They cap out at several hours for gas powered drones or ~1h of flying time for batteries.
But it’s unlikely for you to actually need endurance because you’re not getting signal that far through a cave without repeaters or a long cable. A bigger deal is being able to go underwater or fit through tiny openings.
But it’s unlikely for you to actually need endurance because you’re not getting signal that far through a cave without repeaters or a long cable. A bigger deal is being able to go underwater or fit through tiny openings.