Tail Wag Cures

[JoeW]

MicroHeli redesigned the entire pitch slider/bell crank assembly, here's one link to it here http://www.rotorquest.com/product_in...ducts_id=10245

I've seen other guys do their own custom mod to replace the plastic ball on the pitch slider with a metal ball, or built up with small nuts.

I'd love to see just the metal pitch slider as a optional/upgrade part like they do for the 450. That would be perfect IMHO.

[Socal500]

Well I replaced the bearing in the tail blade holder on the SE and I flew for 3 minutes without the tail issue. Later I put in a new pack and flew for about 3 more minutes and as I landed the tail problem started again. The problem clearly went away when I installed the new bearings but can they really get shot that fast ?

[Helioop]

The stock tail bearings wear out really fast ... but not THAT fast (more like a month or three).

Is there a chance the second battery pack was a better pack than the first. A little more power or head speed can be enough to set off a wag on a setup that's not quite right. With new bearings, now you are back to stiction, servo arm length, servo power, gain, or tail blade issues as suspects.

Do yourself a HUGE favor. PM "Heim Joint" and get his bearing spacer kit. It's the only way to rule out tail slop as an issue. Get his Chinese weights while you are at it. This all costs peanuts, and the improvement is tremendous.

[Socal500]

Originally Posted by Helioop

The stock tail bearings wear out really fast ... but not THAT fast (more like a month or three).

Is there a chance the second battery pack was a better pack than the first. A little more power or head speed can be enough to set off a wag on a setup that's not quite right. With new bearings, now you are back to stiction, servo arm length, servo power, gain, or tail blade issues as suspects.

Do yourself a HUGE favor. PM "Heim Joint" and get his bearing spacer kit. It's the only way to rule out tail slop as an issue. Get his Chinese weights while you are at it. This all costs peanuts, and the improvement is tremendous.

I tried the pack that flew well the first time and it still did it. The one thing I did change is the headspeed. I was running a flatline 50% and bumped up to flat 85% so the new bearings along with lower headspeed may have been it. I will lower headspeed and try again today.

If Im going to go with the full micro heli tail do I even need to bother with bearing spacer kit ?

I also just cut my blades down to 35 and it got worse.

[litehawkdown]

I'm not even flying my 250 yet. But I want to get rid of the bit of slop in my tail anyways.

I noticed that mCPX bearings and washers might work in the tail though in a pinch. But I think I don't even need to bother adding stuff.

I figure the problem is the screw is to long to allow you to tighten the grips down. The screw just bottoms out on the hub. If you were to file the screw down or add a washer it might fix the slop problem. I think I will take a file to the screw tonight and see what happens.

I also played around for a hour or so making sure the pushrod ran as smoothly as possible. Seems The arching motion of the servo causes a slight bind from left to right when pushed to the extreme. If you don't get the rod to sit level to the boom by playing with the servo mounts and servo arm placement the slight binding can become a full on servo stopper as it gitters away.

[Helioop]

Originally Posted by Socal500

I tried the pack that flew well the first time and it still did it. The one thing I did change is the headspeed. I was running a flatline 50% and bumped up to flat 85% so the new bearings along with lower headspeed may have been it. I will lower headspeed and try again today.

If Im going to go with the full micro heli tail do I even need to bother with bearing spacer kit ?

I also just cut my blades down to 35 and it got worse.

I have over 1,000 flights on 250s and have tried it all. Don't bother with the Micro Heli tail. It's pretty, but made of very soft aluminium and it will wear out and/or bend really easily. I tried that route and was dissappointed. The Heim Joint spacer kit in the stock Align tail grips is the best setup on the market, bar none.

I use 40mm blades on both my 250s (with Chinese weights), and have absolutely no tail wag even at high rpm and hard 3D. Get the spacer kit and Chinese weights from Heim Joint. They are cheap and you won't be sorry.

[Helioop]

Originally Posted by litehawkdown

I figure the problem is the screw is to long to allow you to tighten the grips down. The screw just bottoms out on the hub. If you were to file the screw down or add a washer it might fix the slop problem. I think I will take a file to the screw tonight and see what happens ...

The screw isn't bottoming in the hub. It clamps down on the inner race of the bearing. The slop you are seeing is between the tiny balls and the inner and outer races of these bearings. Higher quality bearings have less slop, but unless you "preload" the balls between the races, as is the whole point of Heim Joint's shim kit, you will always have slop and increased wear.

Most 250 tail wag issues aren't because of this ball-to-race clearance slop. It's because of the rapid wear caused by this slop. The races get notches worn into them, then the bearing hangs up on these notches causing the wag. When the stock bearings are brand new, the centrifugal force on the blade grips takes enough of this slop out that it works fine until the notches start to wear in, which can start to show up after only a few dozen flights.

[Socal500]

Well mine finally caused a crash so I'm going to throw in the towel on the 250. They may be inexpensive to repair per crash but it adds up. I promised myself after the 500 I would not get caught up in R&D

[litehawkdown]

Originally Posted by Socal500

Well mine finally caused a crash so I'm going to throw in the towel on the 250. They may be inexpensive to repair per crash but it adds up. I promised myself after the 500 I would not get caught up in R&D

Sorry for you loss. I thought R&D is what life is all about.

[goodhunting]

Ok I'm still int he set up phase and have been for a while. Although I mounted the stock gyro in a way that nothing was touching it except for the stock Align foam pad, the wag was still there. Could it be that the additional pad would help in getting rid of the wag issue?
It seems to me (and I do not claim to have the experience to judge) that the wag appears as the vibrations increase, so there might be a mechanical reason for this...

gh

[Helioop]

Originally Posted by goodhunting

... the wag appears as the vibrations increase, so there might be a mechanical reason for this...

gh

More damping for the gyro is unnecessary and will only mask the real problem (if you are lucky). Vibration CAN be a cause of tail wag, so track down and fix the source of the vibration.

- The main shaft, feathering shaft and tail shaft all have to be PERFECTLY straight.
- The main blades have to be balanced (better yet - CG balanced) ideally to .01 of a gram, and they have to be tracking nearly perfectly.
- The head dampers should be fresh stock Align black dampers (unless you do hard 3D).
- There has to be a tiny amount of clearance between the main gear and the motor pinion at the tightest point in the main gear's circumference.
- There can't be ANY teeth missing on the tail belt.
- The tail blades need to be in very good condition and the tail blade grips must be snug (and thread locked) against their hub.

This is in addition to making sure NOTHING in the whole tail linkage is sticking, even slightly, and that you feed the tail blade grips fresh bearings regularly (at the first sign of tail wag that wasn't there a few flights ago).

A more powerful tail servo helps (DS520 or similar), and Heim Joint's tail rotor shim kit and bearing upgrade really helps (PM Heim Joint for more info).

Attention to detail on your 250 will reward you with one of the best flying micro helis you can wedge into your favorite tight flying space.

[goodhunting]

thanks for the reply. I checked most of the items you mentioned.
Heli is new. I bought the kit and assembled it and then checked and checked it again.
The thing I did not check yet is the belt and its teeth and the clearence between the engine and main gear.

Will check the Heim Joint's tail rotor shim kit also..

If it works it should be fun fun fun...
too bad nobody does the torque tube upgrade for this heli...

gh

[JoeW]

Originally Posted by goodhunting

If it works it should be fun fun fun...
too bad nobody does the torque tube upgrade for this heli...

gh

Tarot has a TT kit. It's just started shipping in the last month... it currently spins the tail backwards... still some work to do there

A TT isn't going to cure any tail problems... the problems aren't with getting power back there.

[litehawkdown]

+1 on the blade tracking.

I mentioned this in other threads but figure I would share here

When I first spooled up my heli all seemed fine as long as I kept it at 1 to 4 feet off the ground. As soon as I hit 5 feet the tail seemed to be wagging on me. I figure here it is the dreaded 250 dog. I then got the skill to fly around it and saw my tracking was way off when the blades were increasing pitch passed that 4 foot range. It looked fine when spooled up on the ground though. I did the cyclic pitch check and dialed the pitch perfectly through the whole rotation (Takes a long while for a newb ). And the wag is now gone. Pop is way better too.

Oh and I found there was a lot of slop in the head that developed after a few batteries. Must be a break in period or something. Anyways I tighten things up and now it is way better. Setting up cyclic pitch was a futile effort when the head was lose. So start there first.

[Harbormaster]

Originally Posted by Helioop

More damping for the gyro is unnecessary and will only mask the real problem (if you are lucky). Vibration CAN be a cause of tail wag, so track down and fix the source of the vibration.

- The main shaft, feathering shaft and tail shaft all have to be PERFECTLY straight.
- The main blades have to be balanced (better yet - CG balanced) ideally to .01 of a gram, and they have to be tracking nearly perfectly.
- The head dampers should be fresh stock Align black dampers (unless you do hard 3D).
- There has to be a tiny amount of clearance between the main gear and the motor pinion at the tightest point in the main gear's circumference.
- There can't be ANY teeth missing on the tail belt.
- The tail blades need to be in very good condition and the tail blade grips must be snug (and thread locked) against their hub.

This is in addition to making sure NOTHING in the whole tail linkage is sticking, even slightly, and that you feed the tail blade grips fresh bearings regularly (at the first sign of tail wag that wasn't there a few flights ago).

A more powerful tail servo helps (DS520 or similar), and Heim Joint's tail rotor shim kit and bearing upgrade really helps (PM Heim Joint for more info).

Attention to detail on your 250 will reward you with one of the best flying micro helis you can wedge into your favorite tight flying space.

Great list. Saving it.

[goodhunting]

I think I fixed my wag problem... Replaced the padding of the gyro and placed gyro far away from the frame... wag is gone...

Will do the test fly this weekend and post an update...

gh

[tommeke]

my wag went away when I put the ball link from the tail control rod not on the ball of the tailservo, but between the ball and the servo horn, worked perfectly

[Jason Asch]

What did you mean about the ball link for your 250 wag resolution?

[Harbormaster]

Originally Posted by NuttyToughGuy

What did you mean about the ball link for your 250 wag resolution?

Yeah, I didn't follow that either.

[tommeke]

The thimgs on the end of the pushrod where the bals go in