What Blackbox Records

Betaflight Blackbox logs several data streams simultaneously at 4kHz (or your PID loop rate). The key channels for tuning are: gyro data (what the sensor measured), setpoint (what your sticks commanded), and PID error (the difference between where the quad was and where it should have been). Motor output is also logged, which shows whether your ESCs are being driven to extremes.

This data tells you a causal story: stick moved → setpoint changed → PID error appeared → motor output responded → gyro responded. When that chain is smooth and proportional, your tune is good. When it's noisy, delayed, or oscillating, you know exactly where in the chain the problem is.

Getting Started: Tools You Need

1. Enable Blackbox in Betaflight Configurator. Configuration tab → Blackbox → enable and set to "Internal flash" (if your FC has onboard storage) or SD card. Set debug mode to "GYRO_SCALED" for most tuning work.
2. Download Betaflight Blackbox Explorer. Free, open source, available at betaflight.com. This is the tool for reading the log files.
3. Copy the log off the FC. For flash storage: Tools → "Save Blackbox data to file" in Betaflight Configurator while connected. For SD card: remove and copy the file directly.
4. Open in Blackbox Explorer. Load the file. You'll see a time-series graph of all logged channels.

The Three Traces to Look at First

1. Gyro (Pre-Filter)

The raw gyro data before any filtering. Look for the noise floor - the baseline vibration level when the quad is flying steady. High noise floor means your frame is transmitting a lot of vibration into the gyro. Low noise floor means clean mechanical and aerodynamic operation. Compare across the RPM range: noise that spikes at specific throttle positions indicates resonant frequencies - exactly what RPM filtering targets.

2. PID Error

This is the gap between where Betaflight wanted the quad to be and where it actually was. Large PID error during fast maneuvers is normal. PID error that oscillates at high frequency even during stable flight indicates too much P-term or too little D-term. PID error that's slow to decay after a disturbance indicates I-term issues or frame flex.

3. Motor Output

Motors should not be hitting maximum output (100%) during normal freestyle flying except at hard punch-outs. If motors are hitting max output regularly during maneuvers, you either need more power (battery, motors) or your PID loop is working too hard due to noise. Motors rapidly toggling between high and low values during stable flight indicates oscillation caused by too-high P or D terms.

Reading Prop Wash in Blackbox

Prop wash - the oscillation during descents with throttle chop - is one of the clearest signatures in Blackbox. It shows up as high-frequency oscillation in the gyro trace and corresponding motor output variations when you chop throttle during a descent. Classic prop wash fix: increase D-term slightly, reduce P-term slightly. The Blackbox trace shows you exactly which axis is most affected (usually roll and pitch together) and how severe it is.

The Frame Signature in Blackbox

Every frame has a noise signature that shows up in the pre-filter gyro data. A stiff, well-machined frame produces a flat noise floor with occasional clean spikes at motor fundamental frequencies - exactly what RPM filtering addresses. A frame with loose joints or inconsistent carbon produces a broader, higher noise floor with multiple resonant peaks that are harder to filter cleanly.

Looking at the pre-filter gyro trace across the throttle range is the most objective way to evaluate a frame's mechanical quality. You can do it yourself, on your own quad, with free software.