File formats

Folder names below are inside Lothal’s data folder. Where files live gives its location on each operating system.

File	What writes it	What reads it	Where
.lothal	Lothal, automatically, as you work	Lothal (Projects screen, Open…)	builds/ (deleted drones in builds/trash/), or wherever you opened it from
.frame.json	The frame designer’s Save	The frame designer (shelf, Open)	frames/
.blade.json	The blade designer’s Save	The blade designer (shelf)	blades/
flight-YYYYMMDD-HHMMSS.csv	Sim, when you record with R	Studio, and the tools/ scripts	logs/
YYYY-MM-DD-<drone>.md	Config → Sheet → Export sheet	Any Markdown or text viewer	sheets/
.svg	The frame designer’s print and cut sheets	Browsers, vector editors, printers; the frame designer’s Import	exports/
.dxf	The frame designer’s cut file	CAD and CAM programs, cutting services; the frame designer’s Import	exports/
.stl	Frame assembly, motor mount stack, prop guard, printed parts	Slicers and 3D programs	exports/, and printed parts also inside the .lothal file
.html	The frame designer’s build sheet	Browsers (open and print)	exports/

The .lothal file

A .lothal file is a zip, so you can rename a copy to .zip and look inside:

Inside	What it is
MANIFEST.json	What kind of file this is and which Lothal wrote it.
project.json	The drone: its name, its parts and its settings.
parts/custom_parts.json	Copies of the custom parts this drone uses.
printed/	One STL per printed-part export, each matching a print record in project.json.

The flight-log CSV

• Line 1 is # followed by a JSON header: the aircraft that flew, the tune, the gyro, the sample rate, the duration, the number of crash restarts, the column list and their units.
• Line 2 is the column names.
• Then one row per physics step: time; for each motor its RPM, thrust, torque, current and blade-pass frequency; total thrust, current, live voltage and charge used; position, velocity and orientation; the true rotation rate (omega_*) and the gyro’s reading (gyro_*); body acceleration, airspeed and g-force; each motor’s electrical frequency and tip speed; and weight.

Readers should select columns by name, not by position: new columns are added at the end.

Settings files

Lothal also keeps these JSON files in its data folder. You do not normally edit them.

File	Holds
custom_parts.json	Your custom parts.
assembly_tweaks.json	The fit settings (shims, standoffs, pack position, GPS mast, camera uptilt), for all drones.
pack_charge.json	How much charge each pack has, and the charging speed.
pid_tunes.json	Tunes you have changed by hand.
sites.json, courses.json, conditions.json	Field sites, courses and conditions.
best_laps.json	Best lap times.
app_settings.json	App settings, such as recent drones.

A damaged settings file does not stop Lothal starting.

Coming in the next release

Not in v0.3.0. The frame designer’s Build sheet (HTML) export writes a self-contained HTML page to exports/, next to the other exports. The exported SVG and DXF cut files also carry a note under each plate: its label, thickness, material, how many to cut, the cutting bit, and any countersunk holes. The DXF puts those notes on a NOTES layer, which is text and not a cut, and screw holes marked countersunk on a <ROLE>_COUNTERSINK layer. Frame documents (.frame.json) also store the cutting bit (cutting_bit_mm), which screw holes are countersunk, and where any upright side plate stands.