Quadcopter unstable in Hover

[Maxy]

I have been flying models since early seventies, but over the last nine months I have had 3 self build quadcopters 600 size all with the KK2 1.5 flight boards which I have found awkward to set up. The main problem I get is that after putting all the gains & limits etc I can get the Quad to fly, but they are never reliable in the hover. With the ratchet removed on my Futaba T6EX, the stick is smooth but after precise adjustment the hover is achieved, but will not stay there , after a few moments the Quad at that throttle setting will either climb or fall to the ground then acend again & just keep going up without any throttle movement. I try to maintain a hover but its unreliable as sometimes the increase in height is quick & just a small decrease sends it down saved by opening the throttle. On all my three Quads its the same, I have adjusted the throttle stick scaling , gains/limits on self level & height dampning to all different settings but it stays the same. I cannot to fly the quads properly because 70% of my effort on the box is just trying to achieve stability before moving on. I fly my Quad at my local club site. I can do to & fro, plus walking the quad but because of the constant risk of increase or decrease in height its difficult. I start my flights with a 2200 3s at 12.60v for five minutes & land with 11.4v. So there is no lack of power. I have now bought a QQ Super flight control board to go into my next quad & see if its any better. Any advice on my hovering instability would be appreciated.

Regards Max

[Biggles' Elder Brother - Moderator]

Hi Maxy,

I have had two quads with KK controllers in - and to be honest I never got either of them to handle really well. At best, fiddling with the gains etc., I could get "OK" stability. Like you the vertical movement seemed to be the biggest problem. It was somewhat better with the KK2.0 board (and re-flashed to 2.1) but neither were great.

At one point I just thought "Well that's what they are like". Then I tried a NAZA V2 controller - the difference was amazing! Admittedly it was in a much larger quad than I had used the KK2.0 in - a DJI Flamewheel F550 - but even making allowances for that system's greater inertia it was 100 times better true long term "hands-off" position holding in the hover. I finally realised, it wasn't how it had to be and it wasn't just "me" - I could set up flight controllers! I just couldn't set up a KK2.0!

Since then I have moved on and I'm using Woo-Kong controllers at present in current multi-rotors being built - but the NAZA's continue to give sterling service day to day.

I know the NAZA is a more costly solution - and I also know some people have claimed to get good results from the KK boards. But in the end, for me the NAZA was a solution. Maybe you get what you pay for?

BEB

PS The set-up documentation for the NAZA is also infinitely better!

[Chris Jones 7]

Naza FCs have altitude hold on them. If your throttle is at 50% the board will hold altitude.

KK boards do not have this facility. If you find a small increase or decrease has a large input on the quad I have found the best way to dampen it is to find out at approximately what throttle setting your quad hovers at, for example on my 355 it is around 35% and then to add exponential in the TX around this point making it less sensitive. If you really want to you can also employ a throttle curve to reset the hover point to the mid stick position and then add expo around that point. Should make things infinitely more comfortable for you.