Build an inexpensive multi-rotor Tri-Copter using wood, zip ties, and 8 screws!
I am using this tri-copter to test servo controllers. There were a few challenges to getting this off the ground and hopefully this helps others with a really cool project, enjoy!
This is a spin off of another one of my projects currently on Kickstarter, check it out also if you get a chance: http://kck.st/ZhKt0j or search for Blue-Rx.
Step 1: Parts List
Click the item for more info...
Various pieces of wood
12 AWG Wire
Shrink Wrap Tubing
3 Props (GWS 10 x 4.7) $17.94
3 Motors (1300 kV) $21.98
3 Speed Controllers (18 Amp) $21.45
1 Battery (LiPo ~3000mAh) $13.73
1 Charger $27.29
1 Servo $4.37
1 Servo Extension Cable $2.16
1 4ch TX/RX $53.82
1 Mult-rotor Control Board $12.99
1 AVR programmer or Arduino ISP $14.99
Total: less than $200.00
Step 2: Create the Frame
Build the frame using 1/2 or 5/8 inch square wood sock. A strong light weight wood is best, but this beast will have enough power to lift almost any frame! The arms are 12 inches long and roughly in a 120 deg pattern. The two arms opposite the servo are the front pair, they are slightly closer to each other then that of the tail, this was purely for aesthetics. The arms are glued and screwed down to the base plate which is a 1/4 inch masonite.
It is best to get the angles accurate between the arms but believe it or not, its not really necessary. If they are close the computer control via the multi-rotor control board will compensate for any error!
Step 3: Wire Up the Motors and Speed Controllers
I didn't use any special connectors for the wiring. I soldered the leads directly together and shrink wrapped the connections. This is the simplest method. If you want to use the motors for another project get some bullet banana plug connectors from a hobby shop or online and solder those to the speed controller leads first.
Make sure your connections are good and wont short together due to vibrations in flight! The battery and speed controllers can put out a lot of juice and could explode or catch fire if the leads are shorted!
For my particular motor and speed controller combination A->Red, B->Black, C->Yellow. If your motor spins in the wrong direction reverse any 2 wires between the motor and the speed controller.
Each motor is wired to a speed controller then each positive lead from each speed controller is wired together and each negative lead from each speed controller is wired together. The positive and negative leads are then wired to a battery connector.
The speed controllers convert the battery voltage to 5.0V to power the receiver and servo through their own servo connectors!
Step 4: Mount the Tail Motor and Servo
The rear motor is screwed to a small piece of wood and then mounted to the tail arm with a wood screw. Make sure the motor assembly can pivot easily around its mounting screw. The pivoting of this rear motor is what allows the tri-copter to spin around its "z-axis", similar to a rudder on a plane.
Glue and zip tie the servo in place and add the necessary servo connectors as shown to allow the servo to control the pivot of the tail motor. I used a small nail loosely nailed to the motor assembly to connect an unused servo arm to the servo.
Step 5: Add Some "Landing Gear"
Use a small piece of foam or carpet pad to create landing gear. I folded up a piece of carpet pad and zip tied it to each arm to provide some cushion for hard landings.
Step 6: Mount the Battery and Control Board
I hot glued the control board to the base plate. Make sure you have the control board pointed in the right direction, the one I used has two arrows pointing forward and is at 45 degrees to the axis.
Zip tie the battery to the front of the base plate.
Step 7: Mount the Motors and Speed Controllers
Zip tie the motors and speed controllers to the arms as shown. Make sure to leave slack in the wires as not to strain any connections.
Step 8: Mount the Rest of the Wiring
Zip tie the battery end of the speed controllers to the base plate leaving room to mount and connect the receiver. Make sure you can connect the battery!
Step 9: Mount the Receiver and Make the Connections
Zip tie the receiver to the base plate and connect the speed controllers and servo to the control board.
Connect the receiver to the control board. You only need 6 wires between the receiver and control board, 4 signals, V+ and Ground.
See the last step for connection details.
The speed controller provide power to the whole system.
Step 10: Finished Lets Fire it Up!
THIS IS A DANGEROUS TOY BE CAREFUL!!!
BE SURE YOU KNOW WHAT YOU ARE DOING BEFORE POWERING ANYTHING ON!!!
DONT LET OTHER PEOPLE NEAR WHEN PRACTICING OR TUNING!!!
KEEP HANDS AND OTHER BODY PARTS AWAY WHEN POWERED UP!!!
POWER ON TRANSMITTER FIRST!!!
POWER OFF TRI-COPTER FIRST!!!
With that said there are a few things you need to do to get this thing in the air.
1. Flash the control board with Tri-Copter firmware. Follow this guide(click here); It is old but everything is relevant. The only difference is I used the newest tri-copter firmware, version 2.9.
2. Connect the receiver to the control board. If you have a Mode 2 transmitter, CH1 -> Elevation, CH2 -> Aileron, CH3 -> Throttle, CH4 -> Rudder.
3. Connect the speed controllers and servo to the control board (M1-M3 for speed controllers) (M4 or M5 for tail servo). Follow this guide(click here) for the initial setup and tuning; Is is for a quad copter but the setup is the same for a tri-copter. The only difference is there is no need to reverse servo direction if using v2.9 firmware, just use the M5 servo connector for the tail servo instead of M4.
4. Initial takeoff! Start the tri-copter on a very flat smooth surface, most people want to try grass but it needs to be able to skim across the ground for the initial setup, so use concrete, asphalt, or dirt instead. Power on the transmitter. Power on the tri-copter. Hold the throttle all the way down and the rudder to the right to ARM the control board, you should see a red LED come on (hold the throttle down and the rudder to the left to DISARM the control board).
Increase the throttle until it barely starts to take off. It will drift along the ground and/or start to spin. Trim the rudder until it quits spinning. Trim the elevation and aileron until it quits drifting. Once the tri-copter barely begins to take off and doesn't spin or drift across the ground you are ready to increase the throttle and take off!
Thanks for looking and let me know if there are questions!
If you want to see one in action here is a cool video. I am good at building things but not the best pilot yet so this is one I found on YouTube, enjoy!