GPro v1.2 rudder bug - tail twitch

[rcflyersd]

I have had the Bluetooth module connected on mine, and it seems the gyro works normally as long as you're not linked up to it with a mobile device. When linked and making adjustments it's disabled.

I would recommend rebooting the Gpro after making any adjustments before flight again.

Mark

[Tiaanj]

Thanks Mark,

Yes I would concede that all it really saves you is the time to plug the BT in and out as jou still have to cycle power, so canopy has to come of anyway! But does save some wear and tear on the gpro plug pins, well at least for a fairly new pilot still coming to grips with all the settings and what they do and how they effect the Heli performance.

[Kibbs]

Hey guys came across this thread as I am looking to resolve similar issue. T-Rex 250 stock servos I did upgrade the tail to the newer revision from Align. GPro firmware 1.2 Spektrum Sat rec, DSMX DMX6 radio. Channel 5 Gear has been set to Gyro.

The issue is I see the snap back affect described here more prevalent on left rudder than right. Heading hold is set gyro is at 90% as described but on the bench the rudder control pushed either way comes back to centre. I thought this would hold until tail movement? Trying to sort this out is my first collective tail.

Thanks

Wayne

[Coolice]

Originally Posted by Kibbs

Hey guys came across this thread as I am looking to resolve similar issue. T-Rex 250 stock servos I did upgrade the tail to the newer revision from Align. GPro firmware 1.2 Spektrum Sat rec, DSMX DMX6 radio. Channel 5 Gear has been set to Gyro.

The issue is I see the snap back affect described here more prevalent on left rudder than right. Heading hold is set gyro is at 90% as described but on the bench the rudder control pushed either way comes back to centre. I thought this would hold until tail movement? Trying to sort this out is my first collective tail.

Thanks

Wayne

Hey Buddy.

Have you trimmed the tail pushrod length while in rate mode to hold a heading before switching into heading hold mode to fly?
If not this will be the cause of the bounce back, as the tail gyro needs to have it's neutral/middle position on the servo set to give the required amount of tail pitch to counteract the torque reaction on the model.

Ian

[Kibbs]

Ian

Going to try this today. I did mess with some setting in the setup reducing a few of the tail setting. It was a little better behaved but do need to tune the centre position on the hardware as well.

Will see how that goes

[Kibbs]

Seems to have done the trick got as close to center as I could adjusting the push rod and that has pretty much eliminated the snap back. Thanks a lot guys.

[tvoth3]

I ran across this thread trying to diagnose this problem as well. I was posting to another forum here:
http://rc.runryder.com/helicopter/t784698p1/

Originally Posted by rcflyersd

In my experience with the Gpro, once mechanically setup correct, using default Gpro tail settings seem to work well. I found that I have to run fairly high gain level shown on transmitter gyro menu, anywhere from 75-90%, while using default Gpro settings.

Is this 75-90% in the -100 to 100 range?

I'm going to try the rate mode setup tomorrow and see if that help although I already have the tail blades set with what looks like 3 deg pitch.

Wondering if Tower ever got this sorted out?

[Coolice]

Originally Posted by Kibbs

Seems to have done the trick got as close to center as I could adjusting the push rod and that has pretty much eliminated the snap back. Thanks a lot guys.

Hey Buddy.

Brilliant, this old school trick of setting up the tails neutral position while flying in rate mode was reinstated during the 3GX era and has transferred over to the Gpro and works well.

In previous conversations about why it makes a difference, I think it's due to the servo stopping at the required amount of pitch to hold a heading following a pirouette. If set any other way, on release of the yaw stick, the tail servo can over or undershoot on the stop, the gyro then has to input a corrective command quickly which upsets the tail. This is just an idea.

Ian
.

[tvoth3]

I've got the tail setup nice and stable in rate mode. Can't get HH gain correct tho'. Walked from 50-90 (in +2 increments, -100, 100 range) and see bad oscillations regardless of setting. I'm wondering how the software tail gain interacts with the transmitter gain. Anyone have an idea here? Note that I am starting with the "beginner" parameters and am wondering if there's an issue there?
Thanks,
--tom

[Coolice]

Originally Posted by tvoth3

I've got the tail setup nice and stable in rate mode. Can't get HH gain correct tho'. Walked from 50-90 (in +2 increments, -100, 100 range) and see bad oscillations regardless of setting. I'm wondering how the software tail gain interacts with the transmitter gain. Anyone have an idea here? Note that I am starting with the "beginner" parameters and am wondering if there's an issue there?
Thanks,
--tom

Hey Buddy.

I must admit I've only used the software gain slider to change my tail gyro gain, it's just as easy with the BT module and my Android phone. But from what I've seen, as you alter the Tx ATV gain channel, the slider moves within the software.

Another couple of parameters that may need tweaking is your P & I Gain, specifically the I Gain, which is like the older Rudder Locking Gain slider in the 3GX menus. If this is too high it can induce a slow wag/hunt that does not disappear with Tx gain changes, as basically the tail gyro is trying to hold on too tight to the tails positioning and get's into an oscillation as it constantly tries to update the tails holding position.

What model is this on?
.

[tvoth3]

Originally Posted by Coolice

Hey Buddy.

I must admit I've only used the software gain slider to change my tail gyro gain, it's just as easy with the BT module and my Android phone. But from what I've seen, as you alter the Tx ATV gain channel, the slider moves within the software.

Another couple of parameters that may need tweaking is your P & I Gain, specifically the I Gain, which is like the older Rudder Locking Gain slider in the 3GX menus. If this is too high it can induce a slow wag/hunt that does not disappear with Tx gain changes, as basically the tail gyro is trying to hold on too tight to the tails positioning and get's into an oscillation as it constantly tries to update the tails holding position.

What model is this on?
.

Hey Coolice,
I've started with the "beginner" settings because I thought they'd be a safe place to start from but perhaps not. I'll play with P and I when I get a chance this week and see what happens.

Thats' interesting that the software tail gain changes when you change the transmitter gain - i'll have to look for that.

The model is a flybarred trex 500e that I'm upgrading to dfc. Interestingly during the process of setting up the gpro I've found that my mechanical original setup was less than optimal and the original gyro was pretty much fine with it. It's *much* better now and still having problems.

Now that I think about it, first thing I'm going to try is use the default (non-beginner) settings and see if that helps my problem.

--Tom

[dksia]

I have seen your video and frankly, the behavior of your tail rotor servo tells me that you aren't operating in heading hold mode. I have seven GPros up and running and have never seen the glitch you report.

This is using an older JR X9303, a new Spektrum DX18, and when using standard receivers and the cable set, as well as using DSM2 or DSMx satellites.

All have V1.2 SW installed. I have used Win 7 as well as the BT adapter to program.

[tvoth3]

Solved my problem by:
1) Setting tail up in rate mode (as many have suggested)
2) Dropping I-gain.
3) lowering left and right rudder stop.
and now flys very nice... and it was windy...
I probably can tune a bit more as there's just a slight wag after piro but much more flyable. I'm gettin' me another gpro!

[Coolice]

Originally Posted by tvoth3

Solved my problem by:
1) Setting tail up in rate mode (as many have suggested)
2) Dropping I-gain.
3) lowering left and right rudder stop.
and now flys very nice... and it was windy...
I probably can tune a bit more as there's just a slight wag after piro but much more flyable. I'm gettin' me another gpro!

Hey Buddy.

Brilliant news, well done.
At least now you can go and enjoy the model, then make minor tweaks along the way.
.

[amastron]

Originally Posted by Hemant T

Thank you RCflyersd... Problem Solved!

I had my tail bitch to 0 degree & as suggested by you made the tail pitch to 3 degrees & now she's Perfect! Thanks once again!

For all Algin Gpro users you have to have 3 degree tail pitch for it to work perfect, unlike other gyros. Happy Landings!

What kind of Pitch Gauge can be used to check tail rotor blade pitch on a Align 450, mine won't go that small.

[tvoth3]

Use rate mode to find correct pitch as noted above. Don't worry about measuring.

[skate223]

I fly a gpro on my TT e700 with a bk hv tail servo and I get the twitch bad. I am using futaba 14sg. My limits are below the 99 value and it seems to only do it in idle 2 for me which is set at 2030. Idle up 1 is set at 1950. I can get the servo to do exactly what your video shows on the bench. I am still looking for a solution. Has align acknowledged this and are they going to be able to fix it is my question? I run another Gpro on my trex 700n and it does the twitch but not nearly as bad as on my e700. Really hoping for a resolution.

[dksia]

I have 8 GPros installed and flying. I have also run a bunch of experiments on my bench. I have seen this behavior on the bench. It is exaggerared if you have low gains, somewhere below about 30% at the TX. Based on my experiments and seeing the helis fly perfectly fine, I believe what people are referring to as a "bug" is nothing more than seeing odd behavior in a heading hold gyro when it is sitting stationary and having no reason to do anything, as there is no motion to prevent or to make happen.

Having been able to see this behavior on the bench, and then seeing that same controller perform flawlessly flight after flight tells me the behavior on the bench is not an indication of anything being wrong, it is how the heading hold gyro behaves when sensing no motion.

Hover in normal mode, adjust the tail linkage for a hover with no nose left or right yaw. Land. Reset the two travel limits. Then, back in HH mode, work with the left and right stop parameters, and the P and I gains as needed. Little additional adjustnent is needed.

[skate223]

I failed to mention the twitch is while flying and it is almost un flyable. I can confirm it does happen in both flight modes. Seems to be more prevelant on right rudder inputs and heavy pitch inputs. I've been trying to diagnose this for months and I finally started searching for answers but I am short for a solution. I have tried every possible setup and parameter. Rate mode it flys perfect and have tried adjusting to high gains low gains. I've tried adjusting stop gains and nothing works.

[krazycarl]

Do i use the subtrim in radio to center the servo horn on my rudder servo or do I use the center setting in the gpro software to center my servo horn. ?