Introduction

The INAV Fixed Wing Group produced a model for most transmitters running OpenTX. The aim of the standard INAV FWG OpenTX model was to get new people up in the air quicker. This Lite OpenTX model has been made for the smaller FrSky X-Lite transmitters. OpenTX is a very powerful operating system, so it’s well worth learning and checking out what else it can do.

Download the Lite Model Here

Click the link below to download the latest version of the INAV Fixed Wing Group Lite OpenTX model pack

Download the Lite OpenTX Model

If you have a regular sized transmitter, you should check out our Standard OpenTX model.

Transmitters and Versions

These models were built using OpenTX Companion 2.3.10. However, due to the functionality in the models; it should work fine in older and newer versions too.

Supported Transmitters

  • FrSky X-Lite, S, and Pro
  • FrSky X9 Lite and S
  • RadioMaster TX12 *Requires OpenTX 2.3.11 and above

You will find an appropriately named model in the zip file for your transmitter.

ExpressLRS

Due to the limitations of ExpressLRS, this model will not work over the protocol. If in the future they implement free use of channels, this will change.

Features

Due to the limited number of switches on the X-Lite, we have had to compromise the features that are available. However, we have included enough to get you started and progress onwards. Some features are only available on the X-Lite S and X-Lite Pro.

We have tried to cater for all pilots. So, while there may be flight modes that you personally wouldn’t use, others may find them invaluable. We all fly differently, some are in it for speed, others distance, others like to just get up in the sky, relax, and enjoy the view. So with these models, we hope to be able to cover all bases and include as many people as possible.

Switch Layout

FrSky X-Lite, S, and Pro

The layout above is using an X-Lite Pro. Please note that the two momentary switches are not available on the original X-Lite.

INAV Fixed Wing Group - Lite OpenTX model - RadioMaster TX12 switch layout

Arming is different on this model. To arm, hold down switch SA for at least 1 second. To disarm, click and immediately release the same switch.

Arming

On the FrSky models, the arming uses a switch. The arming switch can easily be reversed in the Lite OpenTX model (documented below). It is also on it’s own channel, so you to change flight modes on the bench.

On the RadioMaster TX12 model, arming is via the momentary switch SA. Hold the switch down for at least 1 second and the model will arm. It will give warnings if it can’t. To disarm, just click switch SA for a moment. It needs to be released in less than 1 second. Don’t panic, a standard push and release is absolutely fine.

Flight and Navigation Modes

You find the flight and navigation modes on switches SA and SB (SB and SC for the RadioMaster TX12). Unlike our other transmitter models, there is no predefined mode order with this setup. This is because it is impossible to select more than one mode at a time. However, the modes are accessed using a combination of the two switches.

Switch SA (SB TX12) is used to move between 3 sets of flight modes. The modes within the sets are changed with switch SB (SC TX12).

Mode set 1 (SA away from you, SB for TX12)

The first mode set contains the majority of the base flight modes. Move SB (SC TX12) to choose between Manual, Acro, and Horizon.

Mode set 2 (SA in the middle, SB for TX12)

The second set of modes has some basic navigation options. Move SB (SC TX12) to choose between Angle, 3D Cruise, and Loiter (Position Hold). It is recommended to be in 3D Cruise before progressing in to set 3, unless performing a Return To Home.

Mode set 3 (SA towards you, SB for TX12)

The Third mode set contains the automated navigation modes. Move SB (SC TX12) to choose between Return To Home, 3D Cruise, and Waypoint Missions.

All flight modes have voice confirmation. Return to home can be quickly accessed by flicking both mode switches towards you.

Multi-function Momentary switch (Not X-Lite standard)

With the Lite OpenTX model, you can use the momentary switch SF, SH, or SD, depending on your transmitter, as a shortcut to perform functions. Firstly, hold the switch in and you will hear options. Then, release the switch on the option you want to use. The beep at the end signifies that no option will be performed.

  • Reset the flight timer
  • Save the current configuration *
  • Enter the INAV OSD menu*
  • Load Waypoint Mission *

* Requires you to be disarmed

OSDs

The OSD selector is on the S1 pot (S2 slider for TX12). You now have access to 5 different OSD options: default, alt 1, alt 2, alt 3, and off. INAV will select the default OSD automatically during failsafe.

Tuning

You can select servo autotrim and auto tune via the S2 pot (X-Lite), switch SC (X9 Lite), or switch SF (TX12) . A voice confirmation will let you which mode has been selected. There is reminder beep while you are in servo autotrim or auto tune. Also, there is a mechanism that won’t let you arm in either servo autotrim or auto tune modes. There is also a reminder to save the settings after using auto tune. Due to the ease of movement of the X-Lite pots; there is a large central off area, to try to avoid accidental activation on these transmitters.

Arming Warning System

A feature we have added is a smart arming system. It will not let you arm the model if the throttle is not low or you are in a tuning mode. The system will also give you voice feedback on any actions that need to be taken. It will also tell you that the system is armed or disarmed.

Flight Timer

We have incorporated a flight timer on the model. It will start the timer once the you arm and raise the throttle. It will continue until you disarm. To reset the timer, hold the multifunction momentary switch until the reset timer prompt, then let go.

Installing on the Transmitter

If you would prefer to watch a video for the installation, you can find one here.

Getting Everything Ready

Before we start, let’s make sure that we have everything we need to get you up and running. If you have installed this Lite OpenTX model before. Please check the change log at the bottom of this document.

OpenTX Companion

The first thing you will need to download and install is OpenTX Companion. This is the software which lets you backup, update, and modify your Transmitter. You may already have this installed because its very useful. But if not, head over to https://www.open-tx.org/downloads.html where they have the latest version of Companion.

OpenTX Companion download page

At the top of the page, OpenTX shows the latest stable releases or branches. When we took this screen grab, OpenTX 2.2.3 (2019-01-06) was the latest release; as illustrated with the highlight. Click on the latest branch. The next page has release notes and also any warnings for the release. They are well worth reading. However, the part we are looking for is at the very bottom of the page. There are download links for the SD Card contents and what we’re looking for this time, OpenTX Companion. Download and install the correct version for your computer.

Please follow OpenTX’s guide to install and configure OpenTX Companion. The most important part is to select the correct transmitter and settings you need for the firmware downloads.

INAV Configurator

You will need to download and install the latest version of the INAV Configurator. You can find this at https://github.com/iNavFlight/inav-configurator/releases. The latest version will conveniently be at the top of the page.

INAV Configurator download page

Click on the current release, for example INAV Configurator 2.1.4 here. Then scroll down to find the installation files. Download and install the correct version for your computer.

INAV Fixed Wing Group Lite OpenTX Model

You will need to download the model files from our web site.

OpenTX Options – Global Variables

For this setup to work, an option in OpenTX needs to be present. This is easy thing to check for. Its also easy to fix with a firmware update, if it’s not active. This feature should already be active, but we can check on the Transmitter it’s self before we go any further.

On your X-Lite, long press the menu button (right arrow) to go to the model select screen. From here press the right arrow button until you reach the Flight Modes page. Press the enter button to edit the flight default mode FM0, then scroll down, where you should see a list of Global Variables.

If these variables are present, then you should all set and you can continue with the installation. If not, we need to enable the Global Variables by downloading firmware and installing it on the transmitter. There is an appendix at the end of the document showing this process. So, click here to jump to it.

Installing the Lite OpenTX Model on Your Transmitter

Connecting to the Transmitter

To install the files on to your transmitter, you will need the appropriate USB cable to link the transmitter to the computer. Firstly, hold the roll and yaw trims towards the power button and switch the transmitter on. The screen should show the OTX Bootloader. You do not need to select any of the options on the screen. So, plug in the USB cable to the transmitter and the computer.

Installing the Sound Pack

Example of the files on an OpenTX SD Card

Open your system’s file manager, for example Windows Explorer or macOS Finder. You will see two external devices for the Transmitter. One device will have the name of the transmitter, for example Taranis. The other may have the name USB Drive, and will look just like an external drive.

We will be working on the “USB Drive” external disk. If you open it you will see the folders on the transmitter’s SD card. For example, it should look similar to the image shown on the right. Then, enter the SOUNDS folder, you will see folders for the installed languages on your transmitter.

Next, go to the place where you extracted the INAV Fixed Wing Group – OpenTX Lite Model Pack. Find the IFWG OpenTX Sound Pack – Vx.xx zip file. Then extract this file and go in to the IFWG OpenTX Sound Pack Vx.xx folder. Inside there are folders for different languages packs. In the beginning there will only English (en), but we hope to add more as time goes on. Select the folder of the language that you would like to use and drag that folder into the SOUNDS folder on the SD card. This will then copy the new sounds file to your transmitter. This will not overwrite any existing sound files you may have; for example amber will be safe.

Installing the Model

Backup Radio to File

Open OpenTX Companion. Firstly, make a backup of your current models and settings. To do this click the Backup Radio button on the left side menu, then save the file on your computer.

Next we will access the models that are already on your transmitter. To do this click the Read Models and Settings From Radio button, also on the left side menu. This will open a window containing all your transmitter’s models. You can easily edit models here by double clicking on the model name. The page sequence is basically the same as if you were editing directly on the transmitter.

Read Models and Settings From Radio

Now use the File menu and click the Open… option. Find the models that you downloaded from the INAV Fixed Wing Group. Then load the model that you wish to use into OpenTX Companion.

Now we have a choice where we can create a new model on the transmitter, or overwrite an existing model. To create a new mode, click and hold on the model, drag it to an empty space in your model list, then release. This will copy the model to your transmitters’ list.

Copying a model in OpenTX Companion

To replace an existing model, we add an extra step which should save to from having to rebind to your receiver. Firstly, double click on the model that you would like to replace; this will open the Editing Mode window. There is a section on this page showing the details of your radio setup.

OpenTX Companion - Radio selection

What we need to do is take a note of the settings used by the radio, in particular the receiver number. Next click and hold on the model, drag it over the model you want to replace, then let go. OpenTX Companion will ask you if you want to replace an existing model. Click yes. Double click on the model again, only this time you will be setting the radio settings back, based on the notes you previously took. This should mean that you will not need to rebind the model to your transmitter.

After either of these methods, you can now double click on the model and rename it to something meaningful to you. Finally, upload the models back on to your transmitter. Click the Write Models and Settings To Radio button, this will pop up a dialogue box, where you would then click Write to TX.

Once the writing has completed, you can unplug the USB cable and switch off your transmitter. The next time you power it on, the model will be ready for you to use.

You will need to edit the model to set up your receiver settings. By default, the Standard version is configured to use a D16 type receiver (which includes X4R, R-XSR, S6R, etc). It is set to 8 channels, to keep the transmissions in a single frame. The Pan and Tilt version is also set to D16 type receivers; but has been set to use 12 channels, which is the maximum for the L9R. The failsafe has already been set to No Pulses, which is the recommended setting for INAV. You will need to bind with your model’s receiver. 

If using the R9 system or Crossfire, you will need to disable the internal module and setup your external module. Don’t forget to set the R9 failsafe to Hold or No Pulses or the Crossfire failsafe to Cut.

Reversing the arm switch

To reverse the arm switch, on the transmitter, enter the model menu. Page through until you reach INPUTS. Find input 5, Arm. Then long press the enter button and choose Edit. Find the Weight and reverse it. For example 100 would become -100. Exit out of the edit screen back to inputs. Then long press the page button to go backwards through the menu, until you reach the setup page. Scroll down until you find the switch warnings. Reverse the position of the switch warning for switch SC. Exit, and you’re done.

Setting up INAV

The final stage is to set up the modes in INAV. Connect your model via USB and open INAV Configurator. Click the Connect button and go to the bottom option in the menu on the left, CLI. You simply need to copy and paste the code below in to the CLI and press enter. INAV Configurator will save and reboot and you should be good to go. Please not that this is only going to set up the flight modes and enabled the default OSD on Failsafe, you should set everything else up before doing this step.

CLI commands

set osd_failsafe_switch_layout = ON
aux 0 0 0 900 1300
aux 1 1 1 1575 1675
aux 2 2 1 1950 2050
aux 3 3 1 1450 1550
aux 4 3 1 1200 1300
aux 5 11 1 1325 1425
aux 6 10 1 900 1050
aux 7 28 1 1075 1175
aux 8 45 1 1450 1550
aux 9 45 1 1200 1300
aux 10 12 1 1700 1800
aux 11 37 2 900 1300
aux 12 21 2 1700 2100
aux 13 19 3 1800 2100
aux 14 42 3 1200 1400
aux 15 43 3 1400 1600
aux 16 44 3 1600 1800
aux 17 0 0 900 900
aux 18 0 0 900 900
aux 19 0 0 900 900

save

Flight Modes Layout

Once rebooted, your flight modes should look like the graphic below. Unused modes have been graphically removed; but the order is the same.

The setup of the flight modes, and model installation is now complete. You will still need to set up the rest of INAV correctly before flying your model.

Autolaunch

Unfortunately, the FrSky X-Lite is at the limits of the available switches. So if you would like to use autolaunch, we recommend permanently enabling it. It can be disabled by by moving the pitch or roll after arming.

Updating the Firmware to Enable Global Variables

Switch off your transmitter, then hold the yaw and roll trims toward the power button, then switch on the power. The OTX Bootloader menu should now be on the screen. Now take a USB cable and plug the transmitter in to your computer.

Launch OpenTX Companion. The first thing we should do is take a backup of your transmitter, just in case anything goes wrong. Click on the Backup Radio to File button, and save the transmitters data somewhere safe on your computer.

Once that is complete, click on the Read Models and Settings From Radio button in the left side menu. A list of the models on your transmitter will appear, but it will also copy the settings over.

OpenTX Companion settings

Now click on the Settings gear button in the top menu. A window which allows you to choose which optional features are on your transmitter will appear. The feature we are looking for is nogvars. We must make sure that this box is unchecked. Below is an image showing how the highlighted nogvars option should look. Please note that my Radio Type is a FrSky Taranis X9D+, you should have your correct radio type here.

OpenTX Companion - Make sure that nogvars is not enabled

Next, we need to download the OpenTX firmware.

OpenTX Companion - Download firmware

Click on the Download button, then choose Download Firmware. Save the file on your computer; perhaps in an OpenTX firmware folder so that you can find it later.

Once the download is complete; you will be get a question asking if you would like to install the firmware now. Choose yes, and Companion will show another confirmation box, where you can also change your start screen. Click Write to TX and the update will start.

OpenTX Companion - Write the firmware now?
OpenTX Companion - Flash firmware

Once the update has completed, unplug the USB cable, and switch of the transmitter. When you switch the
transmitter back on, you should now be able to find the Global Variables page in the menu. To jump back to
the main document, click here.

Making changes for iNav 3.0

iNav 3.0 has brought it some big changes. Quite a few of them will make setting up and tuning your plane much easier, and give better results. Though there have been some major changes, fortunately, you don’t need to make many changes to your Lite Model to get it working nicely with iNav 3.0. Also, you’ll only need to make these changes if you’re using Lite Model version 1.01 or below. Newer versions will will already have these changes implemented, to just use the iNav 3.0 CLI in the CLI section above, which will appear with Lite Model 1.02.

What changes are we making?

  • The new auto trim feature will be permanently enabled. So, the Servo Autotrim switch will now be the switch for the new Auto Level mode. This automatically tunes the board pitch alignment.
  • Trims on the transmitter will be zeroed and disabled on all flight modes, except for manual. So if you are an RC pilot who prefers to manually trim the plane, this will no longer effect stabilised flight modes. You should of course still land, mechanically adjust the control rods, and zero the transmitter trims in manual. As this will interfere with the new auto trim feature.

Making the updates

The first thing to do is download and install the new Transmitter Sound Pack.

Head in to the modes tab and find the SERVO AUTOTRIM mode. Near to that, you should see the AUTO LEVEL mode.

Create the same range with the same channel as SERVO AUTOTRIM on the AUTO LEVEL mode. Then delete the SERVO AUTOTRIM range.

I am describing these changes in OpenTX Companion. The process on the transmitter will be different, depending on the transmitter model.

  • Go to the Special Functions and find SF35. Change the sound file to ifatlv.
  • Find SF49 and SF51, and change the sound file to ifcrus.
  • Go to Flight Modes.
  • Go to Flight Mode 0 (default) and change the name to Manual.
  • Click the Flight Mode 1 tab. Set the name to Stabilised and the switch to !L56.
  • For Flight Mode 1 (Stabilised), set the trims for Thr, Rud, Ele, and Ail to Trim disabled.
  • For Flight Mode 0 (Manual), the trims for Thr, Rud, Ele, and Ail should be set to Own Trim.

The CLI changes will permanently enable the auto trim feature.

# Features
feature FW_AUTOTRIM

save

That’s it. You’re ready to use iNav 3.0.

Customising this model

If you are looking to customise this model, this page may help you.

Change log

v1.01

10th February 2021

  • Added support for the RadioMaster TX12
  • Changed the names of the model to include the version number
  • Tidied up the user manual

v1.00

20th December 2020

  • Initial release