For this device to work, we'll need a way for the drone operator to release the clip when the time is right. Some drones offer an extra channel onboard to be used for this purpose, but it can't be guaranteed. So we'll create our own, this way we can mount it on any flying machine and have it work.
There are two pieces to this puzzle:
1. A handheld remote with a button to release/open the clip
2. The servo actuate clip on the drone with a wireless receiver
The handheld transmitter uses the Xbee pin mapping to report the state of a momentary switch. The receiving Xbee in the drone clip reports a pin state to an Arduino Mini, which in turn handles the PWM for the micro servo.
It works like this:
Put it all together: