I need help for my self-assembled Quad copter. It is very unstable at the time of attempt of flying, having tilting tendency like moving of aileron / Elevator / Rudder & being inverted suddenly after applying throttle of approx. 50% .
The components I am using are giving below,
1>   450 mm frame,
2>   1400 KV motor with 9x4.5 prop.
3>   11.1V, 2200mah Li-po battery
4>   Fly sky CT6B Transmitter & KK 2.1.5 FC having HW Ver 2.1.X, FW Ver 1.19S1 Pro Steveis   
Writing step by step function done by me,
1)   TX ( FS CT6B ) + Rx binding,  Tx kept in ACRO mode via computer.
2)   Individual ESC ( Simok 30A) calibration done with TxRx Channel 3 to ESC
3)   Rx + Flight Controller (KK 2.1.5) wire connection like Rx Ch-1( aileron) three pin to FC aileron (top most) three pin, then single wire for next channels like Rx Ch-2 to FC 2nd top signal pin & up to Ch-5 ( Aux) to FC pin 5.    FC is fitted on a foam.
4)   Tx ON , Drone battery connection ON  In FC, factory reset done  Acc Calibration done Load Motor Quad x select & Motor wire connection as per CW & CCW done.
5)   Receiver test done & found (on screen of KK board) every function responding fine. Set all stick & trimmer at Zero.
6)   Attempt to fly (indoor) but not steady, even it is getting burst of power suddenly & being total inverted after 50% throttle.
7)   Then I changed PI values given in KK manual for new flyers,
For Roll & Pitch ( Aileron / Elevator)  P Gain =50, P Limit = 100, I Gain=25, I Limit=20
For Yaw (Rudder)  P Gain =50, P Limit = 20, I Gain=25, I Limit=10 
Attempt to fly (in door) again but same problem.
    Replace the KK board with another new one & done all the above process but no result.
9)   Interchanged position of ESC & calibrate again but problem remains same.

Kindly Help.

Quote from: NILADRI on July 02, 2018, 08:42:00 PM

3)   Rx + Flight Controller (KK 2.1.5) wire connection like Rx Ch-1( aileron) three pin to FC aileron (top most) three pin,
then single wire
for next channels like Rx Ch-2 to FC 2nd top signal pin & up to Ch-5 ( Aux) to FC pin 5.

Hi,
Welcome to RCI.
Try usual 3 wire connection between FC and RX for all the channels.
That's how mine is wired.
Regards

Quote from: NILADRI on July 02, 2018, 08:42:00 PM
I need help for my self-assembled Quad copter. It is very unstable at the time of attempt of flying, having tilting tendency like moving of aileron / Elevator / Rudder & being inverted suddenly after applying throttle of approx. 50% .

What do you mean by being inverted? Does the quad flip itself above 50% throttle or the channels are inverted?

Sent from my Redmi Note 4 using Tapatalk

@YashasR
Thanks for your reply.
By using term inverted I want to mean flip i.e one side lifted suddenly & the whole Drone is being roll over.
At starting i am giving partial throttle & observing the movement like turning (rudder) at any direction, lifting tendency of any of the side and by using trimming sliders i am trying to make it neutral. After that i am applying throttle slowly. but when it is near to 50% then suddenly the power going to any of the Motor is increasing ( only conception by sound & observation) & the drone is being up side down.     

Good Evening Iyer Sir. Thanks for your warm welcome.
I used the connection got from KK manual & you-tube. PFA photo of the connection done by me. Please check once ( to avoid any miscommunication) if advice I will connect all three wire as suggested by you.   Regards.

Wow!
Good that you posted a pic.
How did you get into such a situation?
Here's a pic of how to connect to Rx.

I am just wondering...can't a racing quad f.c be used on these large quads? Just flash em with latest betaflight ..flies great at stock pids...what am I missing?

"... if advice I will connect all three wire as suggested by you. ..."

@ Niladri...
Can you confirm if the problem is solved.. i have a similar situation..and i have also wired my FC to Rx just like how you have done... Mine doesnot flip over but its drifting while hovering ...

Please update ... i dont have spare three wire servo wires with me to try it out, thats why asking ...
Thanks...

 Hi, not an expert !
Flipping, -motor order , motor direction ,  correct Prop direction .esc Cal.,FC orientation ........and many more reasons. Just start from scratch.!
and " babying " it on the ground at takeoff may lead to I  term buildup !

Drift-  will drift in any manual mode..!
        If it  Always drift in the same direction,  do another ACC. calibration
and check for any trims in the Tx.

@niladri,
Do you have four 3wire cables?
Did you try it?
Did it work?
Works for me.
I don't remember seeing any single wire instructions for the KK 2.1.5 board...

Quote from: rufussam on July 04, 2018, 09:53:49 AM
"... if advice I will connect all three wire as suggested by you. ..."
@ Niladri...
Can you confirm if the problem is solved.. i have a similar situation..and i have also wired my FC to Rx just like how you have done... Mine doesnot flip over but its drifting while hovering ...
Please update ... i dont have spare three wire servo wires with me to try it out, thats why asking ...
Thanks...

Good Evening Iyer Sir,
The KK FC I purchased having only one "three wire" connector & three pcs of single wire with female connector at both end.
OK i will connect the FC with Rx by "three wire" system ( purchased from market) for all four channels.
Will report after the trial.
Thanks.

Thanks Ambattuhari,
May you guide about "Trims of Tx" what you have written as an advice.

Dear Rufussam,
Will update after trying by connecting all three wire in each of the FC input side.
You may purchase connector wire having female side at both side for this purpose.

Also you can purchase some additional connector wires having one side male & one side female, some having male pin at both sides.
These wires may require in future & price is very less (Rs.30 approx for a set of 10pcs wire). Available in Amazon.

Hi

@niladri,
Don't fry your FCB based only on what I said.
Recheck whatever instructions you're following.
I never saw any single wire setup, and mine is fine with the three wires.
Now that there are two of you with single wire setups, I'd like to see where you got these instructions from. Pl send a link.

@ Iyer Sir,
https://bigdanzblog.wordpress.com/2014/02/08/wiring-the-hobbyking-kk-2-1flight-controller/comment-page-1/

@ambattuhari,
Never saw that before.
Probably power from one Rx channel is enough, the others needing only signal between Rx and FCB.
But since that doesn't seem to have worked for Niladri, might as well try the standard KK setup I used.

@NILADRI
"... Also you can purchase some additional connector wires having one side male & one side female, some having male pin at both sides.
These wires may require in future & price is very less (Rs.30 approx for a set of 10pcs wire). Available in Amazon.."
thank You.. will get few of those and try out..

@K K Iyer
".. Don't fry your FCB based only on what I said.
Recheck whatever instructions you're following.
I never saw any single wire setup, and mine is fine with the three wires.
Now that there are two of you with single wire setups, I'd like to see where you got these instructions from. Pl send a link.. "

Yes Sir that was my worry in the first place whether connecting all three will over load and fry the RX.. single wire setup was done because it was supplied along with the FC... i read about it some where but dont remember where.. i will post link as soon as i find it...

waiting for servo wires to arrive.. thanks

single wire setup is working, adjusting the PI rates and calibration and better battery solved the problem for me..
Thanks