Explainer

What a Betaflight blackbox analyzer can actually measure

A blackbox log is a recording of what the flight controller believed and what the gyro felt. An analyzer's job is to turn that into claims precise enough to be wrong — and to say which claims it cannot make.

What is in the file

• The header: firmware revision, PID and filter values, loop time, logging rate, and the battery reference.
• The traces: gyro, setpoint, PID terms, motor outputs, throttle and RC command, per frame.
• Nothing about the airframe: no prop size, no weight, no motor KV, no camera.

The header is why a tune can start from your values instead of a default. It is also why a 4.2 log must be tuned in CLI integers: that firmware has no simplified slider multipliers to move.

What can be measured

Measurement	What it needs	What it can support
Step response	A held stick step on the axis, logged at a useful rate	Rise time, overshoot, settling and damping verdicts — if the step is chart-grade
Noise spectrum	Enough clean flight time for a stable estimate	Peak frequencies and their likely source, not a filter value on its own
Motor balance	Motor outputs during loaded flight	Whether one corner works harder, which suggests a mechanical cause first
Log quality	The whole file	How much the other measurements are worth

What cannot be measured

Whether the frame is cracked. Whether the tune will feel right to you. Whether the battery was tired. A log records the symptom of those things, and an analyzer that presents a symptom as a cause is guessing with extra steps.

Why the order matters

Quality first, then measurements, then settings. Reversing it produces the familiar result: a tune built on a log that never contained a step input, adjusted until the plots look tidy.

Easyquadtune is not affiliated with Betaflight. Published 2026-10-21. Measurements come from the maintainer's own flight logs; an example is illustrative of the method, not a tune for your aircraft.