500 lb. koolaid man

Just to throw it out there - I'm also asking this question on helifreak. I hope that's ok.

I'm working on an EXI 450 for a friend and the tail always drifts counterclockwise. It has a 401b (401 clone) and an hs-65hb tail servo. No trim or subtrim applied on the tail in the DX7 and endpoints are 100 on both ends.

Things I've tried:

tested it with my 401b and also a telebee gyro

tested it with hxt900 as the tail servo

I also have a 450 (tail is solid) and use a DX7, so I copied my trex 450 binded it to my DX7.

Also moved the tail servo to move the slider to a new spot (off center).

Gyro gain is acting normal, it's around 30% in head hold, any higher and the tail wags (and drifts).

Nothing stopped the drift and I'm out of ideas. I feel like I've tried everything possible, I'm stumped and confused. Doesn't seem to be the gyro, tail servo, or settings in the DX7. Other than this dang drift, the chopper flies great. Any ideas would be greatly appreciated. Thanks!

jerrymac

My Feedback: (2)

Too low a head speed maybe? Does it do it in both normal and stunt mode?
If only in normal mode, try changing the throttle curve so you have a higher head speed at lower throttle.
Does the tail servo "drift" on the bench in HH mode after moving the rudder stick? If you move the rudder on the bench in HH mode, the servo should stay at that position since it did not sense the heli yawing. Give it full left rudder, then back to center and watch the tail servo. Then give it full right rudder, back to center, then watch the servo again. It should stay at the given stick command in HH mode. If it drifts, add "sub"-trim till the servo stops drifting .

I know many people will say to never use any kind of trim on the tail, however, with the cheaper gyros, this is the only way I could ever get the drift out. I never had to do this with my JR gyros, but I did with the Telebees.

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flhyr

Had the same problem, here's how I fixed it:

multiple layers of foam mounting tape under the gyro.
Move the ball link further in on the tail servo arm to be able to set the gain higher without wagging.
Most importantly, whe plugging in the battery, make absolutely sure that the tail is not moving even a little while the gyro is going through its initializiation. For me this meant barely making contact with the connectors, then waiting for the gyro LED to go on steady, then plug in the rest of the way which makes the whole heli wiggle due to the amount of force required to seat the connector.

if all this doesnt' help, seriously consider a new tail, and tail drive gear, and put the belt tension looser than you think it ought to be.

I did all this and it holds pretty well now, drifts randomly, but only after a number of seconds (401b gyro)


Let us know what ends up working for you....