I should have checked this forum first for ideas but I went and built my own quick release system. My concept does not require any servos or electronics and can be flown for several kilometres. I tested this on my farm. I can drop very accurately using the camera for targeting. The idea is that the system uses pivoting airfoils that create very little drag and align with the direction of flight. When you want to drop, you simply reverse the aircraft and the release mechanism drops the payload. The 3D print files and instructions are on Thingiverse if anyone is interested. Drone Quick Release to suit DJI Mavic 2 Pro by PeterBlake