Tricopter Flight test
I've got a couple of flights under the belt now but there's a persistent problem with the front right motor. It keeps stopping dead. This isn't so bad when its 30cm off the ground but when it's a few meters in the air there's potential for more damage. I caught one crash on the trusty little keychain camera, one mounted on my hat and the other mounted on-board the tri when the motor failed.
I checked all the connections, added padding to the gyros for vibration dampening and re-calibrated the throttle and tried again. Unfortunately the same result with that motor stopping mid-flight. I pulled out the trusty iPhone 4.0 and captured some video to help diagnose the problem over at rcgroups.
I've decided it's probably a dodgy motor or maybe the ESC. The motor is out of stock at HobbyKing so I ordered a virtually identical one from lowpricerc.com. At about six bucks each, I considered ordering three to make sure I have identical motors all round but when trying to order them, I got the "out of stock" error here as well! Turns out they had two left so I snapped up both. I'll replace the dodgy motor and keep one spare.
Just in case I grabbed a replacement ESC to help troubleshoot the problem. I went with the Turnigy Plush 18 Amp ESC because I already have the programming card and when I originally bought all the parts, this is the ESC I wanted to use but it was out of stock, surprise surprise.
So now I wait for my replacement motor until I try again. In the meantime I'll go learn some Arduino programming so I can get rid of the 4 HK401B gyros and use the Wii sensors instead. Apparently the Arduino controlled TriWiiCopter is more stable.
Tricopter build: Hooking it all up
Once all the soldering has been taken care of, it's pretty much a case of running all the wires making sure they can reach and connecting them all together. I followed the diagrams shown below. I don't take any credit for the diagrams. I found them by searching through the rcgroups.com forums and in particular this thread here.
Channel 1: Gyro #1 input.
Channel 2: Gyro #2 input.
Channel 3: Gyro #1, 2 & 3 sensitivity input connectors.
Channel 4: Yaw Gyro #4 input.
Channel 5: Yaw Gyro #4 sensitivity input connector.
Channel 6: Gyro #3 input.
Channel 7: BEC input.
Channel 8: LED light strip switch.
The photos below show the wiring before I tidied it up and also swapped the Futaba R617FS 7 channel 2.4Ghz receiver for an OrangeRx Futaba FASST Compatible 8Ch 2.4Ghz Receiver from HobbyKing. I needed the extra channel to make the LED strip switch on and off from the transmitter. Next I'll go through the programming I used for my Futaba 10C radio. This is my first "Heli" setup so I'd be surprised if I get it right first time.
Tricopter build: Wiring harness
I used 14 AWG wire to make the wiring harness connecting the ESCs to the main battery (3S 2200). This is the first project I've not used deans plugs in preference for the XT-60 connectors. Deans plugs were difficult to pull apart and expensive in comparison. To measure the length of wire and get the harness in approximately the right lengths, I started the build from the out tip of the arms and worked my way in. Start with mounting the motors, hook the up to the ESCs, then lay the main power harness wires out such that they all reach back to the probable location of the main flight battery. Once all the wires are cut to length, solder up each of the connectors.
Tricopter build: Yaw control
I've gone with a 1/4" carbon fibre rod inserted and glued into the pine arm. The last 40mm of the arm is left to rotate freely on the CF rod. See this post for further details.
**This configuration will prove to be "not up to it" when it flips on a test flight, the screws in the control arm caused it to split and break free. I'm about to redesign and build something new for yaw control.
Tricopter build: Mounting the motors
The base is cut from 1/4" ply and the arms are 12mm x 12mm Tas oak about 20" long. Excuse my interchanging metric and imperial units but thats what you get building from forums in the US. I'm using a method described on the mongrelgear.com.au site for mounting the motors which is simply cable ties and a bit of glue. I found with the spacing of the motor mount holes and the bend radius of the ties, I needed to insert some carbon fiber rods to take up the slack on the cable tie. By the time it's all finished, the motors are mounted securely, quickly and easily.
Tricopter build: The parts arrive
The main box of goodies has arrived from HobbyKing. The first thing I'm going to do is solder all the connections on the motors and ESCs. I found this handy little guide that mongrelgear provide with their tri-copter kits.
The motors arrive as shown on the left in the photo below (no connections). You need to solder the connectors and apply some heatshrink wrap.
Tricopter motor from Hobbyking
Tricopter build: Yaw mount
The method I'm going to try for the yaw mount is to drill as far into the main arm as my drill bit will go and insert a 5mm carbon rod. Then drill through the remaining block, about 1.5" long which will be able to pivot on the carbon rod. The fit on the rod is snug but not too tight. The hardest part was drilling a vertical hole in the centre of the 12mm x 12mm Tas Oak arm without going crooked and drilling out the side.
Tricoper build: The frame
The frame is cut from 1/4" ply and the arms from 12mm x 12mm Tas Oak. I've used 1/4" metal bolts for now but they'll probably be swapped for nylon down the track. The hardest part was using the jigsaw to cut the base frame around the smaller curves near the arms.
Tricopter build: Parts List
The tricopter bug has bitten and I've ordered the parts to build one. Technically it's a present from Santa so I might have to wait until after Christmas to put it together.
I'm taking direction form two main sources;
- http://www.rcexplorer.se/projects/tricopter/tricopter.html
- http://www.rcgroups.com/forums/showthread.php?t=1142429
Trying to order the exact same parts from either build is tough as a lot of the parts are on backorder at hobbyking () so I'm hoping what I have ordered is suitable.
For those not familiar with Tricopters, here's a video of one someone else has built and successfully flown.
3 x Motors - 2213N 800Kv Brushless motor for AXN Floater-Jet
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8622
3 x Hobbyking SS Series 15-18A ESC
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=6456
4 x Hobby King 401B AVCS Digital Head Lock Gyro
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10113
2 x GWS EP Propeller (RD-1047 254x119mm) (6pcs/set)
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10055
1 x GWS EP Propeller (RD-1147 279x119mm) (6pcs/set)
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10049
1 x Turnigy 380MAX Micro Servo (Metal Gear) 4.1kg / .16sec / 17.4g
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8760
1 x Turnigy 5A (8-26v) SBEC for Lipo
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10312
1 x TURNIGY BESC Programming Card
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=2169
1 x ZIPPY Flightmax 2200mAh 3S1P 20C
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=6306
1 x Hobby King Battery Monitor 3S
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7223
5 x Turnigy Pure-Silicone Wire 14AWG (1mtr) BLACK
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9679
5 x Turnigy Pure-Silicone Wire 14AWG (1mtr) RED
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9678
2 x XT60 Connectors Male/Female (5 pairs)
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9572
2 x Gold Plated Spring Connector 3.5mm (10pair/20pc)
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=4136