T500 tail drift

[bjs]

Hi all,
I know there is much discussion on this subject but I seem to have exhausted all options, I am only hovering and flying slow FF at the moment but I am getting tail drift (not bounce) and cant get rid of it. My settings are:

Stock 500Cf with 5s 4000mAh
DX6i/6200
401/9257
Gyro gain 0=48% 1=-70%
Th Curve-0-55-80-90-100
Pitch Curve 0-43-50-75-100
On 401-Delay set to 0, DS set to On

The drift is not bad but I have to adjust every 5 seconds or so. All my gyro cables are isolated from the servo cables, and I am not using any tail servo trim. Any help would be welcomed.
Barry

[Mike W]

trim the model so there no drift... then measure the difference in the trim to centre trim then adjust the rod to the desired length ... This is how i was shown yesterday ( Thx Steve ) ya need to be in Rate mode when ya do it and facing into the wind if ya doing it outside

So trim model so no drift ..... land and take the measurement from the hub to the box ... then trim it to zero and pop the link off and ajust the rod so its the same length as the first measuremnt ... pop it back on then fly again and see if its still drifting

[bjs]

Mike,
Thanks, just so I understand you. Hover in Rate mode, adjust the tail trim on the Tx so there is no drift, then move the servo on the tail to mechanically counter the trim that I used, remove the trim from the Tx and try it. Is that about right?
Barry

[Mike W]

the servo arm needs to be 90 degrees ..but then move the servo back or forwards on the boom to get the desired trim.. so when ya trimmed it in rate mode ya servo arm will be off centre and then just see which way its going either towards the mainframe or away then move the trim back to zero and move the servo ... might take a while getting it right thats Y i said bout measuring the length of it from the tail hub to the rotor hub .. more accurate

[Thomas]

A 401 does not need to be set 100% accurate, it should just work (but it is good practice to get it to site there in non HH mode)

I guess you are using the pads that came with the 401 and there is nothing touching it - silly point but make sure you don;t move the model while it is booting up - also you could possibly be suffering from interference from the belt rubbing on the boom mount.

[Smoothound]

I'd second what Thomas says

Many people only setup the 401 to work in HH

[bjs]

Thomas, Phil,
I have only every used it in HH mode, I have never set up in Rate mode. I did use the pads that came with the gyro. There is only the slightest drift which is soooooo annoying.
I have just tried it in Rate mode and I think I would need to trim quite alot, if I do that surely it will throw everything out when I then have to move the gyro on the boom to compensate?
Barry

[Smoothound]

Standard gyro theory says you should get the gyro as locked as possible in Rate because it gives HH an easier time. With the 401 many pilots just set it up in HH and never worry about Rate. Just set the pitch slider in the middle of the tail shaft so you can get max travel in both directions with the limit pot as near 100 as possible by adjusting the servo arm length.

If you are getting drift and you are setup like this it is most likely vibration, gyro pad is spliting, gain too low or you are moving the heli while the gyro is booting up

[HiroboFreak]

I'm not familiar with the DX6i, but 401's have a common drift problem with JR radios.

Providing your mechanical setup is satisfactory, the fix is to add the smallest amount of rudder subtrim (in the opposite direction of the drift) to change the centre point reference signal. Less than 5 units of subtrim is required.

Then make sure you switch off both the Rx & Tx & re-initialise the gyro as per the usual procedure.

Not sure why this fixes it, possibly a Futaba/JR clash.

Worth a try anyway.

[bjs]

Many thanks for the replies, I will let you know how I get on.
Barry

[Thomas]

I'm not familiar with the DX6i, but 401's have a common drift problem with JR radios.

Bollocks, who told you that crap? I always flown JR and used 401s as have many others and never heard of a 'common drift' problem.

[Mike W]

I agree ... I know lots with 401's and JR radios and dont encounter n e drift problems when they got it set up ... He can put sum subtrim in to compensate for the drift .. BUT ... then ya not getting the full throw of the servo arm over the arc ....like most have said .... set it up mechanically first then use the radio to fine tune the settings ...

[Smoothound]

Bollocks, who told you that crap? I always flown JR and used 401s as have many others and never heard of a 'common drift' problem.

Very democratically put Thomas

[bjs]

Just went for a quick fly in the park (and dident crash!!) the more power I give it the worse the drift gets, I have up'd the gain until it twitched then backed off but its still drifting bad. Guess I need to start from scratch and set up in Rate, the problem with that is surely with the servo arm at 90, the tail pitch slider will not be central as I assume I am aiming to get the heli tail solid in the hover in rate with no trim? Appreciate your help guys........
Barry

[Thomas]

Check the tail rota it not slipping, if, say, the belt is loose or something is slipping then it could be the cause of the problem