RunRyder - Gyro gain vs Servo arm length

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Radio - Servo - Gyro - Gov - Batt > Gyro gain vs Servo arm length

sparkyman
Senior Heliman
Location: uk

Hi,

I was reading about mechanical gain (servo arm length) versus Gyro gain and was wondering which way was the best set-up?

The author wrote that if, during initial set-up, you can increase your gyro gain to 100% without the tail wagging, then your rudder servo arm length is too short and the ball needs to be moved further out.

After recently setting up my heli, I had to reduce gyro gain from 80 to 70% in order to eliminate wag.

Would it be better for me to shorten the servo arm, reducing mechanical gain, and run a higher gyro gain to try and get closer to 100% before wag ?

Any comments ?

Thanks

07-14-2008 03:53 PM

BarracudaHockey
rrMaster
Location: Orange Park FL

Depends on the gyro. You want the gyro limit or end points at 100 or slightly above, that gives the gyro maximum resolution so in that regard, its better to have a shorter arm and give the servo more throw than to have a long arm and a compressed throw on the gyro.

As with all things, there's a happy medium. It has to do with both the gyro, and the geometry of the linkages that control the tail rotor and the amount of pitch throw it has.

Also tail rotor rpm and blade length, chord, and stiffness all play in to the mechanical gain equation.

AMA 77227
http://www.jaxrc.com

07-14-2008 04:15 PM

sparkyman
Senior Heliman
Location: uk

Hi BH,

Thanks for your input. It's a GY401 - limit pot is set to 100, I seem to feel that a shorter arm with higher gyro gain would be preferable. I think i'll try it next weekend and see how close to 100% gain I can get to before things start to wag again.

I don't have any issues with tail authority at the moment (as I'm only circuit bashing at best), but I was just interested if one setup was preferable to the other. I can see now that using the full amount of servo travel available will give the highest resolution, so it all makes sense to go down this road.

Thanks again

07-14-2008 07:53 PM

BarracudaHockey
rrMaster
Location: Orange Park FL

You don't want 100 percent gain you want 65 or 70 or so

More than that and you're just going to over heat the servo. You don't want to run any more gain than you need to and have the tail hold.

If you're doing rolling tail slides thats going to be more gain than if you're hovering and doing figure 8's

AMA 77227
http://www.jaxrc.com

07-14-2008 08:06 PM

sparkyman
Senior Heliman
Location: uk

BH - point noted - thanks for the info.

07-15-2008 08:30 PM

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Radio - Servo - Gyro - Gov - Batt > Gyro gain vs Servo arm length

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