King 3 tail drifting/battery relations ?

[ku_hi]

Hi,

Yesterday I was trying to set up tail in rate mode.
I am using standard method without trim and subtrim. Just with moving rudder servo along boom until found place there is no drifting.
Gyro - hk401b , tail servo - ds480
I was very surprised when found that tail drifting different with different batteries.
With Zippy 2200 drift slighty to left(tail left looking from behind), and slightly to right with Turnigy 2200.
Weight is about:
Turnigy - 195g 25c
Zippy - 180g. 20c

So, why this?
Obviously Turnigy is heavier and little more head speed need for lift off and hoovering, but tail rotor speed is corresponding with head rotor speed(more head speed-more tail rotor speed).
Why that few grams making such difference. Or there is something else.

Thanks

[chrismechanic]

hello ku_hi... the hk401 gyro is not the best so expect a bit of drift.
you will find that as the battery voltage goes down so the tail will start to drift.
you can use a few clicks of trim to stop the drift but it wont last long before it will drift again requiring more trim...be carefull, too much trim will cause the gyro to go to full left/right travel, this will make the heli piro.
as you said different head speed = different tail speed, this will effect how well the gyro can hold the tail...its best to stick to one type of battery. a faster head speed will hold better than a slow speed.
after you set rate mode did you teach the gyro the new centre point by flicking the hh/rate switch 3 times really quickly?? if not try this as it will hold better....the gyro light will flash 3 times to show its has the new centre.
chris.