Whoop Blackbox Logging: Record a Short Betaflight Log, Read It in Your Browser
Short version: tick BLACKBOX, log to onboard flash at 1/4 rate (about 2 kHz on an 8 kHz loop; 1.6 kHz on a BMI270 gyro), drop fields you don't need, erase the flash, fly one short pack of clean rolls, flips and throttle punches, then pull the .bbl over Mass Storage mode and drop it on the QuadMath Blackbox Analyzer. Nothing uploads.
For 65–75mm whoops after an Air65 PID tune left you with wobble, oscillation or propwash and you want data, not guesses. SD-card loggers, deep filter tuning and 5" quads are out of scope.
Your whoop already has a logger, it's just small
Most whoop AIOs log to onboard flash. Read free space in the Configurator's Blackbox tab. Betaflight says the default 1/4 rate is typically enough for a few minutes of flight, and once the flash is full, logging simply stops. Oscar Liang puts a 16MB chip at roughly 5–10 minutes. My whoops show 16MB in that tab; other AIOs can be smaller, so read your own number. Erase before every session.
Settings: 1/4 rate, trim fields, debug for noise
Keep the 1/4 default. Betaflight's fractions run from 1/1 to 1/16; 1/8 (about 1 kHz) is fine for PID work, and 1/16 only shows gross problems. On a BMI270 gyro, Oscar notes 1.6 kHz is the ceiling, so don't chase 2 kHz.
Oscar says untick fields you won't read: accelerometer, attitude, RSSI,
battery, GPS. Set debug_mode = GYRO_SCALED if you want the
analyzer's unfiltered-gyro noise chart; leave it at NONE if flash is tight.
If you only want part of a flight, add a Blackbox switch in the Modes tab
(radio and AUX setup).
Configurator basics:
first tiny whoop setup.
Fly one short, boring, deliberate pack
Use Oscar's move list, cut for indoors: hover a few seconds, two or three smooth throttle ramps, isolated rolls, flips and yaw spins in both directions, a few throttle pumps, then a couple of split-S or 180s to provoke propwash. Land; the flash fills fast.
Get the file off the quad
In the Blackbox tab, click Activate Mass Storage Device Mode, then copy the .bbl from the drive that appears. It's faster than "Save flash to file" (Oscar). You get one file per power cycle, and each arm inside it is a sub-log. Erase the flash when you're done.
Read it on QuadMath Blackbox
Drop the .bbl, .bfl or .txt on /blackbox.html. Multi-log flash dumps are fine; pick the flight after. It decodes in your browser and the log is never uploaded.
You get findings ranked worst first, each saying what was measured, what it usually means and one thing to try. Charts cover gyro vs setpoint per axis with throttle and a filtered gyro noise spectrum with peaks marked (in-flight only), plus the unfiltered spectrum when you logged GYRO_SCALED. You also get suggested CLI to paste one change at a time and a metrics JSON. The optional Tune Advisor sends only those findings plus firmware, board, craft name and debug mode from the header, never the log, with ten reads an hour per person.
For a deeper dig, Betaflight Blackbox Explorer and PIDtoolbox are the standard tools.
Change one thing, log again
As the analyzer puts it: a log gives direction, not magnitude. Change one thing, fly, log again. Compare your numbers against published cards in the Tune Database and the Air65 PID tune.