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KendallB
07-05-2007, 12:07 PM
Hi Guys!

I have a really wierd problem with the tail on my Synergy that I just cannot figure out. When I put the heli into a hover, if I leave the rudder stick alone and just hold the hover, the tail will twitch side to side very small amounts (kind of like gyro wag, but the gyro is set to a gain of AVCS 35%). The way is not really the problem. The problem is that if I leave it in a hover, the tail will move constantly to the right in small increments. If I leave it in the hover, within about 30 seconds the heli will be 90 degrees from where it started! Eventually it would do an entire pirouette if I left it alone and just held the hover.

I am flying with the 14MZ radio and 14CH synth receiver, and I have tried both channels 34 and 55. I am flying with the GY611 Gyro, and I have it mounted up front near the receiver (not on the gyro mounting plate as I was told that mounting it back there was not really necessary).

I tried moving the gain all the way up to about 55%, but it had no effect on this problem. When I had the gain at or above 40%, I would get tail wag during forward flight, so 35% to 37% appears to be about the max I can go without getting tail wag (and that jibes with the manual).

I did think perhaps my gyro was bad, so I first replaced the sensor with one from my crashed T-Rex 600 (another story!), and that had no effect. So then I tried swapping the amp, and I think it got a little better, but the problem was still present and it would creep sideways still.

So as far as I can tell this problem is not electrical, and has to be somehow related to some wierd mechanical issue in my heli? I went through the tail linkage rod and made sure that the links were not too tight and that it was mechanically centered.

Would this problem be related to the fact that my gyro sensor is not mounted on the rear mounting plate, and is perhaps too far from the main shaft of the heli? I do plan to move it back there to see if that has any effect or not.

The tail on my Raptor 90 is rock solid with the GY611, but I am flying that bird on my JR 9303 still. When I had my T-Rex 600 flying on my 14MZ, the tail on it was rock solid also using the GY611 that is now currently in my Synergy.

Hi Guys!

I have a really wierd problem with the tail on my Synergy that I just cannot figure out. When I put the heli into a hover, if I leave the rudder stick alone and just hold the hover, the tail will twitch side to side very small amounts (kind of like gyro wag, but the gyro is set to a gain of AVCS 35%). The way is not really the problem. The problem is that if I leave it in a hover, the tail will move constantly to the right in small increments. If I leave it in the hover, within about 30 seconds the heli will be 90 degrees from where it started! Eventually it would do an entire pirouette if I left it alone and just held the hover.

I am flying with the 14MZ radio and 14CH synth receiver, and I have tried both channels 34 and 55. I am flying with the GY611 Gyro, and I have it mounted up front near the receiver (not on the gyro mounting plate as I was told that mounting it back there was not really necessary).

I tried moving the gain all the way up to about 55%, but it had no effect on this problem. When I had the gain at or above 40%, I would get tail wag during forward flight, so 35% to 37% appears to be about the max I can go without getting tail wag (and that jibes with the manual).

I did think perhaps my gyro was bad, so I first replaced the sensor with one from my crashed T-Rex 600 (another story!), and that had no effect. So then I tried swapping the amp, and I think it got a little better, but the problem was still present and it would creep sideways still.

So as far as I can tell this problem is not electrical, and has to be somehow related to some wierd mechanical issue in my heli? I went through the tail linkage rod and made sure that the links were not too tight and that it was mechanically centered.

Would this problem be related to the fact that my gyro sensor is not mounted on the rear mounting plate, and is perhaps too far from the main shaft of the heli? I do plan to move it back there to see if that has any effect or not.

Does anyone have any suggestions on what could cause this problem?

jrohland
07-05-2007, 12:45 PM
I had the same symptom on a smaller heli with a Futaba GY240 gyro. It turned out to be excessive vibration. I mounted the gyro on a few more layers of Futaba gyro tape and made sure the safety strap (hook & loop tape) was not too tight. That solved the problem for me.

jrohland

KendallB
07-05-2007, 01:50 PM
Thanks Rohland! I need to put the new Hyperformance R/C hub and dial indicate it with my new engine to try and eliminate any engine vibration. I do already have two pieces of the tape holding the gyro down, along with the metal shield between them. I do not use any straps on the gyro to ensure the tape provides good vibration damping.

Chuckie
07-05-2007, 03:17 PM
The rear gyro mount was added because the servo tray had too much vibration for some maneuvers but others have used it with no problems. I agree vibration may be the cause of your tail drift. How much fuel movement do you have in the tank when full, half, and 1/4?

You could have engine vibrations but also if the TT end at the tail box is not installed straight it will also cause vibrations. Hold the tail box and see of the other end of the TT is not turning true.

The other thing to check is the thrust bearings in the tail grip. Though if the bearings are bad/wrong the tail will not drift but it will oscillate back and forth. Check the outer diameter of each race with a digital caliper. One end should be bigger than the other. The larger inner and outer diameter should be installed in the grip first. The second one with the smaller inner diameter should also have the smaller outer diameter.

Charles

q8hobbytime
07-06-2007, 04:30 AM
Check your tail system from the servo till the tail grips
try hovering with rate mode and let us know how does it go

HiroboFreak
07-12-2007, 07:07 AM
How old is the kit?

Some older batch kits had a problem with the tail thrust bearings being of the wrong specification, causing the thrust bearings to lock up under load & cause a wag. (As Chuckie said)

If you tighten up the locknut & your tail blades don't flap/rock easily, then you have an issue.

The inner thrust race should be quite loose on the hub & tight in the blade grip.
The outer thrust race should be tight on the hub & quite loose in the blade grip.

If the thrust bearing specs are incorrect, Synergy should replace them under warranty.

Cheers,
Dennis.