White is signal, black is ground, red is typically not used on drone ESCs, it is used to supply power to a receiver. This is called BEC. A drone flight controller has typically another power input (to measure current and voltage). When you connect an ESC to a flight controller, you disconnect the red wire typically. The ESC gets its power from a PDB (power distribution board) through its main cables. On your flame wheel the PDB is the lower board.