700 Problem with Tail rotor on trex 600N and 700N

[THOMAS KING]

I have been working on both my 600 and 700 and seem to have the same problem with them on the 600 i am using the align 780 gyro on the 700 using the G401 but while i was hovering the 700 in HH mode i was at two feet off the ground holding hover reduced throttle it went into a left hand spin (thats tail left nose right) and ripped off the tail, so i went back to my 600 and got it setup both in rate mode and HH mode i have pos 1 set at -55 rate, pos 2 at +75 HH and pos 3 - 55 rate. While flying sat i set this up on a training pod so as to have it off the ground while hovering it was holding fine i had to hold a little right rudder to comp for tork but was'nt bad but as soon as dropped throttle it too went into a left hand spin, i was in pos 1 at -55 rate. it seems that on rate the tail will always center but in HH mode it will move very slow and stay on the right or let side and put me in the same spin so not sure what to do. Confused!!! Open for all suggestions Thanks Much

 

[Tony]

The holding the tail blades in the direction of the last input is normal. You gave the gyro a request, and it is going to hold that pitch until it reaches the heading you told it to go to, or until you give it a different request. Rate mode is only there to stop the tail from moving after an outside force hits it. It will always return to center when you let go of the stick.

I always fly with a flat throttle curve because of this issue. I never leave my throttle curve linear because it does act against the tail.

You had stated that you are using the 780 gyro on the 600, what tail servos are you using on these birds?

 

[THOMAS KING]

The holding the tail blades in the direction of the last input is normal. You gave the gyro a request, and it is going to hold that pitch until it reaches the heading you told it to go to, or until you give it a different request. Rate mode is only there to stop the tail from moving after an outside force hits it. It will always return to center when you let go of the stick.

I always fly with a flat throttle curve because of this issue. I never leave my throttle curve linear because it does act against the tail.

You had stated that you are using the 780 gyro on the 600, what tail servos are you using on these birds?

the 600 has a 790 gyro with a DS 650 tail servo, the 700 has a new DS 655 tail servo it was a Futaba S9254 but was damaged in my crash

 

[Tony]

Both of those servos should be fine and should hold the tail very well with the gyros you listed. Yes, the gyros are a little old, but they should do just fine.

When you are in rate mode, is the tail slider centered on the shaft? Have you checked for any binding by disconnecting the linkage rod from the servo and moving it with your hand?

 

[THOMAS KING]

Both of those servos should be fine and should hold the tail very well with the gyros you listed. Yes, the gyros are a little old, but they should do just fine.

When you are in rate mode, is the tail slider centered on the shaft? Have you checked for any binding by disconnecting the linkage rod from the servo and moving it with your hand?

Yes i have done that redid all the links and no binding at all, so why would it throw tail pitch in when dropping throttle ?

 

[Tony]

Is it actually putting pitch on the blades causing it to go nose right, or is the pitch you have set on the blades causing it to go nose right when you reduce the amount of torque being applied to the tail. This is the question that only you can answer since they are in front of you. Unplug the motor from the ESC and run the throttle through the entire pitch range. If you see ANY pitch change, there is a mix in your Tx somewhere that needs to be deleted. If there is no mix and there is no movement on the tail blades, try running a flat throttle curve. I would start, for normal mode, at 0 75 75 75 75. This will be close to a normal throttle setting while in a hover and will give you just a slight bit higher head speed which will equal stability.

And as long as you have a good ESC, they should spool up nice and slow still even with the 0 to 75% jump.

 

[THOMAS KING]

Is it actually putting pitch on the blades causing it to go nose right, or is the pitch you have set on the blades causing it to go nose right when you reduce the amount of torque being applied to the tail. This is the question that only you can answer since they are in front of you. Unplug the motor from the ESC and run the throttle through the entire pitch range. If you see ANY pitch change, there is a mix in your Tx somewhere that needs to be deleted. If there is no mix and there is no movement on the tail blades, try running a flat throttle curve. I would start, for normal mode, at 0 75 75 75 75. This will be close to a normal throttle setting while in a hover and will give you just a slight bit higher head speed which will equal stability.

And as long as you have a good ESC, they should spool up nice and slow still even with the 0 to 75% jump.

thanks ill check my throttle curve to see what i have and note this is a nitro ship.

 

[Tony]

Forgot about the nitro. In that case, are you running a governor? If so, it definitely shouldn't be doing this. If not, I would highly suggest running a gov because it keeps constant head speed. But it is even more important to run a flat curve with nitro than it is electric IMO.