LRS Tricopter build-log

LRS Tricopter build-log

I started with this hobby along with a friend in the fall of 2010, after some very convincing arguments and a thorough sales pitch. We both ordered a Cessna 182 from a local vendor and got building. Long story short, my friend chucked the plane at full throttle while I had full elevator, and after some intense manouvering of the sticks making the Cessna behave more like an epileptic turkey, I looped the plane and dove it right before my feet into a thousand pieces. It was magical... Atleast magical enough to get me hooked. As the winter settled in, I discovered Flitetest to get my fix, and later David Windeståhl and his tricopter.

I chose this as my multirotor FPV platform because I really liked the concept of having greater yaw authority than a traditional quadcopter, and what I think is a smoother flight experience. I also wanted to include a full featured autopilot to have the security of failsafes, and I landed on the 3DR APM. The reason behind this decision is that it's open source and supports a lot of bells and whistles for a smaller price than the competition, aswell as a simple and lightweight OSD using the sensor data from the FC. This won't be revolutionary nor very original though, as David's tricopter-design and versions of it is both thoroughly tested and true, but I've made a modification to the tilt-mechanism which I think makes for a sleeker tail and I wanted to share this build-log and my experiences back with the community which has taught me so much.

So heres the starting point. At the base is David's tricopter kit v3 with the power distribution board.

3x Multistar 4822-690kv 22pole motors

3x Afro 30A ESC reflashed with BLheli

3x 1255 T-style carbon fibre propellers

BMS-A206 MG Digital Mini Servo

APM 2.6

Ublox Neo 6-m GPS w/compass

APM Power module

Maxbotix HRLV-EZ4 Rangefinder

3DR 915Mhz radios

MinimOSD V1.1

GPS Mast from Ebay

ezUHF 600mw tx

ezUHF 8ch diversity rx

Immersionrc 600mw 5.8Ghz Vtx

David Windeståhl's step up/step down converter

I don't have any pictures from making the tilt-mechanism, but it is essentially a main rotor grip from a 600 helicopter (the shaft of those fits perfect inside the 10mm booms rcexplorer uses in his 2.6 build, which I cut one of the sides off using a dremel, Then I rounded it using a grindstone and finished it off with a stroke of paint. I'm running the wires inside the carbon fiber booms, so I didn't want the ESC to end up in the middle of the boom. Therefore I cut the shaft included with the rotorgrips a bit shorter than center. Sanded the surface that was to go inside the arm to make a nice surface for the epoxy to bond to, marked the point of the shaft where the rotor grip stopped when assembled, with a fine tip marker, and mixed up some 30min epoxy. I coated the shaft aswell as applied a small amount inside the arm. Then I pushed it in along with the washer you see in the picture, carefully making sure that no glue touched the washer on the rotor grip side.

The end result looks like this. It's very smooth and I'm really happy about it, as all the weight and load is supported by bearings and the motor height is kept low to the arm. 

The included motor mounts doesent fit my motors, so I had to improvise some from mounts I had laying around. I did the same to these as I did with the rotor grip on the tilt-mechanism. I guess they could look better, but they provide a really rigid fit and work beautifully.

Here's the frame assembled, awaiting all the good stuff

It's advised that the compass in the gps-module has a clearance of around 10cm from nearby sources of interference, and with all the stuff I'm fitting to the frame, It barely works out

The foldable GPS-mast was a bit sloppy, so I glued the base right above the threads with hot-snot, creating a firm fit.

Test fitting the FC, getting the CG just right before I fix it down to the centre-plate

I'm fitting the OSD into an aluminum case, and I'm putting some glue on the solder points just to make sure I'm not running into any trouble

Here's the finished tricopter. I love the rough look with the visible wires wrapped in mesh

Luckily, I got it done and tuned before the trip to our cabin in Femunden, Norway where there's tons of perfect places to fly. I'd be happy to include more pictures of the wiring and settings from the APM, or whatever else if someone wants it. Just leave a comment below. Here's some pictures and video from the FPV maiden where my dad pays close attention. This is my first time flying FPV with a multirotor, so you'll have to excuse the piloting skills.

[video='https://www.youtube.com/watch?v=7Oyq4D-ii_I']

Final thoughts

I think that, despite the small surface-area which the rcexplorer centreplate provides, you can quite easily mount alot of hardware without scaling up the size, and it works a treat, and looks even better. The rcexplorer tricopter seizes to amaze me, and if you're into tricopters, you really can't go wrong either building or buying one, no matter what your purpose is. I guess this is what's called backing up data?  

You can also find me on Droneshare, where you can replay my flights and download my logs and plenty more. Happy FPV-flying and Thanks for reading!