Well, this is not yet fixed for me. Though i am flying regularly, i am still having tail issues with my mini titan, that i want to get get rid of in order to progress further.

When in HH mode, the heli flies perfectly, but occasionally ( once every minute or two ) , i get uncommanded yaw movement. Its like the heli turns 90degrees without any input within 2-3 seconds. I push back on the rudder stick to get the nose back in and it works OK and repeats after another minute or so.

When in Normal mode, i have the heli flying straight, with no need for rudder inputs, and the servo arm is perpendicular as well so i think i have it trimmed.

Gain is set to 30

I suspect Gyro/Servo problem , could this be the case ?
Please help me in resolving this. With these jerky uncommanded movements, i am not confident to go on to practise manoevers.
Thanks !
Gaurav

Start from the basics. 

Are you sure your are changing between modes ?  Does the gain channel need to be reversed in the radio ?  You can confirm these by setting up the radio programming so that you can flip between modes by toggling a switch.  When you do that, watch the light for heading hold and ensure it is correct. 

Do report here what colors you see for each of the modes.  I am beginning to wonder if you got the modes wrong.

And when you ensure such things, reread the manual and make sure what color indicates what and ensure that the right color shows up for the chosen mode.  Note that all this can be done when the heli is idle. I know this sounds like kindergarten stuff, but I have been surprised myself multiple times with such stuff, and have seen it happen many times to others.

It should not be static induced issues, as those are quick/violent tail movements (certainly sub-second times).  Since you said the drift happens over 2 to 3 seconds, we can rule that out.  Plus, nothing is wrong in rate mode.

Thanks Anwar for taking the time to help me.
Yes i have the gain channel connected to CH5, and the toggle switch configured to switch between normal and HH mode. I see green for normal and red for HH . and the manual confirms that I am understanding this correctly.

I do think my tail movement is quite violent .. Its like sudden and moves the nose 20 degree. stops there for a second, and then jerks again 20 degrees.
I have noticed that this is nearly always towards the right..
I havent flown long enough in rate mode to confirm that it does not happen there.
Will try tomorrow.

I have a thought. Is it possible that my motor/ESC getting hot could cause this ? ie the ESC gives a quick bump to the motor,so fast that its not visible,  and tail servo is not fast enough to compensate that ? Because i noted that this issue happens only after about 3-4 minutes of flying...

On all small belted helis, static build up is a possibility.  Various solutions are there, including grounding the boom. 

A simple test is spraying WD40 on both the belt pulleys just before a flight, and see if you can still reproduce this problem.  WD40 is not very good for belts, but one or two times of testing is OK.

You are borderline on the power system, so the ESC misbehaving is another possibility.  But that should also have the heli drop altitude, which you have not reported.

Hmm. I do not have WD40 with me. Should i try connecting the tail boom with a wire to the -ve on the Rx ? Or perhaps the motor mount, is that grounded ?

I am not experiencing a loss of altitude, or an audible difference in RPM.

Yes, you can try grounding the boom using any of those methods.





The second video shows both the grounding and the lubricant methods.

And here is a great video test of the "spray solution".

Now it sounds different from what I thought you were seeing. It could well be a brownout caused by the BEC overheating. Gyros kick just like what you see when there is a brownout. Try this experiment. Disconnect the BEC and power the receiver and servos from a 4 cell rx battery for a few flights. See if the problem goes away.

I'd also expect it to affect throttle like Anwar. But there are a couple of possibilities why that is not happening. The reset threshold of your gyro might be higher than the ESC chip. Some ESCs have separate regulators for the uC and BEC and only the BEC regulators might be experiencing thermal shutdown.

Good point Rajesh.  Remember to use a servo extension to disconnect the  power from BEC (some ESCs allow it to turned off from their programming).

If this is a BEC heat issue, I would expect it to show up more frequently after the first glitch.

Thanks Rajesh/Anwar.

Are these static detectors available locally ?
Also i plan on getting the WD-40 and applying it to the belt today. Hope it will not do much harm ?
I can also do grounding, but are you sure the motor mount would be -ve ?

Lastly, I am also working on reducing the ESC temperature. I increased headspeed to 80% during hover. TT recommended 65 and that was what i was using so far.
Will do a few test flights to see if that helps with the tail problem too.

Be sure to check out the separate battery setup for electronics (ie, NOT using the BEC built into the ESC), as suggested by Rajesh. 

Well, I did a couple of flights today. As its helpful to debug by changing one thing at a time, i reduced my flying time to 6 minutes per pack. Earlier i was doing 8-9 minutes on a 2200mah and relying more on the ESC cutoff which is set to normal mode and led me to do upto 10 min of flying. I was putting back in around 2100 of charge, which i read in other forums was not a good idea, and reduces the battery life.
At 6 minutes, with hovering and motor still hot, i was not able to get those jerky tail movements.
Will continue flying this same setup for the next day or 2 to confirm that extended flying was the cause of these uncommanded tail movements.

Hmm.. this conflicts with your initial post.  I thought you were getting these unintentional drifts much earlier than 6 minutes (like within 2 minutes into the flight), as long as you are HH mode.  So the flying duration alone cannot be the problem !

If you were getting any such drift before 6 minutes into an HH mode flight, the same should be happening now too ?

what are those static detectors called?

I am not able to Google anything by that name.

Just search for "AC voltage detector" (together... i.e. in quotes).

http://www.greenlee.com/product/gt-15/start.html

http://www.amazon.com/Gardner-GVD-504A-Circuit-Non-Contact-Voltage/dp/B00004WLKP (you can see many models here).

Thanks Anwar, Iam now able to DE the items. 

http://www.dealextreme.com/search.dx/search.voltage%20detector

Vinay, you seem to be in with the times preferring to sit in front of computer and order from the net  when you could just run to the neighborhood electrical store get a '"testor". They are far cheaper than DE too, I'd guess under 10Rs.

Or if you prefer DIY, they are nothing but a neon bulb in series with a resistor to limit the current to safe levels.

Hmm. So these testors ( available locally), can they actually detect the static on our helis ? Is the voltage/static strong enough to light the bulbs in them ?

Yes, the neon lamps need very little current. Should be able to detect this level of static easily.

Oh is it? I thought they were special ones. I have 3 testers at home. Thanks for the tip

Same here. When I read the comments on Youtube a while back, some of them mentioned "low power ac voltage detector", giving the impression that these are special purpose ones.

I thought the simple/common ones were not capable of picking up this level of activity.  Now that it has been confirmed, the fact that they can show feeble feedbacks on the neutral line (when earthing is not proper) does come to mind.