X50, Vbar, Torque tube, tail wag. Any ideas???

[maddog7]

Alright all,
I wonder if any of you have any sugestions on this.

My new X50 has a wag that is squeezing my melon.

I can induce it by doing full power climb outs or drops but it happens seemingly randomly just flying gently around too.

Here is a short vid of it today (after tring a few things to resolve it)

I've balanced the main blades (not far out) re-routed the cabling to the vbar and re-secured stuff out of the way, this has eliminated the sensor checksum errors I was getting but still the tail wags. I've tried tuning the engine leaner (from the rich previous setting) and freed up the linkage to the point where it is more free than any of my other 600 size helis (which all fly perfectly) I've tried lower gyro gain and it still happens (only the tail feels more mushy on stops)

I've searched for the issue online and read Mr Mel's responses and watched the vbar 101's but still it persists.

One thing I have noticed in my searching is that the x50 seems particularly prone to tail wag full stop.

I have the TT version which should remove most of the static worry.

Any ideas what I'm obviously missing?

Here is a piccie of the installation of the vbar in the heli:

IMG_4485.jpg

Cheers for any suggestions!
D

[Steve]

I've never had a wag on my X50, which is a belt drive, flybarred version.

Just check the obvious first - are your Tx settings matched correctly with your Rx wiring? i.e. When you adjust the gain on the Tx, are you sending the signal to the correct channel at the Rx end?

It's a common error.

[jph140]

Hi, sounds like you've covered most things already but the bearing in the torque tube hasn't come loose has it? I'd also check the tail gears are not too tight. I applied a small amount of grease on my x50e tail gears and after running 2 packs through it a few weeks ago it's really smooth. Are you able to try different tail blades as well?

Cheers

[coolice]

Hey.

Off the top of my head I can't remember which one it is (never touched mine) but I think this type of wag can be tuned out with the P or I gain parameters. One is similar to Aligns Rudder Lock Gain, which is how aggressive the hold is on the tail rotor. If this setting is too high then after piros, aggressive changes in torque loads on the fuselage a wag can set in as the tail gyro tries to fight any tail swing.

Be careful going too lean on the engine as that can produce a rougher running engine and introduce more airframe vibration which won't help.

Another quick observation from the picture, is the plastic radio tray rigid? Reason I ask is that you have the battery at the very front where there is less material, could the battery be moving the radio tray slightly in flight? The canopy also secures near the front and so can add to any twisting/bending of this tray.

Maybe an idea to move the sensor to the rear of the model if you can to eliminate this possability.
.

[electricsceadu]

flybared and torque tube here and a gy520 = no wag
when it was belt driven = no wag

i'd check
the radio set up
the gears
the tt bearings/ spacing
the engine bearings

[GIXERMAN]

Yeh my ear tells me that motor too lean or maybe you aren't using a gov and just a screamer on curves

[Tommy]

Had few about four tanks through my x50 tt with vbar and first few flights really bad wag which was mainly down to being to lean on tt56 , whoops , and too much gain. I can feel its getting better with every flight and hoping it will settle down as gears bed in etc.

I also think what Coolice said was spot on as tail hold does seem really aggressive and possibly it might have to be dialled out with the P or I parameters

Cheers hope u resolve it

[maddog7]

I've never had a wag on my X50, which is a belt drive, flybarred version.

Just check the obvious first - are your Tx settings matched correctly with your Rx wiring? i.e. When you adjust the gain on the Tx, are you sending the signal to the correct channel at the Rx end?

It's a common error.

Thanks for the suggestion Steve,
Yeah, checked in the vbar software as I flip the switch assigned to the gyro gain the tail rotor gyro gain value changes correspondingly.

[maddog7]

Hi, sounds like you've covered most things already but the bearing in the torque tube hasn't come loose has it? I'd also check the tail gears are not too tight. I applied a small amount of grease on my x50e tail gears and after running 2 packs through it a few weeks ago it's really smooth. Are you able to try different tail blades as well?

Cheers

The TT bearing IS a possibility, a lad at the field mentioned that too, though there's no evidence (other than the wag) to suggest it. I'll check it out.
All gears were lubed with teflon grease before the video
Thank you
:-)

[maddog7]

Hey.

Off the top of my head I can't remember which one it is (never touched mine) but I think this type of wag can be tuned out with the P or I gain parameters. One is similar to Aligns Rudder Lock Gain, which is how aggressive the hold is on the tail rotor. If this setting is too high then after piros, aggressive changes in torque loads on the fuselage a wag can set in as the tail gyro tries to fight any tail swing.

Be careful going too lean on the engine as that can produce a rougher running engine and introduce more airframe vibration which won't help.

Another quick observation from the picture, is the plastic radio tray rigid? Reason I ask is that you have the battery at the very front where there is less material, could the battery be moving the radio tray slightly in flight? The canopy also secures near the front and so can add to any twisting/bending of this tray.

Maybe an idea to move the sensor to the rear of the model if you can to eliminate this possability.
.

Ian,
I'll look into the loop settings and see if changing them helps, thing is, you notice at the start of the video, it will piro fine and stop fine sometimes and especially in one direction but sometimes it does not and other times (not shown in the vid) it will go nuts for no apparent reason (gentle banked turn RWU)

The engine is probably a touch lean in the vid (I'm not using a gov) but this was only for the few minutes of the vid, just before it was taken it seemed about spot on with a lower HS, I'd just leaned it at the point before the vid was taken to see if it helped.

The tray is NOT very rigid but twisting it does not move the sensor, I could see the mass of the battery being either something to increase any vibes or possibly to absorb them.
On my FBL converted Titan se the arrangement is very similar but in fact the Beastx on that model actually sits on the same tray as the battery and it's a perfect handling weapon.

The thing with the X though is that the whole chassis is NOT as stiff as the SE plastic one, I'll try moving the sensor to the rear if poss. Might have to make something to mount it on.

Thanks very much for the suggestions, food for thought.

[maddog7]

flybared and torque tube here and a gy520 = no wag
when it was belt driven = no wag

i'd check
the radio set up
the gears
the tt bearings/ spacing
the engine bearings

Will do thank you.
:-)

[maddog7]

Yes fella it was a little lean I think, no gov though.
Cheers
D

[maddog7]

Had few about four tanks through my x50 tt with vbar and first few flights really bad wag which was mainly down to being to lean on tt56 , whoops , and too much gain. I can feel its getting better with every flight and hoping it will settle down as gears bed in etc.

I also think what Coolice said was spot on as tail hold does seem really aggressive and possibly it might have to be dialled out with the P or I parameters

Cheers hope u resolve it

Tommy,
It seems a common thing to happen to the X50, both FBL and FB. Can't help feeling that some sort of harmonic might be causing issues.

If you hold the frame at the point the tail servo is installed and by the skids and pull it left and right you see how much flex the frame has left to right, quite scarey!

[GIXERMAN]

Yes fella it was a little lean I think, no gov though.
Cheers
D

Maybe drop throttle curve a bit while your trying to sort out and iron out any problems

[maddog7]

One thing I should say is that the same vbar and tail servo showed no signs of this behaviour on my logo 600.