Trex XL won't stop hunting

[dubhouse]

I just finished my trex xl. I can't believe how quiet it is once it gets up to speed. I've got the Futaba GY240 on it with a standard micro servo for tail rotor control. The Trex is very responsive when flying but the tail won't stop hunting. If I turn down the gyro gain, the tail hunts slower with larger gestures. Higher gain results in faster smaller movements. I moved the tail control rod from the middle hole of the servo arm to the outer most hole without much change.

I have some lead attached to the tail for balance. Could the extra weight on the tail be throwing off the gyro or something? If not, anyone have any ideas to get rid of the perpetual hunting?

Thanks, Tavis

[tdswan]

You shouldn't have to balance a T-Rex with lead. The best thing to do it trim it to get it level and happy and/or move some electronics around if the balance is that far off. I'm guessing you're transitioning from plankers to heli's. The lead on the tail COULD be contributing to the problem. The lighter the tail is, the better it will probabaly respond.

A hole out on the servo is the right direction, these gyros are very sensitive and you will take more advantage of it's capabilities by giving it as much throw as you can. You did mention you were using a standard servo on the tail....Not sure what that means, but make sure the servo is quite fast and is recommended for use on the tail of a helicopter. They don't need to be high-torque but speed is critical on the tail. I won't recommend the servo I'm using because I'm not very impressed with it (Hitec HS-50) but I'd check around to see what others are using on the tail. Spending a little extra money here would be a good idea to save headaches.

[dubhouse]

What I mean by standard servo is it's not a really fancy digital servo or anything. It's one of the align servos that come with the Align T-Rex.

The issue with weight concerns me because without the lead on the tail the thing is extrememly nose heavy and the battery is as far back as it will go. No other electronic component moving would be sufficient to the get the CG under the main shaft. I don't think I even have enough trim to get it hover without the lead on the tail. I will try though.

Thanks for the fast response.

-tavis

[Motions]

The Align servo is probably the worst servo you can use on the tail. The HS-50 is not great but it would be better than the Align. The best performing tail servo is the Futaba 9650. They are pricey for a Trex which is the reason I went with the HDS-577. The tail servo is a critical component on a heli so get a descent one. I ran the HS-50 for a while and it holds well until you get into fast backwards flight and it just doesn't have the torque to keep up.

My suggestion at this point is to get a better servo and see how it does. If cost is an issue, try the HS-50. It would still be an improvement.

Another very important suggestion, loose the z-bend control link if you haven't already. It has way too much slop for a tail linkage. Installing a ball link on both ends will make a world of difference.

[CLM]

if you go for a hs 50 zip-tie it to prevent it from popping apart :rolleyes:

Chris

[dubhouse]

I swapped the Align servo with an HS-125MG and the tail has quit hunting. Thanks for the help.

-tavis