I call this beast the Apex Tricopter. It's not a true Tricopter as it has four rotors, but it's certainly not a quad as it forms a triangular pyramid with a rotor at the apex (hence the name). This Tricopter can be made with either a 3d printer or a laser cutter, so if you have one but not the other you're still in luck! This is a lot of information to fit into one Instructables but I'll do my best. If there is anything that I missed or you'd like me to cover more in depth just leave me a comment and I'll do my best to respond. This is sort of an ongoing project so I will probably be posting new versions and updates in the future along with Instructables on future add-ons. If you like what you see please like the Instructables and give me a vote for the contests.
Step 1: Materials
Material for a light Tri:
1- Arducopter and GPS(Has not been tested with other controllers)
2-Transmiter and Receiver: Any 6 channel should work. In this Instructables I used an Airtronics
3- Motors: I used three 980kv motors for the tricopter motors and a 950kv for the central motor. These seemed to be a good size for the weight of the entire system.
4- Rear Servo: I used a MG995 Tower pro but a smaller metal gear servo would probably work equally as well with less weight.
5- Props: For my motors I used three 10x3.7 slow flys and one 10x4.5 MR
6-Lots and lots of cable ties, you'll need them. I got a container of 500 for $10 at home depot.
8- Lock tight or a similar thread lock. You don't want any of your bolts to come undone mid flight, if they do you will almost certainly crash.
9-Bullet Connectors (3mm)
10- #6 bolts and nuts of varying lengths
11- 3 cell 2200 mah lip battery
13- Four thirty amp esc's. You could go smaller but if you ever want to upgrade this just makes it easier.
14- Power Distribution board
16- DX 60 battery plugs
17- 10mm square booms, each one is 30mm in length
18- Tilt Mechanism
Materials for a heavy Tri:
These parts are substitutes for the motors and props if you want to carry a large amount of weight.
1- Four 500kv Gartt motors
2-Four 12in props
3- Four to five cell 5500mah battery
1- Laser Cutter
2- 3d Printer
3- Screw drivers
Step 2: Download Files
I've included both STL's as well as DXF's for 3d printing or laser cutting. With these you will be able to make the entire frame of the tricopter.
Step 3: Tilt Mechanism
For the tilt mechanism you can either print out the one I've included or you can purchase one online. I originally used one designed by David Windestål. You can check out his stuff at rcexplorer.se or you could use one similar to that of flight test's. This is one of the most important parts and if you do it wrong you will most certainly crash. I know from experience.
Step 4: Frame
This is were your tricopter starts to take shape! If you already downloaded the files your set but if not you can scroll up and download them now. If you want to be fast I suggest laser cutting but if you like the look of 3D print like me you can take the time to do so. I actually did both and they seem to fly identically. With laser cutting you are going to want a fairly sturdy thickness I flew with 1/8 plywood but after a couple crashes it broke very easily so I would recommend either 1/4 plywood or MDF. If you decide to 3d print you'll want to make sure to do a decent infill on the landing gear I did 12% and the frame should probably be 50% or more it really depends on the amount of abuse it's going to get the more infill the stronger but also the more weight so it's a choice you'll have to make.
Step 5: Booms
For booms you have a couple of options. You will have to go with some type of square boom any where from 10-12mm in thickness. I started with wood that I had to run over a table saw to get the right dimension but then I switched over to some 12mm aluminum track that you can get form homedepot for less than $10. It's super rigid and very light. I included a picture so you know what I'm talking about. You want to make sure you have something that is rigid enough to withstand some wear but nothing to excessive or heavy. Cheap is also good because you're bound to crash a bit. You can cut wood booms with pretty much any thing. If you choose to use aluminum I would suggest something like a dremel tool. The length that I used was 30 cm. That seemed like a good length. You could probably go a little longer but I wouldn't suggest much shorter.
Step 6: Frame and Boom Assembly
So for this part it's fairly straight forward. You will need to bolt the booms onto the frame as well as the gps holder and battery holder. Important!! Make sure to put lock tight on all of your bolts if you don't you will slowly loosen all your bolts and it may end up falling apart mid flight which would really suck. In the pictures you can probably see that I am attaching everything to a set of landing gear that I bought from the store. I needed them to raise up the Tri high enough to mount a camera gimbal. These landing gear are unnecessary otherwise and the others that I included in the STL's should work great.
Step 7: Frame Continued GPS Holder
To start, you are going to want to grab the top frame piece, four of your #6 bolts and twelve of the nuts. Thred the bolts through the 4 support holes then secure them into place with your first set of bolts(Secure with lock tight). Then three on your second set of bolts just far enough that the bolts will still go through the frame and have room to attach your last set of nuts on the other side of the frame.
Step 8: Frame Continued... Tail Boom
All you have to do is clamp down the rear boom with the four bolt holes below the GPS Holder. You'll need a small screwdriver that can fit through the holes on the GPS holder to do so. Make sure its really tight and doesn't have any wiggle.
Step 9: Frame Continued Booms and Stoppers
This part should be relatively straight forward. If you haven't already cut your booms to length you should do so now and make sure to drill the holes on the two forward booms. Start by threading the bolts through the frame and boom holes through hole 1. As always finish it off with a nut and thread lock. Now through hole 2 slide your second set of bolts through and again secure with a nut. This bolt acts as a stopper preventing the booms from swinging forward in flight but if you crash it should allow the booms to pivot backwards. Make sure this bolt is relatively tight.
Step 10: Connecting the Arducopter to the Receiver
I've included a diagram from arducopters website that should help you with this step. I actually had to switch the elevator and aileron pins but that may have been just because of my specific receiver. Make sure that all of the wires are secure because you don't want them to slip out. If you want to be able to switch between modes you will need to to connect one of your extra switches to aux 5. I had to use my flaps switch.
Step 11: Connect Esc to Arducopter
Simmilar to connecting the receiver now you just have to connect your esc. When connecting your esc remember that the negative wire should be the furthest away from the middle of the arducopoter. Negative outwards. Make sure to connect your esc in the right order. If your looking at it from behind front right should be connecter to Input1 front left to input 2 and rear motor to input 4. The tail servo is then connected to input 7.
Step 12: Power to the ESC's
So I would recommend using a power distribution board that you solder all your ESC's to. I soldered wires to mine with bullet connectors on the ends to connect and disconnect easily from the ESC's. Make sure to use shrink wrap or electrical tape on all exposed connectors so you don't short any circuits. You will also need a power module for the arducopter between the battery and the power distribution board.
Step 13: Software Set Up
Setting up the software shouldn't be to hard so I'm not going to go to in-depth into it. I will say that I have had better luck setting it up with the Mission Planer on Windows then APM for Mac. When you set it up I suggest just using the setup wizard. It's simple and easy to follow. Also I would recommend turning down the sensitivities when you first start to make flying easier but as you get better you can turn it up to suit your flying style.
Step 14: Optional Step..... Add Another Motor!!
So this step is totally unnecessary but is it fun and it should probably make your tricopter fly a little faster. As some of you may have notice the GPS stand off does look a fair amount like a motor mount and that is because it is. If you want you can add a fourth motor right onto the top then split the signal from the receiver one lead going to the fourth motor one going to the arducopter. The main motor will then be controlled solely from the throttle without input from the arducopter. That means you will be able to spin it even if the others are not armed. Also don't worry about it flying odd because it should be right in the center of gravity. Finally no longer can you call it a tricopter but its not really a quad either so you'll have to come up with a cool name for it. Good luck!!