the Sub · system

Propulsion

Six thrusters (aft, lateral, vertical) on a custom ArduSub frame for efficient transit and precise hovering, with fixed X-tail fins for cruise stability — all active control via the thrusters, no fin servos.

Decisions & notes

Propulsion & buoyancy

6× T200 on a custom ArduSub frame: 2 aft (cruise/yaw/redundancy) + 2 lateral (sway) + 2 vertical (heave/pitch).
VBS buoyancy engine (oil + external bladder, self-locking screw) for slow/efficient depth + soft landing; holds depth at zero power.
X-tail fins are fixed/passive — all active control via the thrusters (no fin servos).
Drag: one fixed configuration, then shaped with 3D-printed free-flooding fairings — no folding/retraction. Fair iteratively after assembly.

Parts (7)

First thruster	T200 + Basic ESC	Arrived
Thrusters ×5	T200 (5 more, 6 total)	Arrived
ESCs ×5	Basic ESC R3	Arrived
X-tail fins (fixed)	Fixed X-tail fin set — fabricated HDPE/3D-printed (passive, no servos)	Planned
Thruster guards	T200 intake guards/screens — 3D-printed (tough filament), 6×	Planned
AIS recovery beacon	Ocean Signal rescueME MOB1 (AIS + DSC, 7-yr standby, 24h active)	Arrived
Thruster current ×6	ACS724 30A hall sensor	Arrived