need gy 401 help

[scottyrox]

im basically self taught in rotary flight. learning anything i know about helis from trial and error and forum advice.

so after my last crash i replaced the cheap gyro on my belt cp rtf kit and the tail servo. after installing the gyro and servo im having setup problems.
i watched finless bobs video and have combed the instructions as best i can. in heading hold mode i started at 75% sensitivity and -60 in rate mode. loosley based on the numbers in the gyro guide. after some tinkering im noticing the tail wags back and forth especially when i apply some cyclic. at a low hover it is basically uncontrollable, with the gyro spasming out and overriding my stick inputs. i have a hitec 56 tail servo now, and was trying to decide what delay setting i should start at but im not understanding what the guide is getting at. another thing im confused about is the limit adjustment on the gyro. i set the endpoints in the transmitter and im lost about the function of the limit dial on the gyro, what exactly am i supposed to do with that? one other thing i might note, after the last crash rebuilt the rotor head but have a pretty good start up wobble and was wondering if that wobble might be confusing the gyro.

any advice would be great, thanks

[forjer]

You shouldn't have any binding or resistance in your tail linkage. Pop the ball link off your tail servo and slide it fore and aft in line with how the servo will drive it. If you feel any tightness, that needs to be taken care of. Alternatively, if there is any slop, that should be taken care of as well.

The servo isn't great for a tail. I used an HS-81 for a few weeks but converted to a 9650 as I didn't want to be able to blame the tail servo for any problems. I was confused on the delay pot as well. Another reason for upgrading to a digital servo which can simple allow for a delay of 0.

The rudder endpoints in your radio do not control servo travel when using a gyro (well at least a 401). The endpoints control piro rate or how fast the gyro gets your tail to rotate. If you crank your rudder endpoint up to max, your heli will spin like a top. If you turn the endpoint down to 30, it'll rotate slow even with full rudder stick.

The limit pot on the gyro is what controls servo throw. If you don't want to use rate mode during flight (many, including myself only fly with HH mode), use rate mode for linkage and servo throw setup. Basically, with your dual rates set to 100% and 0 rudder trim / subtrim, you want to maximize servo throw in rate mode using the limit pot in conjunction with adjusting the linkage length (servo position on the boom). You don't want the tail pitch slider to reach the end of its travel before the servo stops driving the slider. Once this is set up, you'll need to adjust the gain to the HH side.

As far as the wagging, generally that means that the gain is too high. Have you tried lowering it to something like 40 or 50?

[scottyrox]

i found a damaged gear, will fix that first.