I managed to get the Hexacopter to fly after a few flips on takeoff. It turns out that the motor configuration and wiring for a Pixhawk is not intuitive or well documented.
You have to search through DIYdrones forums to find the information here.
Connect motors 1 to 4 to Pixhawk inputs 1 to 4, same as a quadcopter.
I decided to go further and build a hexacopter. I was able to use my existing 550 quadcopter parts and purchase an inexpensive hex frame from Banggood.com, two more motors, two more ESCs, and use some extra landing gear parts. Here is what I have so far:
A while back I reviewed the Flysky i10 radio. It is a great radio for the price, but I needed PPM output from the receiver in order to feed my Pixhawk. PPM is a single wire interface for all channels, in place of the one-cable-per-channel PWM interface, which is about 40 years old.
The manual tells you nothing about how to do this, but the online forums were filled with people saying it could be done. I tried everything, and could not find a way to do it.
Finally, I found a bunch of postings about a very helpful fellow at Diamond Hobby, Jim Ogorek, who might be able to help (email: jim@diamondhobby.com). In spite of the fact that I bought the radio through another retailer, Amazon, he helped me by sending me the update software for the radio. Note that there are two versions, US and China. I needed China because my radio showed up as a "CN" device on windows.
After running the software on my PC and connecting up the radio, I was able to update the transmitter, and it then updated the receiver, and bingo, I had PPM! You go to the receiver menu on the transmitter and there is a simple check box for PPM and it enables PPM output on ch1 of the receiver. Works like a charm.
I saw a good deal on Banggood.com for a small ARF (Almost Ready to Fly) Quad called the Eachine Racer 250 and went ahead and purchased it. It is a 250 sized unit with the FPV built in, includes a battery, and charger, and cost around $125. I added a spare Orange DSMX receiver and a Spectrum DX4e transmitter and was up and running! It sends video to my 5.8 GHz integrated receiver-monitor and works like a charm. Build quality is good for the price, packaging was good, and it is designed well. As usual, there are NO INSTRUCTIONS from the Chinese manufacturer in the box and you have to hunt around on the web to find out how to set it up. I found a few good Youtube videos and they guided me through setup without a problem.
The only thing that was challenging was my lack of knowledge of the flight controller, the CC3D, an open source flight controller that is somewhat different from the APM or Pixhawk. I again queried the web and found the ground controller for Openpilot, which supports CC3D hardware. I downloaded the software, installed it, connected USB to the quad, and followed the instructions in the video.
The quad flew, but was very sensitive to control inputs, too much for my flying skill. I again went to the web, found some tutorials, and tried to fix the settings. The tutorials were out of date so I went to the wiki, which seems to be permanently down. I then posted a question on RCgroups.com and got some information.
Unfortunately, there seems to be a schism in the Openpilot community and it has split into three factions: Taulabs, Librepilot, and Openpilot. While Openpilot works, it does not seem to have as much support as it used to. The other 2 options seem to be works in progress. APM and Pixhawk/PX4 are definitely better options if you have a choice.
But I did figure out how to desensitize the quad using the current Openpilot and it flew well in a couple of outdoor test flights. Stay tuned for more info.
