Gaui X3 Tail blow out

[felixthemaster]

I bought the heli second hand and it did not hold the tail well at 60 gain. Through a process of trying to get it to hold (reducing bow of tail slider, upgrading to a faster tail pulley, bigger blades, tightening belt), I have reached 90% gyro and it still kicks when I pump it up. It tail holds for the most part in 2700+ HS (other than tick tocks as mentioned below) and completely gives up when flying backwards or in pitch pumps with anything under 2450HS. I need to practice backwards flight, but I can't do that if the tail swings around when I go faster than 15mph backwards.

Of course, elevator tick tocks make it slide 60 degrees after about 7 of them and it does the same with about 3-4 Aileron tick tocks. Yes, I am not good at tick tocks yet, and I can learn more collective management, but why settle for an under optimal setup?

So I was wondering what else I can do other than use a 1.20x tail gain multiplier in spirit FBL (for 500 helis) to increase tail gain past 100. There is still some stuff I have to try so I haven't given up hope yet. But I would appreciate some more tips on trying to sort out this tail issue. I did lube the tail push rod near the rod support, and the tail pitch slider as well. The servo seems to move without resistance the way way it does when I disconnect the push rod from the assembly, so I think the whole thing is pretty smooth. I have not tried to feel resistance when the tail is spinning yet.

I can't/don't want to use bigger blades than 68mm as it is plenty big already and it cuts a tiny ravine into the grass roots when i land.

[Grumpy]

Is the travel on the tail pitch slider as much as it can be without binding?

[felixthemaster]

Pretty much. I tried to go up to 2mm to the ends but I hear binding noises when adjusting in software until I move a step back and they stop. So I am not sure if I should go on noises alone. I flew them this way but when I landed, spirit logs said that rudder limits were reached, so i dialed it back to about 4mm off the ends. I don't know which one to trust when checking for binding.

Noses stop if I move back a step so that can't be trusted, and the rudder limit message seems to happen even at safish zones. I could pop the ball link to the absolute end for more throw at the risk of resolution, but I never thought it was a limit problem. I do, of course want to go to 2mm off each side, but the logs make me worried I may burn out the servo or something (even though I don't hear binding noises when operating normally).

If someone has spirit and thinks ignoring this warning is fine, then I will try to raise limits and see if that fixes the problem.

[bigpops]

Those are very low head speeds for the X3.

If you're already running 68mm tails and the speed up pully, there's only one thing to do, and that's up the headspeed.
You don't need to go crazy. I run 3000rpm on mine which is still on the low side for an X3. Edge 60mm tail blades are enough to give a solid tail.

[felixthemaster]

I have been enjoying 1900HS (ALZRC 380) with the X3 recently, getting 7 mins of learning to piro hover and fly circles.

After the recent crash, I now have some decent reliable servos on it and a new motor so I went 12T which gives a max of 3150 governed. I tested it in the backyard today and it sounds angry! I have never been as high as 3000 before and I am really scared that it will explode in mid air at IU2 (3010HS) with the replaced blades (Align 360). I saw that video of the guy flying normal 3D at 3K something HS and it just gave up on him, so I have been weary. Since I am back to 360 now, I guess higher HS can't hurt as Align blades aren't that low a quality like ALZRZ. But I hope the tail blades don't fling off with the 14t pulley.

I noticed that there are 4K videos on youtube, but how many flights can it even handle at 4k HS? Can't be too many for safety's sake.

This is the first time hearing that 3K is in the low end! Is that because of the weight of the Gaui? Like the goblin, do these run higher HS to counter act the heavier kits? And damn, 60mm seems extremely small.

[myxiplx]

2400 is low, but it should still hold through most stuff with a speed up pulley and 68mm blades. I mainly fly at around 2800rpm, and at that speed it should hold in backwards flight, sideways, you name it.

You do need to ensure the tail can move to the limits, 4mm off the ends is a huuuuuge amount of pitch you're losing.

I generally set the endpoints the way you first mentioned, increase them until you hear the servo binding, then drop back a couple of three points. It should leave you a tiny fraction of a mm off the maximum travel. If the spirit is saying those limits are too far, that means your servo horn on the servo is a little short, and you should move the link out on the arm to give more travel. That will let you get the same physical travel on the tail, for less rotation of the servo.

If you're going to do that, reduce your endpoints in the Spirit first. Otherwise you can lock up the servo when you reconnect things, and with some servos you can burn them out during setup.

So long as you're not binding on the ends of travel during setup your servo will be fine in flight.

[felixthemaster]

So the limits reached message in spirit has to do with the servo throw rather than an increased amp draw when it binds? That's useful to know. Seems like I have put off touching the tail servo horn long enough, time to move it to the end hole. It is a bit of a PITA due to my sat and wiring so there is a lot to be done to take off the horn.

I will change the hole and report back possibly on Tuesday when I can fly again.

[myxiplx]

Yeah, the further you push those limits in the software, the more the servo arm is rotating. And if it rotates too far it becomes very mushy to control.

Think of the arm when it rotates 90 degrees, rotation of the servo at that point does nothing at all for the tail.

The ideal is to have the maximum rotation in the 40-50 degree range either side of centre. That's nice and fast, and still relatively linear behaviour. Many FBL units will give you a warning during setup if you're getting outside that range, and if you are, you generally just need a longer servo horn.

[Grumpy]

Yep, you need more pitch range. The slider should be just a hair (less than 1mm) from hitting the head or the tail box when at the respective outer and inner limits of its travel. So it does sound like you need a longer arm.

Increasing the pitch range increases mechanical gain which will mean electronic gain can be reduced, plus it gives the tail more ultimate holding power.

[Peteski]

[QUOTE=myxiplx;1208716]
You do need to ensure the tail can move to the limits, 4mm off the ends is a huuuuuge amount of pitch you're losing.
[/QUOTE]

I was thinking that too. You only need to be a fraction of a mm off the stops at both ends.

[yuppyflyer]

If you still have issues with tail performance after trying the above, one other possible solution is to fit the 3 blade tail.
I've been using it for a couple of months and it performs significantly better at lower head speeds using standard tail blades.

One thing I noticed with my X3 is that regardless of head speed and tail setup you can nearly always blow the tail out if you suddenly (clumsily) apply a lot of collective pitch and overload the head

[felixthemaster]

If this doesn't work, I will look into it.

[felixthemaster]

WOW! It worked! Had to turn the gain down to 70 from 98!

Also, after I make any sudden cyclic inputs, seems like the cyclic shake a little. I'll reduced the cyclic gain to hopefully solve this.

But, I am so chuffed, the tail holds pretty nicely! Of course, i can't confirm until I actually go to the field and fly the thing.

[felixthemaster]

Can confirm, tail is solid.

Only issue is, when I take off from grass, the tail blades bend back a little bit so due to the higher angles, it does have the opportunity to touch the tail fin.