AR7200bx, parameter menu, point D

[lahannsven]

Good morning,

On the Microbeast or AR7200bx you can set the "heading lock part" on parameter D.

The manual states to start with a very low value: LED purple.

Default setting is "average": LED red.

I noticed, that with the low settings LED purple you can set a much higher tail gyro gain in your transmitter.

How do you get now to the correct settings (Parameter D and gyro gain transmitter) ?


Sven

[Frenchdress]

Hi,

the heading lock part is influenced by the gyro gain. When adjusting the gyro gain in consequence you will change/amplify the heading lock part. It is not unusual that you can increase the overall gain when you lowered the heading lock part because the heading lock part may have been the limiting factor before and may have had an impact on the other parameters.

For the correct adjustment procedure you start with "low heading lock part" and increase your tail gyro gain just until the tail does not start to wag. This ensures that you've maxed out all other parameters. Then you can start increasing the heading lock part in case the piro rate is inconsistent in fast forward flight or in case the tail does not hold the heading when hovering in side wind condition. Finally it may be necessary to decrease the gyro gain slightly in case the higher heading lock part causes overcompensation of the control loop.

[lahannsven]

Thanks Stefan,

I never had problems with my Trex450 Pro DFC, where parameter D was set to average.

The problems started with the Trex450L and Trex250 Pro DFC. Here I always had a super low gyro setting in the transmitter.

Obviously to start with a low parameter D setting helps to stabilize the tail. Transmitter gyro setting could be increased.

Of course all this needs to be maximised for windy conditions.

Alltogether the Trex450 Pro DFC always behaved perfect in wind with average settings.

For the Trex450L and/or Trex250 Pro DFC it is much harder to find the optimised solution.


Sven

[Crowbar]

I tend to do this: set Parameter D down by one step, see if it's still controllable, down by another step and check things out. If fast forward flight still works fine, leave it for now. Ignore inconsistent piro rates.

Now crank up the main tail gain (10% increments on a 3-way switch work great) and try to trigger tail shakes. Fast backwards turns work great. If the tail starts shaking, unload the disk (center collective stick) to make it stop and "shift down" that gyro gain switch. Fine the gain setting where it's just below tail shaking in those fast backwards turn.

Take the gain number and substract one third (e.g. from +60% go to +40%) and start cranking up D gain until you get bad behavior in backwards flight. If you're not using a governor at all (like me on 450s), then you can stick with the original main gain setting without shaving the third off.

Once you're done with parameter D (i.e. get consisten piro rates on both sides during a fly-by), set the tail dynamics (pot 3). The higher the knob the more aggressive it will stop pirouetting. On a belted tail, you can typically run that higher, having it too high (tail rotor really barking on tail stops) will eat up your torque tube gears pretty quickly. Having it too low makes the tail wander a bit or bounce back when you center the rudder stick. It's more of a personal preference really. I like mine rather soft.

[lahannsven]

Thanks Crowbar,

in fact my troublecase was always my second Trex250 Pro DFC. It was shaking constantly. Turning down parameter D helped a lot and I increased transmitter gyro gain.

By the way, my first Trex250 Pro DFC worked fine with LED red (average setting). Both helis are not crashed. Therefor I guess it's manufacturer's tolerance that drives you sometimes crazy.

My Trex450L was similar, but to lower parameter D helped and a lot of test flying:
- parameter D
- transmitter gyro gain
- poti 1 and 3

I probably only fully understand the "BeastX" after some years.

Sven