gy401 assistance or advice please

[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

[GilUriel]

Hi Scottyrox

Finless series is an amazing one. still .. as for the 401 I had problems with his setup.
I ran into the following link that ... did magics for me.

Hope it will do the same for you
http://www.raptortechnique.com/gy401-dx7.htm

Gil

[Skiddz]

OK, a bit of info first.

1) Endpoints on the radio only set the RATE of yaw.. (i.e how fast the heli will spin if you hold the stick over to one side or the other) They do NOT set the travel limits on the 401.

2) Mechanical travel limits are set with the limit pot on the 401, not the radio. (See what I'm getting at here??)

The 401 is a breeze to set up.. 1st, plug the servo directly into the rudder channel and power up the heli (diconnect the ESC or unplug the motor 1st)

Get the TR servo centered and find an arm that gets you as close to 90 degrees to the case as possible. Use a little subtrim to get it perfectly "squared up" if necessary. Connect your linkage and keep the ball link on the servo horn as close to the center of the wheel as possible. Not sure what the actual length should be on your BeltCP, but try for about 8mm to start. With the servo centered up and linkage attached, slide the servo up and down the boom until the pitch slider on the TR assembly is centered and the pitch slider arm is perpendicular to the boom. (The slider MAY not be centered, but that's ok. Getting the arm perpendicular is more important) Snug up the servo mount to stop the servo from moving which working on the heli, but keep it loose enought that you can do some adjusting to its position.

Now power down, plug in the gyro and plug the servo back into the gyro. Fire up the heli and enter the gyro menu or the gain channel endpoints menu. The gyro should initialize in HH mode (Solid red light) Tweak gain numbers or switch position to get it into rate mode.

Now, hold the TR control over to the right or left and tweak the limit pot until the slide *JUST* touches the TR hub or tail case (Depends on which side you are holding the stick) The "sweet spot" for the 401 is right around 100 on the limit pot. If you have to go well past that, move the ball link on the servo horn out one hole. If you're well under that, move the ball 1 hole in on the horn. Hold the TR control to the opposite side. If the slider binds before you reach full travel of the servo (not the stick, the servo!) you'll need to tweak the position of the servo and check limits on both sides again.

Once you've got the limits adjusted, flick back into HH mode and set your gains. Since you're using an HS56 servo, make sure the digital servo switch is off. Also check the proper direction of the rudder channel and the gyro operation before you spool up.

Start with rudder endpoints at 100 and tweak the piro (yaw) rate from there.

Hope this helps and good luck!

[mujibest]

OK, a bit of info first.

1) Endpoints on the radio only set the RATE of yaw.. (i.e how fast the heli will spin if you hold the stick over to one side or the other) They do NOT set the travel limits on the 401.

2) Mechanical travel limits are set with the limit pot on the 401, not the radio. (See what I'm getting at here??)

The 401 is a breeze to set up.. 1st, plug the servo directly into the rudder channel and power up the heli (diconnect the ESC or unplug the motor 1st)

Get the TR servo centered and find an arm that gets you as close to 90 degrees to the case as possible. Use a little subtrim to get it perfectly "squared up" if necessary. Connect your linkage and keep the ball link on the servo horn as close to the center of the wheel as possible. Not sure what the actual length should be on your BeltCP, but try for about 8mm to start. With the servo centered up and linkage attached, slide the servo up and down the boom until the pitch slider on the TR assembly is centered and the pitch slider arm is perpendicular to the boom. (The slider MAY not be centered, but that's ok. Getting the arm perpendicular is more important) Snug up the servo mount to stop the servo from moving which working on the heli, but keep it loose enought that you can do some adjusting to its position.

Now power down, plug in the gyro and plug the servo back into the gyro. Fire up the heli and enter the gyro menu or the gain channel endpoints menu. The gyro should initialize in HH mode (Solid red light) Tweak gain numbers or switch position to get it into rate mode.

Now, hold the TR control over to the right or left and tweak the limit pot until the slide *JUST* touches the TR hub or tail case (Depends on which side you are holding the stick) The "sweet spot" for the 401 is right around 100 on the limit pot. If you have to go well past that, move the ball link on the servo horn out one hole. If you're well under that, move the ball 1 hole in on the horn. Hold the TR control to the opposite side. If the slider binds before you reach full travel of the servo (not the stick, the servo!) you'll need to tweak the position of the servo and check limits on both sides again.

Once you've got the limits adjusted, flick back into HH mode and set your gains. Since you're using an HS56 servo, make sure the digital servo switch is off. Also check the proper direction of the rudder channel and the gyro operation before you spool up.

Start with rudder endpoints at 100 and tweak the piro (yaw) rate from there.

Hope this helps and good luck!
this all sounds like good advise, the 401 is a great versatile gyro as for the wobble sounds like your main mast has a bend in it, must be perfectly straight another words bending it back into shape yourself doesn't work even on an engineers lathe, or maybe your blades need balancing, if they are damaged chuck em. other variables that can lead to wobble are frame tightness, inappropiate headspeed for your blades and of course a badly set up
gyro. there are probably other reasons but I can't think of them.

[Skiddz]

Head wobble in flight can be caused by stiff dampers and a low head speed. Wobble at spool up is usually the blades getting in phase and should go away once you're up to speed. Try tightening up the blades a smidge and see if that helps.