The standards, and what actually separates them.
Buildlas can tell you that two parts will not work together. These pages explain what they disagree about: which differences are absolute, which have an adapter, and where the names used in shops are misleading enough to cost you money.
- Which goggles work with which video transmitter?Video systems
Analog, DJI, Walksnail, HDZero and OpenIPC are five separate video systems, not five brands of one thing. Choosing one is the decision that constrains the most other choices, and it is close to irreversible.
Decides: Video transmitter, FPV camera, Goggles, Complete drone - Why will my radio not bind to this receiver?Control links and bands
The link from your hands to the aircraft is two separate agreements: the RF protocol between radio and receiver, and the serial protocol between receiver and flight controller. Confusing them is the most common source of "it should work and it does not".
Decides: Radio, Receiver, Flight controller, Flight stack - Will this board actually bolt into this frame?Mounting patterns
Stack and motor mounting patterns are measured in millimetres between screw holes. The numbers are simple; the names given to them in shops are not, and two of the commonest names are rounded off by half a millimetre.
Decides: Frame, Flight stack, Flight controller, ESC, AIO board, Motors - Which battery, and will the plug even fit?Batteries and connectors
Cell count sets the voltage everything else has to tolerate, and the connector sets how much current can get through before it becomes the weakest part of the aircraft.
Decides: Battery, ESC, Flight stack, Charger, Motors - What do nano, micro, mini and full actually measure?Camera sizes
FPV camera sizes are four named mounting widths. Unlike most fit questions, this one usually has a remedy, because adapter brackets between the sizes are stock items.
Decides: FPV camera, Frame - What does 2207 mean, and which KV do I want?Motors and propellers
Motor size is a four-digit code for two physical measurements, and KV is not a quality rating. Both are read against the battery and the propeller rather than on their own.
Decides: Motors, Propellers, Battery, Frame - What do the regulations actually attach to?How the rules are structured
European drone rules hang off three things: the weight of the aircraft, whether it carries a camera, and whether anybody built it themselves. This explains the structure. What applies to you depends on your country, and only your country's regulator can tell you that.
Decides: Complete drone, Goggles, Video transmitter, Frame
The rules themselves
Every compatibility verdict in the planner comes from a named rule with a stated reason. They are all published, with what each one reads and what it does when a specification is missing.
Read the rulesEverything these pages are built on
The complete list, once. This is a short bibliography and it leans on a small number of authors: that is worth seeing rather than disguising. Where two sources disagreed, or where only one could be found for a figure, the guide says so at the point it matters instead of averaging them into a confident sentence.
- Crossfire and ELRS RC SystemsArduPilot documentation · Project documentation · read 2026-07-27
- Is BVLOS possible for flying drones with goggles (FPV)?EASA · Regulator · read 2026-07-27
- Open category: frequently asked questionsEASA · Regulator · read 2026-07-27
- Open category: training and the A1/A3 and A2 certificatesEASA · Regulator · read 2026-08-11
- Receiver Serial ProtocolsExpressLRS documentation · Project documentation · read 2026-07-27
- 868 MHz Listen-Before-Talk discussionExpressLRS on GitHub · Project documentation · read 2026-07-27
- Choose the Best FPV CameraOscar Liang · Editorial · read 2026-07-27
- How to Choose an ExpressLRS ReceiverOscar Liang · Editorial · read 2026-07-27
- How to Choose FPV Drone MotorsOscar Liang · Editorial · read 2026-07-27
- Testing A30, BT2.0, PH2.0, GNB27 and XT30 connectorsOscar Liang · Editorial · read 2026-07-27
- Which FPV System Should You Buy in 2026?Oscar Liang · Editorial · read 2026-07-27
- Flight controller mount adapter, 30.5 / 25.5 / 20 / 16 mmSpeedyFPV · Manufacturer · read 2026-07-27
- DrönareTransportstyrelsen · Regulator · read 2026-07-27
- EASA Drone Regulations 2026: Flying FPV in the Open and Specific CategoriesUAVMODEL · Editorial · read 2026-07-27
- EU EASA Drone Regulations 2026: Open Category A1/A2/A3 and C-class labelsUAVMODEL · Editorial · read 2026-07-27
- FPV Drone Receiver Protocols: SBUS, CRSF, F.Port and IBUSUAVMODEL · Editorial · read 2026-07-27
- VTX Power Limits by Country: FCC, CE and international FPV complianceUAVMODEL · Editorial · read 2026-07-27
- VTX Power Output Explained: 25 mW to 1 W comparedUnmanned Tech · Editorial · read 2026-07-27