I develop flight controller software for multirotors in my spare time, so I also wanted to make my own frame for my copter. The requirements for the frame were good mechanical behavior in a crash, high modularity and good support for future improvements. The multirotor itself is capable of fully autonomous navigation.
The frame was designed in SolidWorks. It is based on a sandwich type approach, where the bottom frame plate is almost always attached and the top plate comes off for maintenance. Both plates are held by nylon screws, which shear in a crash, often saving other components. Most of the frame parts are 3D printed with consideration on the print materials, for example the landing feet are printed from nylon and structural parts from ABS. The frame plates are CNC milled in the current version, but in an early prototype they were also 3D printed.
The copter electronics consist of a powerful ARM Cortex M4 based flight controller, GPS+mag unit, 25 volt LiPo battery, 40A motor controllers and brushless motors. There is a camera onboard, which is connected to an OSD and a 5.8GHz video transmitter. The copter itself talks encrypted bidirectional 433MHz telemetry with a PC for flight time diagnostics and mission control.
Purpose: hobby project
Category: CAD Design, manufacturing
Time: fall of 2014
The copter is fully working and I fly it frequently. I am constantly upgrading it, recently I have changed the flight camera and fitted the copter with a WS2811 RGB status LED, which can be seen from below. I have also built a snap-on carrying handle and a drop rig for the copter. The drop rig can be used to deliver beer or an emergency kit with a parachute, for example.