Rudder drift with new Silverline sensor

Hi,

I just upgraded my Synergy e7 from a blueline to a silverline sensor and i am now experiencing slow counter-clockwise rudder drift in the hover (less than one degree per second). The rudder also drifts on the bench with blades off, and during spool-up. This is visible on the live display and on the tail blades.

I would like to ask advice about troubleshooting because i am not sure if the problem is excessive vibrations or possibly a faulty sensor. At the same time as the silverline sensor was installed, i also switched from a belt driven tail to a torque tube.

I have used two other vbars on this heli and also a 600EFL Pro, so i am judging this drift as abnormal compared to my previous experience with the vbar 5.3 Pro. Unfortunately i don't have a spare sensor right now to swap for testing.

I have attached a screenshot of the spectrum analyser during a hover. (Please ignore the larger transparent green spectrum which was measured during a piroflip.) The main peak at 2225 rpm matches the rpm of the head. The smaller peak at ~180Hz corresponds to the tail blades.

Are my vibration levels high enough to cause a slow rudder drift? The heli is extremely stable in the aileron and elevator axes, no drift at all.

Could you please attach aimage of the sensor mounting?
Which tape did you use?

If you will be able to check on the bench ... please try with stick deadband 100 to exclude a TX/RX issue.

regards (EN) / Gruss (DE)

Rainer Vetter

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Hi Rainer,

I have tested on the bench with rudder dead band of 50 and there is still CCW drift of the rudder. I have also used your TX analyze plugin and have attached the result here. Rudder was working fine with this TX on my other heli a few days ago (a vbar 600E Pro, now sold). I assume the tx is ok?

I have attached images of the silverline sensor mounting. This setup worked perfectly with my previous blueline sensor before i upgraded to the silverline. The sensor is mounted with the supplied tape, and the cable is fixed to the side of the model with double sided tape a few cm from the sensor.

I should mention that the CCW drift during spoolup is quite severe, and always requires pilot correction before takeoff. I have also found that if i tap lightly with my finger on the tail boom (with motor off) the rudder will drift CCW. Vbar log during flight has no errors, apart from the occasional high and extreme vibration warnings during 3D.

Do i need to send this for service?

thanks

Anthony

How do you test on then Bench? With motor running?

Please try another sensor mounting position, just to verify.

I had a report of a heli where a loose bolt cause some strange things. The solution was: Strapping down the sensor even more, and fix the bolt that creats some sort of rattle. You could clearly hear this...

so long ... Uli
http://www.vstabi.de

I have tested in flight (spectrum attached to first post). I have also tested the bench with the motor running and with the motor not running. I have performed these tests at multiple headspeeds (1800 rpm, 2100 rpm, 2300 rpm). I believe that my heli vibration levels are acceptable since no one has commented on the spectrum analyser being too high. There is nothing loose or apparently wrong with the heli mechanics (i have been over it many times, stripped and rebuilt).

Moving the sensor does not affect the bench test, drift still occurs. This drift only started when i upgraded from the blueline sensor to a new silverline sensor. Unfortunately i no longer have the original sensor to test with.

Ok, and it drifts even with motor not running?

so long ... Uli
http://www.vstabi.de

If the heli is sitting on the bench with the vbar powered but with the motor off, it does not drift.

I just performed another test suggested on another forum. It is conducted with the vbar initialised and motor OFF. If i pick up the helicopter and slowly rotate it CW, the vbar and rudder servo corrects for the movement.

However if i rotate the heli slowly CCW, the rudder servo does NOT correct for the movement. I can turn the heli by more than 90 degrees CCW with NO yaw corrections made by the vbar.

If if rotate the model quickly then the vbar corrects in both directions.

Please let me know what you think.

thank you

Anthony

This is normal and does not have to do with the drift in Flight. Its not possible to judge this on ground. I am pretty sure it is a vibration problem, since it really happens only if the motor runs.
Do you have the possibility to change the position of the sensor somwhere different?
If this still does not change it, we shall try another sensor.

so long ... Uli
http://www.vstabi.de

Hi Uli,

This weekend I decided to buy a second brand new silverline sensor for back to back comparison with the drifting one. As well as CCW drifting, i noticed the first sensor allowed the tail to blow out 20-40 degrees on some hard moves.

The new sensor solved the drifting problem and the tail now holds properly (as it used to with the old blueline sensor). I e-mailed Rainer with my observations and i have submitted a service ticket. I will post the drifting sensor for service tomorrow.

(I tried the slow rotation test on the ground with the good sensor and it behaved the same way as the drifting sensor. I won't be using that test again!)

thanks for the help

Anthony

aro03 Wrote:
-------------------------------------------------------
> Hi Uli,
>
> This weekend I decided to buy a second brand new
> silverline sensor for back to back comparison with
> the drifting one. As well as CCW drifting, i
> noticed the first sensor allowed the tail to blow
> out 20-40 degrees on some hard moves.
>
> The new sensor solved the drifting problem and the
> tail now holds properly (as it used to with the
> old blueline sensor).


Did you mount the new sensor in the same position as the one causing the drift problem? I am very curious since I have the identical problem and have already replaced my sensor but am still having the same issue.



Edited 1 time(s). Last edit at 09/09/2012 01:59AM by aramb.

Did you use the extra stiff tape that came with it?

Eddi

Born to fly ...
forced to work.

When i tested the replacement sensor everything was identical. The supplied stiff tape was used for mounting.

Rainer arranged for the faulty sensor to be serviced for me. I now have no drift problems at all, everything is working properly.