Kinetic projectiles are a seldom-used weapon of war, consisting of heavy metal slugs dropped from a great height by aircraft. On the way down to the ground, they pick up enough speed to kill enemy troops and even penetrate light armor. [i did a thing] tried to replicate this simple technology using a consumer drone.
The kinetic projectiles were made on a lathe, using 1045 steel as a good balance between hardness and machinability. Simple mild steel is far too easy to blunt, while tool steel was beyond the machining capability of the tools on hand. Simple fins were added using materials sourced from the local hardware store.
The build relied on a DJI Mavic 2 drone, which has lights on the bottom that can be turned on and off remotely. Thus, for a quick and easy remote-drop system, [i did a thing] hooked up an Arduino Uno to monitor those lights using a simple light sensor. When the Arduino detects the lights switching on, it moves a servo which unlatches a hook holding the hardened steel dart beneath the drone.
Ideally, the dart would be dropped from an altitude of 600 meters, allowing it to reach its terminal velocity of around 432 km/h. However, in testing, the darts were highly inaccurate, which made drop tests unsafe beyond around 100 meters high.
However, even from this lower altitude, the 200 gram metal slugs were able to penetrate the roof of a Holden Commodore automobile, becoming embedded in the floor of the vehicle. Such testing is incredibly dangerous; had the projectiles hit a human, injuries could have been serious or even fatal.
Regardless, it serves to show just how easy it is to drop a payload from a modern remote-control drone. We’ve seen similar projects before, done with some elegant finesse. Video after the break.