V-Stabi Tail over-compensation during cyclic pitch/collective maneuvers?

[cptsnoopy]

Just fishing around to see who else has had this issue. During rainbows, loops, tic-tocs and flips my heli rotates to the right against the torque of the motor/main blades. During punch-outs it holds very well. During aileron rolls and aileron tic-tocs the tail holds well. The tail blades are 92mm NHP's that have a thick profile, a wide chord and most likely heavier than other 92mm blades. They have a lot of authority for their length.

Here is the thread on the V-Stabi forum where I went through a lot of testing to at least figure out it was the tail that was making this Logo600 3D hard to fly. Now we are trying to figure out why and what to do to fix it. http://www.vstabi.de/forum1/read.php?9,3884

Here is another thread on the same forum of another person that had the same problem plus he mentions that a friend of his also had the problem. They fixed their issues by adding a dedicated tail gyro. http://www.vstabi.de/forum1/read.php?9,4611

I had access to another V-Stabi unit (computer and sensor) and it also did the same thing. I could understand it if the tail could not hold against the torque but it is not only holding, it is continuing to rotate against the torque but only during elevator cyclic plus collective maneuvers. It could be my thumbs or something in the tx but my other 3 heli's do not do this. Starting to get stumped...

[Taipan]

I've had a couple of cases where my tail over-compensates in hard left hand turns. That's with the torque though, felt like the tail blew out on me. I've yet to play with the tail settings properly. Using Radix 95 tails at the moment. Maybe my tail isn't strong enough. Prolly will get the 9T Rappy tail pulley to speed up instead of 105's as I fly over long grass.

[cptsnoopy]

It's strange to me that a tail that can handle hard punch-outs would slowly drift during other maneuvers but hold fine in hover and fff flight. I have more stuff to try plus I ordered a set of 95 and 105 rotor-tech tail blades. Since the tail is drifting against the torque I think holding power is not the problem. Maybe just the way I have it trimmed.

[rscamp]

Your problem is really puzzling me. I'm wondering what I would do if I had the same problem.

For clarity, do you find this problem only when you input collective during a flip?

Rob

[cptsnoopy]

Your problem is really puzzling me. I'm wondering what I would do if I had the same problem.

For clarity, do you find this problem only when you input collective during a flip?

Rob

Hi Rob,

Yes, and also a large loop, rainbow etc. But if I do a stationary punch-out the tail is solid. I let another friend fly it today that has a good feel flying heli's and he agreed that it is not a good situation. He commented that the tail felt like it was not really holding very well anywhere during his 5 minutes of flying. The flight before when I tried it today I had the heli slowly drifting to the left just to see if trim was a problem but as soon as I did a flip or loop the nose would go right just like it has been. I know the other two guys on the V-Stabi forum fixed their problem by going to a standard gyro for the tail but I would rather not. The heli appears to be vibe free but who knows? Maybe a high freq vibe causing issues... Maybe I have some wires connected wrong and just don't know it... hmmmm

[OICU812]

Would you say that when you click on the servo test that at your tr neutral your deflection on tail is inward around 5-7 degrees of bite? Curious as habit has it for me to set mechanical bite without HH.

[cptsnoopy]

Would you say that when you click on the servo test that at your tr neutral your deflection on tail is inward around 5-7 degrees of bite? Curious as habit has it for me to set mechanical bite without HH.

Hi Shawn,

I have not been home today to check it but I am pretty sure it is as you describe. I will check it later tonight and let you know. The only things left to try are: another tail servo and the new tail blades when they come in. I have a NIB Logictech 6100 that I can use the servo from.

Charlie :)

[cptsnoopy]

Hi Shawn,

I checked the tail servo for center in test mode and it appears that when I changed the cyclic servo arms from shorter to longer I did a factory reset and never set up the rudder neutral point. I looked back and saved files confirm this. So I set it correctly again and with the test mode activated the servo arm is at 90 degrees with the tail blades pointed about 5-8 degrees to the nose right position. I will try it again tomorrow but I do not have my hopes up as it was set this way before. If it still turns when it should not I will try the Logictech servo.

Charlie
:)

[OICU812]

Hmmm ok keep us posted, your situation is surely unique it seems.....

[NTM]

Try the bigger tail blades before putting in a new gyro.
I went to 105's and in 3mm on the tail servo horn, and it is absolutely locked in every flight regime.

I had similar behaviour to yours when running the small tail blades (92mm), it was fine in fast backwards flight etc., but when loaded up in more dynamic maneuvers, it would get soft. If you're running lowish head speed (under 2200rpm) with the 92mm blades and experiencing further head speed droop under load then that's likely the culprit.
The tail drive ratio on the 6003d was aimed more towards 2200+ rpm on the head.

[cptsnoopy]

Try the bigger tail blades before putting in a new gyro.
I went to 105's and in 3mm on the tail servo horn, and it is absolutely locked in every flight regime.

I had similar behaviour to yours when running the small tail blades (92mm), it was fine in fast backwards flight etc., but when loaded up in more dynamic maneuvers, it would get soft. If you're running lowish head speed (under 2200rpm) with the 92mm blades and experiencing further head speed droop under load then that's likely the culprit.
The tail drive ratio on the 6003d was aimed more towards 2200+ rpm on the head.

Hi Nathan,

will do, they should be here within a week or so. when you say in 3mm are we looking for approx 11 to 12 mm from center?

Charlie
:)

[NTM]

I think mine is 12-13mm from center.

[cptsnoopy]

Just a quick update,

I tried the Logo600 with the neutral reset correctly and there was no change. I am getting better though, I can do a 130 degree piro/tic toc without using any rudder. After that flight I took the NHP tail blades off and put them on my brothers Logo14 V-stabi and with luck we will maiden that today. My longer tail blades were supposed to arrive yesterday and the UPS tracking showed them in Phoenix, AZ at 3 something am but later in the afternoon the tracking info showed them in Las Vegas, NV and then later in Salt Lake City, UT. I guess the blades were worried about being on my heli with me flying so they went AWOL. :)

[Ticidytoc]

I wish I wasn't 6 hours away, I really don't think your issue will be fixed by simply changing tail blades. I'm running 92mm blades with 600 mains, and even if I bog the $hiz out of it with the weaker setups, the tail still holds.

Your tail sevo is a Hitec 9650? Never seen that one before.

[NTM]

I never really liked the nhp tails on my logo 14, didn't work well, perhaps ?

Something is definitally wrong there, mine is rock solid through all of the flight envelope, especially the maneuvers you describe.
And I'm running 690's and 105's at only 2000rpm, although I did have to crank the collective torque compensation up to 25.

What kind of tail servo are you using ?
How used up is it ? They don't last forever and tend to get weak before they croak.
Bearings are all good in the tail, no binding ?

Regards,
Nathan

[cptsnoopy]

Hi Nathan,

The tail servo is a Hitec 6965 running on 5.8v. It has very little time on it. I have a brand new Logictech servo from the 6100 combo that I will try after trying the new blades. (if the blades ever show up.) In addition to getting some 105mm blades I am getting some 95mm and will use those on the 14 if it acts weird. If the Logictech servo works I will see about spending the dough and getting a real tail servo. I don't trust the Logictech setups after one quit working in my Logo10 within two minutes of the first flight on it.

Charlie
:)

[NTM]

That's likely the issue right there, I've tried one of my 6965's on the tail of a swift before with a futaba gy502 and it sucked !
I've heard of people using them as tail servos before, but usually on more docile helis than the 6003d or even the swift I tried it on.

Regards,
Nathan

[Ticidytoc]

We played with one on a Raptor 50 and a 601, not too much good luck with it either. It seemed to hold for the most part but would do strange things so that locked in feeling was never there.

[fogger]

I flew this heli with my own tx last weekend and it is definitely not right, and it's definitely not in the thumbs as is did the same exact things for me. Just felt soft alltogether, and overcompensated rudder on flips. I never saw anything like this before. I'm starting to think it's either servo or vibration.

Hey Charlie,

We can try my align 92mm white carbon tail blades and I think I have a set of Radix 92's that are OK too. Also if it's compatible you are welcome to try my 9256 from the trex 600, I'm just not sure if the vstabi can drive the fast framerate servos?

Have you tried soft dampers, or multiple layers of foam tape? Trying to think of ways to better isolate for vibration.

-Chris

[OICU812]

Well the B251 Brushless is a great servo, really like it, for the few times I flew it anyhow!!

[Ticidytoc]

I'm just not sure if the vstabi can drive the fast framerate servos?

Yes it can run the 9251/9256 like a champ.

[OICU812]

Matt you are officially an avatar whore! :YeaBaby:

[Ticidytoc]

lol just having a little fun. Watchit, i got an idea for yours. :thumbup:

Anyways Id like to see snoop get his tail issues sorted here. Im also wondering about the 8900 JR servo. I have been running an old 9251 with no problems now that the tail got sorted on my bird, and the 105's seem a bit in excess for 600s.

I think the 9256 should make things better for the capt.

[Flybar-less]

The 8900 works great!

[Ticidytoc]

But correct me if im wrong, you replaced your tail for some aftermarket deal. also running larger blades ?