Tail Wag Cures

[Ah Clem]

I posted this on another thread, quite some time ago:

"The tail on mine drove me nuts. I barely flew it as I could not trust the tail.

I read many threads on the forums and tried cutting down the stock tail blades-this reduced the wag to where it was tolerable, but increased the blowouts significantly (shorter blades mask the problem, IMHO, they do not correct it).

A few months ago, I went through the tail again and did the following:

1) Installed the aluminum tail bellcrank (which had a longer input side than my original plastic one did).
2) Installed the latest (fourth) version of the tail blade grips/hub with the largest Chinese weights.
3) Took the tail pitch change links/bushings apart again (the ones that connect to the collective spider on one end and the blade grips on the other), cleaned them really well and worked with them until they were smooth.
4) Changed to KBDD tail blades (full length-40mm-do not shorten).
5) Installed the metal pulleys, front and rear.
6) Went through the entire helicopter and reset it up.
7) Added Cyclic to throttle mixing to help keep the RPM constant (not for wag, but for tail consistency throughout any maneuver).

When this was done, there was still the lightest hint of a wag in the hover (this was with the Spartan 760 gyro). As with the GY520, I put some expo on the rudder channel and the last of the hovering wag went away.

In flight, if I unloaded the head, I would get a high frequency, short amplitude wag. This was eliminated by dropping the gyro gain a half point at a time until it was gone.

For the last few months I have had a Trex 250 the will finally fly backwards and forwards with no wags or blowouts.

The tail servo is a JR 3500G, by the way. The 290 did not work well on my 250.

The tail belt is the stock one.


With regard to the tail grips:

1st versions had no Chinese weights and two bearings
2nd version had no Chinese weights and one bearing.
3rd version had one bearing and small Chinese weights
4th version had on bearing and large Chines weights.

There may be more, but these are the only ones I am aware of."
__________________

More recently, I have converted to the BeastX FBL system. The tail is even more solid (IMHO) than with the Spartan. As you can see, the tail is completely locked in (you can see the Screaming Yellow KBDD Tail Blades, quite clearly in the video):

[ame]http://www.youtube.com/watch?v=NS4CvMsl19I[/ame]

The tail feels very solid now-very similar to that on a good 450.

[CHIEF-X]

thats exactly what im after clem!1 kick ass flight


im getting ready to try the combo of the microbeastx, microheli complete PRO tail unit, carbon fibre servo rod, and jr ds290g. how do u guys think i will fair

[Luisito]

From the post above he didn't have luck with the 290. I just installed the JR3500G and the tail is rock solid. I'm using the Mikado Mini V-Bar. The heli hovers for 10+ seconds hands free. This servo will make flying 3D similar to flying in the sim...

Luis

[Ah Clem]

Thank you for the kind comment chiefs_nut_58 (on my boring "old guy" flying).

"im getting ready to try the combo of the microbeastx, microheli complete PRO tail unit, carbon fibre servo rod, and jr ds290g. how do u guys think i will fair ?"

I am sure the MicroBeast will work great.

I am not sure if the Microheli Pro tail unit is necessary (it might wonderful, I just have no experience with it and so am not qualified to comment-mine flies fine with the later Align tail components).

I am with Luisto on the tail servo-I don't think the 290G is quite up to the job.

The tail on the 250 was the most difficult to tame of any helicopter I have had in the last 35 years (including many moons ago, with no gyro). The forces on the tail servo are pretty intense. I had a 290G and it was not up to the task. Other people seem to have been somewhat successful with it-I did not care for it on my ship.

The 3500G, although it looks huge on the 250 is, I think, much better suited to the job (from both a torque and speed standpoint).

[drfrankencopter]

I did the following:
- Switching the 780 gyro servo type to 'analog' helped with my 250SE super combo.
- Epoxying a carbon fibre tube around the tail rotor control rod and removing the guide helped (a bit less)

But ultimately what made it disappear altogether was:
- Replacing the 780 gyro with a Futaba GY520, and stock align servo with a JR DS290G

Now there's no wag. A little bounce on hard pedal inputs (could use a bit more damping), but no tendency to wag. I haven't found the max gain yet...

Cheers

Kris

[Ah Clem]

Outstanding Kris!

Glad you got it working right!

[supertoyz]

I'd just about tried all of the suggestions in this forum in an attempt to eliminate the tail wag in my Trex 250. Tonight it's finally gone. I should have known all it would take is more $ than the silly thing is worth.

At first I'd tweaked and adjusted everything possible with little luck. Next was Bert's recommended JR DS3500G tail servo. This helped but didn't eliminate the problem. Last week I added a carbon pushrod and carbon blades, no change. Tonight I installed a Quark gyro......not a sign of tail wag....rock solid. I then tried the Align 780 Gyro on a Blade SR which also has tail wag thinking the 780 has to be better than the E-flite Gyro, nope, still wags.....oh well. it was worth a try.

[thefrog]

I switched my ESC to Gov mode yesterday with throttle at 75% for normal and 85% for idle up. Now I've got a serious wag in normal, seems like increasing head speed helps a lot.
The headspeed itself isn't much different from before I enabled the Gov. Is the Gov setup related to the wag?

[al_evans]

My 250SE has had a very minor wag since shortly after I got it. "Minor" means about 5 mm each direction, at a fixed frequency of about 1 cycle per second. This is with the standard Align GP280 gyro and DS420 tail servo.

I assumed this was induced by a resonant frequency of some kind, since it remained exactly the same through crashes, part replacements, repeated setups, throttle curve changes, etc. Except for looking a little ugly, it had no effect whatsoever on flight characteristics. So I haven't been all that interested in fixing it, though I did get a JR DS290G servo to replace the 780 with, since I've been happy with that one on my regular 250.

I finally got around to installing the JR servo the other day, and the wag is gone. I was a little surprised, even though it was the intended effect.

--Al Evans

[bchrny]

Just a thought to find a cure- I am running the jr ds3500g on the tail servo with a twitch in the tail. Recently I spoke with a tech at jr and was told that the servo is 4.8v only and running it with the normal output from the rce was over driving the servo. The solution I was told is to incorporate a voltage regulator via the output from the gyro to the servo. This seems logical, and I am waiting the arrival of a regulator to see if this actually works. If it does I will post my results. Happy tails-KEEP LOOKING UP

[Ah Clem]

My 3500G does have a voltage regulator/step-down installed.

I did this from the beginning as the servo is not rated for the 6 volts that BEC in the ESC puts out.

[25teapot]

I have finally sorted my tail wag which it has had since new.I had tried all the usual points to look at which are listed in this thread but none of them made any considerable difference.My cure was to put a trex 500 tail servo on it,what a massive difference it has made,tic tocs,hovering rolls and flips are now rock solid.I was nearly getting to the point of thinking this tail wag was going to beat me.I hope this helps some other people to cure there waging tail

Edit new tail servo used was align ds 520

[Sonic_BOOMER_SOONER]

For those with the 250SE using the Align780 gyro with the DS420 digital tail servo I got no wag with gyro settings:
Bandwidth - 1520
Servos - Digital
Size - 250/450
and using 42mm straight cut blades, using two guides on the linkage rod which isn't perfectly straight but awfully darn close, ball 4.4mm out on the arm. I've got the gyro on top of the gyro tray and the Rx on the bottom of the tray and used some epoxy to slightly stiffen the gryo tray mount into the frame. The ESC is under the battery and most of the wiring is inside the frame.

I get a kick of around 1-2 inches on a hard collective punchout and a lighter kick on a piro stop but other than that I can fly it hard and the tail holds well backwards. However, when the wind starts blowing 15-20mph it will wag at certain angles.

[aquaanox]

Originally Posted by 25teapot

I have finally sorted my tail wag which it has had since new.I had tried all the usual points to look at which are listed in this thread but none of them made any considerable difference.My cure was to put a trex 500 tail servo on it,what a massive difference it has made,tic tocs,hovering rolls and flips are now rock solid.I was nearly getting to the point of thinking this tail wag was going to beat me.I hope this helps some other people to cure there waging tail

Was that with a 3500g ?

[artta]

My solution was MKS 8910 servo. Yes, it's BIG for 250 but it really solves all problems with tail.

I am using 42mm blades and Spartan quark. Gain is 25%, no wag, no drift, no bouncy stops.

[25teapot]

Originally Posted by aquaanox

Was that with a 3500g ?

It was align ds 520

[Xdrive]

What is your gyro settings?

[Xdrive]

Originally Posted by Sonic_BOOMER_SOONER

For those with the 250SE using the Align780 gyro with the DS420 digital tail servo I got no wag with gyro settings:
Bandwidth - 1520
Servos - Digital
Size - 250/450
and using 42mm straight cut blades, using two guides on the linkage rod which isn't perfectly straight but awfully darn close, ball 4.4mm out on the arm. I've got the gyro on top of the gyro tray and the Rx on the bottom of the tray and used some epoxy to slightly stiffen the gryo tray mount into the frame. The ESC is under the battery and most of the wiring is inside the frame.

I get a kick of around 1-2 inches on a hard collective punchout and a lighter kick on a piro stop but other than that I can fly it hard and the tail holds well backwards. However, when the wind starts blowing 15-20mph it will wag at certain angles.

What is your gyro gain settings?

[luckyflyer]

Who sells the kevlar belts for the 250?
Thanks

[Steve Joblin]

Originally Posted by luckyflyer

Who sells the kevlar belts for the 250?
Thanks

http://www.infinity-hobby.com/main/p...oducts_id=4560