Too much tail movement 1 way not enough the other

[butmuncher]

Hiya guys,
Just moved up from a esky rubbish to a nice shiny raptor rtf from fleabay.
I ran the engine in ecty and done the adjustments, flys smooth as a babys bum, im so happy.
Only problem i have , well not really a problem as i can turn my tail in any direction pretty fast.

problem

The bar that runs the the tail, the bar that the tail rotors move left and right on, there is only a tiny bit of movement left on the right side of bar, maybe about half a cm worth of movment but to the left i have a full sticks movement?!?

as i say it holds nice and will happily turn in any direction, will this create any problems??

Allso i take it that i will need to change the screw thingy on the futaba 401 giro so as not to make the movements bind.
Hope ive explained this right, sorry if i havent

[HiroboFreak]

If the gyro is in heading hold mode, it will not return to centre. Is this possibly what you are taliking about?

When there is no stick input on the rudder, is the light on the gyro on or off?
If i's on, then it's in heading hold mode.
In order to properly check travels, it needs to be in rate mode (non-heading hold)

I'll see if I can dig up my procedure for setting up a 401 which I posted recently.

[HiroboFreak]

Here is my post from another thread.

Bear in mind that I have not explained how to adjust gain.
If you say the tail is holding then you shouldn't need to alter the gain setting.

Adjusting the tail rod so it doesn't drift in rate mode is NOT REQUIRED with Futaba gyros.

If you do this, the tail pitch slider will be offset when initialised which results in reduced tail strength in one direction.

Here is the method I use:

Set rudder trim & subtrim to zero (in all flight modes), make sure revolution mixing is disabled.

Set rudder servo horn to be perpendicular (at 90°) to the tail boom with rudder stick centered in non-heading hold mode.

Don't use subtrim to get it at 90°, get the right horn to get it right!

Keep limit pot over 100. If limit is under 100, go further in on the horn.

Make sure you are getting full throw of tail pitch slider, adjust limit & length of rod to get an equal full throw.
(Pop the link off the tail slider, move rudder stick to full & compare travel of rod to travel of slider in both directions. Adjust limit pot & rod length so get an equal full throw without binding)

Once you have established full throw of the tail pitch slider, go back to Heading Hold mode & re initialise gyro. Go fly. Don't even bother with rate mode. If you want to use rate mode, get yourself a cheap (& nasty) gyro & put up with correcting the tail with the torque change.

Set rudder travel adjust/atv to 100/100, this sets pirouette rate only! Not control throw. Adjust equally to personal preference for pirouette speed.

If you are getting a "bounce" at pirouette stop, this is what the "delay" pot is for.
For a fast servo, set delay to "0"
If you are using an "everyday" servo on the tail (not recommended), increase delay until "bounce" at pirouette stop is minimal.
Also if you're NOT using a Digital servo, set "DS" switch to "Off" or you'll burn out the servo due to too high a framerate.

Hope this helps.

[Made2Fade]

It will move more way compared to the other... this is because it has to compensate for the torque of the motor and blades. Use the limit pot on the top to take any binding out. You will have to hold right stick on the Transmitter when you adjust this so you can see the point its binding at. Back off the pot to the point just before you hear your servos buzzing. As HiroboFreak mentioned above use the ATV'S/End Points in the transmitter on the rudder channel to adjust the speed. Try 80 or 90 % and just work your way up in both directions until you have the tail feeling exactly as you want it. I leave my points the same both directions but i know people that have diffrent endpoints again due to having to work against the torque of the motor in one direction.
Lee

[HiroboFreak]

aaaaah, no.

If it is properly set up, it should move the same amount in both directions & when in rate mode.

[Made2Fade]

not really... depends how you setting it up... i set mine up to hover hands off in rate mode then double flick the gain channel for the gyro to remember it. You slide the servo along the boom/adjust the rod to keep the tail straight in the hover in rate mode. It helps the gyro hold better IMO and also prolongs the life of your tail servo as it doesnt have to work as hard. If setup this way then in rate mode you will seem to have more travel one way than the other. By the way butmuncher... setup in rate mode not HH.
Lee

[HiroboFreak]

Yeah, heard that myth many times.
That method is only for CSM & old JR gyros.

It's not correct for Futaba gyros.

http://www.rcheliaddict.co.uk/showpo...5&postcount=11

[Made2Fade]

Well my answer to that would be... im not a 3D pilot and im guessing butmuncher isnt too. I always keep my EndPoints/ATV's the same just have known people to have them diffrent. I also own an evo 50 and have found without a doubt that it holds better when i offset for 5 degrees of pitch in rate mode. what happens if butmuncher does actually want to use rate mode too??? I dont think he'd want to hold in rudder stick command to keep the tail straight. Ive always done this with my GY401 and i have 4 of them on different helicopters. Every one holds solid. Selecting the right length servo arm is also quite critical to how the gyro behaves. Thinking about it though... the method is definately right for 3D flying without a doubt but i still think that you will get a better hold offsetting in rate.
Cheers
Lee

[HiroboFreak]

Each to their own.

3D is my thing & I know I'd much prefer to utilise the full travel of the slider.



Either method would work for hovering & gentle stuff.

It's aggressive backwards that requires tail strength.

[Made2Fade]

Right you say that your technique is for Futaba... then whats the point in flicking the gain switch for the gyro to remember the point in rate mode??? If it was set to the centre with even travel then why bother having that feature on the gyro as it would seem pointless right? Obviously it will remember the tail centred but what benefit is that when the servo goes to centre anyways? Dont think a gy401 would hold very well doing aggressive backward flight anyways mind mate. I think by that point you would have upgraded the gyro anyways.
Cheers
Lee

[moyesboy]

I started off the other thread the hirobofreak quoted from.
With the 401 here's what I recommend.
Plug the servo direct to the rudder on the receiver (with advanced gyro servos you can't always do this, but all the servos that work with the 401 you can).
Set the end points of the rudder on the tx to 100%, with no trim or sub trim.
Adjust the linkage (servo at the front) or slide the servo (servo on the boom) to place the pitch slider in the midde of the available range at centre stick when the servo arm should be 90 degrees to the pushrod. (note the limit for the pull end is when the pitch slider forks hit the 90 degree bellcrank, and the push limit is when the slider hits the tail hub).
Now its best to size the servo arm so that the full travel takes the slider through the full range without bottoming out and binding.

Now plug the servo via the gyro.
In rate mode adjust the limit pot so you are sure the linkage doesn't bind at full stick (it should already be nearly right).

Now fly the heli in HH mode. IF you change to rate mode it will turn, but if you flick quickly between HH and rate a few times it will stop doing that and will fly well in rate and HH modes.

This is roughly the same as hirobofreak is recommending I think.

To get absolutely the best 3D performance with symmetrical stop characteristincs it is possible that moving the servo horn so it is 90 degrees to the linkage during the hover might work better (during the hover the gyro is applying 6-8 degrees of tail pitch to counteact the main rotor torque), but the 401 cannot have unequal limit travel right and left like more advanced gyros so you have to then make do with less than the maximum possible tail pitch in one direction.
This is where the aguments start...
The 401 gyro remembers the servo position it was using to hold still when the flicking in and out of HH was done, and uses that for centre stick in rate mode - so with the 401 adjusting the linkage to get no trurning in rate mode doesn't get you anywhere. Other gyros allow the centre to be reset to default so the ideal mechanical setup is when the heli doesn't turn in rate mode.

Anyway back to the original problem.
when yuo fly the heli in HH mode it holds ok but will hardly turn one way, and turns easily the other way.
The gyro is using nearly all the servo travel to stay straight.
So adjust the linkage to put more pitch in the direction that the heli wont turn, and then it will be better.
If you follow through the setup advice above (pick the post you want to apply), then it will put the servo more in the middle when you are hovering and it will work better. Its importent that the gyro can't stall the servo, or the servo may burn out, or your battery may prematurely run out of go and everything stops (except the engine)!

[HiroboFreak]

True, I no longer use a 401 (use 611 now) but my only complaint with the 401 was inconsistent pirouette rate.

The 401 will hold very well in fast backwards if set up correctly.

As for the rate mode centre feature, I assume it's aimed at F3C pilots & beginners where the "weathervane" effect is utilised.

In saying that, it's not difficult to follow through with rudder in a turn as you would have already learnt to do this in your slow "lazy 8" turns with no aileron input.

I don't think I can name a single pilot over here who flies in rate mode. (That I know of)

If you use the rate mode centre method, you will need to trim at the beginning of each flight & then flick the gain switch blah blah then back to Heading Hold.

Why bother?

Setup using the 3D method, initialise in HH (as you do anyway) & go fly in HH & be confident that you have the maximum possible tail strength for your configuration.

[HiroboFreak]

Anyway back to the original problem.
when yuo fly the heli in HH mode it holds ok but will hardly turn one way, and turns easily the other way.
The gyro is using nearly all the servo travel to stay straight.
So adjust the linkage to put more pitch in the direction that the heli wont turn, and then it will be better.

Sorry, I have to disagree there.

If setup correctly, it will turn the same in both directions in HH mode. (if of course your rudder atv's are equal)

Turning speed/pirouette rate is controlled by

a: The AVCS sensor in the gyro measuring degrees per second

&

b: your rudder atv's allowing the MAXIMUM AMOUNT of degrees per second.

The gyro will attempt to keep the pirouette rate constant.
You don't need to worry how much tail pitch it is using to do this.

But to do this to it's maximum potential, it needs to have access to full travel of the tail pitch slider in case it's required. If it doesn't need the travel, it won't use it. Simple as that. But if it does need it, you want to hope you have it there to be used or the tail will blow out.

The limit is set so you don't overdrive your servo. The limit says to the gyro "You can't allow the tail servo to go any further or it will bind"
Hardly Rocket Science.

Try it out & see if it turns slower in one direction, then maybe you can base your info on facts.

[HiroboFreak]

Facts.

Taken from http://www.littlerotors.com/setup/tu...helisetup.aspx

GYRO & TAIL SETUP: This is where a lot of people make mistakes… This section is related to Futaba gyros only as that’s the only ones I use and they are the best gyros on the market at the moment.
This gyro is a GY601, but the same principles apply to the GY502 and the GY401 as well.
First up: YOU DO NOT HAVE TO TRIM THE TAIL IN NON-HEADING HOLD FOR THESE THINGS TO WORK!
That’s a carry over from the old days when you had to first get your tail to hold when the gyro is in rate mode by mechanically trimming the tail linkages.
YOU DON’T DO THAT ANYMORE (for Futaba gyros anyway).
You’d be amazed how many people I come across who have problems with their tail and have tried to set up their tails the old skool way.
Futaba gyros don’t care where center (ie where the tail is holding) is. All they care about is the limits that they can move their servo between so they can do their job.
What IS important is that the limits in each direction are the same.
But Si, you aren’t making any sense! We need to set the trim in rate mode!
The reason why you don’t set the trim in rate mode is because the tail trim will be different depending on a LOT of different combinations such as hovering head speed and hovering pitch to name the two main components. You might get the tail spot on mechanically with one combination, but as soon as you go into Idle Up where the headspeed increases, the trim will change. If the engine goes lean or rich, it will change, so what’s the point? The gyro really doesn’t care.
Why is it important to have equal travel on both sides, and why should those values be large???
The gyro wants to know how far it can move the servo to the left and right to make the appropriate compensations. It’s important that these values be equal so the gyro gets a linear progression when it tells the servo to move.
Remember earlier in this article I talked about servo resolution and why you should have your ATV’s set to a relatively high value (ie about 100%)? Well the same goes for the tail servos, the gyro is a finely tuned instrument capable of making minute adjustments to keep the tail steady. If you have cut down the amount of servo resolution by having a low limit value (ie 80% for gyros), then you’re making life harder for the gyro than if you had that value at 120% which gives the tail servo more ‘room to move’.
Another bit of evidence that Futaba gyros want equal limits on both sides is with the GY401. Both the GY601/611 and the 502 have independent limits for both sides, you can set the values to what you want, but the 401 doesn’t. It only has a total limit value, not independent values, it REQUIRES that both sides of travel are equal. You’re required to adjust your mechanical linkages so that the 401 can use the total amount of travel. You should do the same for your 502, 601/611.
Make sure that your tail servo is operating in the correct direction, and also, that your gyro is working in the correct direction.
How do I check my gyro’s direction?
My way is pretty basic, once I’ve established that the tail servo is going in the right direction, I look at which way the servo horn when I move the rudder to the right. Then I grab the boom and swing the nose of the helicopter to the left and make sure that the servo horn moves the same way as it did when I moved the rudder stick to the right. If it didn’t, then you need to alter the gyro’s direction.
Ideally, you want to set your gain to about 37% or so.
On the GY601/611 on my 3D models I have the mode set to 3D. I found that the gyro seemed to perform a little better during pirouetting maneuvers in 3D mode, but it really doesn’t matter much.
How do I know what servo horn to use on the tail?
Ideally you want the tail servo travel to be about 120-130% so adjust your servo horn’s length until you can obtain that.

-------------------------------------

More facts

Taken from http://www.archeli.com.au/cobra/showthread.php?t=110938

Thanks Jafa.


Tail servo installation
We need to correctly install the tail servo

Put the rubber grommets on the servo mounts
You insert the guide eyelets from the back of the servo
so that the eyelet rim will face the mounting bracket (important)
Insert the fours screws but only do them up until they are snug,
you do not want to tighten them firmly as that will crush the eyelets
and prevent the rubber grommets from performing their vibration isolation function.

Use the large round disc that came with the S9254 servo
We need to install the ball for tail push rod at the top of the servo disc
On a Freya or Sceadu position the ball 19mm out from the center
Check with other owners of your model as to what setting they use
(be careful here, get a recommendation from somebody that can and does fly fast backwards!)
The trick is, we need to place the ball exactly on the vertical center line of the servo screw

Moving the ball outwards from the center has the following effects:
-Enables full pitch slider end to end travel to be achieved
-Speeds up the response
-increases the effective gyro gain
-increases load on the tail servo
(don't use this as an excuse to use a closer position - the other factors are more important)

Turn the TX on, set the gyro to rate mode (non heading hold), turn the model on.
Ensure that there is no trim or sub trim on the rudder channel.
The servo is now sitting at the middle position,
place the round disc on the servo but don't insert the screw.
Place a steel ruler on the table and align the ruler edge to go through
the center of the screw hole, visually check the servo line markings with the ruler.
You will note that the Futaba disc has 8 lines which are all numbered.
You can simply remove the disc, rotate forward to the next line
and then check to see if the next line is vertical and in alignment with the ruler edge.
Due to each line being at a different position on the splines,
you will definitely be able to fine one line that is in exactly vertical alignment.
You can also do this with the Futaba 8 fingered star horn.
Once you have found the perfect alignment, note the line number,
pull the wheel off, drill a 2mm hole on that line at the correct distance from the center.

Click on the photo to get a detailed larger than life view!
This image has been resized. Click this bar to view the full image. The original image is sized 2047x1649 and weights 425KB.

An important point has come to my attention,
some heli's (Raptor 50) have the tail servo on an angle,
and people think the horn should be 90 degrees
to the body of the servo - this is incorrect
The horn should be 90 degrees to the tail push rod,
which most often also means 90 degrees to the boom (or table).
Which is why the steel ruler alignment technique works nicely

We want the horm 90 degrees to the control level at middle position
so we get equal effect when moving off center both ways


Tail push rod setup
This is yet again another very important setup issue.

The ball links in each end of the tail push rod need to be correctly sized,
if they are too tight around the ball making the action stiff
this will waste power from the tail servo which is not very strong.
If you connect the round disc with the ball to either end of the tail push rod
you should be able to shake the tail push rod and the ball position should change.
If it stays in the same spot it's too tight.

There is a ball link sizing tool (reamer)
but some people gently squeeze the outside of the ball link while it's on the ball
with a pair of pliers - it's a bit crude but appears to work.

The tail push rod guide need to be aligned correctly in a straight line,
with the tail push rod installed, look down the tail push rod from the rear,
you should be able to see light on each side of the rod through each guide.
Don't put the guides too close to the servo or too close to the tail lever.
At the servo end, the tail push rod goes up and down by 10mm or more
At the tail lever end the tail push rod goes side to side by about 5mm
If the guides are too close to either end they will cause friction
which will over heat the tail servo and slow the action down.
Once again, the tail servo is not very strong, it's built for speed.


Travel setup
Now connect your tail push rod to the servo and the tail lever.
Turn the TX on, set the gyro to rate mode (non heading hold), turn the model on.
Ensure that there is no trim or sub trim on the rudder channel.

Gently move the rubber to each side,
if the tail pitch slider hits the limit of it's mechanical travel
and the tail servo starts buzzing - STOP - you don't want to burn the servo out.
You must ensure that this CANNOT happen in-flight,
but you also much ensure that you get the maximum mechanical travel you possible can.

So lets say that you hit the mechanical limit on left rudder and not on right rudder.
This means we need to adjust the length of the tail push rod
or move the servo position on the boom
to avoid hitting the mechanical limit.
By doing this, we will get more mechanical travel in the other direction as well.

Ok, now you can move the rudder stick fully left and right
and not hit the mechanical limits of the tail pitch slider,
you now need to increase the limit setting on the GY401!
You need to use the maximum left and right mechanical travel that is available,
right down to the last millimeter.
When you increase the gyro limit, say from 110 to 120,
you may find you are back at the previous step where you hit the mechanical limit
on one side and not the other - so you need to adjust the length of the tail push rod
or the position of the tail servo on the boom - again.

By working through this procedure you have given the helicopter
the maximum possible mechanical pitch range to use.
This procedure has also centered the tail pitch slider at the neutral rudder stick position
(it happens naturally due to using the same throw limit in both directions).
With the Hirobo helicopters this neutral position has a little pitch on the tail
which is normally enough to hold the tail in a normal mode hover.

Note: Try to keep the tail servo as far forward on the boom as possible.
The further you move it backwards the more weight we are moving down the boom.
I only mention moving the servo because if you have screwed the ball links
on the tail push all the way in and cannot shorten the tail push rod
you then need to move the servo on the boom in order to perform the above adjustments.


Correct rudder direction
We need to ensure that the rudder operates in the correct direction.

Either remove the main blades or at least extend them to their normal flying position.
Rotate the tail blades until they are vertical,
keep the tail spindle vertical and pull the bottom blade rearwards,
so the tail blades should now look like an L from the side,
think of this as a boat rudder.
Stand behind your heli, move the rudder TX stick to the left and right,
the boat rudder (sorry, the lower tail blade) should follow your TX stick.
If not you need to reverse your rudder channel.

(This holds true for helis where the tail blades revolve backwards, away from the main blades)

GY401 Rev setting
This must be done AFTER getting the correct rudder direction setup - above.

Now we need to ensure that the gyro will generate tail movements in the correct direction.
REV stands for Reverse

Ensure that the TX has the gyro in heading hold mode,
turn the model on and don't touch the rudder or the model, let the gyro initialize
Move the TX rudder stick all the way to the right, the boat rudder will move to the right too.
Let the TX rudder stick return to neutral,
the tail blades will not return all the way to neutral - this is normal,
put the TX down out of the way,
Pick the tail of the heli up vertically by just a foot,
move the tail to the left rotating through 1/4 of a piro/turn on the skids,
do this in one continuous motion (don't start stop and dont change direction)
now put the heli down on the ground.
The boat rudder, the lower tail blade, should be pointing to the left
because the gyro is trying to counter act the un-requested piro
(un-requested because the TX rudder stick is at neutral).
If it stays on the right (it probably moved further to the extreme right again)
then you need to flick the REV setting on the GY401 and perform this test again.

If you get this step wrong, when you spool up and try to lift off,
the heli will go into an uncontrolled fast piro,
if this happens hit your hold switch,
hold the heli at zero pitch and pray.


In flight piro rate
You can adjust the maximum piro rate of your heli.
Increase the ATV setting on the rudder channel to increase the maximum piro rate.
Decrease the ATV setting on the rudder channel to decrease the maximum piro rate.
(Keep the left/right values the same!)

I go into a high stall turn and apply full rudder to get a feel for the speed of the tail,
you will get a feel for what is too fast or slow, everybody has their own preferences.
If you can't do those big stall turns yet then leave the rudder ATV at 100 for now,
it will be fine.


Rudder expo
One common problem that people have is snagging rudder input while using
the elevator in mode one or the collective in mode 2.
Also, people often feel that the rudder is too responsive or even nervous around center stick.
One way to address this is to use rudder expo,
some of us use rather large values too, 30 to 40 % rudder expo is not uncommon.
But too much also makes the rudder slow to respond around center stick and can feel mushy.
You have to find what works for you, but 20% expo would be a safe place to start.

Note:
-20% expo in a Futaba TX
+20% expo in a JR TX

[butmuncher]

It will move more way compared to the other... this is because it has to compensate for the torque of the motor and blades. Use the limit pot on the top to take any binding out. You will have to hold right stick on the Transmitter when you adjust this so you can see the point its binding at. Back off the pot to the point just before you hear your servos buzzing. As HiroboFreak mentioned above use the ATV'S/End Points in the transmitter on the rudder channel to adjust the speed. Try 80 or 90 % and just work your way up in both directions until you have the tail feeling exactly as you want it. I leave my points the same both directions but i know people that have diffrent endpoints again due to having to work against the torque of the motor in one direction.
Lee

Thats the 1.
soory guys i meant there was more travel to the right and only abit to the left.
So i've set all the tx stuff, no binding and it now travels both ways the same as i've set the right large side to the same smaller size of the left side, theres def no probs with tail swinging out ect, i was just worried that that i'd lost alot of left movement on bar in the tailbox, as i say when flying the heli will happily move very fast left and right, setting my d/r ( i think it was called on my tx) gave me the smaller movement i need. Thanks all rfor your inputs