Tail Kicking

[ckoelliker]

I have had my Lepton up and flying for a few days and my tail is kicking in climbout. I have checked the normal fixes but with no luck. I am running the hyperion 10t with align esc. It is a 401 w/9254 on the tail. Gain is about 43% running 80% straight throttle curve. It almost seems like a delayed reaction. The tail has enough holding power but it just takes a little bit longer to get there. I checked the tail for any slop and the only thing wiggling is where the control arm connects to the pitch slider. There is a vertical alen bolt that has a little vertical play. I do not think it is the gyro because it seems so solid everywhere else. My pitch is 11 positive and 11 negative. My esc is set 1/3/2/2/3. Any ideas? How long should my gyro servo arm be?

[3secondsToImpact]

Perferred measurement on tail servo arm is 12.5mm.
At this measurement i still had tail kicking , so i moved it to 13.5 mm and most importantly the setup on the gyro must be done according to instructions, after i went through the proper steps to set up my Gy401 my tail is rock solid now with absolutely no kick whatsoever on a +9G climbout. The most important thing is the gyro setup. Also limit pot should be between 80-100 for best setup. Maybe bring gain up, i run mine at or around 65-75%.

[ckoelliker]

I will measure the length and see what I have. The 401 was set up in rate mode, hovered, and adjusted mechanically.

[Jafa]

ckoelliker's gain figure looks like a Futaba GY Mode setting?
3secondsToImpact gain figure looks like a std/raw ATV?
(75% - 50) * 2 = 50 in GY Mode

I'm running 54% in GY Mode and it seems ok

JK and others regularly warn against running Futaba gyro's
with the limit below 100 as it burns out the tail servo over time
110 to 120 is often reccomended

[ckoelliker]

I think that is right where my limit is but I will double check. What headspeed are you running?

[Jafa]

I don't actually know my headspeed - I am still taking it easy breaking the packs in
I'm running a flat 55% curve in normal mode and 60% in idle up
So I expect my head speed is slower than you guys
It still flys great, loops rolls and tumble weeds
Not doing tic tocs yet cos they would load up the battery

I used 12mm for my my tail servo ball and have ~112 limit setting

[ckoelliker]

Maybe it is the tail blades. Mine are not stock but they are only 62mm and not the 68 that most people are upgrading to. But on the other hand they way it is kicking makes it seem like it is some kind on sloppy linkage, because it moves when I punch the collective but then it seems to catch. Once it is there it seems real solid. I do not know I also do not think I have flown it enough. we will see.

[Jafa]

Yeah - I'm using 68mm

The tail drifting when you punch it means gain or not enough tail strength
It's probably using a lot of tail pitch to hold it

[3secondsToImpact]

Jafa
I am using the gyro sensi menu on my Jr9303 @ or below 50% my AVCS light goes off(rate mode as far as i know) and when i go above 50% my light is solid on(AVCS mode) am i correct on this. I can go as high as 92% before tailwag is noticable.

[ckoelliker]

I flew it again a few times today. The kick is still there. It only does when I punch the collective from hover to full pitch. If I advance it quickly but smoothly it will hold. My head speed is 2720 at 80% with a hyperion 10 turn and hyperion 3700. Does this seem a little slow? When I give it full collective it bogs a little but not much. Is this head speed about right for my setup? What about pitch? I am running +11 to -11.

[N3CAL]

Have you tried going from a straight 80% throttle curve to a slight "v" shaped curve. I didn't think the Align ESC had constant RPM mode. You may need 85% at max pitch....

Cal

[Jafa]

3secondsToImpact - your understanding of the 401 is indeed correct
92% = (92-50)*2 = 84 avcs gain which is very high indeed

[ckoelliker]

I had my curves up to 90% and it still kicked, but maybe I need to make it more of a v-curve to leave some in reserve. I am running 9650's on the cyclic @ 6 volts maybe it just advances it too fast. What about belt tension I think I have mine on the tight side. When the new pinions come out if I drop down to a 23 or 22 will that give my set up more torque?

[3secondsToImpact]

Thanks Jafa
I'm only a 1 year vet at this, so all advice is gold to me.

[Learn to Fly]

Try tightening up the tail belt, mine did this too. I tightened up the belt and it went away. Now the belt on the Lepton needs to be tighter than any heli I have flown.(guitar string tight) Hope this helps.

I used 62 mm tails and it held good. I now have the 68s and it holds rock solid.

Jeff

[ckoelliker]

I will try tightening it. I would have said that it was tight, but it is nowhere near a guitar string.

[ckoelliker]

I pulled the tail about as tight as I could pull it with no change. It is still kicking 5 to 10 degrees on full pitch climbout. I have still not checked the length of my rudder servo arm. I will try that next.

[RotorCycle]

I had this exact issue using the GY401 and 9254 until I (over) tightened the belt. There's still a degree or two of kick even with the 68mm carbon tail blades, but this may be tuned out completely with a v-curve.

[ckoelliker]

I double checked it today. I think my servo arm is too short. People have said 12.5 mm. I do not know what mine is but when I add full right rudder the pitch slider will not contact the tail case. It is not a gyro limit issue I do not think, but rather the servo arm goes so far past vertical that it just does not move the pitch slidder enough. I will give it a try.

[ckoelliker]

Well my servo arm was right at 12.5mm. I did get it set up to where the slider hit all the way to the tail case, but no change in my tail. I am more or less at a loss. It is moving about five to ten degrees. I have my gain anywhere from 42 to 47 on my 9c running at 2800. I am about 78% linear throttle curve on the align 75. My settings on the esc are 1/2/2/2/3. On the t-rex forum there is a post about the align esc's making the rudder servo twitch during its series of beeps. I was in the minority saying that it is normal. The majority of the answers thought that the gyro wire was picking up noise from the motor wires. But on mine when I take the motor pinion off my servo does not twitch. I thought my gyro was reacting to the motor which moves slightly when it is beeping. My gyro is mounted on the back and the wire to the receiver is running between the frames past the main shaft to the receiver which is mounted up front. I do not know how to get the gyro wire any further from the motor than it already is. Beyond the tail kicking the gyro seems to be performing well. I can come out of very fast pirouettes and the tail stops on a dime. The last time I hovered the helicopter the gyro was slowly drifting back and forth during hover. I did not seem like it was hunting when the gain is set to high but rather very slowly drifting an inch to the right then back to the left. I do not know if this is because I did not set the gyro up this time in rate mode. This time I centered the pitch slider and adjusted my limit until I was contacting both sides of the tail shaft. Either way my tail is still kicking some. I guess when it is all said and done it is not running bad, but I think there is room for improvement. The tails on my evo 50 and t-rex both hold very well during climb outs. I have had problems with them but I have always been able to find the solution. Any thoughts? Oh I am running the 9254 on the tail.