Digiflight IIVSGV

[Sticky1]

What are the initial settings for a seawind 3000 with the high torque roll servo...?

[TrutrakTech]

I always recommend the torques set to 12. With the high torque roll servo, you'll need the activity starting up around 16. Vertical activity can be started around 3-4. Thanks!

[Sticky1]

I recently took the plane to Oshkosh. Along the route I turned on the auto pilot and found that the roll servo was hunting back and forth. The lat is set at 16. I went to 13, same. I went to 20, worse. Any Ideas....?:confused: Pitch servo is not installed yet.

[PhantomPholly]

Dial down the lateral activity to 3-4 (or even 1) and see if that works. Keep the torque dialed up to max unless you find it physically difficult to overcome the autopilot in normal flight (safety measure - you want to be able to "out-vote" the AP while fumbling for the Circuit Breaker in the event it misbehaves).

As long as your altitude is good and you're in clear air, there is no danger at all in "experimenting" with TruTrak settings while airborn. If it is still "bad" even at low activity then I would check for play in the servo / aileron actuators. Significant play can cause the servos to "overshoot" a reasonable correction each time it corrects for a perceived change.

My Lancair 320 has lateral activity set at 3, and it is plenty. In smooth air it is rock solid, in rough air I sometimes dial it up a notch or two - but no more.

[TrutrakTech]

I recently took the plane to Oshkosh. Along the route I turned on the auto pilot and found that the roll servo was hunting back and forth. The lat is set at 16. I went to 13, same. I went to 20, worse. Any Ideas....?:confused: Pitch servo is not installed yet.

Two things. One, make sure you power up on the ground while stationary so as not to introduce an offset into the gyros.

Two, you may need to add some lateral microactivity as well. Like Pholly said, make sure your torque is set to 12. I'd reset the lateral activity to 16 and try slowly adding microactivity to the adjustment. See if that cures the hunting. Let me know how it turns out. Thanks!

[PhantomPholly]

Two, you may need to add some lateral microactivity as well. Like Pholly said, make sure your torque is set to 12. I'd reset the lateral activity to 16 and try slowly adding microactivity to the adjustment. See if that cures the hunting. Let me know how it turns out. Thanks!

Never played with Lateral Microactivity - would you explain how that works and what the relationship between Activity and Microactivity is?

:)

[TrutrakTech]

Never played with Lateral Microactivity - would you explain how that works and what the relationship between Activity and Microactivity is?

:)

Sure! Activity is how fast the servo runs through its steps. The higher the number, the greater the velocity.

Microactivity is a little different. Let's say you have a little slack in your control system. This "dead zone" (i.e. lost motion) has to be "absorbed" before you actually make the control surface move. If you allowed the servo to absorb it regularly, you would have hunting. The AP would make a correction, see no result, so command more correction only to see that it over-corrected. Basically the AP would constantly over-correct itself due to that small amount of slack. With Microactivity you can account for that dead zone. By increasing the Microactivity you increase a set, rapid movement made by the servo before it begins its measured stepping. Does that make sense? You use the Microactivity setting to absorb this dead zone.

The dead zone is mostly seen only in cable control system aircraft. Occasionally a push/pull tube setup will need a little bit of Microactivity to get a nice, smooth ride.

I hope this helps explain it some. It always sounds better in my head!

[PhantomPholly]

Sure! Activity is how fast the servo runs through its steps. The higher the number, the greater the velocity.

Microactivity is a little different. Let's say you have a little slack in your control system. This "dead zone" (i.e. lost motion) has to be "absorbed" before you actually make the control surface move. If you allowed the servo to absorb it regularly, you would have hunting. The AP would make a correction, see no result, so command more correction only to see that it over-corrected. Basically the AP would constantly over-correct itself due to that small amount of slack.

Got it - that's exactly what I was describing above to the other fellow. I have zero "slack" so I've never needed it in my Lancair.

With Microactivity you can account for that dead zone. By increasing the Microactivity you increase a set, rapid movement made by the servo before it begins its measured stepping. Does that make sense? You use the Microactivity setting to absorb this dead zone.

So, increased microactivity means that when the servo reverses direction from the last command it will increase the amount of distance it moves before it "counts".

Let me guess, then - if you use microactivity to try to correct for static lag it actually makes it worse...

[TrutrakTech]

Got it - that's exactly what I was describing above to the other fellow. I have zero "slack" so I've never needed it in my Lancair.

So, increased microactivity means that when the servo reverses direction from the last command it will increase the amount of distance it moves before it "counts".

That's correct.

Let me guess, then - if you use microactivity to try to correct for static lag it actually makes it worse...

Bingo!