1.40 weird behavior

[gdesdigu]

Hey guys, I need your help here, let me explain:

I've setup the cgy on my goblin 380 with bk servos and I've noticed two things:

First: I've dialed my general gain at 70% in stability mode 4 and still no wobbles whatsoever but in hovering from time to time it bounces on the elevator quickly.

Second thing: On the bench when I move the aileron stick the swash moves slowly and then somewhere at midrange it jumps to full aileron but it's not happening with the elevator axis... I kind of felt it in flight, much more blade fart on the aileron

Should I put it back to stability mode 5 and keep on increasing the gain till everything sorts out?

Thanks for your help!!

[Dr.Ben]

Is the bounce spontaneous and without a stick input?

Ben Minor

[gdesdigu]

Yes it is, looks like I tickled the elevator stick and let it bounce around center with the spring effect.

little bouncing on FFF as well.

What do you think?

[gdesdigu]

Guys? Nobody had the same problem?

[bparro]

Not had that problem but I would guess that the cyclic gain is too high for your headspeed in hover.

[gdesdigu]

I only fly in idle up, take off ,hover and the whole flight is at the same head speed.
I'll try again tomorrow, I'll up the gain 'til it shakes in hover so that I'll know the limit, back down a little and see how it behaves in flight. Hope it works!

[bparro]

Also check the cg. Tail heavy might make the problem more obvious.

[gdesdigu]

The cg is fine but I'll check again just to be sure. Will report tomorrow!

[Dr.Ben]

Leave everything as it is except lower stability gain a point or two and compare your result. If the model wiggles withOUT a cyclic input or with a constant stick input, you might try reducing the I gain of the affected axis.

Ben Minor

[gdesdigu]

Thanks you Dr Ben, I have lowered the I Gain 10 points on the elevator expert menu, it doesn't wiggle as much as before on hard stops but on FFF the heli tracks like a dolphin, it pitches up and down all the time quickly. It does the same but slower on slower forward flight. Is my main gain too high?

It still wiggles from time to time on the elevator in hover. Other than that I can do some hard 3d without problem, only very few bounces on hard stops after lowering the I gain.

Oh and climb outs are very straight, no corrections needed.

The aileron however is perfect.

Please help!! I don't wanna put a microbeast on it!

[Dr.Ben]

1. What was the effect of lowering the stability gain?

2. What is the cyclic transmitter gain set to?

3. How much static cyclic pitch are you measuring in swash rate mode?

4. Have you tuned else D gain so the elevator stops are clean as per the tuning guide I wrote in the manual?

5. Does the model shudder after a purely collective input stop?

Ben Minor

[gdesdigu]

1. Lowering the stability gain made the heli shake a lot so I had to reduce the main gain and flight wasn't improved by much.

2. Tx gain is set to 75 on both axis.

3. I have 10° of static pitch

4. Well I should be able to lower it a bit more as I'm stil getting occasionally some shakes but it was on very violent stops, the one you make on purpose to see if it will shake or not.

5. In a hover no, but on forward flight it won't hold the angle, it would back it up a bit.

Greg

[Dr.Ben]

Lower transmitter gain to 60%. Item three in the tuning guide.

10D measured in sws.rate? Please confirm as this is critical.

You're not tuning out a shake with D gain. The goal is to adjust so that realistic elevator inputs have a clean stop. Do NOT intentionally make violent stops that bear no resemblance to typical flying as a test for this or any tuning. Don't let the stick spring back to center when adjusting for this.

I'd also like for you to assess the stops with stationary ROLLS. If you see and strike back or kick in the landing skids, lower the control gain by 2 points.


Ben Minor