Flight controllers

Ask five builders what matters most in a flight controller and four will start talking about the processor. That is the wrong end of the decision. Before a chip generation matters at all, the board has to physically bolt to the frame you already chose, and it has to have enough serial ports left over for everything else on the quad that needs to talk to it. Those two constraints eliminate more boards than any spec sheet comparison does, and they are also the two things beginners skip past to get to the part that looks like shopping for a processor.

The mounting pattern comes first, because the frame decides it

A flight controller bolts to a frame's standoffs through a square pattern of mounting holes, and the frame fixes that pattern before you have opened a single flight controller's spec sheet. Three patterns cover almost everything sold today.

• 30.5 x 30.5 mmM3 hardware, the original full-size pattern
• 20 x 20 mmM2 hardware, the compact pattern
• 16 x 16 mmM2 hardware, the whoop and micro pattern

Adapter plates exist to step a smaller board up to a larger pattern, or the reverse, and they are a legitimate way to reuse a board across frames. But an adapter adds stack height, another set of standoffs, and another joint that can flex on a hard landing, so treat it as a workaround, not a default. The straightforward path is to match the board to what the frame was built for.

What the processor generation changes, and what it does not

Betaflight boards are commonly sold by their STM32 chip: F4, F7 or H7.

• F4 (STM32F405)168 MHz
• F7 (STM32F722 / F745 / F765)216 MHz, hardware inversion on every UART
• H7 (STM32H743)480 MHz

Here is the part the marketing skips: none of that changes how a quad flies as much as the number suggests. Betaflight's own recommended looptime is 4 kHz for an F4 board and 8 kHz for F7 or H7, and once each chip is running at the loop rate it was built for, Oscar Liang's own comparison of F4 and F7 boards found the difference "so small most people wouldn't be able to tell them apart in a blind test." A faster chip buys headroom, for RPM filtering across more motor poles, for a busier OSD, for running more Betaflight features at once without CPU load warnings, but it does not fix a bad tune. Most builders are not limited by what their processor can compute.

The gyro is what actually shapes the tune

If one part of the board changes how the quad feels in the air, it is the gyro, not the processor. Betaflight's PID loop reads the gyro at high frequency and has to filter out whatever noise the sensor itself produces before it can react to it. A noisier gyro forces heavier filtering, and filtering is a trade: it smooths the signal, but it also delays it, and that delay is what a pilot feels as a quad that is not quite there on a stick input. A cleaner sensor generation needs less filtering to reach the same noise floor, which is why gyro choice, not clock speed, is the spec that changes what a tune has to fight against. It also means a recent gyro model in an older, well-understood chip generation is not a downgrade.

UARTs are the budget beginners spend without noticing

Every serial device on the quad needs its own UART, and a board's mounting pattern says nothing about how many it has. This is where a first build commonly runs out of room.

• Receiver1 UART, unless it binds over SPI directly to the FC
• Video transmitter1 UART, for VTX control such as SmartAudio or Tramp
• GPS module1 UART, for return-to-home and position on the OSD
• Digital HD camera system1 UART, for the camera menu and OSD data
• ESC telemetry1 UART, on setups that do not share it with the motor signal

Add those up before choosing a board, not after. A four-UART F4 board is plenty for a receiver, a VTX and ESC telemetry. It is not enough once GPS and a digital HD system are both on the wishlist, and finding that out mid-build means either dropping a peripheral or starting over on a bigger board.

Buy the stack, not just the flight controller

"Stack" is the FPV term for a flight controller and its four-in-one ESC sold, and usually bolted, together as one matched pair. The reason to buy them that way rather than mixing brands is not marketing, it is the connector between them. Two boards can share the same chip and the same mounting pattern and still put the wires in a different order on the direct-connect header. Oscar Liang's own build guidance is blunt about it: mix manufacturers and "the connector pinouts are often different, which means you have to cross-check the wiring and re-pin the connector manually," with a wrongly seated harness capable of putting battery voltage onto a signal pad. A matched stack from one manufacturer sidesteps that inspection entirely, which is the whole point of buying one.

The ESC side of that pairing, current rating, motor pole count, firmware, is its own decision. See motors and ESCs for that half of the stack.

Betaflight, and why the target matters more than the headline spec

Betaflight is the firmware almost everyone in this hobby ends up running, and it supports STM32 F4, F7 and H7 chips. What decides whether a specific board works well with it is not the chip family but the target: the firmware build that maps Betaflight's generic code onto that board's exact pin layout, sensors and peripherals. Betaflight ships targets two ways, as a dedicated target built for one specific board, or a unified target that covers several boards sharing a chip and leans on the manufacturer's own default settings layered on top. Where both exist for a board, the dedicated target is generally the safer out-of-the-box choice.

The practical consequence: before buying a board, check that it has an actively maintained target, not just a chip generation you recognise. A board with no target, or one dropped from recent Betaflight releases, is a worse buy than an older board with excellent support, whatever the clock speed says.

What actually limits most builds

None of this is an argument for buying the cheapest board that fits. Build quality, solder joints, and a manufacturer that answers a support ticket all matter. But the honest ranking, in order, is: does it fit the frame, does it have the UARTs the build needs, does it pair cleanly with the ESC, and does it have real firmware support. Processor generation is the last of these, not the first, and a faster chip does not make a badly tuned quad fly well.

This domain sold its own flight controller once, the Flux, alongside a Kamikaze F4X, back when it was Mode 2 FPV, before the site went offline around 2020. Neither is documented beyond having existed; see the archive page for what is and is not known about it.

For the frame side of this decision, start with frames. For everything else in the stack, from KV to current rating, see motors and ESCs, or go back to the components overview.