I've been working on a tricopter using Arducopter after my successful journey using KK board. Unfortunately there isn't much information on building tricopter using arducopter but it makes it more challenging and interesting. Here is the picture of my tricopter 

My copter arms by keeping the rudder to the left and it doesn't change by reversing the rudder which is weird. Worst than that is the movement of the yaw servo. The servo moves perfect using a servo tester but once its connected to the board, it doesn't have full movement. It moves very little and it doesn't change by changing the travel on my transmitter nor changing it in the mission planner. 

It kinda feels that the servo doesn't have any movement in the middle (like when we apply alot of expo) however I have 0 expo right now.

When I try flying it, it yawing to right and I have to apply full left rudder to keep it straight. There is no way to get left yaw in this setup.

any comment on this? Or is there anywhere I could get more info regarding tricopters!

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I have been through the same experience - a homebuilt tricopter that flies nicely with a KK board but behaves like a stuck pig with Arducopter.

My tail servo slams hard one way on power up and being mechanically limited with a big servo, I fear something will break.  This seems to be how the servo position is initialised in the software - to zero, rather than midpoint - so reversing in the Tx will have no effect.  It requires a software fix.

My servo also has very limited and very jerky travel.  I had a very hard time flying at all.  Again, in the software, for some reason there is a large deadzone defined for the tail servo.  Also, the limits are set quite low.  Software fixes again.

It seems that nobody in the current Dev team has a tricopter so the software can't be properly tested.

The options seems to be:

- become a software guru and develop your own fixes

- plead repeatedly on Arducopter until some Dev takes pity and comes to your aid

- build a Quad (which is currently my path ... very reluctantly ... but I want to USE my $250 Ardu-boards).

Hi Dave, 

I had a lot of problems with my tricopter and there is not much info as you said. Does your tricopter arm by keeping the rudder stick to right or left? Mine was arming to the left at first and reversing either in tx or MP didn't help. You have to reverse channel 4 in the board as shown in this picture and everything works perfect

Mine is working perfect now. I have done couple of flights and now i'm doing the tuning. It was hard to get the servo running but it's worth spending time on it rather than switching to Quad :)

Lemme know if this helps

To be honest, I don't recall which way it armed.  I only flew (!) it three times but the servo issues made me revert to the KK until an answer could be found.

I haven't yet started on the Quad - the motors and ESCs are on their way from HK.  I would prefer the Tri as well.  Can you provide more details on what you did to get yours to fly?

I'm in th middle of building a tri as well, but still a few pieces short of starting any tuning and testing. The servo does seem a little spastic when connected to apm.
Perhaps I'm mistaken, but I thought the switches were disabled in newer versions of code, and all the reversing was done in the MP radio setup screens.

Dave I connected all the motor (ESCs) to the board as it's explained in the website. First I had a problem with the motors that they were beeping loud with no arming whenever I connected them to battery, I had to reduce the throttle to minimum of 1000 and that problem was solved. After I had problem with the servo. There is a note on the tricopter configuration page saying that you have to reverse the yaw in your transmitter, I tried reversing it from both tx and MP and non of them worked. I then reversed it on the board as I showed in the picture and it started to work perfectly. 

First I didn't have enough movement in the servo but now it moves perfect and the copter arms by holding the rudder stick to the right. I will finish the tuning by end of this week and will post the configuration I use. In overall my tricopter flew perfect and its as stable as KK board. Here its a pictures of it flying in the gym earlier today

I'm using 2213N 800Kv  motors and 25Amp Red Brick ESCs from HK. 

Dave how exactly your yaw servo react? Are you going to try it again with the channel 4 reversed?

Hi hadi, just picked up on this thread and was pleased to find your tri is as stable as with Kk. This is my route too. I have a apm2 and just can't seem to get a base setting to fly. I have hovered but extremely unstable. My tri is an rcexplorer v2.5 type. It doesn't seem to react to my pid settings. I read a thread that said about zeroing all settings and starting fresh. Even with all zeros in mission planner config page if I raise the throttle in stabilize mode it still reacts to pitch and roll, BUT, the wrong way. Very odd. In aero mode no reaction. It flys like its fighting itself, motors also never smooth always pulsing. Can you cast any light on my predicament. Alex

After some fiddling its as stable as a KK board?? Seriously?  Oy, I'm not spending $200 on a board that requires work before being stable as a $15 board! 

The APM does a bit LOT more than the KK.  You're comparing a simple stabiliser with a full-on UAV system.

I've left the KK on my Tri and built a Quad using the APM.  In the several months I've been flying the Quad, the APM software has had some big advances in stability and has flown better than the KK for quite a while now.  I'm still blown away by how much functionality the Arducopter provides - remember this is all Open Source!

As for the current support for the Tri platform, I can't really comment on that.

Hi Hadi i saw you're yaw mechanism and i like to tell you that's awesome! Did you bought it somewhere or did you make it yourself?

Designed it myself in SolidWorks. If you are interested, I'm selling the exact tricopter in the above pictures Ready to fly. PM me if you are interested.

well i've ordered already some parts but i am very interrested in you're yaw. I've got only one question, if i look at other designs the servo for the yew is most of the time huge how can it come that youre's can be so small?

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