Flymentor - Heli leans to he right.

[Groucho_]

So it seems that all should be fine with my flymentor - Blade 400 setup.

The unit initializes just fine, the swash corrects in all the correct directions, the tail also...

The camera locks on in testing and moves the swash when a newspaper is moved under the heli.

It also locks on in flight, with a steady green led light from the FM unit.

There is only one problem.

From takeoff to landing, my heli leans to the right constantly. The camera although locked on, cannot even begin to keep the heli in position, as it seems to be constantly overridden either by the rightwards leaning, or by my leftwards correction.

Trims have no effect, as expected, and I keep them neutral.

The heli is definitely much more stable with FM switched on, so I know that it is working.

I'd just like to eliminate what seems like this constant right cyclic being applied by an invisible force...

My swash is level throughout the full range, and this issue manifests itself in both balance and position mode.

With FM off, there is no rightwards leaning slash right cyclic on the heli.

The blue wire is connected to the RX and I use my DX6i to switch between FM on or off, and balance or position mode.

My balancer gain values are 20 and 85.

Can anyone help me with this please?

Thanks!

[ChrisH]

Completely normal for any helicopter with a clockwise rotating main rotor. It is due to the thrust of the tail rotor trying to correct the torque of the main rotor.

[pril250]

You either have a vibration issue or the gyro unit is not sufficiently isolated. This could be dangerous and cause your heli to tip over. For vibration check all the usual things like blade tracking and the state of the main and feathering shafts as well as bearings and tail belt if required. How and where is the gyro unit mounted?

[Ivor Hill]

Are all your TX subtrims set to 0 ?.
Is your swash level with FM in balance,position and off modes ?.
Have you tried disconnecting the blue wire from your reciever and test flying.
Have you changed any of the settings on the programme advance page ?.
If the swash is level in positional mode fix the heli down so that it cannot fly and run it up to speed, If the swash ( blades ) tip to one side then you probably have a vibration problem.

[Groucho_]

Pril250 & Ivor - here is some more info based on your questions.

I've not checked blade tracking with a laser, but it seems ok when i look at the blades in hover.

Feathering and main shafts are both new.

Tail belt is tight.

FM Gyro is mounted instead of the factory gyro. I'm going to try and attach an image to this post for clarity.

Subtrims and trims are all zero.

re Swash level in all modes - I'll check that out to be sure, but I believe that it is so.

Haven't tried flying without the blue wire - Will do so next time I fly.

On Helibal Advanced settings I have:

Balancer Gain at 70 - this is rendered redundant as my TX settings of 20 and 85 override it.

Neutral Roll at 0

Total Sensor gain 7
Stick sensitivity gain 3

Position Sens. gain 6
Forward freewheel 2

Manual override 3
Elevator gain 6
Stick response acceleration 3
Positioning speed 3

Will also attempt the test for vibration if I can figure out where and how to do that.

I'll also replace the foam tape currently in use with some Align gel sticky stuff and see if that helps.

I DO have a bit of tail wag, which I haven't worked on yet. That may be causing vibrations.

Also, I can clearly see the horizontal stabilizer vibrating quite a bit during flight, so maybe vibration is indeed the cause.

Also one thing I noticed is that the right cyclic becomes a bit less pronounced towards the end of the flight - maybe something to do with battery power, or maybe my imagination, or maybe just me getting used to counteracting it.

A couple of questions -

Would vibration, however, always cause the heli to drift in one direction? It never varies - Always rightwards.

Are my Balancer gain values ok as they are (20 & 85) ?

Thanks again for the help!

[pril250]

The best way to check is to see whether the swash starts to tilt as you are spooling up to the point the heli is just getting light on its skids. That is a definite sign of the gyro being affected by vibration. Not every type of vibration is detrimental but best is to take care of it.

[Groucho_]

Pril,

I have no issues on take off. The heli behaves quite well. It definitely does not tilt during spool up or lift off. In fact it may even drift to the left for a second or two just after lift off.

The right leaning of the swash happens after lift off is accomplished. Maybe because the speed starts the vibration you mention.

I checked the belt for tightness, and found it loose today. It was tight when I checked it last... That has been fixed.

I also checked for the swash being level while on balance mode, position mode and FM off. It's perfectly level throughout.

What I'd like to do is remove the tail wag, which could be a contributing factor, and mount the FM Gyro with the align gel, or two layers of the foam I'm currently using.

Also, Ivor's suggestion of disconnecting the blue wire will be done too.

Are my gyro figures ok, or should I decrease them?

[Ivor Hill]

Why have you changed all the settings on the advance page ?.

[Groucho_]

Originally Posted by Ivor Hill

Why have you changed all the settings on the advance page ?.

I copied them from a document detailing settings for FM on a Blade 400 with a DX6i - A setup identical to mine.

Have I done something wrong there?

[Ivor Hill]

Yes put them all back to factory setting. Changing neutral roll attack angle may be the reason for your problem. It is rarely necesarry to change any of the setting on the advance page.

[Groucho_]

Will revert to default and report back...

Thanks for the pointer :-)

[BarracudaHockey]

Originally Posted by ChrisH

Completely normal for any helicopter with a clockwise rotating main rotor. It is due to the thrust of the tail rotor trying to correct the torque of the main rotor.

What he said.

Translating tendency is the name for it.

[pril250]

+1 Ivor may have to edit the sticky with a bold CAPITAL entry as regards modifying the settings in the advanced page

[Groucho_]

Originally Posted by BarracudaHockey

What he said.

Translating tendency is the name for it.

I beg to differ...

I doubt it's completely normal for a stabilization system to lean and travel. Otherwise it wouldn't be called a stabilization system...

I don't know if you're familiar with the FM system, but it even has a positioning hold mode which keeps the heli hovering over a fixed spot.

Translational tendancy, even if it is the cause of the problem, is not the issue.

The issue is that the heli's attitude is not being corrected by the FM.

[Groucho_]

Originally Posted by pril250

+1 Ivor may have to edit the sticky with a bold CAPITAL entry as regards modifying the settings in the advanced page

Yes Pril, you're quite correct there... I'm feeling quite silly for doing that...

[Ivor Hill]

Originally Posted by Groucho_

I beg to differ...

I doubt it's completely normal for a stabilization system to lean and travel. Otherwise it wouldn't be called a stabilization system...

I don't know if you're familiar with the FM system, but it even has a positioning hold mode which keeps the heli hovering over a fixed spot.

Translational tendancy, even if it is the cause of the problem, is not the issue.

The issue is that the heli's attitude is not being corrected by the FM.

As these guys are saying it is normal for a heli to lean right but they are missing the bit that said the heli flys fine with stablization switch off and so it it likely that FM is causing the heli to lean more that usual and traveling right.
Neutral roll attack angle changes the aileron attitude but will not compleatly upright the heli. It should not be adjusted for normal heli's, it is there for use on lightweight machines.

BTW it's alway's nice to know where people are and Europe does not tell us much.

[BarracudaHockey]

You can feel free to beg to differ, that doesn't change physics.

In a no wind situation, all tail rotor helis lean to the tail rotor thrust, up to and including full scale.

[Ivor Hill]

Originally Posted by BarracudaHockey

You can feel free to beg to differ, that doesn't change physics.

In a no wind situation, all tail rotor helis lean to the tail rotor thrust, up to and including full scale.

Go back and read the first post the heli is flying ok without stabilization. The flight stabilization system if not set up correctly can cause the heli to lean more than normal and drift even if the swash is set correctly, that's what we are trying to sort out. We are not trying to change the physics we know the heli will lean due to the tail thrust and we are not trying to change that.

[Groucho_]

Ivor, Pril...

Well, it was too windy for a test flight with the default settings these past days, but I had some time to actually observe the difference between my old FM settings and the default settings on a static heli.

And I don't like it.

Specifically, Ivor suggested that the neutral roll attack angle, which had been altered from 4 to 0, seemed to be the one factor which might have been causing the heli to roll right / lean right / seem as though right cyclic were being applied.

So I observed what happened to the swash while I modified the setting back and forth between my previous 0 and the default of 4.

Compared to 0, at a setting of 4 the swash leans further to the right! the further one goes towards 10, the more the swash leans rightwards.

Unless I am missing something - and it could very well be the case, as I am no FM expert - the setting of 4 will only make the rightwards leaning worse while in flight...

I am actually a bit hesitant to actually try lifting off now, knowing that the heli will just lean more than it did previously... Unless, that is, somebody can come forward and tell me that he had an identical problem and that was the solution...

Any thoughts on this?

Am I wrong in my assumptions? Or does this indicate a stronger probability of vibration being the actual problem?

[Ivor Hill]

With the settings back to default and stabilization switched off reset the swash as explained in the set up sticky.