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AS3X+ Nosewheel Setup Guide
This guide will provide an overview of the Nosewheel stabilization feature and how to set it up.
Supported Devices
Transmitters
Supported transmitters include the following
iX20 (with app version 1.10.11+)
iX14 (with app version 1.02.11+)
iX12 (with app versijon 1.20.11+)
All NX Radios (with firmware version 3.13+)
Gen 2 DX Radios (with firmware version 2.10+)
Receivers
Supported receivers include the following (with firmware 3.0.0+)
AR630
AR631
AS6420A
AR637T
AR637TA
AR8360T
AR10360T
AR20410T + Synapse
Nosewheel Parameter Overview
Nosewheel Channel
Description: Radio channel being used to steer the nosewheel. Must be setup as a Mix.
Values: Any channel not being used for any control surfaces, or Inhibit to disable
Notes:
This channel should not have a rudder output directly tied to it. It should be using a Mix with Rudder as the source. Otherwise the nosewheel channel will inherit the main systems yaw stabilization instead of having its own.
Retract Channel
Description: Radio channel used to control retracts. This channel determines when stabilization output on the nosewheel is disabled.
Values: Any channel not being used for any control surfaces, or Inhibit to disable
Notes:
When configured correctly in conjunction with “Retract Position”, nosewheel stabilization will be disabled when gear is retracted.
Retract Position
Description: This is a reverse option to tell the receiver whether the gear is Extended or Retracted based on the current Retract Channel position.
Values: Extended, Retracted
Notes:
Selecting this option will toggle between the Extended/Retracted option (this will not move your gear). The display should show the correct position as you cycle the retracts when correctly configured.
If no Retract Channel is assigned, this value will remain in the Extended position.
Extended Delay
Description: Delay in seconds for stabilization output to kick in when extending the gear. This value should approximately match the time it takes for gear to fully extend.
Values: 0 to 20 seconds
Reverse
Description: Reverse direction of stabilization response for nosegear
Values: Off, On
Gain Channel
Description: If desired, channel to scale configured Rate and Heading gains for nosewheel. Can be left inhibited to use set gains as is
Values: Any channel not being used for any control surfaces, or Inhibit to disable
Rate Gain
Description: Normal AS3X+ gain for nosewheel.
Values: 0% to 100%
Notes:
Response is based on models yaw rotation speed
Heading Gain
Description: Heading AS3X+ gain for nosewheel.
Values: 0% to 100%
Notes:
Response is based on models distance away from center.
Heading Window
Description: Travel window which stabilization is allowed to apply to nosewheel. This is a percentage of the full travel learned.
Values: 0% to 100%
Gain Sensitivity
Description: Multiplier for both rate and heading gain. Can be increased or reduced.
Values: 0.25x, 0.5x, 1x, 2x, 4x
Priority
Description: Determines the amount of priority the users stick input has vs the stabilization output.
Values: 0 to 200
Notes:
Higher values give the user priority much quicker (with less stick input) over the stabilization output.
For more details on Priority, see Priority section in AS3X+ Setup Guide
Nosewheel Radio Setup
This section will briefly go over setting up the nosewheel channel on the radio. A dedicated channel must be used that is separate from the Rudder.
Before starting note the following menu locations
iX Radio:
Model Setup menu is available on the bottom center area of the screen from the Dashboard
Model Adjust menu is available on the bottom left corner of the screen from the Dashboard
NX Radio:
Function List menu is available by pressing the scrollwheel while on the Dashboard
Determine the channel you will use to control the nosewheel. Go to iX: Model Setup > Channel Assign, NX: Function List > System Setup > Channel Assign
If intending to use a trimmer to center the nosewheel on the fly, assign the “Digital” option for that trimmer to the channel.
Test the trim output on the nosewheel. If the trimmer adjustment isn’t working in the desired direction, go to iX: Model Adjust > Servo Setup, NX: Function List > Servo Setup and reverse the selected nosewheel channel.
Otherwise, set to channel inhibited.
(Optional) From the Dashboard, go to iX: Model Adjust > Servo Setup > Names, NX: Function List > Servo Setup > Channel Name, change the assigned nosewheel channel name to “NSW” (short)/”Nosewheel” (Long) or whatever combination makes sense to more easily identify what this channel was setup for in the future, particularly the channel monitor.
From the Dashboard, go to iX: Model Adjust > Mixing, NX: Function List, > Mixing
Select an empty mix and choose the Normal option.
Set the mix as RUD > “Nosewheel Channel” (“Nosewheel Channel” = Channel selected in step 2).
Scroll down to the Switch section.
If retracts are used assign your retract switch.
Otherwise, set the switch option to On.
While the retract switch is set to extended (if retracts are used), set the Rate on both ends to 100% or -100% (whichever gets the nosewheel moving in the correct direction with rudder stick input).
If the travel rate is more or less than desired, it is recommended to adjust the travel range in the iX: Model Adjust > Servo Setup > Travel, NX: Function List > Servo Setup > Travel section
Nosewheel should move with rudder input when the gear switch is in extended position. It should stop moving when the gear is in the retracted position.
Before setting up stabilization, test taxiing the model (ideally without wind. If there's wind, it shouldn’t be a crosswind).
Apply any trim necessary to get it running in a straight line as much as possible (either with the assigned trimmer, or by adjusting subtrim in iX: Model Adjust > Servo Setup > Sub Trim, NX: Function List > Servo Setup > Sub Trim).
Nosewheel Stabilization Initial Setup
This section will go over the stabilization setup for the nosewheel. It assumes the nosewheel has already been setup on the radio using a mix tied to the rudder channel, and First Time Setup for stabilization has already been done on the receiver.
With the receiver on and bound, enter Forward Programming.
In forward programming, go to Gyro Settings > Nosewheel.
Assign the channel being used to steer the nosewheel to Nosewheel Channel.
If retracts are used, or you don’t have retracts but want to assign a channel to enable/disable nosewheel stabilization.
Assign the retract or enable/disable channel to Retract Channel
If the position indicated in Retract Position is incorrect, select the option to toggle reversing it.
For just Enable/Disable purposes, Retracted = Disabled and Extended = Enabled
Set Extended Delay to a value that matches or is slightly above the amount of time (in seconds) that it takes the gear to extend from the retracted state. Leave at 0 if no retracts are used.
Select the Learn Travel option
Make sure the nosewheel is active and at its maximum possible movement rates (if they’re adjustable).
Move the rudder input to both ends to teach the receiver the nosewheel channels travel range.
Select Apply
Go to the next page and set the Heading Gain to 10%.
If a flight mode channel is assigned in the receiver, make sure you are in a flight mode that has AS3X set to Act in the F-Mode Setup. Otherwise, the nosewheel stabilization will be disabled.
Turn the model side to side and make sure the wheel steers in the opposite direction. If it doesn't, go to the previous page and set the Reverse option to On.
This completes the initial nosewheel setup. Tuning will be covered in the next section.
Nosewheel Stabilization Tuning
In this section, we will cover adjusting gains to get proper nosewheel stabilization.
If a flight mode channel is assigned in the receiver, make sure you are in a flight mode that has AS3X set to Act in the F-Mode Setup. Otherwise, the nosewheel stabilization will be disabled.
Go to Forward Programming > Gyro Settings > Nosewheel, followed by going to the next page.
With the model on its gear, lift the nose slightly so the model sits on the main gear.
Pivot the model on its main gear side to side and observe the correction. At a minimum, the nosewheel should point in the same direction (parallel to its starting point) as the model is rotated.
If the nosewheel doesn’t compensate enough to maintain a parallel heading angle, increase Heading Gain until it maintains parallel heading throughout the model movements. If you reach 50% gain and still can’t achieve this, increase the heading multiplier one step.
If the nosewheel over compensates to maintain a parallel heading angle, decrease Heading Gain until it maintains parallel heading throughout the model movements. If you reach 10% gain and still can’t achieve this, decrease the heading multiplier one step.
Once the appropriate Heading Gain is found, set the Rate Gain to the same value.
Exit forward programming and try taxiing the model down a runway in both directions. If performance seems good, increase speed little by little without taking off, and review step 7 if bad behaviors start to happen.
Try the following changes based on observed behaviors.
If the model seems to drift towards the same side of the runway, try increasing Heading Gain by 5% increments until its corrected. Adjust Rate Gain ratio as indicated in step 5.
If the model seems to drift to the same direction relative to itself (regardless of runway direction), make sure the nosewheel is sub trimmed properly. This should be done with Rate Gain and Heading Gain set to 0 (or setting the model to a flight mode with AS3X set to Inh).
If the model seems to do a back and forth oscillation (wide turns), try increasing the Rate Gain by 5% increments. If necessary, increase the Gain Sensitivity and make sure to half the heading gain to compensate.
If the model seems to do a back and forth oscillation (small tight turns), try reducing the Rate Gain by 5 % increments.