Hey guys,

I have a trex 450 se with the 401 gyro and 9650 and the Futaba 6ex fasst radio. The heli flys beautifully but I've noticed for some time now, when I'm in a hover, the tail will hold for about half a minute then the tail will move about 5 degrees to the left. I'll correct it with the trim, it moves back. I'll readjust the gyro, on the radio, and it moves back. My question is, do I have to readjust the delay or limit on the gyro its self? If so, which one?

thanks

Mine does about the same thing and I'm not sure that it's not within normal bounds. Half a minute is a long time.

mine does the same thing, im guessing its due because of the vibration over time causing the gyro to think it needs to correct to the left.

the Gyro is not auto pilot it will drift ,,,, sounds normal to me 30 Sec is a long time for a Gyro to hold

I usually associate a slow drift with excess vibration getting to the gyro.

Possible causes:
Improper foam installation
zip tie safety strap
tight velcro safety strap
gyro physically touching frame (under boom installations)
tight servo wires between gyro and frame zip tie hold down point
excess servo wires bundled up and wedged between gyro and frame

My theory : it's the Coriolis effect, as in : the-earth-is-rotating-under-the-helicopter-while-it-stays-fixed-in-space. The clockwise rotation as seen from above would be consistent with the Inertial Circles observed in wind patterns in the northern hemisphere. Considering that the Coriolis effect has to be taken into account in modern long range ballistics like artillery shells or sniper bullets with flight times as short as 5-10 seconds, I wouldn't be surprised if it played a role in a situation like this.

Whatever the reason, half a minute is a long hover, I never stayed in place long enough to experience what you describe, and I learnt to hover with a Blade CP. It wouldn't hold it's heading for more that 10 seconds, let alone 30. I wouldn't worry about it.

Does this happen in Heading Hold, Rate Mode, or both.

When you adjust the trim ... you do re-initialize the gyro before flying again ... right?? If not ... you need to. It maybe not have anything to do with your problem ... but might as well eliminate the possibles ...

You guys --- coriolis effect?
It takes time for the gyro to warm up because it uses electronic and piezo components, my start up is always the same. Set your tail trim before take-off(in HH tail blades don't move and stays centered), run it up for 30 seconds then shut it down, turn power off then back on and retrim tail and your gyro will be rock solid for all your flights. In cold weather it gets worse you should let your bird sit outside for 5 minutes minimum to stabilize the temperature, then run it at least 1 minute to warm up the gyro before you land, turn power off/on and retrim. If you don't do this the gyro will continue to drift for some odd reason before you turn off to switch packs which is really annoying.
As far as vibration goes I have never had a issue with it, it has always been the gyro gain being set too high leading to drift and tail wag.
Hope this helps and good flying

coriolis effect? My thoughts exactly!!! Thanks Tippy, for a basic, easy to understand, simple solution. I wasn't looking for a lecture on physics