FM gyro problem

[paulmack]

I have recently installed the Flymentor on my Belt CP. The green and blue wires are not connected. When I am in heading mode (input to Helibal), the rudder servo swings full right with the stick centered. The heli will spin right on throttle up.
When in normal mode the rudder works both ways although it is not really centered when the stick is.
As far as I can see all settings are correct.
If I disconnect the FM gyro and use the original (non-headlock) gyro the rudder works ok.
Does this mean my gyro is probably defective?

[pril250]

If you have set the tail correctly so that it holds hover in rate mode and then the gyro seems to drift in HH mode then it is doing what most cheapish gyros do at some point in their life. In 'normal' mode the slider should be off center giving the tail blades some pitch in order to hold, so that is fine.

The FM tail gyro is not that high quality and I would recommend, as many do, to install a better gyro on your bird. BTW what tail servo is being used?

[paulmack]

Thanks for the quick reply.
To get the servo at midpoint using the FM gyro, I need to set the mid pointt at -50 in Helibal. Then,In normal mode, the heli starts to spin counterclockwise at near take-off power. When the throttle is cut back quickly, the tail whips clockwise.
In heading mode it spins clockwise unless the rudder stick is pushed significantly to the right and held there.
The servo is just the stock E-sky variety but works fine with the basic E-sky gyro.
I had a fairly significant crash the first time I tried flying with FM installed. Could that have damaged the gyro enough to cause rudder problems? The balance mechanism seems to work OK at least on the bench.

[Trooper]

There should be no correction in the software. You need to set up your gyro in rate mode first. Adjust your servo position to centre your tail at mid point. Then when you switch to HH it should be OK.

[pril250]

Probably the best thing is as trooper suggested, set up your tail mechanically from scratch with no trims or subtrims from Helibal. If it still gives you grief you might consider using an external tail gyro providing the other two are still intact.

The gyro can get damaged in a crash depending on how hard mother earth was met. I managed to do so and needed a new one, the balancing gyros went south.

[Ivor Hill]

The tail should be set up in rate mode (with little or no gain set) by sliding the servo along the boom or adjusting rod length so the tail holds without trim or stick input. That means that with the servo centered the tail slider will be off centre normally towards the boom. Then set travel,set gain, switch to HH and set gain.
A few clicks of trim and it will normally hold good enough for normal flying.
I always set up this way and the tail holds as well as any inexpensive gyro but if you have been spoilt with a good quality gyro you will not be happy with the FM gyro.
Why heli manufacturers do not build pitch into the tail is beyond me.
Hope this helps. Ivor

[paulmack]

Thanks to all for your suggestions. I will play around with the tail servo positioning some more and report back as soon as I test it.

[paulmack]

This is totally embarassing. I finally realized that the FM rudder control was doing exactly the opposite of what it should be doing.
After reversing the servo in the software, the FM gyro works fine.
The stock gyro worked just the opposite because it was preset to reverse with a little switch on top of it.
I made so many changes in the software, and wiring connections over the course of trying to get FM to work, I got a little lost. Adding to the complexity, I upgraded to metal head and tail parts and a programmable xmtr during the same time frame.

[Ivor Hill]

This is totally embarassing. I finally realized that the FM rudder control was doing exactly the opposite of what it should be doing.
After reversing the servo in the software, the FM gyro works fine.
The stock gyro worked just the opposite because it was preset to reverse with a little switch on top of it.
I made so many changes in the software, and wiring connections over the course of trying to get FM to work, I got a little lost. Adding to the complexity, I upgraded to metal head and tail parts and a programmable xmtr during the same time frame.

No need for embarsassmet, thank you for letting us know. A lot of guys just dont post again so you never know if they resolved there problems or not. Good luck and have fun. Ivor

[pril250]

Yes, I agree, thanks for posting your findings, something worth noting:thumbup: