Batbone Tricopter : various builds

So after the V-Tail build and the gimbal I decided it was time to try a tricopter. After the v-tail build and flying, which for some reason I never quite gelled with, not sure if it was my build and tuning or just the nature of the size of v-tail I built, it just wasnt for me. I tried a f550 hex (to heavy and short flight time with the current gear I have), so I then focused on the reptile/spider quad frame and gimbal which I am happy with for video... at the moment. I wanted a new build. 

So the only frame I haven’t tried was a tricopter... so here it is.

Deciding on a frame was easy since I had dismantled the v-tail build I had the flitetest Batbone frame that I could reuse. I also have the HK talon motor mounts that I could also reuse. The big decision was to figure out what to do for the Yaw mechanism. After doing some searching, the cheapest option for me (Due to living in NZ) was to get an already proven yaw mechanism so I purchased a HK Talon one. I didn’t want to make one for my first tricopter as I wanted a proven platform to remove that as a variable from flight characteristics and tuning. Since I was already ordering parts from HK I also got my servo from HK. In the meantime I was able to source some 950Kv motors, which I believe are of good quality, they seem to be but its hard to find good information in them.

Listed below is the parts list for the first variation of the Tricopter

• Motors : A.K.E DM950 (I got a used set of 4 for $100US)
• Frame : Batbone  : https://store.flitetest.com/rotor-bones-bat-bone/
• Speed controllers : RCTimer 30amp SimonK : 
• Props : HK 10x4.7
• Servo : HK TGY-306G 
• Yaw Mechanism :  HK Talon 
• Motor Mounts : HK Talon 
• Flight controller : KK2 
• Reciver : OrangeRX 
• Arms : 12mm Alloy tube from the hardware store.

Now that I had all the parts I started the build. My first aim was to house all speed controllers in the Batbone body including the powerharness. This wasn’t as easy as I thought is was going to be as the RCTimer ESC are quite long. But after a but of brain scratching I was able to get three ESC inside. (Planned upgrade is to get HK Afro 20amps as they are smaller)

Next step was the arms I used 12mmOD alloy tubing from the hardware store. I had used these on the v-tail and it worked well.  Since the motor mounts are for 14mmOD tube I used some rubber tube on the end of the motor mounts, the thought behind this was to add some vibration isolation. Not sure how successful it is.

Once all the arms were cut and drilled I started on the Yaw mechanism. The HK Talon yaw is mechanism is easy to put together, but on putting it together you can see why some of the comments on the parts page complain about it, the 3mm bolt isn’t sturdy enough, should be 4or5mm and in a tail heavy landing its easily bent. It also does work loose and becomes sloppy.

So planning a head and knowing that there will be heavy landings and crashes I made an over kill motor guard from 20x1.5mm alloy strip I had left over from altering the gimbal arms. I roughly hand formed the circle to go around the rear motor and yaw mechanism. I used longer bolts and the same mounting holes used to mount the servo holder side plates / legs. I wasn’t going for light weight yet… just some safety piece of mind as parts take 10-15days to get here and I didn’t want to bust it on my first flight.  

All motor mounts and motors mounted I then looked at how mount the KK2 board. I was planning to use this as a FPV platform so wanted as much flat surface to mount “stuff” as I could. The easiest way for me to do that was by making my own top plate from some of the fibre glass sheet I made. I used 6mm nylon stand offs to mount that plate to the Batbone frame. I reused the 2 rear holes that I make for the v-Tail modification and drilled two new ones for the front.  

Next I found the CG, I made sure that the motors were on when finding the balance point. Once that was found I marked out the mount points for the KK2, I used nylon spaces to mount the KK2 to my new top plate.

Next was just the electronics and wiring up the motors, After that it was some basic tuning,

• KK2 board settings, Motor lay out, ACC calibration, Batt volt setting
• Motor rotation correct
• Making sure I adjusted the KK2 channel 4 to high for a digital servo
• Adjusting the servo noise to reduce servo chatter
• Basic reduced dual rates on the transmitter 50% ALE/ELV

Then out for a test flight …. Flew pretty darn good, a few tweaks to auto level and even with my limited flying capability I was able to fly around and it handled pretty good. I was quite twitchy, but the arms were only 20cm and running 10x4.7 props gave it plenty of power … probably way to much for my skill level.

So here is the good news of forethought. After a couple of careful flights I started to explore both my and the tricopters abilities … of course mine ran out first, often!! and resulted in numerous crashes of varying severity.  I even had a few direct tail in crashes… but my super ugly motor guard saved the day and prevented any major damage. I’m very glad I put the guard on otherwise I would not still be flying.

But I have to say I loved the feel and dynamic of the tricopter … as David W say … it’s the swooshiness.

I wanted to use this as a FPV platform I put the Mobius camera on and took it for a flight to capture some video …… OMG horrible jello with it just velcroed to the top plate. Even with differing types of foam. I then followed Chads design of using spring wire to create a battery and camera mount. After much trial and error I final got it working well and video has no jello. The key part was to use thicker wire, I used a mountain bike rear brake cable 1.6mm and had the tension of the wire when mounted quite stiff, which stopped the sideways movement.

During this jello elimination process I swapped the alloy arms to 12mm square wooden arms, I also went for the 30cm overall length that David W recommended and this helped alot. The tri was more stable and easier to fly but still very nimble. I then checked the balance of the props, that combined with the new under slung camera mount provided the jello free video you see below.

 In the process of the arm swap.

 Since a square does not fit a a round hole I had to trim the edges of the wooden arms to fit on the motor mounts. But it worked really well.

One other small change I did was to add a 450 copter landing gear to the front of the batbone frame so that when the arms are folded it sits nicely and not on the camera mount. When I get better at flying it I have some CF 11x5 props to fit …. It should move then.

 Other protection is practice foam golf balls on the arm ends and one is also zip tied to the bottom of the yaw frame. These have worked really well in preventing damage on crashes. 

Here is some video taken from the Tricopter with the mobius on the battery & camera mount.

With a turigy 2200 3S I get about 8-8.5 minutes of flight time.

Planned upgrades :

• Lighter home made motor mounts (Fiberglass)
• Titan Yaw mechanism (Fortis Airframes) these looked awesome, I have one on order
• Test flights with my gimbal setup / weight flight times
• FPV: waiting for parts shipment to arrive
• Carbon arms ... once i can find a source for 12mm square tubes

 UPDATE

 The Fortis yaw mechanism showed up so I have now fitted that to the tricopter.

I am super impressed with the service and the quality of the mechanism. Go check out the site for more detials on how it works and build instructions. Titan Yaw mechanism (Fortis Airframes)

I also weighted both the yaw mechanisms.

Talon with my ugly bits 191g verse 126g.

I removed the other motor mounts and used just the zip tie method. to help reduce a little more weight.  After a couple of great test flights I had a crash, everything survived. However since I was over tarmac one of the motors got a chip. I wanted to prevent this. So back to my reliable foam golf balls. I moved the motors in on the arms about 25mm, this left about 20mm to push on a foam golf ball. The foam is high density and you can use a drill to make a nice hole. They just push it on. This has help in my other struggles with gravity, no more damage to report.

Even after this particular nasty crash.

My next mission was to have a "universal" mounting system so could easily put a gimbal, FPV, camera on and off the tricopter.  I still don’t have a goto frame so wanted the ability to move accessory gear to and from my different options.

A while a go I order a universal landing gear from HobbyKing that has rubber mounts and the carbon tubes. Using a square bit of fiberglass to mount the rubber mounts to and then bolted that to the tricopter. Its easily removed if I need to.

After measuring up the holes and drilling them out both for the mounts and to mount to the Batbone frame (Using existing holes) I bolted it to the frame. I now had my universal mounting system.

After A LOT of frustrating trial and error I also changed from the wire method to hold the under sling camera mount and battery holder. I wanted something that wasn’t as tall and simpler to look after.  When I was mucking about trying to get a lower profile using the wire I reintroduced jello… it was very frustrating to try and find that sweet spot.

So I tried silicon tube, I got it from my local pet shop, its 6mmOD and used for air pumps. I reused the base plate but used two loops of the silicon tube. The loops are at a length that when mounted to the tricopter that they are a little stretched.

The result was perfect no jello, this is with crash damaged props not just not balanced, but with bits missing.

I then just zip tied some landing gear to the tubes. Very happy with the end results.

I get about 8.5 minutes of flight in a 2200 3s (the cheap Turnigy ones). So would be interesting to see what the flight time would be on larger capacity battery and 11x5 props.

 A quick video on after the build, it was really windy but no jello.