trex 450xl tail wag

[rcflyer17]

I have a trex 450 xl. I'm running a Futaba 401 gyro on it. I have a pretty good set up on it as far as the head speed and pitch is concerned, but my tail wags and I can't get it stable in a hove. It almost act like it has too much gain. I tried setting the gain at alomst every setting there was and I go tthe same result each time.
I also tried to play with the expo and the atv's to get some stability out of it and stil the same thing. As I gave less expo I kept the atv's the same and it calmed down somewhat but still not where it should be. It is no where near hands free hover. ]
H E LP !!!!! thanks guys .

[Fasrc]

Make sure the links that attach to the tail slider are free. If you tighten those too much you will get similar results.

[rcfan]

Many things could be causing this, i.e. slop, servo, linkage, inconsistent motor rpm, etc. First off, make sure your linkage is a smooth as possible and RPM is smooth or constant through-out pitch changes. Make sure you don't have any rudder (sub-)trim on the radio and that in NORM mode the heli doesn't yaw during a smooth hover (i.e. make sure that mechanically the rudder is as neutral as possible). What gain are you setting the 401 at? Lower gain as far as possible until the tail wag stops but it still holds. Adjust the Delay pot on the 401 to a low value or even zero if you have a quick servo. Depending on setup, you may want to configure different gains for the gyro for different conditions, assuming you're radio allows it.

[rcflyer17]

I am actually in the process of changing the fram eto a carbon fiber. Also I am changing out some of the sock plastic part with metal upgrades. I.E. swash plates, fly bar control links .... Bla Bla Bla. I did check the linkages and they were fine no play. I did see that some of the guys are flying a digital servo " futaba s9650" so I mayt try that as well. Currently I have a HS55 on it.
I will do the upgrades and put the digital servo in and get with you guys on how it flys. Thanks for the responce.

[TomJ]

RC,
Have you tried and set up the rudder with the gyro OFF and ad power just enough to get light and see which way it rotates. Then keep playing with the linkage length untill it pretty much stops rotating, turn ON the HH gyro AFTER you disconnect BATT.. Be sure the trims are centered while doing this procedure. The same thing happend to me on My hornet2 last year when I got into this Heli Stuff. I have the Rex SE and am Reeaallly happy with it. Like on a rail..PS: the HS56's are way faster than me
Tj

[BIGMike350z]

MAKE SURE you have a fast servo!!! The reactions on the 401 are so fast that if the servo reaction is late it wags. I use a S9650 Mini Digital Servo by Futaba. It is small and quick. GREAT FOR TREX TAIL.

[tdswan]

I'm posting this as a general info for all who have struggled with the tail on almost any micro or above Electric heli. I have a T-REX 450XL CDE and (just for the winter) I'm running a JR G500T gyro on it from my Raptor. I have also used another gyro on it and with both, I had the same problem. I will start by defining "tail wag". It's a violent shake from left to right by the tail due to the gain setting being too high on the gyro. There are tons of threads in tons of forums that address this. One tail issue that they do not address is the occasional twitch that occurs in the tail once a stable tail is attained. I have discovered the problem (with mine, anyway). Governor Mode. I don't know how many people out there are using governor mode on their ESC's, I have stopped using it. What was happening was the governor was sensing a minor drop in rotor speed, compensating for it, then torqing the heli thus making the tail have to compensate for the additional torque. This is not a wag, just a lag in the gyro/servo combo that makes a noticeable twitch. Since I started using standard throttle curves like you would a nitro, this has stopped.

I welcome any other's opinions on this topic, whether you think I'm correct or not. I'm not an expert, just an experienced flyer. The T-Rex is my first electric heli, so if I'm wrong, I welcome the pros out there to give me their 2 cents worth.