Adding a part

A custom part in the app

For a part that is not in the catalog, add it yourself in Lab.

• In the part finder for frames, motors, propellers, packs, ESCs or flight controllers, click New custom … (for example New custom motor…). A form asks for the part’s figures.
• For cameras, video transmitters, antennas, receivers, GPS modules and buzzers, use New custom… on the Electronics or Link rail.
• A propeller can also come from the blade designer with Publish as propeller.

Every custom part needs a mass greater than zero, a name, and a source: where its numbers came from (a product page, your kitchen scale). Delete in the finder removes one of your custom parts; it is greyed for catalog parts.

Custom parts are saved in custom_parts.json in Lothal’s data folder (see Where files live). A copy of each custom part a drone uses is also saved inside that drone’s .lothal file.

What Lothal knows about a custom part

Only what you typed. A custom part has not been reviewed like catalog parts, so a build using one shows a note such as custom motor — unchecked. For a motor, Lothal checks that its thrust figure is within the range the catalog’s own motors span, which catches typing mistakes. A motor inside that range is not thereby verified.

A part for everyone: a pull request

Adding a real part to data/parts/ is a good first contribution.

1. Add the part to the right file, following that file’s _schema note and the entries around it.
2. Give it a source that says where every number came from.
3. Run the test suite (see Build from source); every check must pass.
4. Open a pull request that says what you added and where the figures came from.

See Contributing and the CONTRIBUTING.md file.