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Gyro / Wag / Tail / Rudder issue SOLUTIONS!!

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Gyro / Wag / Tail / Rudder issue SOLUTIONS!!

Old 06-07-2008, 10:46 AM
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Default Gyro / Wag / Tail / Rudder issue SOLUTIONS!!

Over on HeliFreak I started a thread as my way to give back to the community there. So I guess I'll copy and paste it all here too. Read through it and you should get plenty of really good info. [link=http://helifreak.com/showthread.php?t=66036]This is the original post over a Helifreak[/link]

General troubleshooting tips for a wagging tail, these apply to all gyros not matter what make or model.

- Make sure the correct servo is being used for tail control. Too slow a servo can cause wag.
- Check to make sure that the gyro is mounted in the correct orientation.
- Make sure that the gyro is secured. A gyro that is loose will vibrate. Vibrations will cause wag.
- When mounting the gyro isolate it from the heli with a layer of foam to absorb any vibrations.
- Make sure there is no excessive slop in the tail linkage. Also make sure there isn't any binding.
- If your heli came with Z-Bends on the tail control rod, replace those with ball links.
- Headspeed that is too low can cause a gyro to misbehave.
- Check that the tail rotor grips aren't too tight. This can create excessive vibration. Vibration is bad for gyros.
- Too loose a tail drive belt can cause wag.
- Verify that tail servo is working 100% especially after any tail first crash. Damaged tail servos can cause wag.
- Verify blades are in track and balanced. Out of track or unbalanced blades can cause vibration and wag.
- Are your BOTH tail blades on right? If one is flipped in the wrong direction it can cause all kinds of problems.
- Believe or not weather can play havoc with some gyros. This seems especially true of very cold temperatures.

- Check that the gyro is not mounted too close to an RF noise source.
- Check wiring too. "Rats nests" (excessively messy wiring) can attract RF noise that can lead to wag.
- Ensure that there aren't any wires chafing against the edges of the frame.
- Loose connections can generate RF noise.

- Check that your gain settings are not too high. But too low will cause tail drift.
- Verify radio programming. Some radios have seperate gyro settings for idle up and normal.
- Did you follow the set up instructions to your particualr gyro or your helis tail control?

- On the DX6 & 7 radios the GER channel is used for the remote gyro gain.

- http://helifreak.com/showthread.php?t=11373 450 size heli build and setup videos!!! Must watch!!
- http://video.helifreak.com/?subpath=...gyro_setup.wmv Futaba GY-401 setup video!
- http://video.helifreak.com/?subpath=...racking101.wmv Blade tracking video!!!
- http://helifreak.com/showthread.php?t=37202 Logitech 6100 gyro setup video!!
- http://video.helifreak.com/?subpath=...=tail_gyro.wmv G90 / Align gyro / Telebee setup video!

- http://manuals.hobbico.com/fut/futm0809-manual.pdf Futaba GY240
- http://manuals.hobbico.com/fut/futm0807-manual.pdf Futaba GY401
- http://manuals.hobbico.com/fut/gy611-manual.pdf Futaba GY611
- http://www.heliguy.com/i/LTG-2100T.pdf Logitech 2100T
- http://www.jrradios.com/Products/Sup...rodID=JRPG500T JR G500
- http://www.jrradios.com/Products/Sup...odID=JRPG7000T JR G7000
- http://www.jrradios.com/Products/Sup...odID=JRPG7703D JR G770
- http://www.e-fliterc.com/Products/Su...odID=EFLRG90HL eFlight G90
- http://www.e-fliterc.com/Products/Su...dID=EFLRG110HL eFlight G110
- http://www.walkera.com/en1/productClass.jsp?proId=T All Walkera gyros

Here is a VERY insteresting if not educational article on gyros from RCHeli magazine.

Specific to the Logitech 2100t/Hitec HG5000:

When setting up the left and right throws, make sure that your endpoints/ATVs are set to their maximum values. That will tell the gyro your particular servos maximum travel. If the gyro doesn’t know the full extent of your travel to each side it will overshoot or bounce after piros.

If you are using an analog servo, using a longer servo arm/locating the link further out on the arm emulates having a much faster servo. If everything is setup correctly and you are still getting some bounce back or are getting less than stellar gyro performance, use a longer servo arm/locate the link further away from center. edit: If the servo you are using is a low resolution servo, a longer arm is NOT always a good idea. Placing the link too far out on the arm/using a longer arm can amplify a problem. This is the case with my tail servo

installation and Setup Guide (copied from a retailers website)

Logictech gyros have a slightly unusual setup which many pilots find confusing the first time or two, even if they have some heli experience under their belt. Here is an attempt to ease the job as well as make it successful, and less frustrating.

First off you will need to let the autoscan select the type of transmitter you are using. This step has always been a little awkward and confusing. If you have a helper to lend an extra pair of hands it does make it much easier. For those who don’t, you are already used to doing things the awkward way just so you can get the job done. This of course takes much more talent than with a helper.

1. Connect the gyro leads to their appropriate places depending on whether or not you choose to use a 6 or 7 channel receiver. Most of us use a micro 6 channel receiver with this setup, as your goal is to save weight. Be sure to change your gyro assigned channel to the gear channel so your TX can communicate with the gyro. In this case the single wire lead from the servo plugs into the gear channel on the Rx. If you are using a 7 channel receiver plug the single wire lead into the aux 2 port and make sure your gyro assigned channel is Aux 2. Also be sure your servo sub trim on the rudder channel is at zero and your end points are set at 140. Also check your servo trim center on the rudder channel (bar graph display) to make sure your digital trim is centered. Lastly change your gyro gain IN THE TX SO BOTH POSITIONS 0 & 1 are down somewhere around 30. The reason for this is to assure the gyro is set up in RATE mode. To verify this; make sure the little green light on the upper left corner is OFF. If its still on go back and recheck everything until it is off. These steps make life much easier throughout the setup process. Now using your extreme talent or your helper (tx power still on), hold the rudder stick either direction to full travel while plugging in the power to your esc/receiver. (You did remember to disconnect 2 out of 3 wires between your motor and speed control so your motor doesn’t run didn’t you?? “Saftey pumpkin safety” as Bill Envol would say!). Now hold it there until the lights on the display cycle through a few times and it locks on with a fast flash to one of the first 3 lights. It should match the brand of TX you are using. This is the most awkward step.

2. It gets easier from here. This step is very important if you are using another brand or non digital servo as failure to choose the correct type can result in destroying your servo. Ever other entry will be made with the battery already plugged in and using the menu select button and rudder stick. We now want to select the servo type and if you are using the matched 3100G it should already be defaulted at the first light, which is “dedicated (Logictech)”. When you press and hold the menu button down for 3-5 seconds you should see the first light come on. If it does you can proceed to the next step. If you are using any of the other servo types press the menu button while holding the rudder stick either left or right until you cycle the light to the corresponding light that matches your application. The light will move in whichever direction you hold the rudder stick. Stop when you have selected the appropriate light that closest matches the description of your servo.

3. In this step we will set the mechanical center of the servo and tail pitch slider on the tail output shaft. There are many theories on how to do this, however we will simplify the procedure until you actually test fly the heli and fine-tune it. If you followed the initial instructions above you can now install the servo arm. Choose the spline position that allows you to install the arm as close as 90 degrees to the servo case as possible. This way the arm can move equal amounts forward and backward. If it is off a slight amount don’t worry! Go to your sub trim on the rudder channel and use a SMALL amount to set it at 90 degrees. Don’t get carried away here as large amounts (20+) affect the gyro’s performance. If you are off a lot try a different arm or spline position. Ideally the ball should be attached about 3/8 to 1/2 inch out from the center of the output shaft. Now with that done we want to adjust the length of the pushrod until the tail pitch slider is close as possible to the center of the output shaft. You can do this by adjusting the ball links or sliding the servo mounts forward or rearward. I prefer this method, as I don’t have to worry about my ball links coming off the rod due to lack of threads holding them on. Now from the rear of your heli visually confirm there is equal space on both sides of the tail pitch slider. If not continue to adjust until there is. When you are satisfied we can move to the next step. Again this is a very basic-get you in the ballpark-setup. You still need to do a test hover in rate mode to finish the actual mechanical setup before you switch to head lock mode.

4. Press the menu button repeatedly until the light indicating the direction is lit. Verify the correct direction of the gyro’s operation by placing your finger between the tail case and the slider (left side of the slider) and quickly spin the heli counterclockwise. You should feel the gyro correct with a slight pressure against you finger. If not (if it moves away from your finger), you will need to change the direction of the gyro. Don’t use your rudder channel servo reverse in your radio. You need to do it here on the gyro in the direction position. The reason is you are changing which way the gyro senses, not the actual servo direction. We are almost done now!

5. Press the menu button repeatedly again until you see the servo limit light come on. Now SLOWLY move your rudder stick to the left until the pitch slider just touches the tail blade grip holder (moves RIGHT) and hold the rudder stick there while pressing the menu button. This sets the limit to the left. Now SLOWLY move the rudder stick to the right until the pitch slider just touches the tail case (LEFT movement) and hold it there and again press the menu button to set the right limit. Another step done.

6. This is the last step for setup then the fun (flying) can begin! What we are doing here is to set what they call the rotate rate. I find it to be more of a braking (stopping) speed. The higher the number on the led (again 1-8 on the top row of leds, with the right one being #8) the harder and faster it stops. You will want a higher number if you are a hard 3-D style flyer. If you are a new pilot or have a milder style of flying I would recommend you try a 5 or 6 led setting first and adjust your point to suit your style of flying later. Its quick and easy to change, just cycle the menu button until you light the rotate rate l.e.d lights in the menu, hold the button down while holding the rudder stick full over and repededly press the menu button to change the setting. If it doesn’t move hold the rudder stick over the opposite direction and press the menu button to move to the correct l.e.d. That’s it! Now you will need to do the required test hover to finish your mechanical setup (finalize step #3). When you get it to hold in rate mode with the nose into the wind with no or very little drift, go back into your gyro gain screen on you tx and change your rates into head lock which will be around 65-75 to start. You want this value as high as possible without getting wag (side to side osculation) when you hover or fly. If you have wag; decrease this amount until it just stops and try a test flight again. It shouldn’t take long to get it perfect and you can tweek it a bit later if need be. It’s that simple!

*As a side note a lot of people ask why the rudder servo moves to one side, does not return to center, or acts funky when they try to set up their gyro on the bench. The reason why is that your gyro is in head lock mode (little green l.e.d. on the upper left is on!) What is happening is not abnormal. You do not have a faulty gyro or servo. In fact it is just what you want it to do! What you are seeing is when you move the rudder stick to check your servo, the gyro in head hold mode senses it as a correction from you (TX), and will hold that position until the heli’s nose moves around to that that point. Since the heli is on the bench, obviously the nose can’t move to that point, so the servo holds that position waiting for the heli to move to that point it was commanded to go to. In the air the heli’s nose will go to where it’s sent because of the servo input and because the heli can yaw to that point. When it gets there the gyro releases the servo’s input and there you are. It holds until it gets another command even if the wind is trying to weathervane it to another position. That’s what head hold (lock) means. It holds until told to do differently.

2.4 ghz systems can cause tail drift/wag!
If not properly set up….

As you may or may not have noticed, when you power up the receiver(s) there is a brief period in which the system does not recognize or accept any input from the radio. The receiver(s) are going through their initialization routine(s). Depending on which receiver(s) you have this can last anywhere from 1 – 5 seconds. These receiver(s) automatically move the servos to their failsafe positions until they complete their initialization routine(s). Once completed, they then connect to the radio and accept any and all control input from the radio. If the gyro initializes before the receiver, the gyro is reading the rudder position, trim, and subtrim settings from the failsafe and not the radio, if the radio doesn’t match the failsafe, guess what? The gyro thinks you are giving input when you are not! This can and will lead to unwanted gyro behavior and eventually poor flight performance.


-Manually unplug the gyro from the receiver before powering up the receiver. Once the receiver is powered up and initialized, plug the gyro back in. This can prove a hassle.

-Add a power switch to toggle the gyro off and on independently of the rest of the system. This is easier to deal with than the previous option, but requires some creative wiring.

-Cycle the power switch once everything initializes and connects. HOWEVER this causes the blinking lights on the Spektrum brand receivers which many find annoying. Also these receivers use those lights as a way to communicate any errors to the user.

-Rebind after mechanically setting the gyro for NO drift in rate mode. Then anytime you power up make sure you do so in rate mode. Now the failsafe and radio match, so if the gyro initializes first it doesn’t matter. This is the best solution albeit the most involved.

Old 06-08-2008, 07:15 AM
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Default RE: Gyro / Wag / Tail / Rudder issue SOLUTIONS!!

Massive amount of information, should never have a gyro problem again.
Thanks very much !

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