OK here we go – I’ve completed my Quadcopter MK1 and I’m finally ready to show the build log.
I started with the frame using the Turnigy Talon v2 frame from HobbyKing. This frame is made of carbon fiber and looks pretty cool. I got all the parts out of the (surprisingly small) box and made sure I had everything. I think this frame has included parts for a KK2 flight controller board (which I won’t be using) so I had a couple of extra nylon spacers I didn’t need. You might need to be creative in adding a custom platform for your electronics as I have done.
I started by assembling the arms and it is here where you might need a hint if you haven’t read some of the forum posts about this frame. From what I can tell, they’ve accidentally machined the motor mounting hole countersinks into the wrong side of the mounting plate. Luckily this isn’t a big deal if you know about it. If you don’t, I can just imagine the frustration you’ll have trying to mount the motors with screws that are likely too short without the countersink. As you can see in this picture, you assemble the motor mount with the countersunk screws facing down which is the opposite of the instructions. The only downside (if there is one) to this orientation is that the screws that tighten the mount to the arm are on the underside and a tiny bit more difficult to tighten. Note the very tiny screw hole in the top. This is for a set (or grub) screw. I used a small screw I had leftover from a hard drive I disassembled and was surprised to learn that the threads on this hole are very easy to strip. Be gentle! I saw that one person drilled a hole into the arm for the screw to fit in, and now I know why.
I should also mention that I used Loctite Blue on every screw. Or at least I tried to – I forgot some and of course those are the ones that loosened or fell out while on my initial test flights. Now I have it on all of them I hope!
After all the arms were done, I assembled the center platform. This is the time when you should attach your battery straps (if you are using such.) I didn’t and had the worst time later getting the traps in place.
At this point I attached the motors and determined the length of the power wires. I decided to run the wires inside the frame arms but this made the assembly more painful than it needed to be. For your first quad, I recommend not doing anything fancy and instead just attach the wires to the outside with zip ties. The aesthetics are good, but repairs are a pain. I also attached the ESCs to the motors at this point and ensured I had the motors turning the right direction. I printed out the page from the Arducopter wiki and had it with me to ensure I got it right. I also labeled each arm with a label maker to ensure I put them in the right place. However, I found it most useful to take a metallic Sharpie and write the motor number on each motor. I did the same with the props making it easy to get the right props on the right motor. It was at this point that I attached power to each of the ESC leads and programmed them to be correct for a quadcopter (using this rcgroups post.) It is really important to make sure you get these programmed correctly because they are different than the default programming for an airplane.
I created wiring harness using the leads from the ESCs and some push-in connectors designed for home electrical. While it is working, I’m not sure this is the cleanest or best solution. I had to tin the ends of the wires about 3/4″ in order to make them stiff enough to push into the connector. You’ll want a connector with at least 5 wires – one for each ESC plus one to go to the main battery.
I tested each ESC and motor by connecting them all to my battery but only connecting one at a time to my radio receiver. I wanted to ensure that each motor and ESC combo were still working great after being put into the lower portion of the platform.
I next spent an evening balancing a set of props. This was surprisingly easy – each one needed just a little bit of clear tape on one side to balance them. I also labeled each prop with a number using my metallic Sharpie to match the motor it is designed for. I chose 2 red props for the front two of the model and 2 black props for the rear two. I thought this would make it easy to see the forward orientation during flight but while it is helpful on the ground it is not easy to see while flying. You might want to select white props (if you can find them) or use some other way to determine the “front” of your quad.
I created a platform for my Arducopter based on a cheap plastic bowl I got at a $1 store with locking clips. It might not be the prettiest, but it holds the components safely and provides a reasonable amount of vibration dampening for the Arducopter. I threaded the leads for the ESCs and for the radio receiver through the lid of the bowl making this the base of my flight controller platform. I attached the GPS unit to the bowl itself, allowing it to be above the flight controller by a good 8 or 9 cm to avoid any radio interference. Speaking of radios, I attached the radio receiver antenna to the frame arms to get the desired 90 degree angle, however as you can see from the picture I don’t know that this hanging approach is the best design. There is a plus in that the way the radio hangs out the aircraft does show the front of the aircraft during flight.
I took a moment then to bring the copter to my PC and plug it in to the Mission Planner to program the Arducopter and to get it working right with my radio. I also updated my Turnigy 9XR to Open9X and it took me a couple of hours to get all the settings right and to my liking. It was surprisingly hard to keep the names (rudder, throttle, elevator, aileron) straight with the channel numbers given that all of them are programmable and reversible. I could create a whole post to describe how to get a programmable radio to work right with a Quad.
At this point I charged up the batteries and started her up. Right away something was wrong – the sound of the props was off and it would not fly. It took me a little while to figure it out, but one of my props was upside down. Sheesh. I was in such a hurry to get it going I completely missed my markings and everything. Well, with that fixed, things went much better. I went through the Autotrim feature a few times because the wind kept messing me up, but eventually I got it dialed in pretty good. Here is a video showing a very good flight using Altitude Hold until I ran out of battery power.