Tail Twitch

[DrScoles]

When I built Ion, used NIB 601 and rx... at first got violent tail twitch but tail still held.... Talked to Russ, he said put metal plate on...did that, it diminished, but still happens....not cool... any suggestions?

I tried two different sensors, gain settings at both extremes....no luck...

Thanks, Mike

[bob00]

I had a bit of a twitch that would only show up when driving the heli backwards or in funnels. It seemed pretty random. After a few flights we noticed that the horz. fin had rotated slightly on the boom.

The horz. fin clamp was as tight, but if you REALLY force it, it will resist then slip suddenly - we think this was happening in flight, producing a sudden and equally sharp correction by the gyro resulting in - the twitch.

We wicked some thin CA btwn the clamp and the boom about 10 flights ago - twitch GONE.

I've since noticed the same thing with my nitro Fury's, though for some reason it seemed more pronounced on the ION.

Hope this helps.
- Rob

[Russ McC]

Hi Mike,

Mine is still rock solid after installing the isolator plate I had originally left out. I’m not getting any fin clamp movement, might be your bug :)

[DrScoles]

I know its not the boom clamp... Its tight as hell and CA'd... Sounds weird, but it does it more at beginning of a flight..then settles down...

Mike

[Russ McC]

I and Wane both had trouble with dry out put shafts giving trouble. Is your shaft adequately lubricated? No pun intended :mrgreen:

[DrScoles]

hahaahaha russ, good one...
I put triflow on before each flight.... guy up in canada dumped his because of that...

Its definitely the gyro giving the servo a command when it shouldn't.... Fairly sure its not mechanical....

Anyway I can shield sensor even more?


Mike

[Russ McC]

I put triflow on before each flight.... guy up in canada dumped his because of that...

Who crashed?

[fitenfyr]

Mike,

Educated guess here, but have you double checked all your connectors to include the motor and ESC?
Might have a loose connector giving intermittent power.
I would think that would show in a PCM lockout from RF noise, but it may just be enough of a loss of power to be picked up by the tail and gyro, but nothing else.
Think of it like a nitro engine running a bit rich and doing the same thing.

[ChrisS]

A couple things I can add here that might help:

Remember that on the Ion-X the tail is going a good bit faster than on a liquid heli. Same ratio, but the head will unload to something over 2K rpm with the 52 tooth layshaft gear. The machine does run smoother, so intuitively, you would think you could get away with more gyro gain. But I think the faster tail negates that. Also, keep the tail blades to the stock length.

Rob, I like your discovery and will look into that.

During the prototype stage of the first pre-prods, both Jason and my machines layshafts were not set screwed tight enough. They had flats, and the setscrews were on the flats, but not nearly tight enough. This would result in a violent and erratic tail kick. I was running a 401 and he had a 601. This is why we are assembling those here. We had to enlarge the flats, go to bigger setscrews and more of them to do it. You might want to check that if you have a tail problem you can't track down.

Chris

[DrScoles]

Thanks for the tips CHris.. Gain is not the prob, I've put it down to 20 with the 85mm sab tailblades...

What is a "layshaft"??? is that a souther word<g>? :lol:

Mike

[ChrisS]

The layshaft is the secondary or as some have called it, "jack shaft". The shaft that contains the smaller white gear and pinion.

Chris

[DrScoles]

It was the gear!!! We took the whole assembly out of mine, and Wayne gave me his(his Ion is in a million pieces :? ) and when he took the set screws out of mine, he could pull the gear off with his hands... most people had to use a lot of force.... So it must have been slipping a little...

Put it on Waynes front lawn.... rock solid,,,,, no twitch at all.....Phew..... I was going crazy.... you know that feeling when something is wrong with your heli and you can't figure it out and you think you have a clue.... :wink:

Mike

[DrScoles]

I spoke too soon.... :( Put new packs in, went to front yard to hover...same thing... I turned the gain down to15...still did it. It seems like at beginning of pack, it does it more, then as pack wears down, it doesnt do it at all,...... weird huh? I'm gonna reroute the radio gear and see if it makes a difference. I managed to get rid of the extension for the tail servo...no help. I might stick a 401 in here and see how it does :( ...

Mike

[ScotY]

A couple of thoughts...are you using an rx battery or BEC? If BEC, might want to try a battery just to eliminate that as a possible cause. How about a ferrite ring for the gyro (and/or servo) leads?

[DrScoles]

thanks for ideas scot, I will entertain them all!!! I am not using BEC, I will look into a ring for the servo... Having a tough time tracking this one down... It seems like it only happens when the pack is fresh..... I'm flying today, so I'll play with it some more...
Mike

[Russ McC]

So what came of it today?

[DrScoles]

Russ,

Flew it today, twitch is gone... but night before hovering it did it a few times, I monkeyed around with the electronics...ie moving wires around....not sure what I did to solve it, I did remove the 4" extender I had for the tail servo...but it twitched right after I took it off....

Hopefully this weekend we'll get a good test... Definitely need to cycle the batteries more! The new packs aren't as strong as Waynes old packs I'm using... I'm on my fourth charge.... Hopefullly get a few more in before brooks...


Later, Mike

[Russ McC]

Sounds good Mike, Looking forward to Brooks! And to trying your new V-Blades, probably won’t be swayed from the SABs but I will give them a look, I prefer white blades over black so long as the white blades can hold there own in performance :)

[WayneR]

While tail twitch got really bad last night. Turns out my one-way was slipping periodically. I pulled the whole main gear assembly out of my SE night ship and put it in the Ion, twitch is gone, even on spool up.

[Tabbytabb]

Mine had a horrendous twitch until I put some stainless under the gyro. Not even a hint of it since then.

Tabb

[WayneR]

Stainless has been there since day1.

[Russ McC]

It looks like there have been multiple causes for this tail twitch. My first Ion had the twitch but I had not installed the isolator plate under the 601 sensor, when I did the twitch went away. Looks like a loose lay shaft gear has also caused it and a slipping split gear and routing of antennas and wiring.

I have one more thing to add, after crashing at the Snohomish FF and repairing I had the twitch. Well In the crash The sensor case was damaged, I CA glued it back together and added a zip tie around it and the frame of the model just for extra security. Removing the zip tie seemed to cure the problem but then it came back again but ever so slight, I found the sensor lead was now touching the canopy stand off and the left battery, I secured the lead away from the battery and stand off and the twitch remains gone!

Good to hear you all seem to be getting on top of this little rascal of a problem!

[DrScoles]

As Wayne stated, it was the main gear!!!! Tim sent me a new one, just ran it up in front yard...zero twitch.....:-) So glad to get rid of that!!!!

Goin to Canada with weekend for Fun fly, Ion will ROCK!!!

Mike

[WayneR]

Cool glad you got it back in the air.

[heliman777]

Drscoles,

So was it the main gear or the one-way? :?: