General 3GX - Tail shutter starts while flying

[mooserider]

I've had this issue for a while now that only happens maybe one in 8 or 10 flights. It's scary as all hell, especially for a guy just learning orientations. Basically, I'll be flying (more like hovering) around and suddenly the tail starts 'over-compensating' back and forth rapidly. So you have this heli flying and it's just twisting back and forth rapidly (yaw I believe). This usually happens after a quick up or down (altitude) change. My guess is that the tail gyro is set too high. So I figure the tail gyro gain is set too high, however, I also have the problem were the tail blows out during harder pitch bumps (which implies I need a higher gyro gain set). So I'm a little confused on how to handle these conditions.

Here are my settings:
Mode: head holding
Throttle curve: 80, 78.5, 70, 78.5, 80
Pitch curve: linear (0, 25, 50, 75, 100)

All my 3GX settings are as Tony describes in his videos for newbies. This is a Trex 450 with a Spektrum DX7 (not S).

In all other respects, it flies as expected.

Thanks all!

 

[Smoggie]

You are right, the tail shake is almost certainly gain too high.
For the tail blowout you might want to run higher headspeed. You will have to reduce gain more when you increase headspeed but it will make ultimate holding power of the tail better.

 

[Derek]

What version of 3gx are you running? I have v5.0 on my Align 450 and the tail gets into that over-compensation, too, just like you are describing. Now, for the most part, my 450 is super solid and it's a real treat to fly. I only get a real bad over-compensation (or wag) when I come out of a fast loop, or something similar, and the headspeed raises (therefore increasing the tail rotor speed). Once the headspeed settles down, the tail gets solid again, lol. It's weird. I think I've just accepted it because the helicopter is just so solid for the rest of the flight.

I'm not suggesting that you accept it, like I have.

 

[murankar]

Tail issues on the 3GX are extremely common. In most cases you cant tune it out. Now some people never have issues with it. Its a hit or miss kind of thing.

 

[Tony]

What tail servo are you using and what tail servo settings do you have in the 3gx?

 

[mooserider]

It's a digital servo that came with it. All I can remember is the first two lights on the 3gx settings for it are green lol! I know the tail assembly is silky smooth, because I just put a new one on it and made sure. I can try upping the head speed, as it does still bog quite a bit when I give it a hard pitch increase. I assume that means just upping the throttle curve? So instead of 80, 78.5, 70, 78.5, 80, change it to something like 95, 92, 90, 92, 95?

 

[Lee]

Try a flat throttle curve, say, 85% flat.
The combo of RPM change and pitch change is putting a lot more force on the tail.
Higher HS will give the tail more authority, but if the headspeed is high enough already, you could try some slightly longer tail blade, or different style, ie wider cord.

As for the tail wag, as you have discovered, the gain is too high. Drop it down.
For those scary moments, when you do get violent wag, most people freeze up and freakout. LOL
By just putting in a rudder input, one way or the other, it normal stops the wag, because you are over ruling the sensitive corrections by the gyro, for actual corrections by you.

Hope this helps out

 

[Derek]

Just like Lee just said....a flat curve may help. I fly my 450 in stunt 1 and stunt 2 only. I use normal mode just to get off the ground. My stunt 1 and 2 curves are flat. Stunt 1 is flat at 85% and Stunt 2 is flat at 95.

 

[mooserider]

Sounds good, I'll go out and give it a shot. Thanks all!