RotorLab logo RotorLabDocs

Compare

Compare, at https://rotorlab.app/compare, takes two flights of the same aircraft and says what changed between them: what was altered in the configuration, how the measurements moved, and which findings appeared or went away. It is the question you ask after a repair or a tuning session: I fixed something, did it work, and did I break anything else?

It compares flight logs against flight logs. It is deliberately not a line-by-line diff of the files: two flights share no records at all, so that would report everything as different and tell you nothing. Compare requires the Crash Analyzer to be enabled on your account, because each side of the comparison is a full crash analysis. See Crash Analyzer for how to enable it.

Selecting the two sides#

The picker has two tabs:

  • Upload two logs. Drop a .bin, .tlog or .ulg file into each of the two slots, Earlier flight on the left and Later flight on the right. Each file is analyzed as you drop it, and the slot fills in with the aircraft, firmware and log duration.
  • Pick from an aircraft. Choose an aircraft from your register, then pick the earlier and later flight from its record. Only flights filed with a log carry a stored analysis, so only those appear in the pickers.

Order matters: the left flight is the earlier one, so every change reads as what happened between then and now. Press Compare when both sides are set.

Reading the results#

The results open with an identity card. Compare checks whether the two logs look like the same airframe (vehicle type, frame class and type, motor count) and says what disagrees if they do not. A mismatch is reported, never enforced, because a rebuilt airframe legitimately reads that way. A firmware change between the flights is called out separately, since a firmware change can move tuning, filtering and failsafe behavior all at once.

Then four sections:

  • What changed. The headline cards, most serious first: findings that appeared, configuration parameters that changed, measurements that moved the wrong way, findings that resolved. When nothing of consequence changed, it says so plainly, because that is a result, not an absence.
  • Measurements. A table of every comparable measurement with the earlier value, the later value, and the change, marked worse or better where a direction is meaningful. The set covers vibration peak and mean, accelerometer clipping, motor output spread, pack internal resistance (total and per cell), sag under load, lowest pack voltage, peak and mean current, hover throttle, mean throttle, worst estimator innovation, minimum satellites, worst HDOP, compass field and its correlation with throttle, and time armed. A measurement has to clear both an absolute and a relative threshold to be called a change, so ordinary flight-to-flight variation stays quiet. Anything present in only one flight, physically impossible, or flagged by the analysis itself as an unreliable fit is listed under Not comparable with the reason, rather than shown as a change from nothing.
  • Findings. What appeared in the later flight, what is no longer present, and what persists in both.
  • Configuration. The parameters that changed, with the old and new value of each. Values that drift on their own (learned hover throttle, compass offsets, ground pressure) are excluded, so an entry here means somebody changed a setting.

Every comparison ends with the same caveat: two flights are not a controlled experiment. A short hover and a full mission differ on nearly every measurement for reasons that have nothing to do with the aircraft's condition, so read a change alongside what was actually flown.

Typical uses#

  • After a repair: confirm the finding that prompted it is gone, and that nothing new appeared.
  • After a settings or firmware change: see exactly which parameters differ and whether behavior moved with them.
  • Watching wear: compare a fresh flight against an older baseline and look for pack resistance, motor spread or vibration trending the wrong way. For trends across many flights, use Fleet health instead.

Downloading the report#

Press Download report (PDF) to save the comparison as a document for a maintenance record. The document is built from the comparison on screen, so the two cannot disagree. Compare two others returns you to the picker.