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Tricopter tailspin???

#1
Hi, I just finished my Tricopter build, and having trouble getting my settings right. All motors seem to spool up evenly and in the proper direction, but just as it starts to liftoff the servo takes a dive one way, or the other, and puts it into an unstoppable tailspin.

My trim setting on my T’‘9x transmitter are all set to zero. I’m using the KK2 Ver 1.6 control board. The board and esc have been calibrated, and on a level ground, and sensor check is OK.

These are the settings i’m using on the KK2.

gyro aileron\elevator
p gain 35
p limit 100
i gain 25
i limit 20
gyro rudder
p gain 45
p limit 100
i gain 20
i limit 20

self lev
p gain 65
p limit 65
i gain 0
i limit 0

Any help will be cheerfully accepted.
 

baddox

Senior Member
#4
Does this happen with self-level mode on and off? Does the servo center itself correctly when you first power up the board (before taking off)? Have you tried taking the props off, powering it on and giving minimal throttle (just so the motors start spinning), then picking it up and tilting/rotating in different directions to try to figure out how it's responding to various movements? Can you counteract the servo at all by yawing in the opposite direction with your transmitter?

Have you tried doing a factory reset and seeing if the problem still happens? I don't think the PI settings or receiver has anything to do with this (you can use the receiver test on the KK2 to verify that it's receiving everything correctly from your transmitter). It sounds more like an issue in mixer settings, or worst case scenario, a malfunctioning servo or KK2.
 

xuzme720

Dedicated foam bender
Mentor
#5
You might need to reverse the yaw channel if the servo is not moving in the correct direction.

Thurmond
Thanks, I did try reversing it. as I said, sometimes it goes one-way or the other without making any changes to the settings.
This reversing Thurmond mentioned needs to be done on the KK2, not the transmitter...not sure if you knew this or not. Just covering the bases...
 
#7
Thanks, That did it for me..... I have watched this video 2 or 3 times, but with the frustration of getting all the new terminology fingered out, I had forgot the digital servo fix. I wish some one would publish a lists of terms and descriptions for us newbies.

Thanks to all for your help.....

Now I can go get all that hair transplanted that I just pulled out. :)
 

earthsciteach

Moderator
Moderator
#8
Yep, it is a frustrating experience. I still can't explain why mine did certain things and why certain things fixed those things. Funny how random button pushing sometimes does the trick.
 

cdraptor

Junior Member
#10
I followed the suggestions above from simple copter - really helped, but I am still having a lot of issues with the tail. I don't know if the HS-65MG servo is just underpowered - What I am getting is a fairly decent takeoff, I can control the tricopter a bit, messed with the trim, knocked down my yaw stick scale and also set some expo, it will drift around, mostly yawing around to the left - but I can for a while yaw it back, then it seems like it starts to get stuck and I have to land, level it - rearm and take off.

Wondering if anyone else has used this servo, if maybe it may be too weak it's a 12.5g servo doing 25oz-in at 4.8V, 31oz-in at 6V
 
#12
(xuzme720), maybe in Texas you can get away with beating your kids, but I thought this forum was talking about Tricopters? :) The suggestions from simple copter really helped me too, and I'm still getting much the same issues will drifting around in all directions. I'm making the same changes that (cdraptor) is making and it's getting better... I think the servo that I ordered for my build (by mistake) is way too heavy(52g) maybe part of my trouble, and I'm Waiting for a BMS-385DMAX Digital Servo (Metal Gear) to show up and see if it make control any better.
 

vk2dxn

Senior Member
#13
Subscribed

I to had problems with my yaw from the kk2.
Mine would centre correctly after arming then if I yaw to left it will yaw to left, I would center my stick and the servo would still be off to the left slightly and same goes for yaw right servo stays to the right when centre stick. I ended up running the servo directly from the receiver "problem solved"
 

xuzme720

Dedicated foam bender
Mentor
#14
(xuzme720), maybe in Texas you can get away with beating your kids, but I thought this forum was talking about Tricopters? :)
Touche, sir! However I would never advocate beating childrens or spouses with a stick, tricopter or any other multirotor or airframe! You're likely going to break something on your models that way! All joking aside, I don't even own a tank-top, so please don't lump me into "that" crowd! :)
I think the servo that I ordered for my build (by mistake) is way too heavy(52g) maybe part of my trouble, and I'm Waiting for a BMS-385DMAX Digital Servo (Metal Gear) to show up and see if it make control any better.
Correct me if I'm wrong but isn't a 52g servo getting close to giant scale? What's a standard size, around 24g or so? Definately make it a bit tail heavy if nothing else... :/
 
#15
(xuzme720) Like I said, the 52g servo was ordered by mistake, but it's all that I have to work with right now. The BMS-385DMAX Servo is only 16.5g. Think it might make a differences? I hope so.

As for beating children, I couldn't resist making some sort of negative comment about it. :black_eyed:

(vk2dxn) Are you using a Digital Servo? Watch the video starting around 34:30. He talks about setting up the rear servo on a tricopter, it was a grate help to me.
http://www.youtube.com/watch?v=LHCatd3XBJ0&feature=player_embedded
 

xuzme720

Dedicated foam bender
Mentor
#16
No worries, brother! I took it with a chuckle...

I don't want to answer for vk2dxn but most of the guys are using digitals on the tail. I am in the quandry right now of deciding between metal gear analog or nylon digital... I really want to use the digital but do not have any digitals with metal gearing in my stock and hobby funds are dangerously depleted...
I'll probably get it up and close to dialed with the MG and swap out for the digitals once it's not slamming into the ground. At least that is the tentative plan.
 
#17
Thanks (xuzme720) my T's not slamming into the ground, but it has become very found of my Roses in my (small) back yard and tries to entangle itself in them way too often.:( I don't dare take it out in public, so I have it tethered to a makeshift stand for testing now. As for depleted hobby funds, I'll be eating beans and rice for the next few mouths........ :confused: Retirement isn't what I had hope for......

Blue Skies....
 

vk2dxn

Senior Member
#18
Hey Mike
I am running a metal gear digital servo.
I have followed Matt Hall's video and made the change for digital servo however this did not correct the problem I was having. Loosing the use of the gyro on yaw doesn't effect me that much as I am still learning how to fly my try correctly "never learnt with the gyro so I won't miss it"