X-Class Power — 5215 Motors, 12S2P Pack, and a Startup Fix

This build pushes the workbench into proper X-class territory: two new 5215 motors, a 12S pack to feed them, and the frame mounts to bolt them on.

New motors — 5215 X-Class

Both are modelled from real manufacturer bench data, not estimates. Same 52×15 stator and 344.5 g weight — the winding is what you choose:

• 5215 500KV — 8S, ~3.3 kW peak, 7.5 kg thrust on a 13×9×3

• 5215 300KV — 12S, ~3.4 kW peak, 7.4 kg thrust on a 13×9×3

Four of either lands you around 30 kg of static thrust. Pick the winding that matches your pack, not the other way round — the sim will tell you when you get it wrong.

New battery — 12S2P Li-Ion

24× 18650 cells: 12S, 6000 mAh, 1240 g. It's the heaviest pack in the build list by a wide margin, and it's meant to be — pair it with the 300KV and watch what the extra mass does to your hover throttle.

Frames

The 13-inch frames now accept M4 motor mounts on a Ø30 bolt circle, so the 5215s actually have somewhere to go. Existing M3 motors are unaffected.

Fixes

• Fixed a startup crash. Roughly one launch in eight could die a few seconds after the world loaded. Root cause was a background resource loader racing the main thread — now removed entirely rather than worked around.

• Better motor calibration. Manufacturer datasheets that publish no RPM column are now fitted correctly instead of silently producing bad coefficients.

Happy building.