TREX 500 ESP GP780 Gyro

[apstringer]

Managed my first test flight over the weekend. Helicopter setup seems ok, but I have horrendous tail wag when the gyro is activated. I have checked the forums for this issue and have tried all of the suggestions made, but with no luck. My setup is the gp780 gyro with an align DS520.

The settings on the Gyro are
1520 micro seconds
Digital Servo
Reverse
Limit set
Delay Medium

I have a DX6I and have tried gyro gain between 52.5% and 80%

If head hold mode is off I get a very small movement in the tail when hovering.

Any help would be apreciated.

[vinny155]

what are your throttle curves,this heli like to be arount the 90 to 100% mark

[apstringer]

Thanks for the response vinny. My throttle curve was at 0,50,80,90,100. Have changed to 0,60,90,95,100
and will give it a go.

[vinny155]

if you are confident with the heli try 0-80-90-90-90,if this doesnt help you to get it sorted id look out for another gyro,the gp780 is what pushed me to try fbl as i spent countless trips to the field trying to get rid of the wag,i didnt manage to get rid of it

post in the wanted section for a 750 or a spartan quark if youve got spare funds,there should be a few about at a good price

[debrooker]

The 780 is very sensitive to vibes, and the 500 does like a good head speed. I ran a flat 100% curve.

With this gyro you need to ensure you have a silky smooth drive train and always pay attention to bearings, such as main shaft. Any roughness will show.

I mounted the gyro on the bottom plate - seemed to work best for me, and managed to get the gyro to 85% (on DX7 gyro sense menu)

[snotvis]

Tail wag is common on the 500 and GP780. You must check that the tail is absolutely smooth, and that the is no loctite in the screws that hold the pitch slider. If that doesn't fix it check how the gyro is mounted - use the metal plate. 500s also like loads of headspeed, so dial that up.
Once you sort it you will love this heli.

[apstringer]

Thanks for all the help, have mounted the gyro as per the diagram on page 19. When you say you have mounted it on the bottom plate, do you mean the receiver plate?

[SaneAdam]

I had the same wag on my 500. I changed to a bigger pinion and it totally cured it. Completely wag free. Think i went from a 13 to a 14 tooth pinion and it sorted it

[debrooker]

the bit the skids screw into - sorry its been a while since i've owned a 500 and can't remember if there was a seperate rx tray

[apstringer]

Thanks for the help, will give it a go.

[Biggles]

You could go mad trying to sort a 780 out...In a word it's C**P. Invest in a CSM 720 or a Futaba 520 and the difference is awesome. I have a 500 and used all three of the gyros mentioned. Opted to keep the 720 in as it felt rock solid. Neat trick with the tail is to do the grip flip as the tail geometry is shocking! As pointed out many times by 3Dbasher ;-)

[apstringer]

Thanks for the help. It is still driving me crazy, going back to the shop tomorrow. They have made a few suggestions from a previous visit, but still no good.

[Jonp]

I tried the supplied Align 780 gyros on my 550 and 700 and had exactly the same issues you describe. My experience to date had always been with Futaba gyros, so I went back to Futaba, a 520 on my 700 and a 401 on my 550 and they fly perfect.
I am sure this is not the answer you were looking for and I am aware that the Align gyros are well regarded but I just could not get along with them.

[stanley1]

the 780 is a good gyro when set properly, but thats the issue finding the sweet spot can be like searching for a needle in a haystack. as mentioned before the whole of the tail assembly must be silky smooth and compleatly free of any binding throughout its entire travel range. flat throttle curve is a must too, something like 0,80,80,80,80 in normal and flat 85/90 in idle 1. i just use flat lines on all flight modes, as long as you have a nice soft start on the esc then its just a flick of throttle hold to go

[SaneAdam]

tried a bigger pinion yet??