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Jun 28, 2017, 03:00 AM
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Bking1340's Avatar

Betaflight 3.1.7 F3 Tricopter setup Tips!

Good day all

Just want to share my setup, especially on the yaw servo using a F3 flight controller (X-Racer F303)on betaflight 3.1.7. Got some help from waltr on the betaflight group. Maybe this will help someone. waltr added some of these info to the wiki:

When I 1st started out on multirotors about 9-10 years ago, multirotors were still in their baby steps - coming from heli`s, it was a great experience, but also difficult to do setups on the old (1st)kk boards, multiwii boards using arduino to change and compile firmware - glad that`s history. FPV what is that?
So multirotor frames were like chicken teeth - not a variety - so sometimes you had to build your own frames using aluminum or wood and used these stupid old airplane motors where you had to use a prop adapter that will pop off mid flight.
After a few quads and hexes, I saw a guy flying a tricopter I build one and it was great - the yaw almost fell like flying a heli.
Okay - back to the present - bought a trifecta when they came out and used a cc3d with openpilot. But used it for maybe 5 flights, because I like my quad fpv scene.
Last week I thought to dust off my tri and use a f3 board that was laying around collecting dust.

Setup: Tri are in front of you with 2 front motors facing forward and rear motor / servo facing you
Motor 1 - rear to motor pin 1
Motor 2 right to motor pin 2
Motor 3 left to motor pin 3

I don`t think it`s a good idea to draw power from the board with a servo (especially on a tricopter), so my red(positive) , black (negative) are going to a pdb 5v output, The yellow or white wire(signal wire) can be connected to motor pin 7 or 8 (I used 8) - other pins will have timer conflicts.

Do your initial setup in betaflight (choose tricopter in configuration tab etc). Go to CLI
If you type resource, you will see that motor 8 and Serial_Rx 2 are on A03.
Resource motor 8 None
Resource Serial_Rx 2 None
Resource servo 1 A03

Now your servo is supposed to work, do not matter if the tri are armed or not. IF you want to disable the servo when it`s not armed, go to cli and type:
set tri_unarmed_servo = OFF .
I did not do this.

Now check if your servo/motor are tilting in the correct direction. If you move your yaw stick to the left, the motor must tilt to the right. If not, there are 2 ways to fix this.
In cli type:
set yaw_control_direction = -1
Or you can just reverse the yaw direction on your tx.

Now check if your servo/motor are compensating in the correct direction. If you quickly move your tail to the right (So nose will tilt left), the motor must tilt quickly to the left.

I removed my analog servo and replaced it with a digital one - my directions were reversed with the digital servo.
Go to betaflight servos tab - Something strange for me was that I thought my servo was set to servo 1 in cli and it will be servo 0 in the servos tab, but this was not true, mine are servo 5 in the servos tab.
I just changed "Direction and rate" from +100% to -100%
Here you can also get your rear motor exactly horizontal with "Mid" and set your endpoints of your servo with "Min" and "Max".
I think you can also reduce your endpoints with "Direction and rate", but not 100% sure.
Also check your digital servo specs and change the pwn rate in cli
Stock is 50 (for a analog servo)
I changed mine to:
set servo_pwm_rate = 250

My yaw gains are basically stock - only increased I with 10 clicks.

I can`t comment on triflight, because I have not use it, but saw a setup video and it also seems great.
Will try it in the following week or 2

I am going to mount a spotlight in front and some led`s on the arms to use this tri as a casual fpv slow night flyer.

I hope this will help some of you.
Last edited by Bking1340; Jun 28, 2017 at 04:15 AM.
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Jun 28, 2017, 12:16 PM
Registered User
LitterBug's Avatar
Have you tried TriFlight0.7 which is being rebased off of BetaFlight?

Jun 30, 2017, 06:48 AM
Registered User
Awesome tip!
Sep 07, 2017, 01:19 PM
Registered User
Hi, thanks for the great post. I'd like to build a tri with the BetaFlight F3 fc and RcExplorer's Baby TriCopter kit, which uses a servo with feedback. Any thoughts on wiring up such a craft?
Sep 09, 2017, 07:05 AM
3Dog Modeling
Switchblade2k's Avatar
Originally Posted by dubadub425
Hi, thanks for the great post. I'd like to build a tri with the BetaFlight F3 fc and RcExplorer's Baby TriCopter kit, which uses a servo with feedback. Any thoughts on wiring up such a craft?
David has a step by step video on how to do this on the RC Explorer site(its a YouTube video)...they have a custom made F3 FC made for the Baby Tri but its no different really if you use an off the shelf.

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