It depends on how long it takes the weapon to lock on and align. If it takes 1s to work out the trajectory and fire, the drone just needs to change its trajecto

It depends on how long it takes the weapon to lock on and align. If it takes 1s to work out the trajectory and fire, the drone just needs to change its trajectory every second. But I guess taking down a drone is not like taking out a mortar shell. It is probably much easier with some sort of flak or even launching a net.