How it works
Medium-keyed star-delta
A switchable wye(star)/delta winding gives a torque-vs-speed "gear shift": star for high-torque low-speed water, delta for high-speed air. This is the keystone patent idea.
Honest build path: no hobby ESC switches windings today, so the prototype uses separate propulsors (four FPV air motors plus one or two sealed underwater thrusters). Winding-switching on a single motor is a funded research extension, not a build blocker.
Seawater range-extender
An aluminium structural electrode plus a magnesium sacrificial rod forms a seawater galvanic cell. Flowing saltwater during a dive generates low-power DC.
Honest limit: roughly 5-30 W. That trickle-charges the avionics and sensor bus and extends loiter; it does not power flight. Flight energy is a 6S LiPo charged at the dock. We do not claim saltwater flight.
Bullet hull + folding quad
A buoyant bullet/torpedo hull houses a dry electronics bay. A ballast pump and depth sensor manage water entry, submerged transit, and water exit. Four folding/tilting arms carry the air rotors; a tool-less payload bay swaps mission modules.
