infamous 1/4 piro....

[wnainebog]

Ok so like the title says I'm having a problem with 1/4 piro. I know this topic has Been discussed a lot and I have done my research but I still CANNOT GET THIS SORTED OUT!

Set up:
-micro heli advanced x frame
-micro heli swashplate
-micro heli rotor hub with button
-micro heli blade grips
-solid cf 2mm tail 150mm
-dual tail motor mod
-airtime rc landing gear
-stock canopy
-stock motor
-solid carbon fibre mainshaft
-blade HP blades
-hyperion 250 batteries
-silicone o-rings throughout for dampening.

I'm at a loss of words. I have gone over this heli time and time again and no avail. Mainshaft is not cracked, blades are balanced, gear is all the way pushed on.

So, any ideas?

-Ian

[Unholyfire]

Tried cleaning out and re-lubing your top/bottom main shaft bearings and swash? Microbinding due to dirt in these bearings can easily be the culprit, cleaning/lubing them very well has resolved this in my experience.

[Liduno]

Bad connections can cause it too, I also had a single battery that would work fine in one heli but make another twitch.

Motors going out can cause it too, if the power is interrupted to the motor for even a millisecond the tail will twitch..

I know you mentioned your main shaft wasn't cracked but they can be difficult to see, I find the easiest way to test them is to hold the main gear and twist the head, if it feels flexible it's cracked.

[vlz91]

Every time I've had this problem, it was a slightly bent feathering shaft.

[Ric66]

Vibration messing up the gyro signals... especially if it's a V2. Try checking your blade balance. Maybe try a different set of blades if you have them handy.

[Andrew73]

Originally Posted by vlz91

Every time I've had this problem, it was a slightly bent feathering shaft.

Same here.

[litehawkdown]

But it's awesome when your tail blows out and you save it and you look like your smacking 3D like a pimp!

[wnainebog]

Tried all suggestions guys but so far no Improvement

[Unholyfire]

You mentioned the dual tail motor mod. Can you give us pics of this, and explain how you have it wired?

[anjoi666]

Originally Posted by Unholyfire

You mentioned the dual tail motor mod. Can you give us pics of this, and explain how you have it wired?

big thread here: https://www.helifreak.com/showthread.php?t=326734

Probably wont solve the 1/4 if you do have vibes.
It works but its a bit of a hassle i think, personally like sr120 with v2/hp05s... Just get rid of the vibes.

[wnainebog]

Yes, I will do that when I get home from work. But its just two standard blade motor mounts. Glued together with a silicone adhesive and two motors from an mcx2.

I really don't think its a tail issue sinse it was there before I did the dual tail motor mod. I did the tail mod thinking it might fix the issue. I even attempted the 120sr tail mod but found is was so tail heavy it didn't fly well with stock main motor.

[Goatkeeper]

I dealt with the tail kick issue for weeks. I couldn't figure it out to saved life. It ended up being a tail wire plug. I direct solder both ends now.

[Drivinfast247]

Mine started it out of nowhere. Makes me angry. I'm going to tin the tail motor plug to see if that helps.

No binding at all. Brand new solid cf main shaft, main gear, feathering shaft, MH frame, MH swash, MH blade grips, MH head, kbdd main blades, v2 tail rotor on extended boom.

It will just piro 45* clockwise randomly.

[DoubleCH]

Why dual-tail mod with stock main? My single stock tail with stock v2 squary tail holds even my c05m brushless main. Dual-tail runs way too much tail-mix with stock main. It's like driving a car on the highway with way out of whack wheel alignment that pulls steering wheel to one side all the time. Sure holding the steering wheel to the other side to make the car go straight works (just like relying on heading hold gyro to hold tail with too much tail-mix), but you're just looking for trouble if you lose hold of the steering wheel for a fraction of a second (just like vibes or anything else that upset the tail gyro for just a tiny fraction of a second).

[SuperBee364]

As others have said, the 1/4 tail kick is pretty much always caused by a vibration problem. The following tip comes courtesy of Spunjah.

To isolate your vibration problem, remove all the parts of the main rotating group down to the motor: The blades, head, swash, main shaft, bearings and main gear. So now you're down to just the motor. Hold the heli in your hand, and just run the motor by itself. Feel the vibration (or lack thereof)? Remember what it feels like, because ideally, this is what you want it to feel like once all the parts are installed. Of course, it won't be *that* smooth once everything is installed, but it should be close.

Now install the bearings, but oil them first. Then install the main shaft, and main gear. Hold the heli in your hands and run it up to speed again. Note any differences in vibration. It should be just as smooth as it was when you were running just the motor. If it's not, you have a problem in either your main gear, shaft, or bearings. If it's still nice and smooth, continue on.

Now install the swash. Hold the heli in your hands, and run it up. Again, compare the vibration to what it felt like with just the motor. While the motor is spinning, deflect the cyclic and collective sticks. Make sure you don't get any increase in vibration when the swash is deflected. If you get more vibrations after installing the swash, you've found the problem: replace the swash. Still no vibes? Continue on.

Install the head (no blades). Hold the heli in your hands and run it up. Compare the vibration. More vibes? If so, you most likely have a problem with the head bolt hole in the main shaft. Still good? Continue on.

Install the blades and pitch links, and run it up again. Compare the vibration. Carefully deflect the control sticks, noting any changes in vibration. If you get more vibes when you are deflecting the controls, you most likely have a bad bearing in one (or both) blade grips. If you get more overall vibes regardless of blade angle change, you might have a bent feathering shaft or need to balance your blades. A bent feathering shaft can easily be checked for by removing one blade, then using a screwdriver to manually turn the feathering shaft. If the remaining blade moves up and down when you turn the feathering shaft with the screwdriver, you have a bent shaft. If your shaft isn't bent, and your bearings aren't bad, your blades are most likely out of balance.

If you follow the above procedure, you're just about guaranteed to find the cause of your vibrations.

Huge thanks to Spunjah for this.

[Andrew73]

If there's any play in the head try adding shims to the spindle and blades, that got rid of the vibes on my v2.

[Drivinfast247]

Just checked over the entire heli again. Everything looks and feels perfect. All the parts are brand new with a few flights on them, no wrecks. I tinned the tail motor wires. I will fly it right now and report back.

[Drivinfast247]

Still does it. Hmmmmm... Not sure what's next.

[DoubleCH]

Originally Posted by Drivinfast247

Still does it. Hmmmmm... Not sure what's next.

What main motor and tail motor? If you have similar setup to OP's stock brushed main and dual-tail, that's his problem right there. See my post #14.

If not, what're you running main and tail motors? Does it happen more often hovering? Touching the ground? Do you feel the tail power jerk trying to do 1/4-turn when you run idle-up while holding the bird in hand? If so, does it happen if you take the canopy off and hold the edges of the 3-in-1 board instead?

[Drivinfast247]

Stock motors. 3 weeks old. It does it while FFF and fbf. I'm gonna go hover a complete pack and report back.