Logictech 2100T Gyro and 3100G Servo

Installation and Setup Guide

Logictech gyros have a slightly unusual setup which many pilots find confusing, even if they have some heli experience under their belt. It is important to remember that to move the lights on the gyro to make your proper selection, you simply need to move the rudder stick in the direction you want the light to move and press the menu button once to move the light one position and so on.

First you will need to let the auto scan on the gyro select the type of transmitter you are using. This step has always been a little awkward, so if you have a helper it does make it much easier to complete the first step. I will be using a Spektrum DX-7 transmitter as an example. There are variations of course with different radios, but most are very similar. Some radios may require you to use the GEAR channel to control the gyro’s gain and to do this simply use the ATV’s (travel adjust).


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 gyro/ servo combo, as our goal is to save weight. In this case the single wire lead from the gyro plugs into the gear channel on the Rx. Your gyro needs to be assigned to the gear channel in the tx. If you are using a 7 channel receiver plug the single wire lead into the aux 2 port and assign the gyro to Aux 2 in the tx. Also be sure your servo sub trim on the rudder channel is at zero and your end points are set at 140-150. Check your servo trim center on the rudder channel (bar graph display) to make sure the trim is centered. Lastly change your gyro gain IN THE TX until 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 it’s still on go back and recheck everything until it is off. Now with the tx power on, hold the rudder stick either direction (I start with the stick to the right first) to full travel WHILE plugging in the power to your esc and 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. Some times the Spectrum receivers will flash as if they are not bound to the tx. This is normal and happens because you reset the power to the receiver without turning the tx off and then back on. To avoid this you can keep the receiver powered up and disconnect the rudder lead from the gyro to interrupt the gyros power. This is the most awkward step and the most critical as you cannot proceed until this step is done.

2. This step is very important if you are using another brand servo or NON digital servo because failure to choose the correct type can result in destroying the servo. From now on all adjustments to the gyro will be made with the battery plugged in and using the menu select button and rudder stick. We now will select the servo type and if you are using the matching 3100G the gyro 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 matches the description of your servo.


3. Step 3 sets the mechanical center of the servo and allows you to properly center the tail pitch slider on the tail output shaft by adjusting the length of the control rod. 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 tail boom as possible. This way the arm can move equal amounts forward and backward as required by the gyro without affecting its operation. If it is off a slight amount don’t worry! Do not use sub trim! Usually by trying different servo arms you can find one that aligns very closely. Ideally the ball should be attached about 3/8 to 1/2 inch out from the center of the output shaft. With that done adjust the length of the pushrod until the tail pitch slider is as close as possible to center on the output shaft. You can do this by adjusting the length of the pushrod 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. Looking 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 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. Follow the instructions in your helicopter and gyros manual to fine tune your particular setup.

4. I n this step we will verify that the gyro is sensing and making corrections to the tail servo properly. Press the menu button repeatedly until the direction light is lit. Verify the gyros correct 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. DO NOT use your servo reverse in your radio to do this. You need to do it here on the gyro. The reason is because you are changing which way the gyro senses, not the actual servo direction.


5. Setting the limits allows full travel both directions on your tail pitch slider. 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.

6. Now for the rotation 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.

7. The final step is to test fly your heli in rate mode as mentioned in step 3. When you are comfortable with the setup in rate mode, I suggest setting your gyro’s gain in both positions to around 65-70 to start. This will get you in the ballpark. If the tail is moving side to side then reduce the gain until the movement stops. If you experience the tail not holding solid then slightly increase the gain until the tail is solid. Then you can fine tune the gain to suit your flying style.

*As a side note a lot of people ask why the rudder servo moves to one side, does not return to center, or acts strange when they try to set up their gyro on the bench. The reason why is usually one of two things. Your gyro has not been set up yet or is in head lock mode (little green l.e.d. on the upper left is on!) What is happening is normal. You do not have a faulty gyro or servo. In fact it is just doing what you are telling it to do! When you move the rudder stick (or move your heli), the gyro (in head hold mode) senses it as a command from you (TX), and the servo/gyro 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. In the air the heli’s nose will pivot to where it’s sent because the heli is free to rotate. After the nose gets to that point the gyro releases the servo’s input and the servo returns to center until it’s given another command. Generally this happens many times per second . In head lock mode a gyro maintains its given command even if it has a severe crosswind acting against. That is where the term “head lock” comes from. Also the 3100G servo will not operate as a normal servo and move both directions when plugged into the rudder channel.

Rick Klages @Heliproz