FC + ESC Stacks Explained

A "stack" is the electronic core of a quad: a flight controller (FC) and a 4-in-1 ESC bolted on top of each other, connected by a ribbon or plug. Buying them as a matched stack avoids the wiring-diagram archaeology of mixing brands.

Reading a stack name

"SpeedyBee F405 V4 55A" decodes as:

F405 — the FC's microcontroller (MCU). F4 family: enough for everything Betaflight does today. F7 adds UARTs and headroom, H7 is future-proofing. For a first build, the MCU matters less than the shop pages imply.
55A — continuous current rating per motor of the 4-in-1 ESC. A 5" freestyle quad peaks at 40-60 A per motor for moments; a 45-55A ESC covers 5" builds with margin. 7" cruisers pull less peak current than racing 5"s despite the bigger props.
V4 — board revision. Check the revision you're actually buying; layouts and BEC specs shift between revisions.

Mounting patterns: the compatibility that actually bites

Stacks mount on standoffs through 4 holes. The hole spacing must match the frame:

Pattern	Where it lives
30.5x30.5 mm	Standard 5"+ frames
25.5x25.5 mm (whoop)	3-4" and toothpicks
20x20 mm	Micro/racing builds
16x16 / 12x12 mm	Whoops, tiny AIOs

Our stacks section lists the mount size and MCU for every board, so you can filter what physically fits before comparing specs.

AIO boards: the stack, flattened

An AIO (all-in-one) merges FC and ESC onto one board - lighter, one mounting deck, and standard on whoops and sub-250 g builds. The trade: a burned ESC means replacing the whole board. Sub-20A AIOs power whoops; 35-45A AIOs now fly full 5" freestyle at ~10 g saved.

What to check before buying

Mount pattern matches the frame (see table above).
ESC rating vs your motors - our motor pages' bench tables show the max current the manufacturer measured per motor; four of those at once is the load your ESC must survive. Cross-check with the current draw calculator.
Voltage rating covers your cells - "3-6S" on the ESC must include the pack you fly (battery basics).
Gyro + firmware target - check the FC's Betaflight target exists and is current before buying, not after.