3GX with trex 250

[DanWright]

I'm running a trex 250 DFC with the align 3gx v3.1 software and I've got a problem which I can't solve!
When I increase the pitch in normal or IU modes, the tail doesn't hold and will rotate to the right, I've managed to reduce the problem slightly by mechanically altering the gain, and also the gain on the transmitter. I've tried various settings on the 3gx software... I've tried adjusting the control rod length, I've tried everything I can think of. And I'm not making any difference now.
Can anyone suggest any solutions? Any hints, tips... Anything before I go insane

Thanks, Dan

[tourerjim]

Is this the 250pro or one you've moded.??? You need to move the servo arm in as far as you can that will just allow enough movement on tial slider.

[DanWright]

This is the new dfc pro. I did have it moved in as far as I could on the servo, but since I moved it out, the problem has been reduced quite significantly. but it's still there

[tourerjim]

If you set a thottle flate line in iu of 88% them try the tail again to see if it does it.

[DanWright]

It's doing it when IU 1 is at a flight line of 80% and IU2 is flat at 90% so I expect it's the same story at 85%

[tourerjim]

Are using sat or rx.???

[tomatwalden]

The tail will kick right under high collective under the following conditions (I believe)

1/. The gyro gain is too low - so the 3GX doesn't respond quick enough to the increased torque.
2/. The response from the 3GX to the increased torque is compromised because of a mechanical reason.

Assuming you have your tail gain high enough, I would start looking at your mechanical tail setup. For starters, when you did the tail setup in the 3GX, have you configured your end points properly such that the 3GX has full throw of the tail slider?

Have you ensured that there is no slipping of the tail drive - ie. torque tube assembly/gearing is OK?
Is the neutral position of the tail slider set correctly (ie. have you done the "90"'s)
Is the tail slider moving freely?

Finally - take a look at this vid ...

Align gp780 (3GX) gyro setup video 1 (freddy can fly) - YouTube
and
Align gp780 (3GX) gyro setup video 2 (freddy can fly) - YouTube

[DanWright]

I'm using the rx, no sats.
My gain is a little high if anything. If I piro and stop the tail suddenly I get a bit of a wag, but nothing major. All mechanical components seem correct and there is no binding anywhere, no loose gears, and nothing is slipping. I might try moving the ball back to the inside hole of the tail servo.
What I have noticed since I've had it, is there is a bit more play than I like with the tail pitch slider but I don't think there's much I can do about that.
Ive also read on another thread, that I should move the two pots on my 3gx from the 12 o'clock position to the 10 o'clock position just for a better over all feel for flying but this hasn't effected the tail either.

[tomatwalden]

3GX with trex 250

What I have noticed since I've had it, is there is a bit more play than I like with the tail pitch slider but I don't think there's much I can do about that.
.

How much play? That would definitely cause the symptoms you describe as the servo would move to correct the torque, but play in the slider control wouldn't allow that servo movement to be reflected in the pitch of the tail blades.

Don't have a 250 myself, but none of my helis with the exception perhaps of my 130x has play in the slider assembly.

[tourerjim]

What colour is the esc, Align have an upgraded the esc because of power problems to servo's, it should now be a blue esc.

[DanWright]

Here's a quick video of the play I have in the tail. When you see it move, the tail rod nor the servo is moving, this is just the amount of free play

Trex250 tail slop - YouTube

[DanWright]

I did have the yellow esc but I kept suffering from brown outs so I up graded to the blue one... No problems since

[tomatwalden]

Here's a quick video of the play I have in the tail. When you see it move, the tail rod nor the servo is moving, this is just the amount of free play

Trex250 tail slop - YouTube

wow! That's horrendous! Sorry, no offence, but if that isn't your problem, I'd be amazed!

[DanWright]

Haha! I always thought it was bad! But after hearing story after story of how the 250 is so fidly, poor the quality can be, I guess I over looked it. Will some simple washers sort the problem do you think, because apart from the play, there is nothing else wrong with the tail set up

[tomatwalden]

3GX with trex 250

That's what I would try .. Maybe a shim behind the umbrella gear on the output shaft. Seems you're not alone on this ...

http://www.youtube.com/watch?v=8SJHH2Zmmmk