"Shudders at Mid Stick"

[wildhorseheli]

Hello guys and gals, I got a Nano for Christmas and outta of the box it had shutters at mid stick while flying around. I added some .001 o-rings to all links and that helped for a bit but now I noticed they're back again right around zero pitch. My feathering shaft if straight, main gear all the way up and all that good stuff. My guess is that it may be just the poor quality of the stock swash plate that has to much slop on it. I guess I'll have to upgrade to an after market swash and hope this solves the shuttering problems. Just thought I'd ask for y'alls opinion. Love this heli btw, oh and Happy New Year to all!!!!

L.T.

[JonJet]

At mid stick, the Nano should still stay on the floor...but if you have a lot of negative pitch, it will certainly cause a shudder.

Try holding it in your hand at midstick at see if there is considerable difference above and below with respect to airflow...it should be equal.

If not, you have a zero-pitch issue which means you are not getting equal amount of positive and negative collective...cured easily in your digital transmitter

[jmtyndall]

Originally Posted by JonJet

At mid stick, the Nano should still stay on the floor...but if you have a lot of negative pitch, it will certainly cause a shudder.

Try holding it in your hand at midstick at see if there is considerable difference above and below with respect to airflow...it should be equal.

If not, you have a zero-pitch issue which means you are not getting equal amount of positive and negative collective...cured easily in your digital transmitter

"At midstick while flying around." As in, he already lifted off


This is the infamous "wet dog shake" while the disk is unloaded. Bullet blades help, o-rings help, a straight feathering spindle helps too. With that said, I have a nano with an entirely new rotating assembly and it still shudders, so idk. A swash may or may not help. I haven't tried one yet.

[wildhorseheli]

Originally Posted by jmtyndall

"At midstick while flying around." As in, he already lifted off


This is the infamous "wet dog shake" while the disk is unloaded. Bullet blades help, o-rings help, a straight feathering spindle helps too. With that said, I have a nano with an entirely new rotating assembly and it still shudders, so idk. A swash may or may not help. I haven't tried one yet.

Yes while flying around in my den and at the point where it's at mid stick it shudders but not while the disc is loaded....

[jmtyndall]

Originally Posted by wildhorseheli

Yes while flying around in my den and at the point where it's at mid stick it shudders but not while the disc is loaded....

Exactly. I've gotten one of them to the point where it only shudders in a light descent. If I give a little negative they go away, and of course climbing out it's fine. If you find a resolution, I'd be willing to try it too.

[JonJet]

It's very possible that you have a bent feathering shaft...or it's not tight enough

[wildhorseheli]

Originally Posted by JonJet

It's very possible that you have a bent feathering shaft...or it's not tight enough

Ok pilots, here's what I did and my results after some adjustments to eliminate shudders at mid stick. I removed the head, blade grips, main shaft/gear and swash plate. I lubricated all bearings with a drop of tri-flow. Checked the feathering shaft and it was straight as an arrow. I did notice that my blade grips were a little loose which I tightened just enough to where they turned smoothly. Adjusted all swash links and confirmed I had zero pitch at mid stick. Glued the bottom of the main gear with white glue and allowed to dry. Flew one pack in the my den doing FFF, sharp turns and some pitch pumps and I'm happy to report that all my shudders at mid stick have disappeared !!!!! I think the main problem was the loose feathering shaft which was causing one blade grip to wobble and not having 100% zero pitch at mid stick as well. Now when my timer goes off at 4 minutes and I land in stunt mode and hit throttle hold the heli doesn't vibrate with the throttle at mid stick the way it did before during spool down. Sorry for the long explanation, I just hope my findings will help someone that may have similar problems as I had experienced....

[Guapo131]

The OP seems to have solved his problem, but i wanted to throw another possibility out there - Dirty Servos can be another cause of wet dog shakes.
So to summarize (expanding on jmtyndall's ideas):

• clean the servos (dirty servos can get jumpy/sticky/notchy. sometimes in as little as 20 flights, but usually more like 50-100 flights).
• Bullet blades (as opposed to the performance, non-bullet blades)
• o-rings on all of the ball link connections (7 total)
• ensure straight feathering spindle, and FS tightness set appropriately
• upgrade to a metal swash (the stock plastic swash has some slop), also ensure the plastic swash isn't partly broken - that's happened to me
• ensure the blade grips are tightened appropriately and equally
• ensure the main gear is pushed all the way up and secured with glue of some sort.

[wildhorseheli]

Originally Posted by guapo131

The OP seems to have solved his problem, but i wanted to throw another possibility out there - Dirty Servos can be another cause of wet dog shakes.
So to summarize (expanding on jmtyndall's ideas):

• clean the servos (dirty servos can get jumpy/sticky/notchy. sometimes in as little as 20 flights, but usually more like 50-100 flights).
• Bullet blades (as opposed to the performance, non-bullet blades)
• o-rings on all of the ball link connections (7 total)
• ensure straight feathering spindle, and FS tightness set appropriately
• upgrade to a metal swash (the stock plastic swash has some slop), also ensure the plastic swash isn't partly broken - that's happened to me
• ensure the blade grips are tightened appropriately and equally
• ensure the main gear is pushed all the way up and secured with glue of some sort.

As guapo131 stated above, if you have the shudders/wet dog shakes on your ncpx try some of the fixes he listed. In my case it was the blade grips being to loose causing up & down movement on one of the blade grips that caused the shakes. I will definetely upgrade to a metal swash plate in the near future because as stated the stock swash does have a lot of slop...

[seth556]

What's the appropriate tightness of the feathering shaft? Mine shudders just like you guys are saying and I think I've done everything but play with the tightness of the FS.

Also I'm guessing a metal swash would help a lot, mine seems to have a lot of play.

[JonJet]

Check your zero pitch...if you have negative pitch while spooling up or past mid-stick, that will cause a shudder...had that with My mCPX BL after I installed the DFC kit

[Soulfly]

Next time it shudders, push the main gear up the shaft so that it's closer to the frame.
I don't know if anyone has mentioned this yet.. But when you crash some times it pushes that gear down on the shaft, and it gives lots of collective movement allowing it to shudder.

[JonJet]

Originally Posted by Soulfly

Next time it shudders, push the main gear up the shaft so that it's closer to the frame.
I don't know if anyone has mentioned this yet.. But when you crash some times it pushes that gear down on the shaft, and it gives lots of collective movement allowing it to shudder.

Both index fingers pressing downward from the rotor hub while both thumbs press up on the gear...sometimes it will give an audible snap when it goes back in

[wildhorseheli]

Originally Posted by seth556

What's the appropriate tightness of the feathering shaft? Mine shudders just like you guys are saying and I think I've done everything but play with the tightness of the FS.

Also I'm guessing a metal swash would help a lot, mine seems to have a lot of play.

What I did for blade grip tightness is 1st I snapped off the (2) dog bone links from BG to swash, 2nd removed main blades of course then used the supplied tools and tighten the blade grips until they were binding while turning the BG with one in each hand. 3rd then I loosened them little by little until there was no binding and they were spinning freely then re-assembled everything. Also as previously mentioned make sure you have zero pitch at mid stick, main gear pushed up all the way, etc. This got rid of the shudders / wet dog shakes for me...