The Physics in Plain English
squashed X frame: In this book's convention, wider side-to-side than fore-aft motor-center spacing. Manufacturer terms vary; use the exact drawing. It is not a performance midpoint between true X and deadcat.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
stator size: The diameter and height of the motor stator, commonly written as numbers such as 0802 or 1002. It gives a rough sense of motor torque, weight, and prop compatibility.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
storage voltage: The storage target specified for the exact battery chemistry and charger program. Values such as 3.80 or 3.85 V per cell are examples, not interchangeable universal settings or proof that a pack is healthy.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
strain relief: A mechanical support method that prevents a wire, connector, or ribbon cable from taking crash or handling force directly at the solder joint or fragile plug.Chapter 3 · The Radio Link, the Video Link, and the Goggles
sub-250 g toothpick: A lightweight open-prop FPV quad in the 3-inch to 4-inch prop class, sized to keep AUW below 250 g for small-field flying and EU Open A1 planning. For a privately built aircraft, A1 also requires maximum operating speed below 19 m/s and every other applicable condition. The book's selected Build Two toothpick is a cruising 4S/1404 2750 KV planning route, not a definition of every toothpick. Its component plan totals 232 g; weigh the completed aircraft with its actual carried pack.Chapter 1 · What FPV Actually Is
target hex: The compiled Betaflight firmware file for a specific flight controller target; flashing the wrong target can leave hardware features unmapped or unusable.Chapter 14 · Maintenance, Troubleshooting, and Crash Repair
telemetry: Data sent back from the quad to the radio, such as receiver link quality, signal readings and battery voltage when supported and configured. The radio's sensors and spoken alarms require their own setup and verification. Loss of returned telemetry is not by itself proof of lost uplink control or FC failsafe.Chapter 3 · The Radio Link, the Video Link, and the Goggles
threadlocker: A thread-retaining adhesive used only where the exact fastener, threaded materials and equipment instructions permit the identified product. Color or strength alone does not establish compatibility, amount, cure or torque. Some products can stress-crack plastics; keep adhesive out of bearings, windings and electronics. TPU surrounding a metal insert does not by itself identify the threaded joint. Loctite is a brand, not one formula.Chapter 10 · Building the Quad
throttle management: The habit of using small, timed throttle changes to control altitude and momentum instead of stabbing the throttle after the quad is already falling.Chapter 5 · Sim Before Sky
thrust: The force a motor-and-prop combination produces by pushing air. A conventional quad's thrust direction is body-relative, so tilt changes its vertical component. Net vertical force changes vertical velocity; upward net force can slow a descent and does not by itself prove the quad is climbing.Chapter 2 · The Physics in Plain English
thrust-to-weight ratio: Total thrust divided by weight, with both expressed as forces. The common table shortcut divides thrust in gram-force by AUW mass in grams under standard gravity. Name the exact test conditions and distinguish a required ratio from demonstrated data; a sizing target is not guaranteed flight performance.Chapter 2 · The Physics in Plain English
timer conflict: A conflict between incompatible uses of a hardware timer. Its relevance depends on the exact board and firmware implementation; a missing motor output or telemetry value does not uniquely diagnose it.Chapter 14 · Maintenance, Troubleshooting, and Crash Repair
tinning: Coating a wire end, soldering iron tip, or pad with a small amount of solder before making the final joint.Chapter 7 · Building the Whoop
tinywhoopwhoop: A small FPV quad with propeller ducts or guards, often used for indoor practice. The name does not establish durability, safe operating conditions or flying mass. Chapter 6 keeps separate analog and named digital planning carts; use each selected component ledger and later measured AUW, not a generic class range or automatic route from a goggle brand. After first introduction, "whoop" is acceptable as informal shorthand.Chapter 1 · What FPV Actually Is
torque: A turning effect, or moment, about an axis. Prop reaction torques act on the aircraft; their net yaw effect must balance for steady non-rotating hover. Roll and pitch moments also depend on each thrust force's lever arm.Chapter 2 · The Physics in Plain English
TPU: thermoplastic polyurethane (flexible 3D-printing filament). Thermoplastic polyurethane, a flexible 3D-printing material often used for antenna mounts, camera wedges, ducts, and small protective parts. The material name alone does not specify a part's stiffness, damping, retention or suitability for a particular camera, fastener or installation.Chapter 6 · Picking Your First Quad — The Whoop Build Sheet
training log: A simple record of date, duration, drills attempted, drills landed, and rate/expo settings used so progress is visible instead of guessed.Chapter 5 · Sim Before Sky
Tramp: A VTX-control serial protocol distinct from SmartAudio and MSP. The exact VTX must support it; choosing the name in a menu cannot make an unsupported device use it. Check that model's wiring, firmware and controls.Chapter 3 · The Radio Link, the Video Link, and the Goggles
transponder: An electronic device carried by an aircraft for detection by a compatible race-timing system. It is not a pilot account ID or an assigned VTX channel; confirm the event's actual timing requirements before choosing equipment.Chapter 15 · Your First Year as an FPV Pilot
true X frame: In this book's geometric convention, four motor centers at the corners of a square. Equal fore-aft and side-to-side spacing does not establish the assembled center of gravity, inertia or handling.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
Turtle mode: An optional, equipment-dependent crash-recovery function, called Flip Over After Crash in Betaflight, that uses supported ESC motor-direction commands to try to right an inverted quad. It is not a simulator reset or a first-flight requirement. Chapter 8 explains qualification, safe retrieval and the conditions in which powered recovery must not be attempted.Chapter 5 · Sim Before Sky
TVS diode: A transient voltage suppression diode that clamps voltage spikes on a power rail, often used as extra protection against hot-plug and motor-induced transients.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
twisted pair: Two conductors twisted around one another. Their electrical roles and the installation determine whether pairing is appropriate and how it affects interference; twisting alone proves neither correct wiring nor noise reduction. Three motor phases are not a supply/return pair, UART TX/RX are not a differential pair, and camera coax is a different cable construction. Follow the exact equipment's grouping, bend and strain-relief instructions.Chapter 10 · Building the Quad
UART: universal asynchronous receiver/transmitter (a serial port). A hardware asynchronous serial interface. Flight-controller UART connections commonly expose transmit (TX) and receive (RX) signals with a shared ground; they are not a power rail or an RX/TX differential pair. Count actual connected devices and reserved onboard services using the exact board map. A supported MSP/DisplayPort combination may share one UART; unrelated peripherals cannot simply be combined on it.Chapter 3 · The Radio Link, the Video Link, and the Goggles
unibody frame: Arms and the central lower plate form one structural piece. Damage to an arm may require replacement of that piece under maker criteria; the construction label does not establish mass, stiffness or repair price.Chapter 9 · Picking Build Two — 5-inch Freestyle or Sub-250 g Toothpick
venting: Release of gas or vapour from a failing battery. It can accompany dangerous heating and fire. Do not touch, carry or bag an actively failing pack; move people away, avoid fumes, evacuate and call emergency services.Chapter 4 · Power — LiPos, Chargers, and Not Burning Your House Down
visual line of sight (VLOS)VLOS: Direct sight of the aircraft without vision-extending equipment; corrective lenses are allowed. A camera feed is not VLOS. The applicable rules determine pilot, control-person and observer duties; an observer is not a universal substitute for every duty or Remote ID condition. For this book's outdoor FPV exercises, brief an observer alongside the pilot and complete Chapter 8's go/no-go record. Chapter 15 separates the U.S. and EU routes. Unresolved requirements mean no flight.Chapter 1 · What FPV Actually Is
VRX (video receiver)VRX: The receiving radio in an FPV video system, mounted in the goggles or as a separate unit that feeds a display. Its radio side must support the transmitter's system and mode. An external HDMI VRX also needs a compatible display input, video mode, cable and power supply; it does not make that display's built-in radio cross-compatible with another digital ecosystem.Chapter 3 · The Radio Link, the Video Link, and the Goggles
VTX (video transmitter)VTX: The airborne transmitter that sends camera video to a compatible receiver/display system. Both analog and digital designs vary in physical integration; a camera and VTX can be separate connected components. Chapter 3 explains the selected video families and their compatibility requirements.Chapter 1 · What FPV Actually Is
Walksnail Avatar: A digital FPV video ecosystem from Caddx/Walksnail that offers HD video, multiple air unit sizes, and goggles/VRX options outside the DJI ecosystem.Chapter 1 · What FPV Actually Is
Walksnail Avatar Mini: A name used across small Walksnail Avatar VTX/camera kits. Record the exact Mini 1S version, board and camera before relying on voltage, storage, mass or mounting claims; a family name does not identify interchangeable parts.Chapter 1 · What FPV Actually Is
wallet-card: A printed, field-bag checklist small enough to laminate or sleeve, used as a fast reminder when conditions, nerves, or friends at the field make memory unreliable.Chapter 14 · Maintenance, Troubleshooting, and Crash Repair
wetting: The way molten solder flows onto and bonds with the metal surfaces of the pad and wire instead of sitting on top as a blob.Chapter 7 · Building the Whoop
X-class: A very large high-power racing or demonstration quad category, far outside the beginner build path.Chapter 1 · What FPV Actually Is
XT30: A compact power-connector family used on small FPV builds. Match the exact connector variant and mating pair. Current capacity depends on the manufacturer's rating conditions and the complete installed connection, not the XT30 name alone.Chapter 3 · The Radio Link, the Video Link, and the Goggles
XT60: A battery connector type used by this book's five-inch route and some charger leads. Cell count alone does not identify the connector; match the exact pack, aircraft lead and charger connection.Chapter 3 · The Radio Link, the Video Link, and the Goggles