It was in 2014 that I decided I needed a new hobby that I could enjoy during retirement. I was just over one year away from retiring and had always wanted to try RC model flying. Quadcopters, or multi-rotors if you prefer, were getting popular and I decided to build one. This write-up is not going to detail everything I did during the build. Newer models are avaiiable as are newer electronics. The market has exploded with quadcopters since I built mine. I'm just going to highlight a few things I did when making mine.
I built mine pretty much from scratch. Most of the electronic parts and the frame came from RCtimer.com, an online Chinese retailer. They have good prices but shipping is typically around 2~3 weeks so if you want it fast, buy from a retailer in the U.S. or your local hobby shop. I continue to use RCtimer for electric motors, speed controllers, props, and servos. The RC transmitter and other radio components were purchased from a couple of U.S. companies. Getting warranty work from a U.S. retailer is usually much easier than shipping things back and forth to Asia.
The frame was big enough, at 450 mm, so I wasn't trying to squeeze everything into a tiny package. The frame was carbon fiber which allowed for a good amount of strength while keeping the weight down at the same time. The frame used a lower deck comprised of two pieces that sandwiched the legs. Attached to this lower deck was a larger mid-deck that provided space for battery back and camera mounting. The upper deck, which was attached to the mid-deck provides a platform for mounting the flight controller and all of its associated electronics. The decks are connected using screws and thread locking adhesive or Nyloc nuts. This keeps the vibrations from loosening the screws and causing an in-air failure of the quadcopter's frame.
Due to the motor requirements for this sized quadcopter, I used 30 amp ESCs (electronic speed controllers) which were mounted in pre-cut areas of the lower deck as seen in the photo. Each of the electric motors requires its own ESC. One of the flight controller's jobs is to regulate the current flow of all four ESCs. The ESC takes the battery's DC power and converts it to 3 phase AC power which is then directed to the electric motor. Changing the power output of the ESC, via the flight controller, changes the speed of the motor and thus a propeller's thrust. This change in thrust by one or more props causes the quadcopter to change pitch, yaw, and roll which equates to a change in direction and altitude. It is a really neat piece of electrical engineering, in my opinion.
Did I mention that building your quadcopter from scratch will require soldering skills? There is a lot of wiring that needs to be properly soldered in order to safely fly the quadcopter. Many people opt to purchase a ready-to-fly quadcopter from one of the many manufacturers for this reason. The diamond shaped board with the round pads on it is the power distribution board for my quad copter. The red and black wires come from the four ESCs and will be soldered to the power distribution board. Another set of power wires connect the power distribution board to the flight battery. The outputs of the ESCs are soldered to the electric motors. I used gold plated connectors for this connection which makes swapping out a motor very easy. Some folks prefer to solder these connections directly.
The quadcopter's brain is the flight controller (FC). Here is the
flight controller connected to a 915 Mhz radio telemetery module which I was
testing at the time. The FC has a microprocessor, memory, barometer,
lots of input/output (IO) ports, among many other things. In the above photo,
a CN06 Plus
GPS module is attached to the top of the FC with threaded nylon spacers.
The GPS module provides the FC with accurate positional data which is both
processed and stored in
the FC memory along with lots of other flight data. The software used by
the FC can be updated via a USB port using your laptop or desktop computer.
This allows the FC developers to add enhancements as well as fix issues found by
4x4 Off-Road Homestead Firearms RC Flying