I'm starting with a basic Y6 DIY kit from 3drobotics.com and a FrSky Taranis x9d radio that I ordered from Rangevideo.com. I printed out the instructions, checked out all the parts, and got organized. The instructions are pretty good, so I won't reiterate everything that is included in the instructions, just the minor points that I think might have been helpful.
The first step involves mounting motors onto mounting plates. I initially mounted all the motors in the same orientation relative to the plates. There are basically two mounting choices that fit the holes, with the difference being the relative location of where the wires stick out of the motor. I found that the top and bottom motors should be mounted in opposite orientations so that the wires stick out on the same side of the arm after they are mounted to the arm. This way, the wires go through the hole in the arm nicely. See the picture below:
Also, the instructions just mention that you should assemble the blue arms, and forget about the black arm. Obviously you will need to assemble that one too.
The basic frame assembly goes pretty smooth. There is nothing too difficult with attaching the arms and plates. These are small screws, don't over torque them or else they might strip. Also you don't want to distort the plastic spacer tubes. There are no spares for most of the screws and nuts. I think I ended up with 2 small 5mm screws as spares at the end. Oh, and don't use locktite on the plastic / nylon screws. One memorable experience at work demonstrated to me that loctite can melt different types of plastic and nylon.
Getting all the wires to fit in between the two plates (power distribution board, power module, ESC wires) is a challenge. Pull the multi colored esc signal wire out the top. Accessory power cable can go to pixhawk for back up power, or route out the bottom for gimbal.
Triple check that your ESC control plugs are correctly plugged into the corresponding number plug on the power distribution board. If things aren't working out as planned with your first test flight, this is one of the first things you will be directed to check. The power plugs can be rearranged and plugged into whatever connector helps with the wire arranging.
I opted to load current firmware onto the Pixhawk before assembling it into the copter, just in case something bad happened. It went smooth.
When hooking up wires to the Pixhawk:
- Avoid plugging and unplugging the small connectors. The connectors and wires are fragile. At first I thought it would be good to loop extra cable length through the holes of the plates. That turned out to be a bad idea just making things more difficult later on.
- When stuffing the extra cables into various spots, avoid anything that will push down on the Pixhawk, compressing the mounting foam. This could cause the Pixhawk controller to be off level relative to the copter.
Here is a video showing the general assembly process (until my batteries died in the camera):
When setting up the receiver, I ran into a few challenges. First I had to bind the receiver to the transmitter. The FrSky x8r receiver that I am using can be setup to bind in several different modes. The one page setup guide that comes with the receiver, and is available online, describes binding in modes 1 through 5. The basic choices are around Telemetry being enabled or disabled, # of channels, and channel setup. I set it up in Mode 5, which has telemetry enabled and 16 channel capability. One other minor advantage is that this mode does not require any jumpers on the receiver pins. I was concerned that my transmitter kept indicating that telemetry was lost, telemetry recovered (voice notification) at first, but after a few minutes, I figured out that if I was holding the transmitter too close to the receiver, it would cause a loss of the telemetry signal. The Taranis x9d transmitter has to be set to D16 mode for binding (this is the default) for mode 5 binding.
I was a bit surprised to find that the receiver only has one cable connected to it. The s.bus connection provides power to the receiver, and provides control / receives telemetry signals to/from the Pixhawk. That may show how long it's been since I've used an RC system. I'm used to the separate battery connection, and each servo requiring its own connector and power. Anyway, after cycling power, I was able to see that the Pixhawk was receiving inputs from the transmitter by using the radio calibration screen in Mission Planner.
The configuration of control sticks was not what I needed. I had to rearrange transmitter signals in the setup screens on the transmitter. Eg: left up/down control should be Throttle, not elevator.
To be continued...