Automatically destroyed when master vehicle is eliminated
This is one of the most common drones used in the war against the GLA. It is armed with a small machine gun effective against enemy infantry. The feature which makes it unique is its ability to repair vehicles. It can be bought for 200$. Because of its autonomous nature it cannot be ordered to land for a repair (At an Airfield or War Factory for example), meaning that when damaged it can only be repaired by either having an Ambulance in proximity (Only in Zero Hour) or by the General controlling a Tech Repair Bay . Due to it's airborne nature an EMP can cause it to crash into the ground, typically causing it's destruction.
It seems that the Airforce General was supposed to be able to build individual Battle Drones. It would certainly fit him, but at the same time there's no point in it since the weapon of the Battle Drone is very weak and they're quite fragile.
Point Defense Drone.The Battle Drone of the Superweapon General was supposed to get a Point Defense Laser to protect its master from incoming missiles and to help combat infantry. It is present in the code, but never used in the game.