Tail holding issues

[beans07]

Hi all, I am having some tail holding issues on my E5. The problem is a big kick against the torque about 45 degrees. I have checked everything mechanically and it all is very smooth.

It seems mechanical though to me. As I feed in collective and it loads up the degree of kick increases. Fast changes kick the tail out fast until the the load comes off. When doing a tail down or aileron tic toc it lets go.

Thus far I haven't found anything wrong mechanically. I have tried lots of tuning with the Brain with not a lot of success. Doesn't seem to make a real lot of difference.

Setup as follows:

E5 with MSH Brain on 600 sized profile
CC 120 HV with CC BEC Pro on 8v
MKS BL 665 HV on cyclics
MKS BL 669 HV on tail, servo horn @ 16mm
Scorpion 1100kv on 14t pinion
EDGE 553 mains
Rail 96mm tails with about 4deg of pitch on the tails
CC Gov Set RPM, 15 gain, HS of 2400
Boom is pinned front and back exactly as the manual states
60C 6s Revolectrix Diamond series packs

Servo specs here http://www.mks-servo.com.tw/goods.php?goods_id=hbl669

I run a Trex550e (Brain too) on 6s with Castle gov 2400HS on EDGE 553's and 90mm tails and the tail on it holds perfectly.

I would of thought that 96mm tails would be enough to hold the tail? Do I need to go up to 105mm tails? Anything mechanical I may of overlooked? Anything else?

Any help very much appreciated as I can't fly this heli the way it is.

[steffgiguere]

Have you tried to increase the tail gain? Can you adjust the tail gain?

[wbefield]

The Brain does have a pre comp setting, however I've always been able to dial the kick  out with the gyro gain. My E5 has the same servo, and they are definitely up to the task.  Just to double check, I would start  by disconnecting your tail control rod from the servo and make sure it moves smooth as butter.  If it is not smooth, start working your way back until you find what is giving resistance.  You may need to  size your ball links on the tail control rod and pitch links.

[beans07]

Hi guys thanks for your replies.

I tried again today after rebuilding the tail and even using a tail grips and hub that is already working out of my E7. I have tried all the gains to no avail.

The assembly is silky smooth.

I am now fairly certain it is the tail servo. The tail servo is binding up and feeling notchy when turning it with a  servo horn. It is going in increments rather than silky smooth. A friends MKS 980 is silky smooth and so is my Outrage 9188 servo but this one is far from it. I took the top of the servo case off and all is very smooth running but once the top case is introduced it binds up again. Once there is any pressure on the shaft of the center gears it binds up. So either it is slightly bent or the case where it rests in a bush is off center and causing it to bind up.

wbefield is your tail servo smoothy or very rough like mine?

I have requested an RMA with the place of purchase.

I will fit a BLS 251 and add a drop down reg to the servo and see how it goes. This should tell me for certain.

[wbefield]

Hi Beans,
I wouldn't say HBL 669 is ultra smooth like the HBL980 that I have in my N5C, but it is not rough or gritty by any means.

[Matt Botos]

A few things on tail performance (some of which sound like you have already checked)

1. Make sure tail push rod is free
2. Make certain you are running the pivot ball in the correct position (usually 16mm from center)
3. Make sure your FBL system is using all of the available throw in both directions.
4. Check to make sure your thrust bearings are installed correctly. Improper installation will cause the grip to bind.
5. Increase the gain on your tail gyro until you get a wag in fast forward flight and then back off until its gone.
6. Use a good tail servo which is capable of 760us frame rate. The tail servo is the last place you want to try and save money. Use something that is proven to work like a Futaba BLS256.

Thanks,

Matt

[beans07]

Thanks for your suggestions guy's.

Definitely was the tail servo. I put on a trusty old BLS251 and the tail is perfect without the need to touch the brain settings.

[Chris Sexton]

Thanks for your suggestions guy's.

Definitely was the tail servo. I put on a trusty old BLS251 and the tail is perfect without the need to touch the brain settings.

Glad you got it sorted, I hope MKS helps you on the servo.