Tail Wag Cures

[myxiplx]

You'd be surprised, 13g is a significant chunk and you can feel it in flight, especially if you also have to add weight up front to CoG it.

Its not the end of the world though, and it is an easy fix :-).

[efron]

To my new Trex250 pro dfc (bought in 2015), the MKS ds95i servo was THE SOLUTION. The tail was slowly wagging with stock tail servo all the time. Never flew a full battery with it - it was really horrible.

I've just finished installing the MKS ds95i tail servo and in the first test hover the tail was head locked. Really IMPRESSIVE considering also that the tail system of this heli has plenty (too much) play. Really too poor Align design for that price

Waiting for its real first flight ... but as far as I've seen, the price for the MKS ds95i tail servo is worthy so far

[myxiplx]

Oh yeah, the DS95i is the absolute guaranteed fix. There are ways you can finesse it, but for a simple solution that utterly transforms the tail look no further :-)

[skunkworx]

Or you can spend about half that and get an H1. Same results, less weight.

[Harbormaster]

Originally Posted by skunkworx

Or you can spend about half that and get an H1. Same results, less weight.

(Speaking as an absolute DS95i fanboy) I'm glad you got great results from the H1, and that's what matters, but I'd be willing to bet that the H1 would not come close to matching the 95i's awesomeness in a side-by-side test. Even the 95i's voltage ringing waveforms on a tester is better. It's simply that great.

The specs pretty much tell the story:
H1 Speed s/60°:
@6.0V: 0.06
Torque:
@6.0V: 38.9 oz./in. (2.8 kg./cm.) <--H1 17% more torque

DS95i:
6.0V: 0.04 sec/60° <-- DS95i 50% faster!
6.0V: 33.3 oz-in (2.40 kg-cm)

Again, I'm happy to hear that the H1 is working great for your needs, but if you're saying that they're the same and just priced differently, that's wrong.

[Kennihs]

The solution for me, was to change the stock tail servo!

i tried everything else in this thread!

[daveapplemotors]

My two HK250GT's are 6 years old. For the last 6 months both have had CC3D - Atom FBL controllers.

Tail hardware: both HKs use Align 37 mm blades, Chinese weights and double bearings, metal control rod (not straight) , HK parts all the rest.

I tried a few inexpensive servos. Inolab 202 works really well in one bird. A Turnigy S3066 HV, a few grams heavier, in the other. Both of them took a few tuning flights to get the tails strong, fast , and solid with no wag. Capable of 720 degree per second rotation with solid stop. My favourite tail servo is E-Flite DS76t but I had trouble with input frequency.

No matter how slow (or fast) the servo is (within reason).
No matter how much slop or flexibility there is in tail controls.
No matter how long (or short) the blades are.

Since the control parameters are so comprehensive you can make any combination of tail parts work well.

Both of my HKs / Atoms fly better than the Beastx or Align 3grs (sp?) ever did but they took a long time setting-up.

[pinguin]

Originally Posted by Kennihs

The solution for me, was to change the stock tail servo!

i tried everything else in this thread!

What tail servo are you using?

[gimbleguy]

Originally Posted by Harbormaster

(Speaking as an absolute DS95i fanboy) I'm glad you got great results from the H1, and that's what matters, but I'd be willing to bet that the H1 would not come close to matching the 95i's awesomeness in a side-by-side test. Even the 95i's voltage ringing waveforms on a tester is better. It's simply that great.

The specs pretty much tell the story:
H1 Speed s/60°:
@6.0V: 0.06
Torque:
@6.0V: 38.9 oz./in. (2.8 kg./cm.) <--H1 17% more torque

DS95i:
6.0V: 0.04 sec/60° <-- DS95i 50% faster!
6.0V: 33.3 oz-in (2.40 kg-cm)

Again, I'm happy to hear that the H1 is working great for your needs, but if you're saying that they're the same and just priced differently, that's wrong.

I'd take the one that offers more torque for the Tennis racket effect(force).

My current tail servo is 3.1Kg, at half the price of an H1. Works well

[pgoelz]

Originally Posted by Kennihs

The solution for me, was to change the stock tail servo!

i tried everything else in this thread!

FWIW, I have been working on a slowly wagging tail on my Trex 250Pro DFC in a scale Hughes 500 body. It flew fine but the tail had a small wiggle all the time. I initially thought it was linkage slop since there was some. But after I addressed most of the slop, the wag remained.

Turned out that the stock tail servo was absolutely the cause, and it is easy to see why. Simply slowly rotate the body CW and CCW in small increments and watch (and listen to) the tail. The stock servo has appreciable deadband.... for small body movements, there is NO servo reaction at all. I replaced the stock servo with an Eflite DS76T and the servo reaction to small movements is instant and continuous, with no noticeable deadband. In flight, the slow wag is utterly gone. Not a trace left.

I did notice that the stop gain seems to be lower.... I used the same servo horn length, but it may be the the DS76T rotates less than the stock servo for a given signal change. Next time I have it open I'll move the link out one hole.

Paul

[skunkworx]

Originally Posted by gimbleguy

I'd take the one that offers more torque for the Tennis racket effect(force).

My current tail servo is 3.1Kg, at half the price of an H1. Works well

I agree, the H1 seems to handle the tail on my 250 better than the 95i (hence why it's sitting in my tool box and I'm on all H1s).

I'm curious which servo you're referring to? The only one I was aware that had more torque out of a micro tail servo was the BK, but those are about $20 more than an H1.

[cduuuub]

Yesterday I took my 250 for it's first hover/flight. I just get her up in the air and boom tail wag, baaad. So I dial it down till I can get a steady hover, now I've got some other problems unrelated to tail wag. So Im doing a test and tune at this point. Got it locked in nice, hands free hover, super stable for a 250.

At this point I decided (and I had a feeling I shouldn't have) that I'm gonna actually do a couple circles maybe a fig 8 or two and call it a day. Come up 20' or so and start flying. I make a right hand banked turn and as I exit the turn the tail goes crazy. I lost a bit of altitude by this point, and I'm close to the ground but I've got it under control, its all good and fine, thank god....then my right thump went full dumb. Caught the earth with the tip of the blade...I didn't get to TH fast enough. Minor damage, tail boom, one way bearing, main gear, feather shaft, and tail boom brace, blade grip (blade grip makes me mad, only because the threads pulled out, seriously?!?!?!) I will add the the tail wag exiting the turn was far worse then it was when I made my initial gain adjustments.

I'm only 4 months into this hobby so bare with me please. This would be a mechanical issue since the hover was good correct? Or do i still need to turn the gain down even more?

Futaba gy520 gyro
Spektrum radio sys.
Align electronics.

[nflanagin]

When you say crazy did it just start piro'ing uncontrollably - counter clockwise (counter to the main blade) or did it develop a fast wag left and right.

If it piro'ed uncontrollably, I'll bet the rear umbrella torque tube gear is no longer solidly attached to the tail drive gear shaft. The one mounted in the tail gear box driven from the main gear. After you pull the gear box, hold the umbrella gear and spin the drive gear and if it spins - it's the umbrella gear.

If that is the case, search the treads in the forum on how to epoxy it back on and include a new set of drive gears with your parts order - they wear out, too. In fact, since it's the start of the season, I would order two sets of both the tail drive gears and the torque tube umbrella gears. Crashes can mess up those umbrella gears and you start getting bad vibes.

[cduuuub]

No piros. Left to right fast, much worse then the initial tw before adjustments.

Belt driven tail.

[bazsound]

Originally Posted by cduuuub

No piros. Left to right fast, much worse then the initial tw before adjustments.

Belt driven tail.

Sounds like WOD sometimes you can stop it by giving rudder input and slowly returning stick to centre.

what FBL controller, tail servo?

too high stop gains or I gain can sometimes cause it

[bazsound]

i solved my tail issues by repalcing the anologue servo i had (which wasnt that slow 0.06sec) with a turnigy tgy-306 ulltra precise digital servo.

its a little heavy, but im at 42% gain with the bar at default settings (microheli) not a hint of wag.

ive also got a carbon fibre rod on from the guiy 200 (trimmed slightly as it was too long)

i did have a home made chinese wight mode using servo balls, but this caused problems with the tail wanting to go full pitch on its own once you reached a certain trafvel point, removed it and my tail is actually pretty easy to move by hand at full headspeed.

i havnt tried piros yet, but when i tested it indoors with default settings and even low gain the tail would just go into WOD after a few seconds of hover, and everytime i gave rudder input. the only thing that stopepd it was low accel values.

but with new sevo it hink i can increase the accel and stop gains to get super crips tail.

[homeunt]

Okay it took me some days to finish this entire thread. I have a 250 with OEM gyro and OEM servo and I have controlled down the wagging as much as I can with servo positioning, lubrication, belt tension and etc. As everyone here agrees even then there is still so friggin much mechanical play on the tail pitch system even whil tail servo is holding.

I am going to get myself a DS95i probably in April or May, but has anyone actually solve this mechanically? Also no one here mentions how long does the DS95i last, does it survive crashes okay?

I am probably going to pair it with a Futaba GY401 when it eventually gets here.

[Steve Joblin]

I would seriously think twice about investing any time or money on your heli... There are so many better choices that are significantly more advanced (OMP M2, Eachine 180, etc.)

[shifter]

I just bought a 250 combo and will be going through this too soon. I do love a project though.